Open Access

Elsholtzia: phytochemistry and biological activities

  • Zhiqin Guo1,
  • Zizhen Liu1,
  • Xiaohong Wang1,
  • Weirui Liu1,
  • Rui Jiang1,
  • Ruiyang Cheng1 and
  • Gaimei She1Email author
Chemistry Central Journal20126:147

DOI: 10.1186/1752-153X-6-147

Received: 8 September 2012

Accepted: 8 November 2012

Published: 5 December 2012

Abstract

Plants of the genus Elsholtzia (Lamiaceae) have a long history of medicinal use in folk. The phytochemical investigations revealed the presence of flavonoids, phenylpropanoids, terpenoids, and other compounds. Abundant volatile components are also identified. Pure compounds, volatile constituents and crude extracts from the genus exhibited a wide spectrum of in vitro and in vivo pharmacological activities. The aims of this review hopefully provide comprehensive information on the distribution, phytochemistry, volatile components, and pharmacological research of Elsholtzia for exploring the potential and advance researches.

Review

Background

Elsholtzia is a genus containing at least 33 species in the family Lamiaceae. They have been widely distributed and applied in East Asia, Africa, North America, and European countries for centuries. The genus Elsholtzia plants are mostly aromatic plants, always used as domestic folk medicine, herbal tea, food, spices, beverages, perfumeries, cosmetics, aromatherapies, and the source of honey manufacture.

As folk medicine, the plants in the genus have been used for the treatment of colds, headaches, pharyngitis, fever, diarrhea, digestion disorder, rheumatic arthritis, nephritises, and nyctalopia in China [13]. Another important application of the plants is to repair soil that is contaminated by heavy metals. A growing number of research works are focusing on the function of the genus for repairing soil. The most known one is from E. splendens (E. haichowensis), which is a Cu-accumulator plant widely distributed in Cu-mining wastes and Cu-contaminated soil in China [47].

The paper intends to provide a significant insight into the distribution, phytochemical and pharmacological investigations and hopefully to provide preliminary data for further study and development of the clinical uses of the genus.

Distribution

The genus Elsholtzia (Lamiaceae) was widely found in East Asia, Africa, North America, and Europe, especially in China, Korea, Japan, and India. So far, it is reported that at least 33 species plants of the genus are distributed in China [1, 2]. And most of Elsholtzia live at an altitude of 1000 to 3000 meters. E. splendens survives at altitude from 200 to 300 meters. E. cephalantha, E. strobilifera and E. eriostachya grow in high altitude of 3000 to 4000 meters.

Elsholtzia generally exists at hilly grasslands, waste areas, forests, thickets, or valleys in warm area. E. saxatilis, named ‘Yansheng Xiangru’ in Chinese, grows in rocky crevices. And E. saxatilis is different from other plants of Elsholtzia, being distributed in the northeast of Asia, such as northeast of China, Korea, Russia, and Japan, where are cold compared with in South Asia. So far, E. communis and E. argyi have been cultivated in Yunnan province (China) and Vietnam. Except for the two mentioned species, most other plants in the genus are wild [13]. The distribution of all 33 species of Elsholtzia is shown in Additional file 1: Table S1.

Chemical constituents

Previous phytochemical investigations showed that flavonoids are major ingredients in Elsholtzia. They are characterized by the presence of the substitutional groups and modes, as well as their glycosides. Phenylpropanoids, terpenoids, phytosterols, and cyanogenic glycosides are also main chemical constituents in this genus. In this section, we summarize and classify all reported constituents from Elsholtzia. Compounds 1144 and the corresponding plant sources are list in Additional file 2: Table S2 and the structures 1132 are showed in Additional file 3: Figure S1.

C6-C3 constituents

Up to now, there are 68 C6-C3-C6 compounds isolated and reported from Elsholtzia, including flavonoids and their glycosides. Its number and content are the most in all secondary metabolites derived from the genus.

Firstly, compounds 1 30 are flavones, in which several hydroxyls, methoxyls and glycosyl groups are linked to the mother nucleus. The oxygenic function groups are most commonly attached to the C-5 and C-7 positions in the flavones. A small amount of 5, 6-dihydroxy-7, 8-dimethoxy flavone (2) from E. splendens was obtained by preparative TLC, which is the second report except its first isolation from the roots of Scutellaria ramosissima[8]. Luteolin 7-O-[6"-(3"'-hydroxy-4"'-methoxy cinnamoyl)]-β-D-glucopyranoside (28) and luteolin 7-O-(6"-feruloyl)-β-D-glucopyranoside (29) are very semblable in structure. The difference is that the glucose moiety C-6 position is attached to a 3"'-hydroxy-4"'-methoxy cinnamoyl in 28, while a 6"-feruloyl in 29. 28 was isolated from the whole plants of E. bodinieri as a new compound [9]. Secondly, 14 flavonols, 31 44, were isolated from the genus. A number of free hydroxys are attached to the C-3 positions in 32 34. Compounds 35 44 are 3-O-flavonol glycosides, linked with diverse glycosyl groups, i.e. glucopyranosyl, galactosyl or rhamnopyranosyl. Also, four prenyl-flavonoids (45 48) occur in E. rugulosa and E. stauntonii, among which 5, 7, 3', 4'-tetrahydroxy-5'-C-prenylflavone 7-O-β-D-glucoside (46) and muxiangrine III (47) were reported as new compounds [1013]. 3"-Hydroxy-4", 5"-dimethoxyfuranoflavone (49) and 3", 4", 5"-trimethoxyfuranoflavone (50) are furanoflavone. They possess the characteristic of an unsaturated oxygen-containing furanyl fused into the ring-A's C-6 and C-7 positions. They are the two unique furanoflavones discovered in the genus so far [14]. Structurally compounds 51 55 are all characterized by a gem-dimethylchromene moiety and one hydroxyl attached to C-3' and C-4' of ring-B. Muxiangrine I (51) and muxiangrine II (52) were isolated from E. stauntonii[11, 12]. Compounds 53 55, named sifanghaoines I–III, were new compounds from E. blanda respectively [15, 16]. 5'-Dihydroxy-7-acetoxyl-6,8,3",3"-tetramethylpyran-(3',4')flavone (53) and 5,5'-dihydroxy-7- (α-methy1) butyroxyl-6,8,3",3"-tetramethylpyran-(3', 4')flavone (54) are structurally similar. The distinguishment is that 53 is linked by an acetate group at C-7 position, while 54 is linked by a (α-methyl) butyroxyl moiety. A methylenedioxy is substituted C-6 and C-7 positions in 5,5'-dihydroxy-6,7-methylenedioxy-8,3",3"-trimethylpyran-(3',4')flavone (55). The same substituent ion also occurs in 47.

Furthermore, eight flavanones (56 63) and one flavanonol (64) are listed in Additional file 2: Table S2. Compounds 58 62 glycosylated at C-7 position, are mainly existed in E. bodinieri[17, 18]. Eriodictyol 7-O-(6"-feruloyl)-β-D-glucopyranoside (59) and eriodictyol 7-O-[6"-(3"'-hydroxy-4"'-methoxy cinnamoyl)]-β-D-glucopyranoside (60) were isolated from E. bodinieri as new flavanone glycosides [17]. The feruloyl is attached to the glucosyl C-6" position in compound 59. Compound 60 is an isomer of 59, with -OCH3 and -OH groups at the C-3"' and C-4"' positions in the 3,4-substituted coumaroyl unit. The substituent positions of -OCH3 and -OH groups are opposite of 59. The distinguishment in 59 and 60 is the same as that in 28 and 29. They were all obtained from the plants E. bodinieri[17]. It is worth noting that one -O-CH2-O- group is connected with C-6 and C-7 of ring-A to get a furyl-ring in compound 63.

Additionally, iso-formononetin-4'-O-β-D-glucopyranoside (65), amentoflavone (66), (+)-catechin (67), and (−)-epicatechin (68) were also isolated from Elsholtzia[11, 1922].

Compounds 69 73 are linear furanocoumarins, in which 70 73 were found in E. densa as new furanocoumarins [11, 14, 23]. 69 72 exhibit a prenyl group or prenyl derivative in the C-5 position and a methoxy group in the C-8 position.

Only three lignanolides were reported in the genus. They are 3-hydroxyarctiin (75) and arctigenin (76) from E. eriostachya, together with saussurenoside (77) in E. ianthina[24, 25].

Terpenoids

Triterpenoids are other major constituents in this genus. The oleanane-type triterpenes (82 89) were mainly isolated from the aerial part of E. bodinieri[2629]. The glycosyl is linked to the C-28 (−COO-) of 23-hydroxyechinocystic acid by ester-bond in compounds 87 89. The C-3 position is attached a caffeoyl in compound 87, and linked to an arabinosyl in 88 and 89, respectively. Three ursane-type triterpenes including ursolic acid (90), corosolic acid (91) and 2α,3β,19α-trihydroxyurs-12-en-28-oic acid (92), are obtained from E. rugulosa, E. ciliata and E. bodinieri[17, 3032].

Two unusal 18,19-secoursane glycopyranosides, bodiniosides A (93) and B (94), were isolated from the whole plant of E. bodinier[17, 27]. It was the first report that E-secoursane glycosides occurred in the Lamiaceae family. In addition, 2,3,19-trihydroxy urs-12-en-28-oic acid (92) and hypadienic acid (95) were also simultaneously obtained from the E. bodinier. Compounds 93 95 could be derived from 92 in the biogenetic relationships [17].

Compounds 98 102, five diterpenoids, were isolated from E. bodinier[21, 27, 33, 34]. Ludongnin 5 (98), a tetracyclic kaurane diterpenoid, is connected a γ-lactonic at the C6-C19 positions. 98 also has significant and extensive antibacterial effect [34, 35]. Sandaracopimar-15-en-8β,12β-diol (99), a tricyclic pimarane diterpenoid, was isolated from Elsholtzia for the first time [21]. An abietane-type diterpenoid, (+)-hinokiol (100), is a minor diterpenoid occurring in plants. Its consuming inhibitive and deactive effects against Staphylococcus aureus, Streptococcus, Escherichia coli, and Pseudomonas aeruginosa attract the researchers [33]. It is the infrequence O-H…π stacking that was found in the packing of the crystal structure of 100 except for the existence of hydrogen bonding, when its molecular configuration and conformation were characterized by X-ray diffraction analysis [36]. Two hardwickiic acid glycopyranosides, 6-hydroxy-(−)-hardwickiic acid 2'-O-β-D-glucopyranosylbenzyl ester (101) and 6,7-dihydroxy-(−)-hardwickiic acid 2'-O-β-D-glucopyranosylbenzyl ester (102) were firstly reported in E. bodinieri as two novel clerodane diterpenoids [27].

Three eudesmane-type sesquiterpene glycopyranosides, dictamnoside G (103), 3β,5α,11,12,13-pentahydroxy-eudesm-4(15)-ene 3-O-β-D-apiofuranosyl-(1–4)-α-L-rhamnopyranosyl- (1–3)-β-D-glycopyranoside (104) and integrifoside A (105) were obtained from the root bark of E. bodinieri[37].

So far, only one monoterpenoid, 2,6-dimethyl-8-hydroxyl-2,6-octadienic acid-8-O-β-D-glucoside (106), was obtained from E. bodinieri as a new one [18].

Others

Up to now, only three compounds (107 109) containing nitrogen atoms were reported from the genus, all from E. rugulosa. Prunasin (107) and amygdalin (108) are cyanogenic glycosides [30, 38, 39]. This was the second report of cyanogenic glycosides in Lamiaceae plants. The first case was from an Australian plant Clerodendrum grayi. Since Armeniacae semen (apricot kernel) containing these compounds, it has been used for cough remedies in Europe and China. The result chemically supported the use of E. rugulosa for the treatment of colds and coughs in China. Three maltol glycosides, maltol 3-O-β-D-glucopyranoside (110), maltol 6'-O-β-D-apiofuranosyl-β-D-glucopyranoside (111) and maltol 6'-O-(5-O-p-coumaroyl)-β-D-apiofuranosyl-β-D-glucopyranoside (112) were isolated from E. rugulosa[38]. Here, 112 linked with a cinnamoyl can also be classified in the C6-C3 group. Besides, four phytosterols, 113 116, were reported from the genus [11, 2022, 2527, 3032, 39, 40], and a stilbene's hydroxylated derivative, trans-3,4,3',5'-tetrahydroxy-4-methyl-stilbene 4-O-β-D-xylopyranosyl-(1→6)-β-D-glucopyranoside (130), was isolated from the root bark of E. bodinieri, as a new compound [33].

Volatile chemical constituents

The plants Elsholtzia are aromatic herbs in general, as they possess plentiful volatile oils. The oils have been developed and utilized as medicines, food and the source of honey manufacture [1]. Many phytochemistry and pharmacology scientists are interested in the volatile constituents and its biological activities. The latest paper reported that the volatile constituents exert strong inhibition against central nervous system and take on considerate analgesic effect [41]. It also shows antibacterial effects [4244].

A total of 572 volatile constituents were identified from the 21 species of Elsholtzia by hydro-distillation and gas chromatographic-mass spectrometry (GC-MS). Among them, α-pinene, β-pinene, acetophenone, caryophylene oxide, carvacrol, benzaldehyde, β-caryophyllene, 1,8-cineole, α-phellandrene, and α-terpineol widely exist. Especially, α-pinene and β-pinene are most significant two, which were detected and identified in 15 species in the genus [4566]. Acetophenone, caryophylene oxide, carvacrol, benzaldehyde, β-caryophyllene, α-phellandrene, and α-terpineol are also major examples. It is a remarkable matter that the plant source, growing environment, harvesting time, extraction methods, and analysis methods of the study plants play important impact on the sorts and contents of some volatile components [45, 6770]. For instance, the content of α-pinene in E. blanda was up to 4.84% in Yunnan province, and decreased to 1.43% in Sichuan province, China [46, 47]. A paper illustrated that the content and sort of volatile components from E. stauntonii were obviously contrasted with different extraction methods, respectively [67, 69]. The researches foucing on the volatile components from E. splendens, E. bodinieri, E. stauntonii, and E. ciliate are much more than on other species [45, 51, 52, 55, 56, 6163, 6778]. The identified volatile components from the genus are shown in Additional file 4: Table S3, associated with the corresponding plant sources.

Pharmacological activities

Pharmacological investigations on the extracts and pure compounds from Elsholtzia cover the activities of antiviral, antibacterial, anti-inflammatory, anti-oxidant, and myocardial ischemia protection, as well as other activities. Researchers are increasingly concerning on the pharmacological activities of the genus.

Antiviral activity

Apigenin (12), apiin (15), luteolin (16), galuteolin (20), luteolin 3'-glucuronyl, methyl ester (30), and the ethyl acetate extract of E. rugulosa were reported to exhibit remarkable inhibition against the neuraminidases (Nas) from three typical influenza viruses A/PR/8/34 (H1N1), A/Jinan/15/90 (H3N2) and B/Jiangsu/10/2003. They inhibited influenza NAs at the different half maximal inhibitory concentration (IC50) values ranging from 7.81 μg/mL to 28.49 μg/mL. Especially, 12 and 16 exhibite significant effect against H3N2, with its IC50 values of 1.43 and 2.06 μg/mL, respectively. And the antiviral ability of 12 is 3 times higher than positive control, ribavirin. 16 has a similar capacity of antiviral activity with 12[79]. Many Elsholtzia species, such as E. bodinieri and E. blanda contain rich luteolin (16) and its derivatives (16 23) [8082]. Its high content, such as up to 16.0 mg/g in the leaves of E. blanda, provide a convenient for the development of antiviral activity [80].

Essential oil from E. densa showed a significant inhibitory properties against Asia influenza virus A and Orphan virus in vitro. And it can postpone the symptom appearance by 72–96 h after being infected by virus in vivo. Also, it showed inhibition against H3N2 subtype of influenza A virus, and exhibited remarkable therapeutic effect on mouse pulmonic induced by influenza virus when the mouse was administered with the essential oil (100 mg/kg) [41].

Antibacterial activity

Luteolin (16), quercetin (33) and ludongnin 5 (98) were isolated from the roots of E. bodinieri[9, 21, 26, 34]. An antimicrobial assays indicated that these compounds had the inhibitory and bactericidal activities against S. aureus, Bacillus subtilis and E. coli in varying degrees. The minimal inhibitory concentrations (MIC) of 98 are 5, 10 and 80 μg/mL, respecitvely. The MIC values of 16 against E. coli and S. aureus 50 and 40 μg/mL and of 33 against S. aureus and B. subtilis with its MIC values of 60 and 90 μg/mL, respectively [34].

The ethanol extracts of E. blanda and E. rugulosa exhibited remarkable inhibitory activity against methicillin-resistant S. aureus, with its MIC values of 1.32 and 1.43 mg/mL, respectively [83].

Besides, some Elsholtzia essential oils also showed antimicrobial activity against bacterias, i.e. E. coli, Shigeitn flexneri, S. epidermidis, beta Streptococcus, Bacterium paratyphosum B, B. typhi murium, B. dysenteriae, B. diphtheriae, B. meningitidis purulentae, B. proteus, Allthrax bacillus, and Neisseria intracellularis[41].

Essential oils from E. splendens are inhibitory against S. aureus, P. acnes and S. epidermidis. Its MIC against P. acnes was 0.31 μL/mL. As we known, P. acnes and S. epidermidis are involved in the formation acne, thus the inhibition against the two bacteria supports the considerable potential of the E. splendens essential oil for the treatment of acne [42]. It was also reported that volatile components from E. ciliata and E. rugulosa inhibit common bacteria, such as S. aureus, P. aeruginosa, B. enteritidis, B. subtilis, Proteus vularis, Shigella dysenteriae, and E. coli[43, 44].

Anti-inflammatory

The 75% ethanol extract of the aerial part of E. splendens can significantly inhibit acute inflammation (mouse ear edema by croton oil-inducing) and subchronic inflammation (ear edema by phorbol ester inducing). E. splendens significantly inhibited PGE2 production by pre-induced cyclooxygenase-2 of lipopolysaccharide-treated RAW 264.7 cells. It was thus believed that inhibition against cyclooxygenase-2 is probably one of the function mechanisms [84].

On chemical view, luteolin (16), a widely contained flavone with many hydroxyl substitutions, is a bioactive constituent in Elsholtzia plants for anti-inflammatory activity. It can inhibit the production of NO and generation of other inflammatory cytokine, such as TNF-α, IL-1β, IL-6, NF-κB, etc. [41]. Therefore, rich production of hydroxylated flavone and/or its derivatives is one of reasons to some extend to explain the anti-inflammatory action for Elsholtzia plants.

Anti-oxidant activity

The extracts of the aerial parts of E. rugulosa and E. bodineri displayed significant anti-oxidant activity in a radical-scavenged assay, which perhaps can elucidate why E. rugulosa has an anti-aging effect [85, 86]. The flower of E. rugulosa is rich in flavonoids with its content up to 0.2352 mg/mL, and the flavonoids significantly scavenge the OH- and O2- ions, with its scavenging rate 30.8 and 40.5%, respectively [87]. The extract and extract-loaded nanoparticles of the flower of E. splendens showed a concentration-dependent manner in DPPH radical scavenging assay. E. splendens was also found to activate the antioxidant defense system against 7,12-dimethyl-benz(a)anthracene (DMBA)-induced oxidative stress and reduce several biomarkers of oxidative stress such as thio-barbituric acid reactive substance, protein carbonyls, serum 8-hydroxy-20-deoxyguanosine, and ovary CHO-K1 cells aging [8892]. The maxium LPO inhibition ratio of the flavonoid extracts of E. blanda was 70.8% with the IC50 0.23 mg/L. And the inhibition of LPO was induced by OH free radical [93]. The genus Elsholtzia owns rich polyphenols, thus having radical scavenging effects [94, 95].

Myocardial ischemia protection

The total flavones from E. blanda (TFEB) could improve the recovery of myocardial function, and keep heart from ischemic damage due to coronary occlusion in Beagle dogs. The effect was achieved by the inhibition of serum creatine kinase-MB (CK-MB) and malondialdehyde (MDA), together with by the lowing of mean arterial pressure (MAP), coronary vascular resistance (CVR), etc. [96]. The TFEB not only could reduce infarct size during acute myocardial infarction (AMI) by inhibiting myocardial apoptosis through modulation of Bcl-2 family [97], but also might decrease the myocardial ischemia and ‘Xiongbi Symtom’ [98]. Luteolin 7-O-β-D-glucopyranoside (15) could protect cultured neonatal rat cardiomyocytes from oxidative damage obviously, and the beneficial effects may be related to its anti-oxidant properties and reduction of intracellular calcium overload [99].

Other activities

Besides the summarized functions above, the constituents or extracts from Elshozia plants have also some other activities. It is notable that apigenin (12) and luteolin (16) from E. rugulosa displayed protecting effects against the Alzheimer's disease (AD) in cell models. 12 protects rat cerebral microvascular endothelial cells (CMECs) against amyloid-β peptide 25–35 (Aβ25–35) -induced toxicity. Endothelial cells of cerebral capillaries forming the blood–brain barrier play an important role in the pathogenesis and therapy of AD. Aβ 25–35 showed toxicity on CMECs, and breaked the barrier integrity and function [100]. Copper can trigger the neurotoxicity in amyloid precursor protein Swedish (APPsw) overexpressing cells, which exacerbated the amyloid-β (Aβ) neurotoxicity and can be taken as a model of AD. Luteolin (16) treatment exerted neuroprotection through mechanisms that decrease amyloid-β precursor protein (AβPP) expression, lower Aβ secretion, regulate the redox imbalance, preserve mitochondrial function, and depress caspase family-related apoptosis [101]. E. splendens exhibited significant analgesic activity against mouse acetic acid-induced writhing. And the inhibition is up to 50% at 400 mg/kg [84].

A study indicated that E. splendens could obviously relieve symptoms of premenstrual syndrome. And the scores of depression and anxiety and the premenstrual instability decreased significantly [102]. The extracts of E. splendens had the potential of inducing structural aberration of chromosome. The ethanolic extracts of E. splendens have been found for reducing blood lipid by lowing low-density lipoprotein (LDL)-cholesterol [103, 104]. And ‘Ciwujia Xiangru Decoction’, one of Chinese Traditional Compound Medicines consisting of Acanthopanax senticosus and E. splendens, has been investigated the mentioned effect and used in clinic [105]. The extracts of E. splendens and E. stauntonii had fumigant toxicity, and may be potential fumigants for integrated pest management programs of stored-grain insect [106, 107]. Additionally, E. bodinieri extracts exhibited certain effect on depressing blood-lipid by reducing the level of total cholesterol of rats [108].

Conclusion remarks

The review paper summarized a total of 144 compounds and abundant volatile components that were reported from the genus Elsholtzia, with 117 references cited. We noted that Elsholtzia has an extensive distribution, diverse biological and pharmacological activities of pure compounds, extracts and volatile components described. Previous phytochemical researches on the genus revealed the extensive presence of flavone, coumarin, terpenoid, and other compound types, together with prolific essential oils. The pharmacological activities of volatile constituents mainly were regarded on antioxidant, antiviral and antibacterial activities.

From the review, it can be seen that phytochemical investigations mainly focus on 10 Elsholtzia species, E. blanda, E. bodinieri, E. ciliata, E. cristata, E. densa, E. eriostachya, E. ianthina, E. rugulosa, E. splendens, and E. stauntonil. And the volatile constituents’ analyses primarily concentrated on 20 species. However, related chemical and biological toward other Elsholtzia species, including E. kachinensis, E. capituligera, E. cephalantha, E. cyprianii, E. eriocalyx, E. flava, E. glabra, E. heterophylla, E. hunannensis, E. kachinensis, E. luteola, E. ochroleuca, E. oldhamii, E. penduliflora, E. pilosa, E. pygmaea, E. saxatilis, E. souliei, E. stachyodes, and E. winitiana, are still blank. So, plenty of further studies are necessary in order to illustrate the chemo-diversity and to make full use of the biological significance of the compounds and extracts of Elsholtzia, especially the antiviral and anti-inflammatory activities. The authors wish the review can provide a valuable data for explorations and advanced researches of Elsholtzia species.

Declarations

Acknowledgements

This work was financially supported by a grant from Beijing Nova Program (NO. 2011070) and Exploration of the Total Quality Management of Educational Science at Beijing University of Chinese Medicine (NO. XJY12006).

Authors’ Affiliations

(1)
School of Chinese Pharmacy, Beijing University of Chinese Medicine

References

  1. Wu ZY, Li XW, Huang SR: Flora reipublicae popularis sinicae. Beijing: Science press. 1977, 66: 304-348.Google Scholar
  2. Flora of China. 1994, http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=111493 (On line)
  3. State Administration of Chinese Medicine: Chinese Materia Medica. 1999, Shanghai: Science and technology press, 7. 6033–6043Google Scholar
  4. Zhang HX, Zhang FQ, Xia Q, Wang GP, Shen ZG: Excess copper induces production of hydrogen peroxide in the leaf of Elsholtzia haichowensis through apoplastic and symplastic Cu Zn-superoxide dismutase. J Hazard Mater. 2010, 178: 834-843.Google Scholar
  5. Sun LN, Zhang YF, He LY, Chen JZ, Wang QY, Qian M, Sheng XF: Genetic diversity and characterization of heavy metal-resistant-endophytic bacteria from two copper-tolerant plant species on copper mine waste land. Bioresource Technol. 2010, 101: 501-509.Google Scholar
  6. Wu B, Zoriyb M, Chen YX, Beckerb JS: Imaging of nutrientel elements in the leaves of Elsholtzia splendens by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Talanta. 2009, 78: 132-137.Google Scholar
  7. Tian SK, Peng HY, Yang XE, Lu LL, Zhang L: Phytofiltration of copper from contaminated water: growth response, copper uptake and lignin content in Elsholtzia splendens and Elshiltzia argyi. Bull Environ Contam Toxicol. 2008, 81: 85-89.Google Scholar
  8. Wollenweber E, Roitman JN: New reports on surface flavonoids from Chamaebatiaria (Rosaceae), Dodonaea (Sapindaceae), Elsholtzia (Lamiaceae), and Silphium (Asteraceae). Nat Prod Commun. 2007, 2: 385-389.Google Scholar
  9. Li RT, Li JT, Wang JK, Han QB, Zhu ZY, Sun HD: Three new flavonoid glycosides isolated from Elsholtzia bodinieri. Chem Pharm Bull. 2008, 56: 592-594.Google Scholar
  10. She GM, Guo ZQ, Lv HN, She DM: New flavonoid glycosides from Elsholtzia rugulosa Hemsl. Molecules. 2009, 14: 4190-4196.Google Scholar
  11. Zheng SZ, Kang SH, Shen T: Chemical constituents of Elsholtzia stauntonii Benth. J Northwest Norm Univ (Nat Sci). 2000, 36: 51-57.Google Scholar
  12. Zheng SZ, Kang SH, Shen XW, Sun LP: Three new C-methylated flavones from Elsholtzia stauntonii. Planta Med. 1999, 65: 173-175.Google Scholar
  13. Kang SH, Li YB, Wang L, Zheng SZ: Flavones from Elsholtzia stauntonii. Indian J Chem B. 2004, 43B: 1332-1334.Google Scholar
  14. Shen XW, Zheng SZ, Yin ZD, Song ZW, Wang L: Five new compounds from Elsholtzia densa. Chem J Chin Univ. 1994, 15: 540-542.Google Scholar
  15. Lv JS, Shen T, Guo Z, Shen XW, Zheng SZ: Chemical constituent of Elsholtzia blanda. Acta Bot Sin. 2001, 43: 545-550.Google Scholar
  16. Zheng SZ, Lv JS, Shen T, Liu HY, Shen XW: New C-methylated flavones from Elsholtzia blanda Benth. Indian J Chem B. 2001, 40B: 232-234.Google Scholar
  17. Li RT, Li JT, Wang JK, Han QB, Zhu ZY, Sun HD: Two new E-secoursane glycosides: bodiniosides A and B, isolated from Elsholtzia bodinieri. Helv Chim Acta. 2005, 88: 252-258.Google Scholar
  18. Chen RL, Zhou CX, Chen HY: Chemical constituents of Elsholtzia bodinieri. Chin Trad Herbal Drugs. 2004, 35: 1084-1086.Google Scholar
  19. Hu HB, Zheng XD, Liu FS, Liu JX: Five phenolic constituents from roots of Elsholtzia bodinieri. Chin Trad Herbal Drugs. 2007, 38: 329-332.Google Scholar
  20. Zheng XD, Hu HB: Chemical constituents of Elsholtzia ciliata (Thunb) hyland. Chemical Research. 2006, 17: 85-87.Google Scholar
  21. Hu HB, Zheng XD, Hu HS, Zhang YQ: Studies on chemical constituents from Elsholtzia bodinieri vaniot (I) in Gansu, China. J Baoji Univ Arts Sci (Nat Sci). 2006, 26: 196-199.Google Scholar
  22. Hu HB, Liu JX, Zheng XD: Chemical constituents of Elsholtzia bodinieri. Chin Trad Herbal Drugs. 2006, 37: 18-20.Google Scholar
  23. Sun LP, Yin ZD, Fu ZS, Zheng SZ, Shen XW: The chemical constituents of Elsholtzia densa Benth. Acta Bot Sin. 1996, 38: 672-676.Google Scholar
  24. Zheng SZ, Li XR, Shen XW, Pan XF: Chemical constituents of Elsholtzia eriostachya Benth. Acta Bot Sin. 1992, 34: 705-711.Google Scholar
  25. Ding CX, Zhou LY, Ji LJ, Ji WH, Ma YH: Studies on chemical constituents from Tibetan medicine Elsholtzia ianthina. Acta Bot Boreal Occident Sin. 2004, 24: 1093-1095.Google Scholar
  26. Zhao DB, Yang YX, Zhang W, Liu XH, Zhai CP, Wang HQ: Studies on chemical constituents from Elsholtzia bodinieri Vaniot. J Chin Med Mater. 2005, 28: 94-96.Google Scholar
  27. Hu HB, Cao H, Jian YF, Zheng XD, Liu JX: Two new clerodane diterpenoid glucosides and other constituents from the roots of Elsholtzia bodinieri Van't. Indian J Chem B. 2008, 47B: 166-170.Google Scholar
  28. Zhu WM, He HP, Wang S, Zuo GY, Hao XJ: Two new triterpenoid glycosides from Elsholtzia bodinieri Van't. Chin Chem Lett. 2002, 13: 253-255.Google Scholar
  29. Hu HB, Zheng XD, Hu HS, Jian YF: Triterpenoid saponins from Elsholtzia bodinieri. B Korean Chem Soc. 2007, 28: 1519-1522.Google Scholar
  30. Lai GF, Zhu XD, Luo SD, Wang YF: Chemical constituents from Elsholtzia rugulosa. Chin Trad Herbal Drugs. 2008, 39: 661-664.Google Scholar
  31. Zheng SZ, Shen XW, Lv RH: The chemical constituents of Elsholtzia ciliata (Thund.) hyland. Acta Bot Sin. 1990, 32: 215-219.Google Scholar
  32. Isobe T, Noda Y: Studies on the chemical constituents of Elsholtzia herb. Nippon Kagaku Kaishi. 1992, 4: 423-425.Google Scholar
  33. Hu HB, Wang X, Liu JX, Cao H, Jian YF: Study on the antifungal components in the root of Elsholtzia bodinieri vaniot. J Sichuan Univ (Nat Sci). 2006, 43: 913-917.Google Scholar
  34. Hu HB, Jian YF, Cao H, Zheng XD: Phenolic compounds from Elsholtzia bodinieri van't. J Chin Chem Soc (Taipei, Taiwan). 2007, 54: 1189-1194.Google Scholar
  35. Yang YB, Liu SQ, Wang BD, Zhu C, Zhu DY, Kong XM, Yang YQ: Studies on diterpenoid in Rabdosia phyllopodia (Labictae). Chin J Appl Environ Biol. 1997, 3: 79-81.Google Scholar
  36. Tian GH, Liu CF, Lai PH, Shi J: On the infrequence O-H…π stacking interation in the crystal structure. J Shaanxi Univ Technol (Nat Sci). 2008, 24: 73-76.Google Scholar
  37. Hu HB, Jian YF, Zheng XD, Cao H: Three sesquiterpene glycosides from Elsholtzia bodinieri. Bull Korean Chem Soc. 2007, 28: 467-470.Google Scholar
  38. Li HZ, Tatsuya N, Takashi T, Zhang YJ, Yang CR, Isao K: Two new maltol glycosides and cyanogenic glycosides from Elsholtzia rugulosa Hemsl. J Nat Med. 2008, 62: 75-78.Google Scholar
  39. Liu Y, Li XF, Liu AL, Li ZH, Du GH, Qin HL: Chemical constituents from leaves of Elsholtzia rugulosa. Chin Trad Herbal Drugs. 2009, 40: 1356-1359.Google Scholar
  40. Zhao Y, Li QC, Zhao Y, Chen YG: Studies on the constituents from the herb of Elsholtzia rugulosa. China J Chin Mater Med. 2004, 29: 1144-1146.Google Scholar
  41. Liu AL, Lee SMY, Wang YT, Du GH: Elsholtzia: review traditional uses, chemistry and pharmacology. J Chin Pharm Sci. 2007, 16: 73-78.Google Scholar
  42. Kim SS, Oh HJ, Baik JS, Oh TH, Yun PY, Kim CS, Lee NH, Hyun CG: Chemical composition and biological activities of Elsholtzia splendens essential oil. J App Biol Chem. 2008, 51 (2): 69-72.Google Scholar
  43. Hu HB, Cao H, Jian YF, Zheng XD: Extraction and antibacterial activity of active constituents of Elsholtzia ciliata hyland. Pratacultural Sci. 2007, 24 (8): 36-39.Google Scholar
  44. Hu HB, Zheng XD: Extraction, separation and antimicrobial activity of volatile oil from Elsholtzia rugulosa. Chin Hosp Pharm J. 2006, 26 (1): 14-16.Google Scholar
  45. Fu LZ, Li HZ, Li RT: Constituent analysis of two Elsholtzia volatile oils. J Kunming Univ Sci Technol (Sci Technol). 2010, 35 (1): 88-92.Google Scholar
  46. Fang HJ, Duan HJ, Xu YQ, Zhou TH, Lin JT: Studies on the chemical components of the essential oil of Elsholtzia blanda. Sepu. 1993, 11 (2): 69-71.Google Scholar
  47. Ren P, Shen XW, Zheng SZ: Studies on the chemical components and application of essential oils of Elsholtzia blanda Benth. J Northwest Norm Univ (Nat Sci). 2002, 38 (3): 58-60.Google Scholar
  48. Zhou WS, Zhu GP, Yang SF: Essential oils of Elsholtzia pentuliflora. Chin Pharm J. 1990, 25 (2): 79-80.Google Scholar
  49. Zhang GB, Wang MK, Chen YZ, Li ZL: GC/MS and GC/FTIR in the study of chemical constituents of volatile oil from Elsholtzia calycocarpa Piels. Chin Pharm J. 1994, 29 (10): 602-603.Google Scholar
  50. Zhang J, Wang ZH, Yao J, Yang YL, Huang AL, Gu LP, Wang J, Guo XL: Studies on the chemical constituents of essential oil from Elsholtzia feddei robusta. J Lanzhou Univ (Nat Sci). 2004, 40 (5): 69-72.Google Scholar
  51. Hyang SC, Kyung CM: Aroma-active compounds of Elsholtzia splendens using AEDA and HS-SPME-GC-O dilution analysis. Flavour Fragr J. 2008, 23: 58-64.Google Scholar
  52. Li ZW, Zhou TH: Studies on the components of essential oils of Elsholtzia spledens Nakai ex F. Maekawa (I) and Origanum vulgare L (II). Acta Pharm Sin. 1983, 18 (5): 363-368.Google Scholar
  53. Kang SH, Shi YQ: Supercritical CO2 fluid extraction of Elsholtzia fruticosa and GC/MS analysis. J Chin Mass Spectrom Soc. 2009, 30 (1): 36-40.Google Scholar
  54. Sun LP, Wang JX, Kang SH, Zheng SZ, Sheng XW: Studies on the chemical constituents of volatile oils from Elsholtzia densa Benth var calycocarpa. J Northwest Norm Univ (Nat Sci). 2000, 36 (2): 48-49.Google Scholar
  55. Du HQ, Zhao X, Fang HJ: Components of essential oils of Elsholtzia stauntonii Benth. Chin J Pharm Anal. 1989, 9 (1): 18-21.Google Scholar
  56. Yang HP, Wang SW, Liu YK: Study on the constituents of essential oils of flower from Elsholtzia stauntonii Benth. Chin Mod Appl Pharm. 2009, 26 (11): 871-873.Google Scholar
  57. Melkani AB, Dev V, Beauchamp PS, Negi A, Mehta SPS, Melkani KB: Constituents of the essential oil of a new chemotype of Elsholtzia strobilifera Benth. Biochem Syst Ecol. 2005, 33 (4): 419-425.Google Scholar
  58. Xu JH, Lai YG, Yao TW, Zeng S, Lou YJ: Simultaneous determination of seven components of volatile oil in Elsholtzia blanda by headspace gas chromatography. Chin Pharm J. 2008, 43 (6): 458-461.Google Scholar
  59. Fujita Y, Tanaka Y: Essential oils of plants from various territories. XXI. Essential oil of Elsholtzia nipponica. II. Nippon Kagaku Zasshi. 1965, 86 (10): 1078-1079.Google Scholar
  60. He FJ, Shi XF, Li HG, Tian YJ, Yang JP, Su W, Chen JK, Zhao YJ: Chemical components of essential oils of Elsholtzia patrini Garcke. Chin J Pharm Anal. 1995, 15 (5): 20-22.Google Scholar
  61. Liu G, Wang H, Zhou BH, Song JC: GC-MS analysis of essential oil from Elsholtzia ciliata. Chin J Experim Trad Med Formulae. 2006, 12 (11): 18-21.Google Scholar
  62. Zheng XD, Hu HB: Study of chemical compositions of volatile oil of Elsholtzia ciliata (Thunb) Hyland from Qingyang. Chin J Spectro Lab. 2005, 22 (1): 179-182.Google Scholar
  63. Kim JH, Jung DH: Variations in volatile compounds from Elshoizia cilliata. J Plant Bio. 2003, 46 (4): 287-289.Google Scholar
  64. Zhao Y, Qiu L, Li QC, Wang L, Zhu HY: Studies on the chemical components of essential oils of Elsholtzia rugulosa Hemsl. J Yunnan Univ (Nat Sci). 1998, 20 (Suppl): 462-464.Google Scholar
  65. Chen N, Zhang HD, Zhang SG: Volatile components of Elsholtzia enistacha Benth. J Lanzhou Univ (Nat Sci). 1988, 24 (4): 160-162.Google Scholar
  66. Ahmad A, Siddiqui MS, Misra LN: Composition of Elsholtzia polystachya leaf essential oil. Phytochemistry. 1988, 27 (4): 1065-1067.Google Scholar
  67. Zheng SZ, Limao CR, Dai R, Kang SH, Ren P, Shen XW: Composition of Elsholtzia stauntonii essential oil prepared by steam distillation and supercritical CO2 fluid extraction. J Northwest Norm Univ (Nat Sci). 2001, 37 (3): 37-40.Google Scholar
  68. Hu HB, Zheng XD: GC-MS determination of chemical components in volatile oil extracted from Elsholtzia bodinieri vaniot by supercritical CO2 fluid extraction. PTCA (Part B: Chem Anal). 2006, 42 (9): 712-714. 716Google Scholar
  69. Zheng SZ, Kang SH, Gao LM, Shen XW, Lv JS, Liu HY: Studies on the chemical component of essential oils of Elsholtzia stauntonii Benth. J Northwest Norm Univ (Nat Sci). 1999, 35 (3): 60-64.Google Scholar
  70. Hu HB, Zheng XD: Analysis of the chemical constituents of essential oil from Elsholtzia bodinieri by GC/MS. J Longdong Univ (Nat Sci). 2006, 16 (1): 53-55.Google Scholar
  71. Zhu GP: Comparison of chemical constituents of essential oils from Elsholtzia splendens and cultivated Mosla chinensis by GC-MS analysis. Acta Pharm Sin. 1992, 27 (4): 287-293.Google Scholar
  72. Wang SY, Jiang YJ: Study on bioactive action of volatile oils of five Chinese medical herbs against stored-products insects. J Zhengzhou Grain College. 1998, 19 (3): 1-11.Google Scholar
  73. Zhou LZ, Ma YJ, Jiang JH, Xu CD, Zhang CM: Study on chemical composition of the essential oil from Elsholtzia bodinieri Vaniot. J Anhui Agr Sci. 2009, 37 (18): 8461-8463.Google Scholar
  74. Cheng WX, Gu K, Li C, Guo YL, Li YC: Analysis on the chemical constituents of the essential oil from Elsholtzia bodinieri vaniot of Yunnan. J Yunnan Nationalities Univ (Nat Sci). 2004, 13 (2): 86-87.Google Scholar
  75. Xie YX, Zhang ZW, Jiang YJ, Zhang XJ: Study on the chemical components of volatile oil of Elsholtzia stauntonii Benth. J Chin Mass Spectro Soc. 1997, 19 (2): 70-74.Google Scholar
  76. Korolyuk EA, Koenig W, Tkachev AV: Composition of essential oils of Elsholtzia ciliata (Thunb.) Hyl. from the Novosibirsk region, Russia. Khimiya Rastitel'nogo Syr'ya. 2002, 31-36. 1
  77. Jin XL, Li DH: Analysis of volatile oil in Elsholtzia from Changbai Mountain. J Yanbian Univ (Nat Sci). 1996, 22 (1): 32-34.Google Scholar
  78. Dembitskii AD, Kalinkina GI, Bergaliev ES: A new terpene ketone component of the essential oil of Elsholtzia ciliata. Chem Nat Comp. 1993, 29 (6): 823-824.Google Scholar
  79. Liu AL, Liu B, Qin HL, Lee SMY, Wang YT, Du GH: Anti-influenza virus activities of flavonoids from the medicinal plant Elsholtzia rugulosa. Planta Med. 2008, 74: 847-851.Google Scholar
  80. Lai YG, Xu JH, Jiang HD, Zeng S, Zhao Y: HPLC simultaneous determination of three flavonoid aglycones in Elsholtzia blanda Benth. Chi J Pharm Anal. 2006, 26 (10): 1404-1407.Google Scholar
  81. Chen HY, Fan J, Cao JX: Determination of flavones in Elsholtzia bodinieri by HPLC. China J Chin Mater Med. 2007, 32: 2385-2387.Google Scholar
  82. Wang FM, Yao TW, Zeng S: Analysis of luteolin in Elsholtzia blanda Benth. by RP-HPLC. Pharmazie. 2005, 60: 648-649.Google Scholar
  83. Zuo GY, Wang GC, Zhao YB, Xu GL, Hao XY, Han J, Zhao Q: Screening of Chinese medicinal plants for inhibition against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). J Ethnopharmacol. 2008, 120: 287-290.Google Scholar
  84. Kim DW, Son KH, Chang HW, Bae KH, Kang SS, Kim HP: Anti-inflammatory activity of Elsholtzia splendens. Arch Pharm Res. 2003, 26: 232-236.Google Scholar
  85. Guo ZQ, Lv HN, Chen QL, She GM: DPPH and ABTS radical scavenging capacity of Elsholtzia rugulosa. Chin J Experim Trad Med Formulae. 2010, 16: 180-183.Google Scholar
  86. Zhang JC, Liu W, Yan HP, Li Y, Xue CL: Study on antioxidant activity of Elsholtzia bodinieri Vaniot and determination of microelements. Food Sci Technol. 2007, 4: 206-207.Google Scholar
  87. Wen MQ, Li L, Yang SM, Yang YM, Yang YL: Extraction of flavonoids from Elsholtzia rugulosa and their effects on scavenging of reactive oxygen species. Lishizhen Med Mater Med Res. 2010, 21: 1444-1445.Google Scholar
  88. Lee JS, Kim GH, Lee HY: Characteristics and antioxidant activity of Elsholtzia splendens extract-loaded nanoparticles. J Agric Food Chem. 2010, 58: 3316-3321.Google Scholar
  89. Lee JS, Kim GH, Lee HG: Optimization of extraction conditions for Elsholtzia splendens and its antioxidant activity. J Food Biochem. 10.1111/j.1745-4514.2012.00662.x.
  90. Choi EJ, Kim GH: In vivo antioxidative characteristics of extracts from thearomatic herb Elsholtzia splendens. Food Sci Biotechnol. 2008, 17: 1128-1130.Google Scholar
  91. Choi EJ, Lee YS, Kim GH: Antioxidative characteristics of extracts from aromatic herb Elsholtzia splendens. Food Sci Biotechnol. 2007, 16: 489-492.Google Scholar
  92. Choi EJ, Kim T, Kim GH: Antioxidant effects of Elsholtzia splendens extract on DMBA-induced oxidative stress in mice. Food Sci Biotechnol. 2008, 17: 1341-1344.Google Scholar
  93. Gao YT, Li L, Dai JH, Bei YX, Guo Y: Extraction of flavonoid from Chinese materia medics by ultrasonic extraction coupling with propyl-alcohol ammonium sulfate aqueous two-phase separation and its antioxidation of extractives. Chin Pharm J. 2009, 44: 736-739.Google Scholar
  94. Song FL, Gan RY, Zhang Y, Xiao Q, Kuang L, Li HB: Total phenolic contents and antioxidant capacities of selected Chinese medicinal plants. Int J Mol Sci. 2010, 11: 2362-2372.Google Scholar
  95. Li MJ, Qing WX, Yang YX, Zhao DB, Liu XH, Liu KZ: Scavenging activities of seven natural flavonoids for superoxide anion radicals. Chemical Research. 2006, 17: 73-75.Google Scholar
  96. Ling HY, Lou YJ, Lou HG, Wu HH: Protective effect of total flavones from Elsholtzia blanda (TFEB) on myocardial ischemia induced by coronary occlusion in canines. J Ethnopharmacol. 2004, 94: 101-107.Google Scholar
  97. Ling HY, Lou YJ: Total flavones from Elsholtzia blanda reduce infarct size during acute myocardial ischemia by inhibiting myocardial apoptosis in rats. J Ethnopharmacol. 2005, 101: 169-175.Google Scholar
  98. Lou HG, He QJ, Wu HH, Lou YJ: Experimental research on total flavone from Elsholtzia blanda against xiongbi symptom. J Chin Med Mater. 2003, 26: 878-880.Google Scholar
  99. Mu YL, Hu ZL, Zhou L, Zhang Q, Wang XJ, Xie YY: Protective effects of luteolin-7-O-β-D-glucopyranoside on neonatal rat cardiomyocytes injury induced by H2O2. J Shandong Univ TCM. 2009, 33: 63-65.Google Scholar
  100. Zhao L, Hou L, Sun HJ, Yan X, Sun XF, Li JG, Bian Y, Chu Y, Liu QS: Apigenin isolated from the medicinal plant Elsholtzia rugulosa prevents β-amyloid 25–35 - induces toxicity in rat cerebral microvascular endothelial cells. Molecules. 2011, 16: 4005-4019.Google Scholar
  101. Liu R, Meng FR, Zhang L, Liu AL, Qin HL, Lan X, Li L, Du GH: Luteolin isolated from the medicinal plant Elsholtzia rugulosa (Labiatae) prevents copper-mediated toxicity in β-amyloid precursor protein Swedish mutation overexpressing SH-SY5Y Cells. Molecules. 2011, 16: 2084-2096.Google Scholar
  102. Chung MS, Kim GH: Effects of Elsholtzia splendens and Cirsium japonicum on premenstrual syndrome. Nutr Res Pract. 2010, 4: 290-294.Google Scholar
  103. Shim SM, Choi MH, Kim GH: Safety evaluation of Elsholtzia splendens extracts: assessment of acute toxicity and mutagenicity. Food Chem Toxicol. 2008, 46: 1042-1047.Google Scholar
  104. Choi EJ, Kim GH: Effect of Elsholtzia splendens extracts on the blood lipid profile and hepatotoxicity of the mice. Food Sci Biotechnol. 2008, 17: 413-416.Google Scholar
  105. Shi ZZ, Liu CL, Li RX, Li DD, Shen SL: Effect of the mixture of Acanthopanax senticosus and Elsholtzia splendens on serum-lipids in hyperlipemia patients. Chin J Integr Med. 1990, 10 (3): 155-156. 188Google Scholar
  106. Wang SY, Jiang YJ: Study on bioactive action of volatile oils of five Chinese medical herbs against stored-products insects. J Zhengzhou Grain College. 1998, 19: 1-11.Google Scholar
  107. Lv JH, He YQ: Fumigant toxicity of Ailanthus altissima Swingle, Atractylodes lancea (Thunb.) DC. and Elsholtzia stauntonii Benth extracts on three major stored-grain insects. Indust Crops Prod. 2010, 32: 681-683.Google Scholar
  108. Wu YG, Tang ZP: Experimental study of pharmacodynamics of Elsholtzia bodinieri vaniot. Res Pract Chin Med. 2009, 23: 51-53.Google Scholar
  109. Chen HY, Zhou CX, Lou YJ, Duan ZH, Zhao Y: Chemical constituents from Elsholtzia blanda. Chin J Chin Mater Med. 2005, 30: 1589-1591.Google Scholar
  110. Sun LP, Zheng SZ: New furancoumarin from Elshotzia densa Benth var. calycocarpa (Dields) C. Y. Wu et S. C. Huang. 2005, Washington, DC: 230th ACS National MeetingGoogle Scholar
  111. Zheng SZ, Yin ZD, Shen XW: Six flavonoids in Elsholtzia densa, Beuth. J Northwest Norm Univ (Nat Sci). 1991, 27: 33-36.Google Scholar
  112. Lee YH, Lee IR, Won WS: Park Chung Hee: Flavonoids ofElscholtzia cristata. Arc Pharm Res. 1988, 11: 247-249.Google Scholar
  113. Sun LP, Wang JR, Li XR, Zheng SZ, Shen XW: Studies on the chemical constituents of eriostachya Elsholtzia (Elsholtzia eriostachya). II. Isolation on identification of flavonoids constituents. Chin Trad Herbal Drugs. 1997, 28: 646-648.Google Scholar
  114. Peng HY, Yang XE: Volatile constituents in the flowers of Elsholtzia argyi and their variation: a possible utilization of plant resources after phytoremediation. J Zhejiang Univ Sci B. 2005, 6B (2): 91-95.Google Scholar
  115. Zheng SZ, Song ZJ, Hu HB, Huang BD, Shen XW: Chemical constituents of the essential oil of Elsholtzia cypriani. J Northwest Norm Univ (Nat Sci). 2004, 40 (4): 52-54.Google Scholar
  116. Wang XF, Wang ZZ: Analysis of essential oils from different organs of Elsholtzia fruticosa (D. Don) Rehd. Acta Bot Boreal Occident Sin. 2008, 28 (3): 606-610.Google Scholar
  117. Peng YF, Li WL, Zhou SS, Yang X: Optimization of ultrasonic extraction in volatile oil of Elsholtzia rugulosa. J Chin Med Mater. 2009, 32 (11): 1764-1766.Google Scholar
  118. Lu CM: Chemical components of essent ial oil of Elsholtzia sp. J Chin Cereals Oils Assoc. 1998, 13 (4): 40-42.Google Scholar

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