Open Access

Comparative studies on phenolic profiles, antioxidant capacities and carotenoid contents of red goji berry (Lycium barbarum) and black goji berry (Lycium ruthenicum)

  • Tahidul Islam1,
  • Xiaoming Yu1,
  • Tanvir Singh Badwal2 and
  • Baojun Xu1Email author
Chemistry Central Journal201711:59

https://doi.org/10.1186/s13065-017-0287-z

Received: 18 November 2016

Accepted: 15 June 2017

Published: 24 June 2017

Abstract

Background

The study on phytochemical difference between red and black goji berry is limited.

Methods

Antioxidant activities and phenolic profiles in terms of total phenol content, total flavonoid contents, condensed tannin content, monomeric anthocyanin content, and total carotenoid content of red goji berry (Lycium barbarum) and black goji berry (L. ruthenicum) were compared using colorimetric assays.

Results

All goji berries were rich in phenolics. Black goji berry had the highest phenolic, condensed tannin content and monomeric anthocyanin content. Black goji berry samples possessed higher antioxidant capacities than red goji berry, while the red goji berry had the highest carotenoid content. Goji berries exhibited a positive linear correlation between phenolic compounds and antioxidant capacities. The average value of carotenoid content in red goji berry was 233.04 µg/g.

Conclusion

The phenolics and antioxidant capacities are much higher in black goji berry than red goji berry, while carotenoid content is much higher in red than black.

Keywords

Goji berryAntioxidantPhenolicsCarotenoids Lycium ruthenicum

Background

Natural products, in the form of pure compounds or extracts with antioxidant activity, may help the endogenous defense system of the body [1]. Antioxidants obtained through diet are taking on major significance as possible protector agents to diminish oxidative damage. As carcinogenic properties have been reported for some synthetic antioxidants, recent research on the potential applications of natural antioxidants from natural food products, for stabilizing foods against oxidation, have received much attention [2]. Antioxidant supplements or antioxidant containing foods may be used to help the human body to reduce oxidative damage or to protect food quality by preventing oxidative deterioration [3]. The antioxidants contained in foods, especially vegetables, are phenolic compounds (phenolic acids and flavonoids), carotenoids, tocopherol and ascorbic acid [3]. These compounds are important protective agents for human health [4]. Goji berry is a typical example that might be used as nutraceuticals or directly eaten in the diet to maintain good health [5].

Chinese traditional medicinal food goji berry is used for its anti-aging properties, tranquilizing and thirst quenching effects, as well as its ability to increase stamina. The benefits include preventing conditions such as diabetes, hyperlipidemia, cancer, hepatitis, immune disorders, thrombosis, and male infertility [68]. There are several clinical and experimental reports showing an anti-diabetic effect of Lycium barbarum as it is well-known in traditional Chinese herbal medicine for diabetes. L. barbarum reduced oxidation in patients with retinopathy [9]. The presence of various functional components like polysaccharides, flavonoids and carotenoids in L. barbarum fruits is believed to be responsible for these effects [7, 10, 11]. A group of lipid-soluble compounds is carotenoids with color ranging from yellow to red, have been shown to be present in large quantity in fruits of L. barbarum [12]. Several physiological studies have focused on polysaccharides and carotenoids; however, flavonoids have been less investigated, especially for their antioxidant activity [13, 14]. L. barbarum fruit and polysaccharide from it possess a range of biological activities, including anti-aging, neuroprotection, increased metabolism, glucose control in diabetics, glaucoma, anti-oxidant properties, immunomodulation, anti-tumor activity and cytoprotection [13, 15, 16]; Lycium ruthenicum fruit contains abundant anthocyanins and a highly branched arabinogalactan protein [17, 18]. Goji berries contain carotenoids (beta-carotene, lutein, lycopene, zeaxanthin, zeaxanthin dipalmitate), polysaccharides (comprising 30% of the pulp), vitamins (ascorbic acid glucopyranosyl ascorbic acid, and tocopherol), fatty acids, betaine, and peptidoglycans [1922].

As compared to the red goji berry, the study on black goji berry (L. ruthenicum) is limited. It is necessary to compare the differences between red and black goji berry in terms of phytochemical and antioxidant capacities. The objectives of the present study aim at assessing the phenolic profile, antioxidant properties and carotenoid content of red goji berry (L. barbarum) and black goji berry (L. ruthenicum), and provide scientific insight into the phenolic and antioxidant functions of both red and black goji berry to consumers and nutraceutical industry.

Methods

Goji berry samples

Dried fruits of goji berry (L. barbarum and L. ruthenicum) belonging to the family of Solanaceae, were produced from Ningxia Autonomous Region and Qinghai Province, China. The sample information is listed in Table 1, and the morphological features based on place of origin of dried goji berry fruits are presented in Fig. 1.
Table 1

Sample information of goji berry collected

Sample ID

Common name

Scientific name

Place of origin

R1

Red goji berry

Lycium barbarum

LiuYing Village, Xinbao Town, Zhongning County, Zhongwei City, NingXia Hui Autonomous Prefecture

R2

Red goji berry

Lycium barbarum

Xinxiaoxian in Xixia District, Yinchuan City, NingXia Hui Autonomous Prefecture

R3

Red goji berry

Lycium barbarum

Huangbin Village, Ningan Town, Zhongning County, Zhongwei City, NingXia Hui Autonomous Prefecture

R4

Red goji berry

Lycium barbarum

Helan county, Yinchuan City, NingXia Hui Autonomous Prefecture

B1

Black goji berry

Lycium ruthenicum

The second battalion of Nuomuhong Farm from Qinghai Province

B2

Black goji berry

Lycium ruthenicum

South gate No. 43. Xining City, Qinghai Province

B3

Black goji berry

Lycium ruthenicum

Nuomuhong Farm,Qinghai Province

B4

Black goji berry

Lycium ruthenicum

The first battalion of Nuomuhong Farm, Qinghai Province

Fig. 1

Pictures of red goji berry (L. barbarum) and black goji berry (L. ruthenicum) fruits

Chemicals and reagents

2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), Folin–Ciocalteu reagent, 2-diphenyl-1-picryhydrazyl (DPPH), potassium persulphate (K2S2O8), sodium carbonate, gallic acid, sodium hydroxide, sodium nitrite, sodium acetate, acetic acid, hydrogen chloride, 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), ferric chloride, ferrous sulfate, aluminum chloride hexahydrate, (+)-catechin, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), acetone, phosphate buffer saline (PBS), hydrogen chloride (HCl), potassium chloride (KCl), vanillin, methanol, butylated hydroxytoluene (BHT), potassium hydroxide, n-hexane was obtained from Sigma-Aldrich Co. (Shanghai, China). Absolute ethanol was from Tianjin Fuyu Fine Chemical Co., Ltd. (Tianjin, China). Other chemical reagents were supplied by Tianjin Damao Chemical Reagent Co., Ltd. (Tianjin, China). All chemicals were of analytical grade unless specially mentioned.

Extraction of goji berry sample

The goji berry sample extraction procedure was described by Xu and Chang [23]. Briefly, pestle and mortar were used to grind dried goji berry fruits, .5 g of dry ground goji berry samples (in triplicate) were extracted two times with 5 mL extraction solvent of acetone/water/acetic acid (70:29.5:.5) each time. Extracts were shaken for 3 h at 300 rpm using an orbital shaker, then samples extracted were placed in the dark for 12 h. After 12 h the extract samples were centrifuged at 3000 rpm for 10 min. The supernatants were stored at 4 °C in dark for determination of total phenolic content (TPC), total flavonoid content (TFC), total condensed tannin content (CTC), monomeric anthocyanin content (MAC), and antioxidant activities.

Determination of TPC

Total phenolic content was determined using a colorimetric method as described by Singleton et al. [24, 25]. The absorbance was measured by a UV–visible spectrophotometer (TU-1901) at 765 nm. The TPC was expressed as gallic acid equivalents (mg GAE/g sample) in accordance to standard calibration curve of gallic acid with linear range of 50–1000 µg/mL (R2 > .99).

Determination of TFC

Total flavonoids content was determined using a colorimetric method as described by Heimler et al. [26]. The absorbance was measured by a UV–visible spectrophotometer (TU-1901) at 510 nm. The TFC was expressed as catechin equivalents (mg CAE/g sample) in accordance to standard calibration curve of catechin with linear range from 10 to 1000 µg/mL (R2 > .99).

Determination of CTC

Condensed tannin content was determined using a colorimetric method as described by Broadhurst and Jones [27]. The absorbance was measured by a UV–visible spectrophotometer (TU-1901) at 500 nm. The CTC was expressed as catechin equivalents (mg CAE/g sample) in accordance to standard calibration curve of catechin with linear range of 50–1000 µg/mL (R2 > .99).

Determination of MAC

Monomeric anthocyanin content monomeric anthocyanin content was based on a pH differential method described previously by Lee et al. [28] with no modifications. The MAC was calculated in the form of w/w % of total anthocyanin in the samples using the molecular weight for cyanidin-3-glucoside (449.2 g/mol) and its extinction coefficient (26,900 L cm/mol). MAC was expressed as cyanidin-3-glucoside equivalents because of its historical usage for similar assays and its wide commercial availability [28].

Determination of DPPH free radical scavenging capacity

DPPH was determined using a colorimetric method as described by Chen and Ho [29]. The absorbance was measured by a UV–visible spectrophotometer (TU-1901) at 517 nm using extraction solvent to replace the sample as blank. The DPPH was expressed as Trolox equivalents (µmol TE/g sample) according to standard calibration curve of Trolox with a linear range from 100 to 750 µM (R2 > .99).

Determination of Ferric reducing antioxidant capacity

Ferric reducing antioxidant capacity (FRAP) was determined using a colorimetric method as described by Benzie and Strain [30]. The absorbance was measured by a UV–visible spectrophotometer (TU-1901) at 593 nm using extraction solvent to replace the sample as blank. The FRAP value was expressed as mmol of Fe2+ equivalents per 100 g of sample (mmol Fe2+ E/100 g sample) according to standard calibration curve of Fe2+ with linear range from 50 to 1000 µM (R2 > .99).

Determination of ABTS radical scavenging assay

ABTS was determined using a colorimetric method as described by Brown and Miller [31], and Re et al. [32]. The absorbance was measured by the UV–visible spectrophotometer (TU-1901) at 734 nm after 6 min reaction in spectrophotometer set at 30 °C, extraction solvent used as blank. The ABTS value was expressed as Trolox equivalents (µmol TE/g sample) in accordance to standard calibration curve of Trolox with linear range from 50 to 1000 µM (R2 > .99).

Determination of total carotenoid content (TCC)

TCC was determined using a colorimetric method as described by Sanusi and Adebiyi [33], with slight modifications. Briefly, a .5 g goji berry sample in triplicates was extracted with 5 mL of ethanolic butylated hydroxyl toluene (ethanol/BHT–100:1, v/w) for isolation and the release of carotenoids. Then, it was mixed completely, and placed in a water bath at 85 °C for 5 min. After that, .5 mL of 80% KOH was added for saponification and properly vortexed before putting it back to 85 °C water bath for 10 min. The mixture was cooled down in an ice-water bath and was added to 3 mL of cold deionized water. Then n-hexane (3 mL) was mixed with the mixture before centrifugation at 7500 rpm for 5 min for the separation of two layers. The upper layer with yellow was transferred and collected. This procedure was repeated four times until the upper layers became colorless [34]. Therefore, a total of 12 mL of hexane was put into each centrifuge tube and the final volume of each tube was recorded. The samples were read at the wavelengths of both 450 nm and 503 nm against the hexane as the blank [35]. The concentration of total carotenoid in the extract was calculated by following equation: Ccarotene = 4.642 × A450 − 3.091 × A503, where is C concentration of carotenoid expressed in μg/mL, A450 = absorbance value at 450 nm, and A503 = absorbance value at 503 nm [35]. Finally, the total carotenoid content in dry fruits was expressed in μg/g.

Statistical analysis

All of the assays were conducted in triplicate extracts and the results were expressed in means ± standard deviations on the basis of dry weight. The significant differences between mean values of samples were determined by analysis of variance (one-way ANOVA) using LSD significant difference test at a significance level of p ≤ .05.

Results

Total phenolic content of goji berry

The total phenolic contents (expressed in mg GAE/g) of 8 goji berry samples are presented in Table 2. Black goji berry samples B1, B3, B2 and B4 (9.01, 8.95, 8.08 and 7.26 mg GAE/g) had relatively higher total phenolic content, while the red goji berry samples R3, R2, R1, and R4 (2.17, 2.87, 3.12, 4.48 mg GAE/g) had relatively lower phenolic content.
Table 2

TPC, TFC, CTC, and MAC of goji berry

Sample no.

TPC (mg GAE/g)

TFC (mg CAE/g)

CTC (mg CAE/g)

MAC (mg/g)

R1

3.12 ± 0.28e

2.67 ± 0.21c

1.24 ± 0.28e

.25 ± 0.98d

R2

2.87 ± 0.28e

2.78 ± 0.21c

1.17 ± 0.28e

.22 ± 0.98d

R3

2.17 ± 1.00f

2.69 ± 0.21c

1.06 ± 0.28e

.21 ± 0.98d

R4

4.48 ± 1.00d

3.16 ± 0.21c

.86 ± 0.28e

.28 ± 0.98d

B1

9.01 ± 0.77a

10.37 ± 0.11b

17.36 ± 1.00d

60.52 ± 1.00c

B2

8.08 ± 1.00b

12.32 ± 0.25a

23.51 ± 1.00a

82.58 ± 0.95a

B3

8.95 ± 0.77a

11.90 ± 0.25a

22.13 ± 1.00b

82.41 ± 0.95a

B4

7.26 ± 1.00c

9.77 ± 0.11b

20.49 ± 1.00c

65.94 ± 1.00b

Data were expressed as mean ± standard deviation (n = 3). The data in the same column marked with different small case letters were significantly (p < .05) different

TPC total phenolic content, TFC total flavonoid content, CTC condensed tannin content, MAC monomeric anthocyanin content

Total flavonoid content of goji berry

The total flavonoid contents (expressed in mg CAE/g) of 8 goji berry samples are presented in Table 2. The relatively higher content of flavonoids was recorded in black goji berry samples B2, B3, B1 and B4 (12.32, 11.90, 10.37 and 9.77 mg CAE/g) while the least content of flavonoids was recorded in red goji berry samples R1, R3, R2 and R4 (2.67, 2.69, 2.78 and 3.16 mg CAE/g).

Total condensed tannin content of goji berry

The total condensed tannin contents (expressed in mg CAE/g) of 8 goji berry samples are presented in Table 2. The relatively higher content of condensed tannin was recorded in black goji berry samples B2, B3, B4 and B1 (23.51, 22.13, 20.49 and 17.36 mg CAE/g) while the least content of condensed tannin was recorded in red goji berry samples R4, R3, R2 and R1 (.86, 1.06, 1.17 and 1.24 mg/g).

Total monomeric anthocyanin content of goji berry

The total monomeric anthocyanin contents (expressed in anthocyanins mg/g) of 8 goji berry samples are presented in Table 2. Black goji berry samples B2, B3, B4 and B1 (82.58, 82.41, 65.94 and 60.52 mg/g) had relatively higher total phenolic content; while the red goji berry samples R3, R2, R1, and R4 (.21, .22, .25 and .28 mg/g) had relatively lower monomeric anthocyanin content.

FRAP radical scavenging activity of goji berry

FRAP (expressed in mmol Fe2+ E/100 g) of 8 goji berry samples is presented in Table 3. The relatively higher FRAP were recorded in black goji berry samples B3, B2, B1 and B4 (36,346.61, 33,930.79, 28,957.95 and 27,821.53 mmol Fe2+ E/100 g), while the least antioxidant capacities were found in red goji berry samples R3, R2, R1 and R4 (2639.03, 3303.13, 3473.79 and 4651.04 mmol Fe2+ E/100 g).
Table 3

Antioxidant capacities (DPPH, FRAP, ABTS) of goji berry

Sample no.

FRAP (mmol of Fe2+ E/100 g)

DPPH (µmol TE/g)

ABTS (µmol TE/g)

R1

3473.79 ± 0.09de

16.07 ± 0.35e

64.38 ± 0.58d

R2

3303.13 ± 0.09de

16.61 ± 0.09de

53.92 ± 0.58f

R3

2639.03 ± 0.28e

16.46 ± 0.09de

55.87 ± 0.08ef

R4

4651.04 ± 0.13d

17.47 ± 0.09c

62.40 ± 0.58de

B1

28957.95 ± 0.13c

35.86 ± 0.74a

150.51 ± 0.33c

B2

33930.79 ± 1.00b

35.68 ± 0.74a

180.03 ± 1.00a

B3

36346.61 ± 1.00a

33.30 ± 0.08b

167.59 ± 1.00b

B4

27821.53 ± 0.13c

32.29 ± 0.08b

147.00 ± 0.33c

Data were expressed as mean ± standard deviation (n = 3). The data in the same column marked with different small case letters were significantly (p < .05) different

FRAP ferric reducing anti-oxidant capacity, DPPH free radical scavenging capacity, ABTS radical scavenging assay

DPPH free radical scavenging activity of goji berry

The DPPH free radical scavenging activity (expressed in µmol TE/g) of 8 goji berry samples is presented in Table 3. The relatively higher DPPH scavenging abilities recorded in black goji berry samples B1, B2 B3 and B4 (35.86, 35.68, 33.30 and 32.90 µmol TE/g) while the least DPPH scavenging abilities were found in red goji berry samples R1, R3, R2 and R4 (16.07, 16.46, 16.61 and 17.47 µmol TE/g).

ABTS radical scavenging activity of goji berry

The results of ABTS radical scavenging activity of 8 goji berry samples are presented in Table 3. Black goji berry samples B2, B3, B1 and B4 (180.03, 167.59, 150.51 and 147.00 µmol TE/g) exhibited the relatively higher ABTS radical scavenging, while the lowest were found in red goji berry samples R2, R3, R4 and R1 (53.92, 55.87, 62.40 and 64.38 µmol TE/g).

Total carotenoid content of goji berry

The total carotenoid contents of 8 goji berry samples are presented in Table 4. R1, R3, R4 and R2 (233.08, 224.21, 222.63 and 212.24 µg/g) had the highest carotenoids while the lowest were found in B4, B1, B2, and B3 (1.51, 1.96, 2.77, and 3.19 µg/g).
Table 4

Carotenoids (TCC) of goji berry

Sample no.

TCC (µg/g)

R1

233.08 ± 1.00a

R2

212.24 ± 1.00c

R3

224.21 ± 0.61b

R4

222.63 ± 0.61b

B1

1.96 ± 0.62d

B2

2.77 ± 0.62d

B3

3.19 ± 0.62d

B4

1.51 ± 0.62d

Data were expressed as mean ± standard deviation (n = 3). The data in the same column marked with different small case letters were significantly (p < .05) different

TCC total carotenoids content

Discussion

Phenolic compounds in goji berry

The highest TPC value was recorded as 9.01 mg GAE/g while the lowest TPC value was recorded as 2.17 mg GAE/g. The average value of 4 black goji berry samples rich in TPC was recorded as 8.33 mg GAE/g which was 2.6 times higher than the rest 4 red goji berry samples. Average TPC in these 4 red goji berries was recorded as 3.16 mg GAE/g, which differed significantly (p < .05) from black goji berry. This finding indicates that the goji berry species are a significant source of phenolics.

The highest content of flavonoids was recorded as 12.32 mg CAE/g, while the least flavonoids were recorded as 2.67 mg CAE/g. The average TFC value was recorded as 11.09 mg CAE/g from 4 black goji berry samples, which was 3.9 times higher than the 4 red goji berry samples, the average TFC value of 4 red goji berry samples was 2.83 mg CAE/g, which differed significantly (p < .05) from the 4 black goji berry samples.

The highest condensed tannin content was recorded as 23.51 mg CAE/g in black goji berry, while the least condensed tannin content was recorded as .86 mg CAE/g in red goji berry. The tannin content of black goji berry samples 20.87 mg CAE/g, was 19.3 times higher than the 4 red goji berry samples, the average condensed tannin content of 4 red goji berry sample was 1.08 mg CAE/g, which differed significantly (p < .05) from the 4 black goji berry samples.

The highest monomeric anthocyanin content was recorded as 82.58 mg MAC/g from black goji berry, while the least condensed tannin content was recorded as .21 mg MAC/g from red goji berry. The average monomeric anthocyanin content was recorded 72.86 mg MAC/g from 4 black goji berry samples, which was 30.4 times higher than the 4 red goji berry samples, the average monomeric anthocyanin content of 4 red goji berry samples was .24 mg MAC/g, which differed significantly (p < .05) from the 4 black goji berry samples.

Antioxidant capacities of goji berry

The highest scavenging activity of goji berry extract was recorded as 35.86 µmol TE/g, while the least DPPH scavenging activity was recorded as 16.07 µmol TE/g. The average value of 4 black goji berry samples was 34.28 µmol TE/g, which was 2 times higher than 4 red goji berries. The average value of 4 red goji berries was 16.65 µmol TE/g.

Table 3 presents the reducing capability of 8 goji berry samples, the highest FRAP value was recorded as 36,346.61 mmol Fe2+ E/100 g, and the lowest FRAP value was 2639.03 Fe2+ E/100 g. The principle of FRAP assay states that, with reductant (antioxidants) at low pH, ferric tripyridyltriazine (Fe(III)-TPTZ) is reduced to ferrous tripyridyltriazine (Fe(II)-TPTZ) that has an intensive blue color and can be detected at a wavelength of 593 nm [23].

The highest ABTS radical scavenging activity was recorded as 180.03 µmol TE/g from black goji berry, while the lowest ABTS radical scavenging activity was recorded as 53.92 µmol TE/g. The average of 4 black goji berries was 161.28 µmol TE/g, while the lowest value was 59.14 µmol TE/g from 4 red goji berry samples. The ABTS radical scavenging activity is a more sensitive radical that is used for the estimation of antioxidant activity. The reduced ABTS radical is colorless in a color-quenching reaction [36].

Carotenoid content in goji berry

The total carotenoid contents (TCC) of goji berries are shown in Table 4. The highest carotenoid was 233.08 µg/g from red goji berry, while the lowest value was recorded as 1.51 µg/g from black goji berry. The average value of 4 red goji berries was 223.04 µg/g, while the average value of 4 black goji berries was 2.36 µg/g. The current results are similar as a previous study by Liu et al. [37], in which red goji berry was found to accumulate high levels (a maximum of 508.9 µg/g on fresh weight basis) of carotenoids, while the carotenoids were from 34.46 µg/g to undetectable in the black goji berry.

Correlation between antioxidant capacities and phenolic compounds

The correlation between antioxidant capacities and phenolics is shown in Table 5. The results of TPC, TFC, CTA, and MAC exhibited positive linear correlation at the level of .01 (r = .5). The results of FRAP, DPPH, and ABTS exhibited a positive linear correlation at the level of .01, where r = .643 for FRAP and DPPH, r = .571 for DPPH and ABTS, and r = .786 for FRAP and ABTS. The correlation between phenolics and antioxidant capacities of 8 goji berry samples exhibited a positive linear correlation at the level of .01, where r = .857 for TPC and FRAP, r = .786 for TPC and DPPH, r = .643 for TPC and ABTS, r = .786 for TFC and FRAP, r = .875 for TFC and DPPH, r = .714 for TFC and ABTS, r = .857 for MAC and FRAP, r = .643 for MAC and DPPH, r = .786 for MAC and ABTS, r = .643 for CTC and FRAP, r = .429 for CTC and DPPH, r = .714 for CTC and ABTS. Between carotenoid (TCC) and phenolics, carotenoid (TCC) and antioxidant capacities of 8 goji berries samples there is a negative correlation. The results dictate that phenolic compounds could be important contributors toward the antioxidant capacities of these goji berries. Phenolic compounds, such as flavonoids, phenolic acids, and condensed tannins, are usually considered to be major contributors to the antioxidant capacities of plants [38].
Table 5

Correlation analysis among the antioxidant, phenolics and carotenoids

 

TPC

TFC

FRAP

DPPH

ABTS

MAC

CTC

TCC

TPC

 Correlation coefficient

1.000

.643a

.857b

.786b

.643a

.714a

.500

−.500

 Sig. (2-tailed)

.026

.003

.006

.026

.013

.083

.083

 N

8

8

8

8

8

8

8

8

TFC

 Correlation coefficient

.643a

1.000

.786b

.857b

.714a

.786b

.571a

−.571a

 Sig. (2-tailed)

.026

.006

.003

.013

.006

.048

.048

 N

8

8

8

8

8

8

8

8

FRAP

 Correlation coefficient

.857b

.786b

1.000

.643a

.786b

.857b

.643a

−.357

 Sig. (2-tailed)

.003

.006

.026

.006

.003

.026

.216

 N

8

8

8

8

8

8

8

8

DPPH

 Correlation coefficient

.786b

.857b

.643a

1.000

.571a

.643a

.429

−.714a

 Sig. (2-tailed)

.006

.003

.026

.048

.026

.138

.013

 N

8

8

8

8

8

8

8

8

ABTS

 Correlation coefficient

.643a

.714a

.786b

.571a

1.000

.786b

.714a

−.286

 Sig. (2-tailed)

.026

.013

.006

.048

.006

.013

.322

 N

8

8

8

8

8

8

8

8

MAC

 Correlation coefficient

.714a

.786b

.857b

.643a

.786b

1.000

.786b

−.500

 Sig. (2-tailed)

.013

.006

.003

.026

.006

.006

.083

 N

8

8

8

8

8

8

8

8

CTC

 Correlation coefficient

.500

.571a

.643a

.429

.714a

.786b

1.000

−.429

 Sig. (2-tailed)

.083

.048

.026

.138

.013

.006

.138

 N

8

8

8

8

8

8

8

8

TCC

 Correlation coefficient

−.500

−.571a

−.357

−.714a

−.286

−500

−.429

1.000

 Sig. (2-tailed)

.083

.048

.216

.013

.322

.083

.138

 N

8

8

8

8

8

8

8

8

aCorrelation is significant at the .05 level (2-tailed)

bCorrelation is significant at the .01 level (2-tailed)

Conclusions

The 8 black and red goji samples have substantial antioxidant capacity and contain large amount of phenolic compounds. A significant correlation between the DPPH, FRAP and ABTS values suggested that antioxidant assays are reliable. The highly positive correlation between antioxidant capacity, phenolic, flavonoid, condensed tannin and anthocyanin content indicated that phenolic compounds could be the main contributors to the antioxidant activities of these goji berries. The black goji berries have relatively higher antioxidant capacities, total phenolic, flavonoid, condensed tannin and anthocyanin, and it could be an important dietary source of natural antioxidants for the prevention of diseases caused by oxidative stress in human body. This study portrayed an in depth detail on the antioxidant functions of goji berry which is of significant importance to consumers, nutritionists and food researchers.

Declarations

Authors’ contributions

TI conducted lab work, data processing, statistical analysis and manuscript drafting. XY collected all experimental samples and conducted parts of lab work. TSB was involved in the sample preparation and conducted parts of lab work. BX made experimental design, conducted quality control for lab work, and took charge in manuscript revision and paper submission. All authors read and approved the final manuscript.

Acknowledgements

This research was jointly supported by two research grants (UIC R201624 and UIC R201714) from Beijing Normal University-Hong Kong Baptist University United International College, China.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
Food Science and Technology Program, Beijing Normal University-Hong Kong Baptist University United International College
(2)
Agricultural and Food Engineering Department, Indian Institute of Technology

References

  1. Orhan I, Üstün O (2011) Determination of total phenol content, antioxidant activity and acetylcholinesterase inhibition in selected mushrooms from Turkey. J Food Compos Anal 24(3):386–390View ArticleGoogle Scholar
  2. Gu L, Weng X (2001) Antioxidant activity and components of Salvia plebeia R. Br.—a Chinese herb. Food Chem 73(3):299–305View ArticleGoogle Scholar
  3. Yildirim NC, Turkoglu S, Yildirim NUMAN, Ince OK (2012) Antioxidant properties of wild edible mushroom Pleurotus eryngii collected from Tunceli province of Turkey. Digest J Nanomater Biostruct 7:1647–1654Google Scholar
  4. Cosio MS, Buratti S, Mannino S, Benedetti S (2006) Use of an electrochemical method to evaluate the antioxidant activity of herb extracts from the Labiatae family. Food Chem 97(4):725–731View ArticleGoogle Scholar
  5. Ferreira IC, Barros L, Abreu R (2009) Antioxidants in wild mushrooms. Curr Med Chem 16(12):1543–1560View ArticleGoogle Scholar
  6. Jung K, Chin YW, Kim YC, Kim J (2005) Potentially hepatoprotective glycolipid constituents of Lycium chinense fruits. Arch Pharmacal Res 28(12):1381–1385View ArticleGoogle Scholar
  7. Kocyigit E, Sanlier N (2017) A review of composition and health effects of Lycium barbarum. Int J Chin Med 1(1):1–9Google Scholar
  8. Li XM, Ma YL, Liu XJ (2007) Effect of the Lycium barbarum polysaccharides on age-related oxidative stress in aged mice. J Ethnopharmacol 111(3):504–511View ArticleGoogle Scholar
  9. Li W, Wang L, Deng X, Jiang L, Zhang C, Zhang C (2000) Study of the fragility and abnormality rate of red blood cells in patients with type-2 diabetes and the effects of Lycium barbarum polysaccharides. Hebei J Tradit Chin Med 22(8):585–586Google Scholar
  10. Fraser PD, Bramley PM (2004) The biosynthesis and nutritional uses of carotenoids. Prog Lipid Res 43:228–265View ArticleGoogle Scholar
  11. Luo Q, Cai Y, Yan J, Sun M, Corke H (2004) Hypoglycemic and hypolipidemic effects and antioxidant activity of fruit extracts from Lycium barbaru. Life Sci 76:137–149View ArticleGoogle Scholar
  12. Weller P, Breithaupt E (2003) Identification and quantification of zeaxanthin esters in plants using liquid chromatography–mass spectrometry. J Agric Food Chem 51:7044–7049View ArticleGoogle Scholar
  13. Amagase H, Farnsworth NR (2011) A review of botanical characteristics, phytochemistry, clinical relevance in efficacy and safety of Lycium barbarum fruit (goji). Food Res Int 44:1702–1717View ArticleGoogle Scholar
  14. Potterat O (2010) Goji (Lycium barbarum and L. chinense): phytochemistry, pharmacology and safety in the perspective of traditional uses and recent popularity. Planta Med 76:7–19View ArticleGoogle Scholar
  15. Jin ML, Huang QS, Zhao K, Shang P (2013) Biological activities and potential health benefit effects of polysaccharides isolated from Lycium barbarum L. Int J Biol Macromol 54:16–23View ArticleGoogle Scholar
  16. Yu MS, Leung SK, Lai SW, Che CM, Zee SY, So KF, Yuen WH, Chang RCC (2005) Neuroprotective effects of anti-agingoriental medicine Lycium barbarum against beta-amyloid peptide neurotoxicity. Exp Gerontol 40(8–9):716–727View ArticleGoogle Scholar
  17. Peng Q, Lv XP, Xu QS, Li Y, Huang LJ, Du YG (2012) Isolation and structural characterization of the polysaccharide LRGP1 from Lycium ruthenicum. Carbohydr Polym 90:95–101View ArticleGoogle Scholar
  18. Zheng J, Ding CX, Wang LS, Li GL, Shi JY, Li H, Wang HL, Suo YR (2011) Anthocyanins composition and antioxidant activity of wild Lycium ruthenicum Murr. from Qinghai-Tibet Plateau. Food Chem 126:859–865View ArticleGoogle Scholar
  19. Breithaupt DE, Weller P, Wolters M, Hahn A (2004) Comparison of plasma responses in human subjects after the ingestion of 3R,3R’-zeaxanthin dipalmitate from wolfberry (Lycium barbarum) and non-esterified 3R,3R’-zeaxanthin using chiral high-performance liquid chromatography. Br J Nutr 91(5):707–713View ArticleGoogle Scholar
  20. Chang RC, So KF (2008) Use of anti-aging herbal medicine, Lycium barbarum, against aging-associated diseases. What do we know so far? Cell Mol Neurobiol 28(5):643–652View ArticleGoogle Scholar
  21. Peng X, Tian G (2001) Structural characterization of the glycan part of glycoconjugate LbGp2 from Lycium barbarum L. Carbohydr Res 331(1):95–99View ArticleGoogle Scholar
  22. Zhao R, Li Q, Xiao B (2005) Effect of Lycium barbarum polysaccharide on the improvement of insulin resistance in NIDDM rats. Yakugaku Zasshi 125(12):981–988View ArticleGoogle Scholar
  23. Xu BJ, Chang SKC (2007) A comparative study on phenolic profiles and antioxidant activities of legumes as affected by extraction solvents. J Food Sci 72:159–166View ArticleGoogle Scholar
  24. Singleton VL, Lamuela-Raventos RM (1999) Analysis of total phenols and other oxidation substrates and antioxidants by means of Folin–Ciocalteu reagent. Methods Enzymol 299:152–178View ArticleGoogle Scholar
  25. Singleton VL, Rossi JA (1965) Colorimetry of total phenolic with phosphomolybdic–phosphotungstic acid reagents. Am J Enol Vitic 16:144–158Google Scholar
  26. Heimler D, Vignolini P, Dini MG, Romani A (2005) Rapid tests to assess the antioxidant activity of Phaseolus vulgaris L. dry beans. J Agric Food Chem 53:3053–3056View ArticleGoogle Scholar
  27. Broadhurst RB, Jones WT (1978) Analysis of condensed tannins using acidified vanillin. J Sci Food Agric 29:788–794View ArticleGoogle Scholar
  28. Lee J, Durst RW, Wrolstad RE (2005) Determination of total monomeric anthocyanin pigment content of fruit juices, beverages, natural colorants, and wines by the pH differential method: collaborative study. J AOAC Int 88:1269–1278Google Scholar
  29. Chen CW, Ho CT (1995) Antioxidant properties of polyphenols extracted from green and black teas. J Food Lipids 2:35–46View ArticleGoogle Scholar
  30. Benzie IF, Strain JJ (1996) The ferric reducing ability of plasma (FRAP) as a measure of “antioxidant power”: the FRAP assay. Anal Biochem 239(1):70–76Google Scholar
  31. Brown JM, Miller WR (1993) Impact of motivational interviewing on participation and outcome in residential alcoholism treatment. Psychol Addict Behav 7(4):211Google Scholar
  32. Re R, Pellegrini N, Proteggente A, Pannala A, Yang M, Rice-Evans C (1999) Antioxidant activity applying an improved ABTS radical cation decolorization assay. Free Radic Biol Med 26(9):1231–1237Google Scholar
  33. Sanusi RA, Adebiyi AE (2009) Beta carotene content of commonly consumed foods and soups in Nigeria, Pakistan. J Nutr 8:1512–1516Google Scholar
  34. Carvalho LM, Oliveira AR, Godoy RL, Pacheco S, Nutti MR, de Carvalho JL, Fukuda WG (2012) Retention of total carotenoid and β-carotene in yellow sweet cassava (Manihot esculenta Crantz) after domestic cooking. Food Nutr Res 56:15788View ArticleGoogle Scholar
  35. Song Y, Xu BJ (2013) Diffusion profiles of health beneficial components from goji berry (Lyceum barbarum) marinated in alcohol and their antioxidant capacities as affected by alcohol concentration and steeping time. Foods 2:32–42View ArticleGoogle Scholar
  36. Elekofehinti OO, Kamdem JP, Kade IJ, Adanlawo IG, Rocha JBT (2013) Saponins from Solanum anguivilam fruit exhibit in vitro and in vivo antioxidant activity in alloxan induced oxidative stress. Asian J Pharm Clin Res 6:249–254Google Scholar
  37. Liu Y, Zeng S, Sun W, Wu M, Hu W, Shen X, Wang Y (2014) Comparative analysis of carotenoid accumulation in two goji (Lycium barbarum L. and L. ruthenicum Murr.) fruits. BMC Plant Biol 14:269View ArticleGoogle Scholar
  38. Cai YZ, Luo Q, Sun M, Corke H (2004) Antioxidant activity and phenolic compounds of 112 traditional Chinese medicinal plants associated with anticancer. J Life Sci 74:2157–2184View ArticleGoogle Scholar

Copyright

© The Author(s) 2017