Bioactive compounds and antioxidant potential of mango peel extract

Bioactive compounds such as polyphenols, carotenoids and anthocyanins present in fruits and vegetables are receiving increased attention because of their potential antioxidant activity. Consumption of such antioxidants offers health benefits including protection against cardiovascular diseases and cancer. Mango peel is a major byproduct obtained during the processing of mango products such as mango pulp and amchur. In the present study, the antioxidant activity of mango peel extracts was examined. Polyphenol, anthocyanin and carotenoid contents in acetone extract of peels were determined. Ripe peels contained higher amount of anthocyanins and carotenoids compared to raw peels while raw mango peel had high polyphenol content. Antioxidant activity of ripe and raw mango peels extracted in acetone was determined using different antioxidant systems such as reducing power activity, DPPH free radical scavenging activity, iron induced lipid peroxidation of liver microsomes and soybean lipoxygenase inhibition. The IC₅₀ values were found to be in the range of 1.39–5.24 μg of gallic acid equivalents. Thus, the mango peel extract exhibited good antioxidant activity in different systems and thus may be used in nutraceutical and functional foods.     

Antioxidant capacity of methanolic and water extracts prepared from food‐processing by‐products

This study aims to evaluate the antioxidant capacity of mango peel, roselle seed, okara (by‐product of soya milk industry), cocoa shell and pink guava (by‐product of pink guava industry) in comparison to 6‐hydroxy‐2,5,7,8‐tetramethylchroman‐2‐carboxylic acid (Trolox). The β‐carotene bleaching, 1,1‐diphenyl‐2‐picrylhydrazyl and reducing power assays were used to determine the antioxidant capacity of selected by‐products by measuring the absorbance at 470, 520 and 700 nm, respectively. The results showed that methanolic extracts of pink guava and cocoa shell exhibited the highest antioxidant activity and free radical scavenging activity compared to other studied samples. Roselle seed water extract exhibited the highest antioxidant activity and free radical scavenging when extracted with water. Pink guava possessed the highest reducing power in methanolic extract at a concentration of 0.16 mg mL^?1. At the same concentration, mango peel exhibited the highest reducing power when extracted with water. The present study shows that pink guava, roselle seed and cocoa shell are potential sources of antioxidant components that can be exploited as food preservative agents or nutraceuticals. Copyright © 2006 Society of Chemical Industry     

Comparative antioxidant and antiproliferative activities of red and white pitayas and their correlation with flavonoid and polyphenol content

Pitaya, commonly known as dragon fruit, has generated considerable consumer interest because of its attractive color and micronutrient content. The present study investigated the total polyphenol and flavonoid content, antioxidant activity against various free radicals, and antiproliferative effect on several cancer cell lines of extracts of flesh and peel of white and red pitayas, collected from Jeju Island, Korea. The total polyphenol and flavonoid contents of 80% methanol extracts of red pitaya peel (RPP) and white pitaya peel (WPP) were approximately 3- and 5-fold higher than those of red pitaya flesh (RPF) and white pitaya flesh (WPF), respectively. Overall, the total flavonoid and polyphenol contents of these extracts were RPP>WPP>RPF>WPF and WPP>RPP>RPF>WPF, respectively. In addition, a study involving nontargeted high-performance liquid chromatography coupled with a photodiode array and electrospray ionization mass spectrometry (HPLC-PDA-ESI-MS) of different pitaya extracts indicated the presence of phenolic, hydroxycinnamic acid derivatives, flavonol glycosides, betacyanin, and its derivatives with a few unknown compounds. Separately, peel extracts of both red and white pitayas showed higher 2,2-diphenyl-1-picrylhydrazyl, hydroxyl, and alkyl radical-scavenging activity than did the corresponding flesh extracts. Both peel extracts also showed stronger antiproliferative activity against AGS and MCF-7 cancer cells than either flesh extract. There was a direct correlation between the phenolic content and antioxidant effect, but no correlation observed between antioxidant activity and antiproliferative activity. These results suggest that the peel of white and red pitaya may be a valuable ingredient in foods and may also be useful in cosmetic, nutraceutical, and pharmaceutical applications.     

Antioxidant,Antibacterial, and Antiproliferative Activities of Free and Bound Phenolics from Peel and Flesh of Fuji Apple

This study was conducted to investigate the antioxidant, antibacterial, and antiproliferative activities of flesh free (FF), flesh bound (FB), peel free (PF), and peel bound (PB) phenolics from Fuji apple. The PB, which had highest total phenolic contents (126.15 ± 2.41 mg/100 g wet weight) and lowest total carbohydrate contents (34.68 ± 2.78 mg/100 g wet weight), showed the strongest 2,2’‐azinobis‐(3‐ethylbenthiazoline‐6‐sulphonate) (ABTS) radical scavenging activity (EC₅₀ = 0.36 ± 0.02 mg/mL), 1,1‐diphenyl‐2‐picryhydrazyl (DPPH) radical scavenging activity (EC₅₀ = 0.26 ± 0.01 mg/mL), and ferric reducing antioxidant power (Ferric reducing antioxidant power; EC₅₀ = 0.19 ± 0.02 mg/mL) compared with those of FF, FB, and PF. The PB also showed the strongest antibacterial activities on Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes and it also showed the highest antiproliferative effects on Caco‐2 human colonic cancer cell (EC₅₀ = 1.44 ± 0.01 mg/mL) and Hela human cervical cell (EC₅₀ = 2.81 ± 0.01 mg/mL). Both free and bound phenolics from Fuji apple showed good antioxidant, antibacterial, and antiproliferative activities in our study, and bound phenolics had significantly higher activities compared with those of free phenolics.     

Antioxidant and Antitumor Activities of the Extracts from Chinese Yam (Dioscorea opposite Thunb.) Flesh and Peel and the Effective Compounds

The aims of this study are to investigate the antioxidant and antitumor activities of the water and ethanol extracts isolated from Chinese yam (Dioscorea opposite Thunb.) flesh (CYF) and peel (CYP) and the effective compounds. It was found that all peel portions have a better effect on reactive oxygen (ROS) scavenging assay than meat portions, especially for the water extract of Chinese yam peel (CYP‐W). Its IC₅₀ values for hydroxyl radical (OH?) scavenging assay (744.25 ± 3.46 μg/mL) and for 1,1‐diphenyl‐2‐picrylhydrazyl scavenging assay (374.85 ± 6.78 μg/mL) were both lower than that of yam flesh (CYF‐W). Furthermore, the antitumor property of yam peel was more effective than that of yam flesh (CYF‐W) on mouse models, with tumor inhibition rates were 47.92% and 27.41% for Ehrlich Ascites Tumor (EAC) model and 40.44% and 24.22% for H22 hepatocarcinoma tumor (H22) model. Meanwhile, extracts of peel showed higher allantoin, total flavonoids, and total phenolics contents than extracts of flesh. In conclusion, this study demonstrated that CYP‐W exerted better antitumor activity than flesh extracts and the scavenging ROS effects were also significantly higher in the CYP‐W in vitro. Moreover, the data indicated that allantoin may play an important role on antioxidative and antitumor capacity in yam peel.     

蛇菰提取物体外抗氧化活性研究

采用DPPH·法及Fe3+ 还原力法对蛇菰提取物的抗氧化活性进行研究,分别测定蛇菰乙醇提物、石油醚提取物、氯仿提取物、乙酸乙酯提取物、正丁醇提取物、水层部分、水提粗多糖及碱提粗多糖的抗氧化作用,同时以VC 作为阳性对照。结果表明：蛇菰提取物具有较强的抗氧化活性,尤其是乙酸乙酯提取物、正丁醇提取物、总醇提取物及水提粗多糖;它们对DPPH·的清除作用与VC 相当,其中乙酸乙酯提取物IC50 值为6.0μg/mL,活性略高于VC,同时以上提取物对Fe3+ 也具有很强的还原能力。     

Total phenolic content and antioxidant capacity of extracts obtained from six important fruit residues

The extracts from kinnow peel, kinnow seeds, litchi pericarp, litchi seeds, grape seeds, and banana peel were screened for total phenolic content (TPC), trolox equivalent antioxidant capacity (TEAC), 1,1 diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, as well as reducing power. Kinnow peel extract exhibited the highest reducing power, TEAC, and DPPH free radical scavenging activity, whereas, the phenolic content of 37.4 mg GAE/g-dw was highest for grape seed extract. Banana peel extract with a low TPC showed the lowest reducing power, TEAC as well as DPPH free radical scavenging activity among the fruit residue extracts examined in the present study. Correlation analysis between the reducing power and DPPH radical scavenging ability; reducing power and ABTS radical scavenging activity; and ABTS and DPPH radical scavenging abilities showed a high degree of correlation (r² = 0.85-0.91). However, r² of 0.36, 0.66, and 0.49 between TPC and DPPH radical scavenging activity; TPC and reducing power; and TPC and ABTS radical scavenging ability, respectively, indicated that some non-phenolic compounds also contributed to the total antioxidant activity in fruit residue extracts examined in this study. To the best of our knowledge, this is the first paper presenting comprehensive data on TPC, reducing power, and antioxidant activity for the six fruit residues. This study demonstrated that kinnow peel, litchi pericarp, litchi seeds, and grape seeds, can serve as potential sources of antioxidants for use in food and pharmaceutical industry.     

Phytochemical composition,cellular antioxidant capacity and antiproliferative activity in mango (Mangifera indica L.) pulp and peel

Cellular antioxidant activity (CAA) and inhibition of hepato‐cellular carcinoma (HepG2) proliferation were evaluated for the first time in the pulp and peel of mango cultivars. Comparatively, peel had high flavonoids and tocopherols content and showed significant antioxidant activity. Among all the studied cultivars, the Xiao Tainong peel was predominant with highest fistein, mangiferin and alpha‐tocopherol content and significant cellular antioxidant activity value 2986 ± 380 μmol QE/100 g FW. The HepG2 cells antiproliferation was maximum in the peel of Da Tainong and pulp of Aozhou with lowest EC₅₀ values, 2.35 ± 0.65 (peel) and 185.4 ± 10.9 (pulp) mg mL^?1, in a dose‐dependent manner. Negative associations of flavonoids and tocopherol compounds with CAA and antiproliferative activity in mango confirmed synergistic, additive or antagonistic actions of phytochemicals. The current study suggests that mango peel could be used as a value added ingredient or functional food and may contribute considerably to promote consumer health.     

丝瓜花不同溶剂提取物抗氧化活性及其酚类成分分析

以无水乙醇、70%乙醇、40%乙醇和水分别对丝瓜花进行提取,并测定各提取物中总酚、总黄酮含量,采用DPPH·清除能力、超氧化物自由基清除能力、FRAP抗氧化能力和亚铁离子螯合能力等方法评价其抗氧化活性,通过HPLC分析其中酚类成分。结果表明,70%和40%乙醇提取物总酚及总黄酮含量较高,而且DPPH·清除活性、FRAP还原力最强,40%乙醇提取物、水提物分别具有最强的超氧阴离子自由基清除活性和亚铁离子螯合能力。总酚含量与DPPH·清除活性之间存在较强的相关性(R²=0.8688)。HPLC分析检出提取物中9种酚类化合物,其中含量最高的为杨梅素。试验结果说明,70%乙醇、40%乙醇可能是丝瓜花抗氧化性物质提取的较好溶剂。结果表明丝瓜花是一种较好的抗氧剂资源。     

Antioxidant activities of red pepper (Capsicum annuum) pericarp and seed extracts

In this study, we examined the antioxidant activities of red pepper (Capsicum annuum, L.) pericarp and red pepper seed extracts. The extracts were evaluated by various antioxidant assays, including 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, superoxide anion radical scavenging, hydroxyl radical scavenging, [2,2′‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulphonic acid)] (ABTS) radical scavenging, ferrous chelating activity, superoxide dismutase (SOD) activity and reducing power, along with the determination of total phenolic and flavonoid contents. All the extracts showed strong antioxidant activity by the testing methods. The red pepper pericarp extract exhibited strong ferrous chelating activity and high scavenging activity against free radicals, including both the hydroxyl and DPPH radicals, but it exhibited weaker scavenging activity for the superoxide anion radical and for SOD. In contrast, the red pepper seed extract exhibited strong SOD activity and high scavenging activity against the superoxide anion radical, but showed weaker ferrous chelating activity, hydroxyl radical scavenging, and DPPH radical scavenging. We observed that the reducing power level and ABTS radical scavenging activity of the red pepper seed were higher than those of the red pepper pericarp at the highest tested concentration. Most of the test results for the red pepper seed and red pepper pericarp extracts increased markedly with increasing concentration; however, the metal chelating, SOD and ABTS radical scavenging activities did not increase with the concentration. Highest total phenolic and flavonoid contents were obtained from the red pepper pericarp extracts. Overall, the red pepper seed and red pepper pericarp extracts were highly effective for the antioxidant properties assayed, with the exceptions of ferrous chelating activity, hydroxyl radical scavenging and SOD activity.     

Antioxidant activity and antiproliferative action of methanol extracts of 4 different colored bell peppers (Capsicum annuum l.)

Methanol extracts of 4 different colored (red, orange, yellow, and green) bell peppers (Capsicum annuum L.) were examined to (1) determine the total phenolic content (TPC), (2) compare the antioxidant activities, (3) assess the protective effects of extracts on H₂O₂-induced and 4-hydroxy-2-nonenal (HNE)-induced DNA damage using the Comet assay, and (4) examine the antiproliferative action of their extracts on HT-29 cells. Red and orange bell peppers had significantly higher levels of TPC than yellow or green bell peppers. Orange bell pepper exhibited the highest level of radical scavenging activity and total antioxidant activity, while green bell pepper exhibited the highest superoxide dismutase-like activity. These results suggest that the difference in antioxidant activities may depend on the kinds of antioxidant compounds related to the color of the pepper. It was found a significant negative correlation between TPC and radical scavenging activity inhibiting capacity (IC)₅₀, and a significant positive corretation between TPC and total antioxidant activity. All extracts of bell pepper inhibited H₂O₂-induced and 4-hydroxy-2-nonenal-induced DNA damage in human leukocytes and showed potential toxicity on HT-29 cells. These findings suggest that the 4 different colored bell peppers may be useful as antioxidants and cancer prevention in food.     

黑枸杞提取物对HBV的抑制作用及抗氧化能力测定

目的:研究黑枸杞提取物对抗乙肝病毒的作用并检测其抗氧化活性。方法:体外培养HepG22.2.15细胞,MTT法检测黑枸杞提取物对HepG22.2.15细胞的细胞毒作用,双抗体夹心法检测HepG22.2.15细胞培养液中HBsAg和HBeAg的表达。测定黑枸杞不同浓度提取物的还原能力和对羟自由基、DPPH自由基的清除能力。结果:MTT法检测黑枸杞提取物对HepG22.2.15细胞无明显细胞毒作用。与阴性对照组比较,黑枸杞提取物对HepG22.2.15细胞HBsAg和HBeAg的表达有抑制作用(p<0.05)。且随着黑枸杞提取物浓度的增加,其还原能力与清除羟自由基、DPPH自由基的能力逐渐增强。结论:黑枸杞提取物对乙肝病毒有抑制作用,并且有着良好的抗氧化能力。     

Radical Scavenging,Total Antioxidant Capacity,and Antiproliferative Activity of Phenolic Extracts from Extra Virgin Olive Oil by Cultivar ‘Frantoio’

The beneficial health effects of extra virgin olive oil are due to both its high content of monounsaturated fatty acids and its high content of phenolic compounds, which have recently attracted research interest. In this context, the aim of this work was to examine the in vitro antioxidant and antiproliferative activities of the phenolic extract obtained from extra virgin olive oil from O. europea cultivar ‘Frantoio’ (samples 1–4), one of the main varieties cultivated in Italy. The total phenolic content was determined by Folin–Ciocalteu method and instead the phenolic profile was obtained by HPLC coupled to a diode array detector and mass spectrometry. Extra virgin olive oil extracts exhibited high antioxidant activity through different mechanisms of action and these activities are related to the phenolic content. Sample 3 demonstrated the strongest free radical scavenging activity with IC₅₀ value of 56.5 μg/mL. The reducing ability measured with FRAP assay revealed that samples ranged from 91.3 to 156 μM Fe(II)/g. The same interesting trend was observed with Trolox equivalent antioxidant capacity value. Moreover, the virgin olive oils showed a good oxidative stability ranging between 19 to 32 h. Antiproliferative activity evaluated by SRB assay revealed that phenolic extracts from the cultivar ‘Frantoio’ showed a strong antiproliferative activity against CORL-23 cell line with an IC₅₀ value of 14.5 and 55.9 μg/mL for samples 3 and 1, respectively, and these results are comparable to the positive control vinblastine. Overall, these results showed that extra virgin olive oils from the cultivar ‘Frantoio’, may represent an interesting source of phenolic compounds as functional components that could be consumed in diets and/or used for the elaboration of functional food and pharmaceutical industries.     

超高压预处理对西番莲果皮抗氧化能力及对HepG2细胞氧化损伤保护作用的影响

酚类化合物以游离态、酯化态和不溶性结合态存在于植物中,本实验通过超高压预处理紫色西番莲果皮(the peel of Passiflora edulis Sims,PEP),研究超高压预处理后PEP游离态、酯化态和结合态酚类化合物的多酚含量、抗氧化活性和细胞保护作用的变化,从而确定超高压预处理对PEP抗氧化能力及对Hep...     

柑桔皮提取液的抗氧化作用研究

采用微波强化浸提法提取桔皮中的活性物质,测定提取液对羟自由基、超氧阴离子和过氧化氢的清除效果.实验结果表明：桔皮提取液对活性氧具有很高的清除作用,0.5 mL桔皮提取液对羟自由基的清除率达到100%,对超氧阴离子的清除率达到98%以上,稀释100倍的桔皮提取液0.7 mL对过氧化氢的清除率仍可达25%左右.在保藏猪油的抗氧化应用实验中,0.5%添加量的桔皮提取液的抗氧化效果与相同添加量的Vc的抗氧化效果相当.     

Antioxidant Activity of Loquat (Eriobotrya japonica Lindl.) Fruit Peel and Pulp Extracts in Stabilization of Soybean Oil During Storage Conditions

The antioxidation activities of Eriobotrya japonica (Lindl.) fruit peel and pulp extracts were determined using DPPH, β-carotene, and Rancimat methods. Results showed that ethanol-water extract of peel and ethanol extract of pulp had the highest antioxidant activity. Protective effects of extracts in stabilization of soybean oil were tested and compared to tert-butyl hydroquinone by measuring peroxide values, free fatty acids, thiobarbituric acid, oxidative stability, and conjugated dienes and trienes values during storage (65 days at 25°C). Results showed that the ethanol-water extract of peel at 400 ppm exhibited stronger antioxidant activity, but the highest effect was observed in tert-butyl hydroquinone.     

Effect of loquat (Eriobotrya japonica) extracts on LDL oxidation

The antioxidative activity of the extracts of loquat fruits, Eriobotrya japonica Lindley was examined. Loquat fruit was separated into three parts (peel, flesh and seed), and each part was extracted with either water or ethanol. The extracts were then assessed for their free radical scavenging ability and effects on the oxidation of human low density lipoprotein (LDL) in vitro. Results in this study show that the ethanol extracts of all three loquat parts and the water extract of the peels exhibited a strong ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Among extracts of different loquat parts, the ethanol extract of loquat seeds was the most potent one. The ethanol extract of the seed was also effective in suppressing the oxidation of linoleic acid which was demonstrated by a slow discoloration of β-carotene/linoleic acid conjugation system. The ethanol extract of loquat seeds as compared to other extracts could also suppress significantly the 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) (MeO-AMVN)-induced LDL oxidation. When the content of total polyphenolic compounds in different loquat parts (peel, flesh and seed) was examined, a significantly higher level of total polyphenols was found in the seed than the peels and flesh. Using reverse-phase HPLC-ESI EM analysis, significant levels of polyphenolic compounds such as chlorogenic acid, cyanidine glucoside, epicatechin, epigalocatechin gallate and procyanidin B₂ in the ethanol extract of different loquat parts were identified and quantified. The latter two compounds were found mainly in the ethanol extract of loquat seeds, but not in peels and flesh. Therefore, it is suggested that the high ability to scavenge free radicals and suppress the LDL oxidation exerted by the ethanol extract of loquat seeds was at least in part due to the high content of polyphenolic compounds in the seeds.     

Isolation and identification of an antioxidant flavonoid compound from citrus-processing by-product

BACKGROUND: Large amounts of citrus by‐products are released from juice‐processing plants every year. Most bioactive compounds are found in the peel and inner white pulp. Flavonoids are a widely distributed group of bioactive compounds. The methanolic extract of citrus peel powder has been shown to possess strong antioxidant activity. Therefore the aim of this study was to isolate the major antioxidant flavonoid compound from Citrus unshiu (satsuma) peel as citrus by‐product and evaluate its antioxidant activity. RESULTS: The major flavonoid isolated from C. unshiu peel was identified as quercetagetin. The structure of the compound was determined by tandem mass spectrometry and ultraviolet spectroscopy. Its antioxidant activity was assessed by assays of 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical, hydroxyl radical and intracellular reactive oxygen species (ROS) scavenging and DNA damage inhibition. Quercetagetin showed strong DPPH radical‐scavenging activity (IC₅₀7.89 µmol L^?1) but much lower hydroxyl radical‐scavenging activity (IC₅₀203.82 µmol L^?1). Furthermore, it significantly reduced ROS in Vero cells and showed a strong protective effect against hydrogen peroxide‐induced DNA damage. CONCLUSION: The results of this study suggest that quercetagetin could be used in the functional food, cosmetic and pharmaceutical industries. Copyright © 2011 Society of Chemical Industry     

生何首乌体外抗氧化活性及抗菌活性的研究

研究生何首乌不同提取物的体外抗氧化活性及抗菌活性。在体外化学模拟的条件下,采用比色法,测定了何首乌水提物和醇提物对DPPH自由基的还原能力及抗脂质过氧化能力,羟基自由基的清除能力以及总体抗氧化能力。同时测定了何首乌水提物和醇提物的总酚酸和总黄酮的含量。利用滤纸片扩散法测定了何首乌水提物和醇提物对6种微生物的抗菌活性。何首乌醇提物的体外抗氧化活性强于水提物,具有显著的DPPH自由基和羟基自由基清除能力和较强的抗脂质过氧化能力,具有一定的还原能力,其总体抗氧化能力也比较强。何首乌水提取物和醇提取物的总酚酸和总黄酮含量分别126.52、77.25μg/mg和153.04、126.11μg/mg。另外何首乌的醇提物对金黄色葡萄球菌、四联球菌和大肠杆菌显示出较强的抑制活性,水提物对金黄色葡萄球菌和荧光假单胞菌显示出一定的抑菌活性。何首乌具有强的抗氧化活性与一定的抗菌活性。     

Antioxidant and tyrosinase inhibitory activity of mango seed kernel by product

The antioxidant and tyrosinase inhibitory properties of extracts of mango seed kernel (Mangifera indica L.), which is normally discarded when the fruit is processed, were studied. Extracts contained phenolic components by a high antioxidant activity, which was assessed in homogeneous solution by the 2,2-diphenyl-1-picrylhydrazyl radical and 2,2′-azinobis (3-ethylbenzothialozinesulfonic acid) radical cation-scavenging assays and in an emulsion with the ferric thiocyanate test. The extracts also possessed tyrosinase inhibitory activity. Drying conditions and extraction solvent were varied, and optimum conditions for preparation of mango seed kernel extract were found to be sun-drying with ethanol extraction at room temperature. Refluxing in acidified ethanol gave an increase in yield and the obtained extract had the highest content of total phenolics, and also was the most effective antioxidant with the highest radical-scavenging, metal-chelating and tyrosinase inhibitory activity. The extracts did not cause acute irritation of rabbit skins. Our study for the first time reveals the high total phenol content, radical-scavenging, metal-chelating and tyrosinase inhibitory activities of the extract from mango seed kernel. This extract may be suitable for use in food, cosmetic, nutraceutical and pharmaceutical applications.