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 and antiproliferative activities of mango (Mangifera indica L.) flesh and peel

The antioxidant and antiproliferative properties of flesh and peel of mango (Mangifera indica L.) were investigated. The cytoprotective effect of mango flesh and peel extracts on oxidative damage induced by H₂O₂ in a human hepatoma cell line, HepG2, were determined, and the underlying mechanism was examined by a single-cell electrophoresis assay (comet assay). Treatment of HepG2 cell with mango peel extract prior to oxidative stress was found to inhibit DNA damage. The free radical scavenging activities of mango flesh and peel extracts were evaluated by electron spin resonance (ESR). The mango peel extract exhibited stronger free radical scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) and alkyl radicals than mango flesh extract, regardless of ripeness. Similarly, peel extract exhibited significant antiproliferative effect against all tested cancer cell lines, compared to that of flesh extract, in a dose-dependent manner. The result also showed that the antiproliferative activity of mango flesh and peel extracts correlated with their phenolic and flavonoid contents. Thus, mango peel, a major by-product obtained during the processing of mango product, exhibited good antioxidant activity and may serve as a potential source of phenolics with anticancer activity.     

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.     

Regulation of the levels of health promoting compounds: lupeol,mangiferin and phenolic acids in the pulp and peel of mango fruit: a review

There is a demand for feasible methodologies that can increase/maintain the levels of health-promoting phytochemicals in horticultural produce, due to strong evidence that these compounds can reduce risk of chronic diseases. Mango (Mangifera indica L.), ranks fifth among the most cultivated fruit crops in the world, is naturally rich in phytochemicals such as lupeol, mangiferin and phenolic acids (e.g. gallic acid, chlorogenic acid and vanillic acid). Yet, there is still much scope for up-regulating the levels of these compounds in mango fruit through manipulation of different preharvest and postharvest practices that affect their biosynthesis and degradation. The process of ripening, harvest maturity, physical and chemical elicitor treatments such as low temperature stress, methyl jasmonate (MeJA), salicylic acid (SA) and nitric oxide (NO) and the availability of enzyme cofactors (Mg²⁺, Mn²⁺ and Fe²⁺) required in terpenoid biosynthesis were identified as potential determinants of the concentration of health-promoting compounds in mango fruit. The effectiveness of these preharvest and postharvest approaches in regulating the levels of lupeol, mangiferin and phenolic acids in the pulp and peel of mango fruit will be discussed. In general spray application of 0.2% iron(II) sulphate (FeSO₄) 30 days before harvest, harvest at sprung stage, storage of mature green fruit at 5 °C for 12 days prior to ripening, fumigation of mature green fruit with 10⁻⁵ mol L⁻¹ and/or 10⁻⁴ mol L⁻¹ MeJA for 24 h or 20 and/or 40 µL L⁻¹ NO for 2 h upregulate the levels of lupeol, mangiferin and phenolic acids in pulp and peel of ripe mango fruit. © 2019 Society of Chemical Industry     

Metabolic profile and biological activities of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco: Studies on the essential oil and polar extracts

We investigated the metabolic profile and biological activities of the essential oil and polar extracts of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco collected in south Portugal. Gas chromatography–mass spectrometry (GC–MS) analysis revealed that oxygen-containing monoterpenes was the principal group of compounds identified in the essential oil. Camphor (40.6%) and fenchone (38.0%) were found as the major constituents. High-performance liquid chromatography with diode array detection (HPLC–DAD) analysis allowed the identification of hydroxycinnamic acids (3-O-caffeoylquinic, 4-O-caffeoylquinic, 5-O-caffeoylquinic and rosmarinic acids) and flavones (luteolin and apigenin) in the polar extracts, with rosmarinic acid being the main compound in most of them. The bioactive compounds from L. pedunculata polar extracts were the most efficient free-radical scavengers, Fe²⁺ chelators and inhibitors of malondialdehyde production, while the essential oil was the most active against acetylcholinesterase. Our results reveal that the subspecies of L. pedunculata studied is a potential source of active metabolites with a positive effect on human health.     

Using drying treatments to stabilise mango peel and seed: Effect on antioxidant activity

The aim of this work was to study the effect of different drying treatments on the antioxidant activity of mango peel and seed. Freeze-drying allowed the peel (when extraction was carried out with ethanol:water) and seed to be stabilised without diminishing their antioxidant activity. In addition, this treatment improved mango peel’s antiradical capacity against ABTS^?+ (in ethanol:water), as well as the capacity of the seed to scavenge free radicals and to inhibit the lipid peroxidation. Oven-drying at 70 °C (with static or forced air) was the treatment that had the most negative effect on the antioxidant capacity of mango peel (when extraction was carried out with ethanol) and seed. Because the effect of drying methods on the phenol and anthocyanin content of mango peel or seed is related to antioxidant activity (with a moderately strong significant correlation, p < 0.003), it can be concluded that the phenol content of both materials is largely responsible for their antioxidant activity.     

Polyphenolic compounds characterization and reactive nitrogen species scavenging capacity of Oenothera paradoxa defatted seed extracts

Biological investigations have revealed high scavenging capacity of Oenothera paradoxa defatted seed extract on reactive nitrogen species such as NO and ONOO⁻. The characteristics of the polyphenols present in the extracts were checked using high performance liquid chromatography coupled with electrospray negative ionization ion trap mass spectrometry. Extracts contained five groups of compound: phenolic acids (gallic acid, ethyl gallate, ellagic acid and ferulic acid pentoside), flavanols (catechin, catechin gallate) and oligomeric procyanidins, flavonols (quercetin-3-O-glucoside, quercetin-3-O-glucuronide, quercetin-3-O-pentoside and quercetin), and gallotannins (tetragalloyl glucose, pentagalloyl glucose and hexagalloyl glucose). Penta-O-galloyl-β-d-glucose were present in the extracts in concentrations from 9.44 to 16.75 mg/g, which demonstrated a significant NO and ONOO⁻ scavenging activity with IC₅₀ 0.20 and 0.06 μM, respectively, may be considered as an O. paradoxa extract quality marker.     

Chemometric profiling of pre-climacteric Sri Lankan mango fruit (Mangifera indica L.)

There is no published information on the genotypic variation of major biochemical constituents in mango fruit endemic to Sri Lanka. Accordingly, non-structural carbohydrates, non-volatile organic acids and total phenolics were determined from the peel and pulp of pre-climacteric Sri Lankan mango cultivars (viz. Willard, Karutha Colomban, Vellai Colomban, Ampalavi, and Malgova) at three different maturity stages. Principal components analysis revealed distinct clustering of samples according to their biochemical profiles of peel and pulp at three maturity stages. Sugar concentrations generally declined with maturity in both peel and pulp except for cv. Willard. Fructose was the predominant sugar in both peel (56.2–106 mg/g dry weight (DW)) and pulp (67.4–141 mg/g DW), followed by glucose and sucrose. Starch concentration increased with maturity and was higher in pulp (26.0–55.0% DW) than peel (18.2–38.9% DW) at full mature stage. Dry matter as a proportion of fresh weight (FW) increased with maturity.     

Total phenolics,antioxidant activity,and functional properties of ‘Tommy Atkins’ mango peel and kernel as affected by drying methods

Mango processing produces significant amount of waste (peels and kernels) that can be utilized for the production of value-added ingredients for various food applications. Mango peel and kernel were dried using different techniques, such as freeze drying, hot air, vacuum and infrared. Freeze dried mango waste had higher antioxidant properties than those from other techniques. The ORAC values of peel and kernel varied from 418–776 and 1547–1819 μmol TE/g db. The solubility of freeze dried peel and kernel powder was the highest. The water and oil absorption index of mango waste powders ranged between 1.83–6.05 and 1.66–3.10, respectively. Freeze dried powders had the lowest bulk density values among different techniques tried. The cabinet dried waste powders can be potentially used in food products to enhance their nutritional and antioxidant properties.     

Characterisation of calamansi (Citrus microcarpa). Part I: Volatiles,aromatic profiles and phenolic acids in the peel

Volatile compounds in the peel of calamansi (Citrus microcarpa) from Malaysia, the Philippines and Vietnam were extracted with dichloromethane and hexane, and then analysed by gas chromatography–mass spectroscopy/flame ionisation detector. Seventy-nine compounds representing >98% of the volatiles were identified. Across the three geographical sources, a relatively small proportion of potent oxygenated compounds was significantly different, exemplified by the highest amount of methyl N-methylanthranilate in Malaysian calamansi peel. Principal component analysis and canonical discriminant analysis were applied to interpret the complex volatile compounds in the calamansi peel extracts, and to verify the discrimination among the different origins. In addition, four common hydroxycinnamic acids (caffeic, p-coumaric, ferulic and sinapic acids) were determined in the methanolic extracts of calamansi peel using ultra-fast liquid chromatography coupled to photodiode array detector. The Philippines calamansi peel contained the highest amount of total phenolic acids. In addition, p-Coumaric acid was the dominant free phenolic acids, whereas ferulic acid was the main bound phenolic acid.     

Antihypertensive properties of flavonoid-rich apple peel extract

Hypertension is a major public health problem rising across the globe. Inhibition of angiotensin converting enzyme (ACE) is identified as a main therapeutic target in controlling high blood pressure. The present study investigated the ACE inhibitory property of a flavonoid-rich apple peel extract (FAE), its constituents, selected flavonoids and some quercetin metabolites using a biochemical assay of ACE inhibition and a human umbilical vein endothelial cell (HUVEC) model. FAE, all the tested flavonoids except genistein, and two quercetin metabolites (quercetin-3-O-glucuronic acid and quercetin-3-O-sulfate) significantly (p < 0.05) inhibited ACE. Enzyme kinetic analysis revealed that flavonoids are competitive inhibitors of ACE. In the HUVEC model, FAE, quercetin-3-O-glucoside and quercetin-3-O-glucuronic acid inhibited significantly (p < 0.05) ACE activity. Overall, FAE and most of the flavonoids tested showed ACE inhibition in vitro which needs further investigations using animal and human clinical trials.     

Characterization of phenolics of Sarcandra glabra by non-targeted high-performance liquid chromatography fingerprinting and following targeted electrospray ionisation tandem mass spectrometry/time-of-flight mass spectrometry analyses

In this study, we successfully characterised the phenolic profiles of Sarcandra glabra (Thunb.) Nakai by high-performance liquid chromatography (HPLC) fingerprinting analyses and mass spectrometry (MS) identification. We first established a specific and valid HPLC approach for fingerprint analysis of S. glabra based on HPLC–UV detection. Using several chemometric methods such as similarity evaluation and principal components analysis, we determined herb-markers peaks from many HPLC peaks. The structures of these herb-markers were further identified targetedly by electrospray ionisation tandem mass spectrometry (ESI-MS/MS)/time-of-flight mass spectrometry (TOF-MS) analyses. As results, four phenolics, including chlorogenic acid, caffeic acid, 4-O-glucopyranosyl rosmarinic acid and rosmarinic acid, were characterised as major herb-markers for the stems of S. glabra, while another three phenolics, including kaempferol-3-O-β-d-glucuronic acid, chlorogenic acid and rosmarinic acid, were characteristic components for the leaves. The compounds may be very useful for further phenolome analysis.     

Phenolic compound characterisation and antiproliferative activity of “Annurca” apple,a southern Italian cultivar

In Annurca apples, a southern Italian variety, polyphenols were studied. The phenolic composition of Annurca apple peel was determined by HPLC coupled with electrospray negative ionisation multistage ion trap mass spectrometry (HPLC/ESI–ITMSⁿ). In addition, the antiproliferative and pro-apoptotic activities of peel extracts enriched in polyphenols and prepared from Annurca (APE), Red Delicious (RDPE) and Golden Delicious (GPE) varieties were evaluated on an HL-60 cell line. APE exhibited the highest total phenol content among the three apple cultivars tested, as determined by Folin–Ciocalteau’s procedure and HPLC–UV analysis. APE also showed higher amounts of chlorogenic acid, procyanidins, flavonols, dihydrochalcones and cyanidin-3-O-galactoside than GPE or RDPE. All three apple extracts were able to significantly decrease cell viability, from 50% to 80%, with APE appearing the most effective, while GPE was the least cytotoxic among the three samples. Similarly, APE and RDPE induced a significant increase of caspase-3 activity, whose activation represents a hallmark of apoptosis.     

Major Mango Polyphenols and Their Potential Significance to Human Health

ABSTRACT: The mango is a rich source of various polyphenolic compounds. The major polyphenols in the mango in terms of antioxidative capacity and/or quantity are: mangiferin, catechins, quercetin, kaempferol, rhamnetin, anthocyanins, gallic and ellagic acids, propyl and methyl gallate, benzoic acid, and protocatechuic acid. The nutraceutical and pharmaceutical significance of mangiferin, which is a special polyphenol in the mango has been extensively demonstrated and continues to attract much attention especially in its potential to combat degenerative diseases like heart diseases and cancer. The amounts of the different polyphenolic compounds in the mango vary from part to part (pulp, peel, seed, bark, leaf, and flower) with most polyphenols being found in all the parts. Mango polyphenols, like other polyphenolic compounds, work mainly as antioxidants, a property that enables them to protect human cells against damage due to oxidative stress leading to lipid peroxidation, DNA damage, and many degenerative diseases. Use of pure isolated compounds has been found to be less effective than the use of crude mixtures from the particular mango part suggesting that synergism of the various mango polyphenols is important for maximum antioxidative activity. In this article, we review the major mango polyphenols, looking at their proposed antioxidative activity, estimated amounts in the different parts, their structures, suggested modes of action, and related significance to human health, with great emphasis on mangiferin.     

Optimisation of serine protease extraction from mango peel (Mangifera Indica Cv. Chokanan)

This study investigated the possible relationship between the enzyme extraction variables, namely amount of buffer (25–75 ml, X₁), temperature (−20, 25 °C, X₂) and mixing time (1–3 min, X₃) on total protein (Y₁), total activity (Y₂), specific activity (Y₃), storage stability (Y₄), temperature stability (Y₅) and pH stability (Y₆) of serine protease from mango peel. It was found that there was significant (p < 0.05) fit of the response surface models for all the response variables investigated. There was indication of high coefficient of determination (R²) values (between 0.954 and 1.000) in the regression models describing variations of the response variables. It was found that there was no significant (p > 0.05) difference between the experimental and predicted values. This ensured that the response surface models used to indicate property changes of serine protease as a function of enzyme extraction conditions were sufficient.     

Agro-industrial potential of the mango peel based on its nutritional and functional properties

The mango peel represents from 15% to 20% of the total weight of the fruit. The aim of this review is to discuss the nutritional, functional, and nutraceutical properties of mango peel. It also shows several ways to add value to the mango peels, and their uses. Mango peel contains considerable content of antioxidants and dietary fiber. The mango peel offers a range of possibilities to develop value-added products. By-products from the agro-industrial processing of mangos can potentially make a significant contribution to the design of natural products rich in dietary fiber for widespread consumption. Additionally, food rich in soluble dietary fiber from mango peels could be designed for diabetic persons, since the mango peel reduces the speed with which glucose reaches the blood. Optimal extraction methods and drying technologies that do not impair the functional properties need to be further investigated. Economic, nutritional, and environmental benefits could be obtained with the proper use of this processing by-product.     

Characterisation of the key odorants in a squid broth (Illex argentinus)

The characteristic flavour of cooked squid has been studied by gas chromatography–olfactometry (GC–O) and gas chromatography–mass spectrometry (GC–MS) in order to identify and quantify the compounds responsible for this aroma. Squid meat (Illex argentinus) was boiled in water and the volatile compounds of this soup were isolated with different sample preparation techniques. 2-Acetyl-1-pyrroline was identified for the first time in squid aroma and turned out to be the key odorant. In addition, 3-(methylthio)propanal, 2-furfurylthiol, 2-methyl-3-furanthiol, sotolon, furaneol and butyric acid were also found to be important odorants present in the cooked squid extract.     

Composition of peel essential oils from four selected Tunisian Citrus species: Evidence for the genotypic influence

The peel essential oils from four selected Tunisian Citrus species: sweet orange (Citrus sinensis Osbeck), mandarin (Citrus reticulata Blanco); sour orange (Citrus aurantium L.) and pummelo (Citrus grandis Osbeck), cultivated under the same pedoclimatic and cultural conditions have been analysed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). The essential oils content ranged from 1.06% to 4.62% (w/w) in pummelo and mandarin, respectively. The qualitative and quantitative analysis led to the identification of 70 components in all oil samples. The analysed oils consist mainly in monoterpene hydrocarbons (97.59–99.3%), with limonene (92.52–97.3%) and β-pinene (1.37–1.82) being the major constituents. The remaining chemical classes were weakly represented (<1%). Both qualitative and quantitative differences between oil samples have been observed and numerous components have been proposed as marker compounds. Since the influence of different environmental factors has been eliminated, the observed chemical variability between the studied species and cultivars seems likely to results from the genetic variability.     

Utilization of mango peels as a source of pectin and polyphenolics

Two different options for the combined recovery of pectin and phenolic compounds from mango peels, a byproduct of industrial mango processing, were developed. After extraction of dried mango peels with diluted sulfuric acid, the phenolic compounds were adsorbed using a styrene–divinylbenzene copolymerisate resin, and pectin was obtained from the effluent by precipitation with ethanol. Phenolic compounds were recovered from the resin with methanol and the eluate was lyophilized (Process I). Alternatively, the pectin was precipitated by adding the crude extract to ethanol. After removal of the organic solvent, the phenolic compounds were obtained from the aqueous phase of the precipitation bath using the adsorbent resin as described before (Process II). While in total, 129.4 mg/g polyphenols were detected in the lyophilizate obtained from Process I, only 71.0 mg/g dm could be recoverd from Process II. The profiles of the polyphenols were almost identical, revealing that during pectin precipitation preferential adsorption of polyphenolic compounds to the pectin may be excluded. Besides the characterization of the pectins and the phenolic compounds, investigations into the influence of the drying temperature on the polyphenolic content of the peels were carried out, indicating a significant loss of flavonol glycosides depending on heat exposure. On the other hand, some xanthone glycosides were formed during the drying process. Furthermore, antioxidative capacities of the lyophilized eluates were investigated using the DPPH, TEAC and FRAP assays. The antioxidative capacity of the extracts exceeded that of mangiferin and quercetin 3-O-glucoside, respectively, thus demonstrating mango peels to be a suitable source of health-beneficial compounds. The lyophilizates obtained from Process I showed higher antioxidative capacities in all three assays. These findings indicate a correlation between the amount of phenolic compounds and the antioxidative capacity.

Industrial relevance

Byproducts of mango processing amount to 35–60% of the total fruit weight. Their complete exploitation for further product recovery is a promising measure from both an environmental and economic point of view. In our previous study mango peels were found to be a rich source of pectin, with a high degree of esterification and phenolic compounds, like flavonol O- and xanthone C-glycosides. Therefore, two alternative processes for the combined recovery of pectin and polyphenols, which can easily be integrated in an existing pectin production process, were developed in the present study.     

发酵法制备芒果皮膳食纤维工艺研究

以芒果皮为原料,以1∶1比例混合的保加利亚乳杆菌和嗜热链球菌作为发酵菌种,以菌种接种量、发酵温度、发酵时间对膳食纤维得率的影响为评价指标,通过单因素实验和正交实验对发酵法制备芒果皮膳食纤维的工艺条件进行优化。结果表明,发酵法制备芒果皮膳食纤维的最佳工艺为:接种量3%,发酵温度38℃,发酵时间3 h,在此条件下制备的膳食纤维得率为31.74%,其总膳食纤维含量为68.00%,持水力、持油力、溶胀度分别为11.19 g/g、5.11 g/g、1.07 m L/g,与发酵前相比,均有明显提高,进一步说明发酵法是一种可行的芒果皮膳食纤维制备方法。