Antioxidant activity of Annona crassiflora: Characterization of major components by electrospray ionization mass spectrometry

The polar components of Annona crassiflora pulp, peel and seeds ethanolic extracts were investigated by direct infusion electrospray ionization mass spectrometry (ESI-MS) both in the negative ion mode. Characteristic ESI mass spectra with many diagnostic ions were obtained for the extracts, serving for fast and reliable information. The technique provided information of component structures revealing the presence of important bioactive components widely reported as potent antioxidants such as ascorbic acid, caffeic acid, quinic acid, ferulic acid, xanthoxylin, rutin, caffeoyltartaric acid, caffeoyl glucose and [quercetin+hexose+pentose−H]⁻¹ This is the first report on the composition by ESI-MS of araticum peel and seed ethanolic extracts demonstrating excellent antioxidant activity.     

Antioxidant activity of 4 cultivars of persimmon fruit

In this study, the antioxidant activity of persimmon fruit of 4 different persimmon cultivars cultured at Korea was evaluated. There were 3 astringent persimmon cultivars [‘Bongok’ (BO), Japanese Hatchiya; ‘Cheongdobansi’ (CB); and ‘Dogeunjosaeng’ (DJ), Japanese Tonewase] a 1 non-astringent persimmon cultivar [‘Seochonjosaeng’ (SJ), Japanese Nishimurawase] fruits. After preparing extracts of fruits according to parts (calyx, pulp, and peel) with 4 different solvents (acetone, ethanol, methanol, and water), total phenolic contents (TPC) and antioxidant activity were determined. The extracts of calyx showed significantly higher TPC and antioxidant properties than those of the other persimmon parts. The highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC₅₀=43.36±1.78 μg/mL) and reducing power (IC₅₀=81.93±1.18 μg/mL) were found at acetone extract of SJ calyx, while SJ pulp extracts showed relatively lower antioxidant activities. Astringent persimmons showed relatively higher antioxidant activity than non-astringent persimmons in peel and pulp parts. These results indicated that persimmons have different antioxidant activity depending on cultivars and parts.     

Analysis of phenolic compounds including tannins,gallotannins and flavanols of Uapaca kirkiana fruit

Tannins and phenolic acids were extracted from Uapaca kirkiana unripe pulp, seed coat, peel and embryo, as well as from ripe pulp, seed coat, embryo and peel portions of the fruit. Extraction was done using 50% methanol. More tannins were detected in the embryos of both ripe and raw fruit. Both ripe and raw seed coat contained the least amounts of tannins. The flavanoids and gallotannins also followed the same trend, with most of them in the embryos of both, the ripe and raw, fruit portions whilst the least were found in the seed coat. Tannins were, however lost during sun-drying compared to oven-drying, even though the differences were not very large. Also, raw fruits showed high concentrations of tannins compared to the ripe fruits. Hydroxybenzoic acid was found in the peel and pulp but none was detected in the seed coat or in the embryo. Similar phenolic acids were detected in the seed coat, except for caffeic acid and protocatechuic acid, detected in the embryo by both the UV florescence and Folin spray.     

Pilosocereus arrabidae (Byles & Rowley) of the Grumari sandbank,RJ, Brazil: Physical,chemical characterizations and antioxidant activities correlated to detection of flavonoids

The fruits of Pilosocereus arrabidae (Cactaceae) is found in the Grumari shoal, located in the Rio de Janeiro state, Brazil and, several studies have already highlighted the importance of consuming its fruits. This work aims to investigate the physical, mineral and physicochemical properties of its fruits as well as to establish the knowledge about their chemical constituents and antioxidant properties. The peel (Pe) and pulp (Pu) extracts were obtained by maceration with the following solvents: hexane (HX), dichloromethane (DCL), ethyl acetate (EAC) and ethanol 70% (ET). The extracts were analyzed by Gas Chromatography coupled to Mass Spectrometry (GC–MS) and, by High Performance Liquid Chromatography (HPLC–DAD and HPLC–MS) for its chemical investigation. For the antioxidant activity investigations the ORAC, DPPH and ferrous ion chelating capacity (FICC) tests were performed. As results, we found higher yields for peels (72%) compared to pulps (28%). By the physical–chemical analyses we point out the fruits as a good source of fiber (pulp: 6.01 mg/100 g; peel: 8.02 mg/100 g). The minerals were analyzed by the method of issuing flames and indicated high levels of selenium (DRI for pulp and peel: 147%) and manganese (DRI pulp: 97.69% and DRI peel: 269.56%). The total flavonoid contents of the fruits performed by HPLC–DAD presented 0.45 μg equiv. in quercetin/mL of peel EAC extract and 0.25 μg equiv. in rutin/mL of pulp EAC extract. The antioxidant activities by the ORAC, FICC and DPPH methods indicated that the ET extracts showed antioxidant activities above the standards adopted for the tests. Among these, we highlight the ET extract of the pulp with EC₅₀ of 17.57 ± 0.27 μg/mL, lower than Ginkgo biloba EGB761® (23.40 ± 0.04 mg/mL). By the FICC test the EAC extract of the peel and pulp showed 70.0% and 53.4% activity, respectively, at 500 mg/mL, higher than the standard quercetin (50.0%). By the HPLC–DAD and HPLC–MS methods there were detected, for the first time on this species, the presence of the following flavonoids on the EAC extracts: quercetin, rutin, catechin, dihydrokaempferol, quercetin 3 or 4′-O-glucoside, kaempferol and isorhamnetin. By the GC–MS analysis there were detected on the DCL extracts saturated fatty acids (palmitic and stearic) and, on the HX extracts, methylated sugars (peel) and menthol (pulp). To sum up, the fruits of P. arrabidae display antioxidant potential correlated to flavonoid presence, and, high levels of selenium, manganese and fibers, characteristics that can promote beneficial effects on human health.     

Phytochemicals and antioxidant activity of different fruit fractions (peel,pulp, aril and seed) of Thai gac (Momordica cochinchinensis Spreng)

Three fractions (peel, pulp and aril) of gac fruit (Momordica cochinchinensis Spreng) were investigated for their phytochemicals (lycopene, beta-carotene, lutein and phenolic compounds) and their antioxidant activity. The results showed that the aril had the highest contents for both lycopene and beta-carotene, whilst peel (yellow) contained the highest amount of lutein. Two major phenolic acid groups: hydroxybenzoic acids and hydroxycinnamic were identified and quantified. Gallic acid and p-hydroxybenzoic acid were found in all fractions. Ferulic acid and p-hydroxybenzoic acid were most evident in pulp. Myricetin was the only flavonoid found in all fractions. Apigenin was the most predominant flavonoid in pulp (red), whereas rutin and luteolin gave the highest content in aril. The extracts of different fractions exhibited different levels of antioxidant activity in the systems tested. The aril extract showed the highest FRAP value. The greatest antioxidant activities of peel and pulp extracts were at immature stage, whereas those in the seed extracts increased from mature stage to ripe stage. The contents of total phenolic and total flavonoid in peel and pulp decreased during the fruit development stage (immature > ripe fruit) and subsequently displayed lower antioxidant capacity, except for the seed.     

Phenolic Profiles,Antioxidant Activities,and Neuroprotective Properties of Mulberry (Morus atropurpurea Roxb.) Fruit Extracts from Different Ripening Stages

The present work investigated the phenolic profiles (including nonanthocyanin and anthocyanin phenolics), antioxidant activities, and neuroprotective potential of mulberry fruit (MF) (Morus atropurpurea Roxb.) grown in China at different ripening stages. High‐performance liquid chromatography‐tandem mass spectrometry method (HPLC‐MS/MS) was used to identify and quantify the phenolic compounds. The antioxidant capacity, total phenolic content (TPC), total flavonoid content (TFC), and total monomeric anthocyanin content (TAC) were determined using spectrophotometric methods. The neuroprotective effects of MFs at different ripening stages were investigated using Aβ_25‐35‐treated PC12 cells as the cellular model of Alzheimer's disease. Of the 19 phenolic compounds characterized from the MF extracts, the contents of rutin and anthocyanins increased and that of chlorogenic acid decreased significantly with maturity. At the fully ripened stage, MF extracts showed the highest amounts of TPC (11.23 mg gallic acid equivalents/g fresh weight), TFC (15.1 mg rutin equivalents/g fresh weight), and TAC (1177 mg cyanidin 3‐O‐glucoside equivalents/100 g fresh weight). Meanwhile, antioxidant activity of MF extracts at this stage was highest according to ABTS (an IC50 value of 4.11 μg/mL) and DPPH (an IC50 value of 10.08 μg/mL) assays. Cellular assays revealed increased cell viability in cells treated with the ripe MF extracts; compared with the control groups, the ripening fruits also increased the antioxidant enzyme levels in PC12 cells. Together, these results suggest that the antioxidant activities and neuroprotective properties of ripening MFs are related to the contents and types of phenolic compounds that are present in the fruits.     

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.     

Polyphenolic Composition and Antioxidant Activities of Grape Seed Extract

Grape seed extracts (GSEs,) obtained from Italian and Rhine Rieslings, were examined for polyphenolic composition and antioxidant activities using HPLC and ESR spectrometry. The seed extraction was carried out with ethyl acetate and ethanol. The contents of polyphenols, flavan-3-ols and antioxidant activities were found to be higher in ethyl acetate than in ethanolic extracts. IC₅₀ values were 0.1045 mg/mL and 0.0599 mg/mL for the stable DPPH radical in ethanolic and ethyl acetate extracts, respectively. The values for the short-lived OH radical were 0.1989 mg/mL and 0.0362 mg/mL, in the given order. The significant correlations between the antioxidant activities of GSEs and polyphenols were established (P < 0.05). Owing to their antioxidant activities, the cultivars could be used as a source to produce a GSE.     

Optimization of Extraction Parameters of Total Phenolics from <Emphasis Type="Italic">Annona crassiflora</Emphasis> Mart. (Araticum) Fruits Using Response Surface Methodology

In this study, response surface methodology was used to optimize the extraction temperature (25–75 °C) and ethanol concentration (0–70 %, ethanol/water, v/v) to maximize the extraction of total phenolic compounds (TPC) from araticum pulp. The efficiency of the extraction process was monitored over time, and equilibrium conditions were reached between 60–90 min. A second-order polynomial model was adequately fit to the experimental data with an adjusted R ² of 0.9793 (p < 0.0001) showing that the model could efficiently predict the TPC content. Optimum extraction conditions were ethanol concentration of 46 % (v/v), extraction temperature of 75 °C and extraction time of 90 min. Under the optimum conditions, the araticum pulp showed high TPC content (4.67 g GAE/100 g dw) and also high antioxidant activity in the different assays used (46.56 μg/mL, 683.65 μmol TE/g and 1593.72 μmol TE/g for DPPH IC₅₀, TEAC and T-ORAC_FL, respectively). From our extraction procedure, we successfully recovered a significantly higher amount of TPC compared to other studies in the literature to date (1.5–22-fold higher). Furthermore, TPC and antioxidant activity were present in the fruit in levels that are difficult to find in other common fruits. These results expose a potential approach for improving human health through consumption of araticum fruit.     

Effects of blanching, drying and extraction processes on the antioxidant activity of yam (Dioscorea alata)

The effects of blanching, drying and extraction processes on the antioxidant activities of one kind of Taiwanese yam peel, Darsan (Dioscorea alata), were investigated. The antioxidant measurements included total phenolic content, reducing power and α ,α‐diphenyl‐β‐pricryl‐hydrazyl (DPPH) radical‐scavenging activity. The 50% ethanolic, hot water and water extracts from the peel all had much higher antioxidant activities than those extracts from the flesh. Among three extraction methods, 50% ethanolic extraction resulted in the highest antioxidant activities in the peel, while hot water extraction was more appropriate for the flesh. Blanching by immersing the peel in 85 °C water for 30 s caused significant reductions in the antioxidant activities of all the extracts from the peel. Generally speaking, freeze‐dried peel maintained higher antioxidant activities than hot air‐dried peel.     

雪莲果皮多酚提取工艺及其抗氧化、抑菌活性的研究

以雪莲果皮为试验材料,以多酚提取率为指标,在单因素试验的基础上,采用正交试验法对超声辅助提取雪莲果皮多酚工艺参数进行优化,通过扫描电镜分析不同提取方式对雪莲果皮粉末表面微观形态的影响和提取得率的关系,同时评价雪莲果皮多酚的抗氧化活性及抑菌活性。结果表明最佳提取条件为:料液比1:35(g/mL)、提取温度65 ℃、乙醇体积分数40%、提取时间55 min。在此优化条件下,雪莲果皮多酚的提取率为193.87 mg/g;扫描电镜分析显示物料的破碎程度为:超声波提取法>加热回流法>浸提法>原材料粉末;抗氧化试验结果表明雪莲果皮多酚3 mg/mL浓度下对DPPH·清除能力为70.23%,IC₅₀值为0.71 mg/mL;对ABTS⁺·清除能力为97.96%,IC₅₀值为0.68 mg/mL;5 mg/mL浓度下总抗氧化能力为46.28 μmol Trolox/mL;抑菌试验结果表明雪莲果多酚对大肠杆菌和金黄色葡萄球菌均有一定的抑制作用,供试菌种的最小抑菌浓度(MIC)分别为2.5 mg/mL和0.625 mg/m...     

Extraction optimization and profile analysis of oligosaccharides in banana pulp and peel

This study evaluated the effect of ethanol concentration (EC, 0–70%) and temperature (25–75 °C) on the oligosaccharides extraction from ripe banana pulp, as well as the profile of mono‐, di‐, galacto‐, fructo‐, malto‐ and xylooligosaccharides in ripe banana pulp and peel. According to response surface plots, EC of 52% (vol/vol) and 75 °C provided the maximum oligosaccharides extraction from banana pulp. High‐performance anion exchange chromatography coupled to pulsed amperometric detection showed the presence of glucose, fructose, sucrose, maltose, arabinose, 1‐kestose, xylopentaose, and xylohexaose in banana pulp and glucose, fructose, sucrose, 1‐kestose, maltotriose, xylopentaose, and xylohexaose in banana peel. Banana pulp and peel showed 6.47 and 1.42 mg/g dw of total oligosaccharides, respectively. The chromatographic analysis showed fructo‐ and xylooligosaccharides as the main banana oligosaccharides. Finally, banana can contribute to the intake of sugars and prebiotic oligosaccharides.

Practical applications

The extraction is the first step in the evaluation of the plant composition and several factors influence the recovery of the target compound. Oligosaccharides present a wide variety of applications in food science and industry and they are extensively studied in fruits metabolism. Methods with extraction conditions optimized and chromatography conditions well‐defined are very important to obtain reliable results. Furthermore, banana is one of the most consumed and processed fruits around the world and, consequently, the extraction procedure and analytical technique showed in this study can be helpful for quality control of banana and their products.     

厚朴籽不同溶剂萃取物抗氧化活性比较分析

为研究厚朴籽抗氧化成分,测定厚朴籽90%乙醇粗提物及其石油醚、乙酸乙酯、正丁醇和水萃取物的1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除活性,2,2-联氮基-双-(3-乙基苯并噻唑啉-6-磺酸)二铵盐(2,2-azino-bis(3-ethylbenzthiazoline-6-sulonic acid),ABTS)自由基清除活性和铁离子还原能力(ferric reducing antioxidant power,FRAP),同时测定其总酚及总黄酮含量。结果发现,乙酸乙酯萃取物的总酚和总黄酮的含量最高,含量依次为(253.64±7.25)和(179.11±0.61)mg/g。厚朴籽乙醇粗提物和萃取物具有一定抗氧化活性,其中乙酸乙酯萃取物的抗氧化活性最强,DPPH自由基清除活性显著(P<0.05)高于阳性对照BHT,其IC₅₀仅为(29.33±2.31)μg/mL;乙酸乙酯萃取物ABTS自由基清除活性与V_C相当,IC₅₀分别(30.33±1.53)和(31.67±3.06)μg/mL;厚朴籽乙醇粗提物和萃取物对铁离子的还原能力较低,均显著(P<0.05)低于阳性对照V_C和BHT。相关性显示,厚朴籽三种体外抗氧化活性均与总酚和总黄酮极显著相关(P<0.01)。以上结果表明,乙酸乙酯可以富集厚朴籽酚类物质,为下一步厚朴籽抗氧化物质分离奠定了理论依据。     

不同品种李子多酚组成及抗氧化活性

为研究不同品种李子果皮、果肉多酚组成及抗氧化活性,以9个不同品种的李子(芙蓉李、巫山李、玫瑰李、红布李、黑布李、西梅李、脆红李、江安李、青李)为原料,提取游离酚和结合酚,测定其1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除能力和抗氧化能力(oxygen radical absorbance capacity,ORAC)值,并通过高效液相色谱分析其多酚组成。结果显示:9种李子果皮总酚含量范围为111.52~775.88 mg GAE/100 g;果肉总酚含量范围为120.65~301.91 mg GAE/100 g,其中红布李果皮、果肉总酚含量均最高,西梅李总酚含量均最低。在多酚组成上,游离酚含量显著高于结合酚,且多酚组分主要为酚酸(原儿茶酸、绿原酸、咖啡酸)。体外抗氧化结果显示:9种李子果皮、果肉多酚均具有一定的抗氧化活性,DPPH自由基清除IC50值范围为4.38~46.46μg/m L,ORAC值范围为0.24~210.50μmol TE/g,其中巫山李果肉游离酚对DPPH自由基的清除能力最强,红布李果皮游离酚ORAC值最高。     

响应面试验优化石榴皮多酚提取工艺及石榴不同部位多酚的抗氧化活性分析

以石榴皮为原料,通过单因素试验及响应面试验优化石榴皮多酚的最佳提取工艺条件为：乙醇体积分数40%、超声波功率250 W、浸提温度60 ℃、料液比1∶27.5（g/mL）、超声时间39.3 min。此工艺条件下的多酚提取量为（1.13±0.26）mg/g。在优化条件下分别对石榴皮、石榴瓤和石榴籽中的多酚类化合物进行提取并比较其抗氧化活性,得到石榴不同部位的抗氧化活性大小依次为石榴皮＞石榴籽＞石榴瓤;进一步研究了人工模拟胃肠液对抗氧化活性最强组分石榴皮多酚活性的影响,发现经人工胃液处理后,石榴皮多酚的抗氧化活性升高（P＜0.05）,而经人工肠液处理后其抗氧化活性降低（P＜0.05）,推断石榴多酚类化合物在模拟胃肠液条件下其结构和功能的变化是不同的。     

Potent Antidiabetic Activity and Metabolite Profiling of Melicope Lunu‐ankenda Leaves

Diabetes mellitus is normally characterized by chronic hyperglycemia associated with disturbances in the fat, carbohydrate, and protein metabolism. There is an increasing trend of using natural products instead of synthetic agents as alternative therapy for disorders due to their fewer side effects. In this study, antidiabetic and antioxidant activities of different Melicope lunu‐ankenda (ML) ethanolic extracts were evaluated using inhibition of α‐glucosidase and 2,2‐diphenyl‐l‐picrylhydrazyl (DPPH) radicals scavenging activity, respectively; whereas, proton nuclear magnetic resonance (¹H NMR) and ultra‐high performance liquid chromatography‐tandem mass spectrometric (UHPLC‐MS/MS) techniques were used for metabolite profiling of ML leaf extracts at different concentrations of ethanol and water. Sixty percent of ethanolic ML extract showed highest inhibitory effect against α‐glucosidase enzyme (IC₅₀ of 37 μg/mL) and DPPH scavenging activity (IC₅₀ of 48 μg/mL). Antidiabetic effect of ML extracts was also evaluated in vivo and it was found that the high doses (400 mg/Kg BW) of ML extract exhibited high suppression in fasting blood glucose level by 62.75%. The metabolites responsible for variation among ML samples with variable ethanolic levels have been evaluated successfully using ¹H‐NMR–based metabolomics. The principal component analysis (PCA) and partial least squares(PLS) analysis scores depicted clear and distinct separations into 4 clusters representing the 4 ethanolic concentrations by PC1 and PC2, with an eigenvalue of 69.9%. Various ¹H‐NMR chemical shifts related to the metabolites responsible for sample difference were also ascribed. The main bioactive compounds identified attributing toward the separation included: isorhamnetin, skimmianine, scopoletin, and melicarpinone. Hence, ML may be used as promising medicinal plant for the development of new functional foods, new generation antidiabetic drugs, as a single entity phytomedicine or in combinational therapy.     

Solvent effects on antioxidant properties of persimmon (Diospyros kaki L. cv. Daebong) seeds

The aim of this study was to investigate the antioxidant activities of persimmon seed extracts (PSE) using different solvents such as ethanol, methanol, acetone, and their aqueous 80% solvents. The EC₅₀ values of the extracts from absolute ethanol (EE) and methanol (ME) in 2, 2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical–scavenging assay were 49.71 and 51.15 μg mL^?1, respectively, while the EC₅₀ of butylated hydroxyanisole (BHA) was 70.82 μg mL^?1. However, the EC₅₀ value of reducing power for the absolute acetone extract (AE) was higher (210.06 μg mL^?1) than that of BHA (212.67 μg mL^?1). Although the absolute ME had the highest antioxidant activity, it exhibited the lowest total phenolics and flavonoids. In contrast, the antioxidant activities of the aqueous solvent extracts showed a good correlation with total phenolics and flavonoids when compared to the absolute solvent extracts. The results showed that PSE could potentially be used as an inexpensive source of natural antioxidant in food and pharmaceutical industries.     

百香果黄酮提取工艺优化及其抗氧化活性研究

采用响应面法优化从百香果果肉及果皮中超声辅助提取黄酮类化合物的提取工艺,并通过体外检测对羟自由基清除率及超氧自由基清除率,评价在最佳工艺条件下提取的黄酮类化合物的抗氧化活性。结果表明,百香果果肉黄酮化合物提取的最佳工艺为:料液比1:8 g/mL,超声时间51 min,乙醇体积分数70%;对于果皮的最佳工艺为:料液比1:47 g/mL,超声时间41 min,乙醇体积分数70%。在果肉及果皮各自的最佳提取工艺条件下,黄酮得率分别为1.04%和2.71%。当各自黄酮类化合物的浓度达到0.285 mg/mL时,其羟自由基的清除率分别达到51%和55%,超氧负离子的清除率分别到达51%和58%,表明百香果果肉及果皮中的黄酮化合物均具有较好的抗氧化活性。     

Antioxidant and tyrosinase inhibitory activities of different parts of guava (<Emphasis Type="Italic">Psidium guajava</Emphasis> L.)

The antioxidant and the tyrosinase inhibitory activities of 4 different solvents (acetone, ethanol, methanol, and water) for preparation of extracts from guava (branch, fruit, leaf, and seed) were evaluated by measuring total phenolic contents (TPC), DPPH radical scavenging activity, ABTS radical scavenging activity, reducing power (RP), and tyrosinase inhibitory activity. The extracts of branch and leaf showed relatively higher antioxidant properties than those of fruit and seed. The highest TPC (141.28 mg/g gallic acid equivalents), DPPH radical scavenging activity (IC₅₀=34.01 μg/mL), ABTS radical scavenging activity (IC₅₀=3.23 μg/mL), and RP (IC₅₀= 75.63 μg/mL) were found in acetone extract of leaf, while water extract of seed had the lowest antioxidant activity. The tyrosinase inhibitory activity of ethanol extract from guava leaf was 69.56%, which was the highest activity among the extracts. These results indicate that useful bioactive substances exist in the guava branch as well as leaf extracts.     

Antioxidant capacities of phenolic compounds and tocopherols from Tunisian pomegranate (Punica granatum) fruits

This article aims to determine the phenolic, tocopherol contents, and antioxidant capacities from fruits (juices, peels, and seed oils) of 6 Tunisian pomegranate ecotypes. Total anthocyanins were determined by a differential pH method. Hydrolyzable tannins were determined with potassium iodate. The tocopherol (α-tocopherol, γ-tocopherol, and δ-tocopherol) contents were, respectively, 165.77, 107.38, and 27.29 mg/100 g from dry seed. Four phenolic compounds were identified and quantified in pomegranate peel and pulp using the high-performance liquid chromatography/ultraviolet method: 2 hydroxybenzoic acids (gallic and ellagic acids) and 2 hydroxycinnamic acids (caffeic and p-coumaric acids). Juice, peel, and seed oil antioxidants were confirmed by ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) methods. The highest values were recorded in peels with 25.63 mmol trolox equivalent/100 g and 22.08 mmol TE/100 g for FRAP and ORAC assay, respectively. Results showed that the antioxidant potency of pomegranate extracts was correlated with their phenolic compound content. In particular, the highest correlation was reported in peels. High correlations were also found between peel hydroxybenzoic acids and FRAP ORAC antioxidant capacities. Identified tocopherols seem to contribute in major part to the antioxidant activity of seed oil. The results implied that bioactive compounds from the peel might be potential resources for the development of antioxidant function dietary food.