In vitro antioxidant activity of banana (Musa spp. ABB cv. Pisang Awak)

The methanolic extract of Musa ABB cv Pisang Awak was investigated for the polyphenolic contents and antioxidant activity. The total phenol and flavonoid contents of the fruit extract were found to be 120 mg gallic acid equivalents (GAE) and 440 mg quercetin equivalents (QE)/100 g of sample dry weight, respectively. The antioxidant activity of the Pisang Awak methanol extract (PAME) (20-500 microg/ml) was determined using 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, reducing capacity, 2-2'-azinobis-3-ethylbenzothiozoline-6-sulfonic acid (ABTS) radical cation decolourization and hydroxyl radical scavenging capacity (OH*). The EC50 values of DPPH, ABTS and OH* activities of the PAME and butylated hydroxy toluene (BHT) were found to be 65 and 9 microg/ml, 29 and 6 microg/ml, 36 and 42 microg/ml respectively. The reducing capacity increased with increasing concentration (31.5-1000 mg/ml) of the fruit extract and the activity was comparable with the standard BHT. The high performance thin layer chromatography (HPTLC) analysis of the extract revealed the presence of polyphenols. The strong and positive correlations were obtained between total phenol/flavonoid contents (R2 = 0.693-1.0) and free radical scavenging ability was attributed to the polyphenols as the major antioxidants.     

Total phenolics, flavonoids and antioxidant activity of Saptarangi (Salacia chinensis L.) fruit pulp

Salacia chinensis L. has various beneficial properties including antidiabetic and antioxidant activity. The S. chinensis fruit pulp (SCFP) was extracted with four different solvents (Methanol, ethanol, acetone and water) and was screened for total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity (AOA). The AOA was assessed by evaluating the 1, 1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and metal chelating assay. Methanolic SCFP extract exhibited the highest phenolic content (3.20?±?0.12 mg GAE/g FW) whereas, ethanolic extract showed highest flavonoid content (0.31?±?0.68 mg RE/g FW). The methanolic extract possesses highest antioxidant activity towards DPPH (92.44 %), FRAP (1.939 O.D) and metal chelating activity (74.16 %). AOA (DPPH and FRAP) was significantly correlated with TPC. The results indicated that SCFP is a good natural source of antioxidant compounds for use in food and pharmaceutical industry.     

Antioxidant and free radical scavenging properties of N-acetylcysteine amide (NACA) and comparison with N-acetylcysteine (NAC)

The antioxidant potential of N-acetylcysteine amide (NACA), also known as AD4, was assessed by employing different in vitro assays. These included reducing power, free radical scavenging capacities, peroxidation inhibiting activity through linoleic acid emulsion system and metal chelating capacity, as compared to NAC and three widely used antioxidants, α-tocopherol, ascorbic acid and butylated hydroxytoluene (BHT). Of the antioxidant properties that were investigated, NACA was shown to possess higher 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging ability and reducing power than NAC, at all the concentrations, whereas the scavenging ability of H₂O₂ differed with concentration. While NACA had greater H₂O₂ scavenging capacity at the highest concentration, NAC was better than NACA at lower concentrations. NAC and NACA had a 60% and 55% higher ability to prevent β-carotene bleaching, respectively, as compared to control. The chelating activity of NACA was more than 50% that of the metal chelating capacity of EDTA and four and nine times that of BHT and α-tocopherol, respectively. When compared to NACA and NAC; α-tocopherol had higher DPPH scavenging abilities and BHT and α-tocopherol had better β-carotene bleaching power. These findings provide evidence that the novel antioxidant, NACA, has indeed enhanced the antioxidant properties of NAC.     

栎生桑黄和忍冬桑黄液体培养过程中发酵液抗氧化能力

桑黄孔菌属Sanghuangporus是药用木生真菌资源中一个重要的属,但是该属仅有少数几个种类被用于人工栽培,且栽培面积较小。此外,桑黄孔菌属中大部分种类的药用功能仍未完全明确。因此,本研究以桑黄孔菌属近期新发表的新种栎生桑黄S. quercicola和关注度较低的忍冬桑黄S. lonicericola为主要研究对象,通过测定它们液体培养过程中第2、4、6、8、10、12和14天的菌丝生物量以及发酵液的粗多糖含量、多酚含量、黄酮含量、抗坏血酸含量、DPPH自由基清除能力、ABTS自由基清除能力、总抗氧化能力、超氧化物歧化酶活性、羟自由基清除能力、超氧阴离子清除能力、铁离子还原能力和亚铁离子螯合能力等12个抗氧化指标,对桑黄的抗氧化能力进行评定。2种桑黄真菌各选取一号菌株,其发酵液均表现出强抗氧化能力。相比之下,栎生桑黄的多糖、抗坏血酸和超氧化物歧化酶含量更高,而忍冬桑黄的多酚和黄酮含量更高。相应的,栎生桑黄和忍冬桑黄在其他一些抗氧化指标上也表现出强弱程度及出现时间的差异。上述研究结果为桑黄孔菌属真菌的药用功能开发提供了新资源,为不同抗氧化代谢产物的分离纯化提供了科学依据。     

In vitro free radical scavenging activity of wild edible mushroom, Pleurotus squarrosulus (Mont.) Singer

Cellular damage caused by reactive oxygen species has been implicated in several diseases and hence antioxidants have significant importance in human health. Cold water, hot water and methanolic extract of Pleurotus squarrosulus were evaluated for antioxidant activity against hydroxyl radical, DPPH (1,1-Diphenyl-2-picrylhydrazyl) radical, superoxide radical, nitric oxide (NO) scavenging, reducing power, ferrous ion chelating ability and beta-carotenellinoleic acid assay. Total phenol, flavonoid, beta-carotene and lycopene content were also determined. Hot water extract showed significant antioxidant activity in all the test systems. Hydroxyl radical scavenging activity of all the extracts has been significant compared to positive control. Hot water extract has been found to have higher phenolic, total flavonoid, beta-carotene and lycopene content than cold water and methanolic extract of the mushroom. Results of this study showed that, hot water extract has maximum antioxidant property and may be utilized as a promising source of therapeutics.     

Effect of eco-safe compounds on postharvest quality preservation of papaya (<Emphasis Type="Italic">Carica papaya</Emphasis> L.)

Early ripening and susceptibility to microbial infection are major postharvest problems in papaya fruits. Being a tropical climacteric fruit, low-temperature storage is not successful in papaya. In this study, we demonstrate the effect of aqueous salicylic acid (1 and 2 mM), nitric oxide (1 and 2 mM), and calcium chloride (1 and 2%) to enhance the papaya shelf life at the ambient conditions with reduced disease incidence. Calcium chloride 2% was the most effective for maintaining postharvest quality. The fruits had good firmness and maintained TSS, acidity, total chlorophyll, free radical scavenging activity and ascorbic acid on the 6th day during ambient storage. Moreover, the weight loss, yellow color development and disease incidence were minimum in calcium chloride 2%, followed by 1% solution of calcium chloride. The nitric oxide (2 mM) maintained higher antioxidant capacity and total phenol content in fruits that was followed by 1 mM salicylic acid during storage. The result suggests that application of calcium chloride 2% could be an easy and effective technique for extending the shelf life without impairing fruit quality during storage.     

The induction of salt stress tolerance by propyl gallate treatment in green microalga <Emphasis Type="Italic">Dunaliella bardawil</Emphasis>, through enhancing ascorbate pool and antioxidant enzymes activity

The effect of propyl gallate (PG), a synthetic antioxidant, on antioxidant responses and salinity tolerance was investigated in the cells of the green microalga, Dunaliella bardawil. Algal suspensions grown at three salinity levels of 1, 2, and 3 M NaCl were incubated with 1 mM of PG. The number of cells was significantly lower in all PG-treated cells compared to untreated controls. Despite PG-induced cell death, the fresh weight of all PG-treated cells was considerably higher than controls. PG-treated cells had enhanced antioxidant capacity because of increased levels of Chlorophyll a, β-carotene, reduced ascorbate, protein, and enzymatic activities, but accumulated lower levels of malonyldialdehyde and hydrogen peroxide compared to untreated cells. The results suggest that PG acts as a signal molecule both directly by reducing of free radical oxidants and indirectly by augmenting ascorbate pool levels, β-carotene production, and antioxidant enzymes activity to boost the capacity of antioxidant systems and radical oxygen species scavenging. Therefore, induction of salt stress tolerance by PG in D. bardawil is associated with metabolic adjustments through activation or synthesis of both enzymatic and non-enzymatic molecules involved in antioxidant systems.     

Radical scavenging activities of Heracleum aquilegifolium Wight (Apiaceae) fruit oils in vitro

The fruits of Heracleum aquilegifolium Wight (Apiaceae) were collected from Western Ghats of the Indian Peninsula. The essential oils were extracted by hydrodistillation. The chemical composition of the essential oils was analysed by gas chromatography and gas chromatography-mass spectrometry (GC-MS). Beta-Pinene (22.3%), 1,8-cineole (20.3%), and beta-phellandrene (12.4%) were the main components of H. aquilegifolium fruit oils. The antioxidant properties of essential oils of H. aquilegifolium were examined by different procedures namely reducing power ability, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, nitric oxide radical scavenging activity, hydrogen peroxide scavenging activity, hydroxyl radical scavenging activity, superoxide anion scavenging activity, and metal chelating activity. The antioxidant activities were compared with those of synthetic antioxidants and standard drugs such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), ascorbic acid, alpha-tocopherol, curcumin, and quercetin. The study confirmed the possible antioxidant potential of essential oils tested with various in vitro antioxidant methods. The presence of monoterpenes in combination with other components in the oils could be responsible for the activity.     

Improved functional and nutritional properties of tomato fruit during cold storage

The use of synthetic antioxidants has been associated with serious concerns for human and environmental health. During ripening stages, tomato fruit is exposed to different abiotic stresses which not only influence its nutritional, mechanical, and functional properties at harvest, but also affect the quality and shelf life of the fruit during storage. This study investigated the pattern of changes in dietary antioxidants during various ripening stages of tomato fruit (cv. Red Rose) and their impact on storage behavior of the fruit during cold storage. Tomato fruits were harvested at mature green, breaker, turning, pink, light-red and red stages of maturity. Then, they were analysed for flesh firmness, soluble solids content, titratable acidity, total sugars, pH, dry matter content, lipophilic (lycopene, β-carotene, and total carotenoids), and hydrophilic (ascorbic acid, phenolic and flavonoids) antioxidants. Additional fruits were harvested at each maturity stage and divided into three equal lots, then were subjected to low-temperature (10 ± 1 °C) storage with 80 ± 5% RH, for 7, 14, and 21 days. Flesh firmness, and the levels of dietary antioxidants were analysed following the subsequent storage periods. The results revealed that the peak of hydrophilic antioxidants such as ascorbic acid, phenolic compounds, and flavonoids was between the ‘pink’ and the ‘light-red’ stages of fruit maturity. Whereas tomatoes harvested at the ‘red’ stage of maturity had the highest levels of lycopene and β-carotene. Both the stage of fruit maturity at harvest and duration of cold storage influenced flesh firmness, organoleptic and functional properties of ‘Red Rose’ tomato fruit. In conclusion, the results of the current investigation have practical implications in formulating foods with improved functional properties at processing industries.     

Antioxidants characterization in selected cyanobacteria

Antioxidants—molecules that have the ability to inhibit the oxidation of other molecules and have many medicinal and industrial applications—are commonly found in algae. Due to the harmful effects of common synthetic antioxidants, their replacement with natural antioxidants would be advantageous. The goal of this study was to examine the efficacy of antioxidants (including antioxidant content, antioxidant activity and antioxidant enzymes) among 11 species of freshwater blue-green algae. Antioxidant activities were evaluated by assaying radical scavenging activity, reducing power and chelating activity. The results showed that Spirulina platensis has the highest radical scavenging activity and reducing power (524 and 244 % more than the control, respectively) and Nostoc linkia has the highest chelating activity (195 %). Examination of some antioxidant contents such as chlorophyll a, carotenoids and phenolic content revealed that S. platensis has the highest contents [10.6 mg/g dry weight (DW), 2.4 mg/g DW and 9.7 mg gallic acid equivalent /g DW, respectively]. The positive correlation (P <0.01) between algal content and antioxidant activity may be attributed to the potent antioxidant activity of these contents. Variation in the activity of three antioxidant enzymes (superoxide dismutase, catalase and peroxidase) was also reported. This study showed that the Cyanobacteria are promising sources of antioxidants.     

CuO nanoparticles significantly influence in vitro culture,steviol glycosides,and antioxidant activities of <Emphasis Type="Italic">Stevia rebaudiana</Emphasis> Bertoni

Copper oxide (CuO) nanoparticles (NPs) synthesized through co-precipitation method were employed in MS media during in vitro culture of Stevia rebaudiana. Physiological characteristics, production of steviol glycosides, and antioxidative parameters were investigated in regenerated plants. CuO NPs had crystalline monoclinic cubic cuprous oxides with average size 47 nm. The NPs were applied at 0, 0.1, 1.0, 10, 100 and 1000 mg/L in MS media for direct organogenesis of S. rebaudiana from nodal segments. Shoot organogenesis was found highest (88.5%) at 10 mg/L CuO and average shoot length, mean number of shoot per explant, and fresh weight were also found significantly higher at the same concentration. High performance liquid chromatography (HPLC) illustrated significant rise of bioactive major steviol glycosides (rebaudioside A and stevioside) at 10 mg/L CuO NPs in MS media. The oxidative stress produced by CuO nanoparticles on S. rebaudiana was affirmed by antioxidant activities i.e. total antioxidant activity (TAC), total reducing power (TRP) and 2,2-diphenyl-1-picryl hydrazyl (DPPH)-free radical scavenging activity. The oxidative stress generated by NPs involved production of antioxidative molecules total phenolic content (TPC), total flavonoid content (TFC) depending on NPs concentration. The study concludes that copper oxide nanoparticles functions as a stimulator of bioactive components productions, and can be employed in in vitro batch cultures.     

Alterations in metabolite profile and free radical scavenging activities of <Emphasis Type="Italic">Withania somnifera</Emphasis> leaf and root extracts under supplemental ultraviolet-B radiation

The effects of supplemental ultraviolet-B (s-UV-B; 3.6 kJ m^?2 day^?1 above ambient) radiation on plant metabolite profile and free radical scavenging activities of Withania somnifera (an indigenous medicinal plant) under field conditions were investigated. The metabolite profiles of both leaves and roots were analyzed via GC–MS. The methanolic extracts were examined for their DPPH radical-, superoxide radical-, hydrogen peroxide-, hydroxyl radical-, and nitric oxide radical scavenging activities, ferrous ion chelating activity, and reducing power. GC–MS profile of leaves revealed increment in compounds such as isophytol (138.1 %), β-stigmasterol (183.05 %), trans-squalene (233.3 %), and Withaferin A (155.0 %), while compounds such as eugenol, β-carotene, lycopene, and vitamin E were detected in s-UV-B-treated leaves only. In roots, compounds such as ledol, neophytadiene, palmitic acid, retinol, sitosteryl oleate, and campesterol registered their presence only under s-UV-B. Methanolic extracts of treated plant organs were found to be more potent as free radical scavengers (their EC₅₀ values being lower than those of control extracts). Anomalies were observed for nitric oxide radical scavenging in both leaves and roots. The present study indicates that s-UV-B alters the composition and contents of plant metabolites leading to an increase in their free radical scavenging activities. Hence, s-UV-B-treated plant organs might be more effective in combating oxidative stress as well as from a nutritional and health perspective.     

Antioxidant and free radical scavenging properties of N-acetylcysteine amide (NACA) and comparison with N-acetylcysteine (NAC)

The antioxidant potential of N-acetylcysteine amide (NACA), also known as AD4, was assessed by employing different in vitro assays. These included reducing power, free radical scavenging capacities, peroxidation inhibiting activity through linoleic acid emulsion system and metal chelating capacity, as compared to NAC and three widely used antioxidants, alpha-tocopherol, ascorbic acid and butylated hydroxytoluene (BHT). Of the antioxidant properties that were investigated, NACA was shown to possess higher 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging ability and reducing power than NAC, at all the concentrations, whereas the scavenging ability of H(2)O(2) differed with concentration. While NACA had greater H(2)O(2) scavenging capacity at the highest concentration, NAC was better than NACA at lower concentrations. NAC and NACA had a 60% and 55% higher ability to prevent beta-carotene bleaching, respectively, as compared to control. The chelating activity of NACA was more than 50% that of the metal chelating capacity of EDTA and four and nine times that of BHT and alpha-tocopherol, respectively. When compared to NACA and NAC; alpha-tocopherol had higher DPPH scavenging abilities and BHT and alpha-tocopherol had better beta-carotene bleaching power. These findings provide evidence that the novel antioxidant, NACA, has indeed enhanced the antioxidant properties of NAC.     

Investigations on diverse sesame ( S. indicum L.) germplasm and its wild allies reveal wide variation in antioxidant potential

Free radicals, the key mediators of a range of oxidative reactions involved in lipid oxidation are responsible for food quality deterioration leading to several health hazards. Antioxidants synthesized naturally or synthetically are capable of preventing oxidation of lipids and other related compounds. However, natural antioxidants have many benefits over synthetic ones. Sesame seeds contain large amount of natural bioactive components with high antioxidant potential. In the present study, 14 accessions of sesame containing wild species and cultivars were investigated. The antioxidant potential of sesame seed meal extract was evaluated by total phenolic content (TPC) method using Folin–Ciocalteu reagent, linoleic acid peroxidation by Ferric thiocyanate method, and free radical scavenging assay with 2,2-diphenyl-1-picryl hydrazyl radical. S. laciniatum showed highest mean values for total polyphenol content with maximum % inhibition of linoleic acid peroxidation on 10th day of course of the reaction span and highest antioxidant scavenging power. S. indicum subsp. malabaricum and S. radiatum also showed high total phenol content and radical scavenging capacity. Among the Sesamum indicum cultivars, Gujarat til 2 showed high TPC and high radical scavenging activity. Higher antioxidant property of Sesamum species in comparison to sesame cultivars highlights the need to utilize the wild genepool for the improvement of cultigens for enhanced nutraceutical value.     

7种广西产甜茶抗氧化活性的比较

通过清除二苯代苦味酰基(1,1-diphenyl-2-picrylhydrazyl,DPPH)法、铁离子还原测定(ferric reducing antioxidant power,FRAP)法、亚铁离子螯合(ferrous ion-chelating,FIC)法、β-胡萝卜素-亚油酸法等4种体外抗氧化活性测定方法,首次比较了3种茶科属茶叶和7种广西产甜茶水提物的抗氧化活性,同时用Folin-Ciocalteus法测定了其总多酚的含量。研究结果表明,多穗柯甜茶和藤茶的总多酚含量高于其他供试品。藤茶具有很好的清除DPPH·的能力,高于绿茶及阳性对照水溶性维生素E(Trolox)和人工合成抗氧化剂二丁基羟基甲苯(butylated hydroxytoluene,BHT)。甜叶菊茶和悬钩甜茶的金属离子螯合能力均高于绿茶。其中,黄杞和牛白藤两种植物的抗氧化活性为首次报道。由此可见,广西产甜茶均具有较高的开发利用价值,是治疗和防治慢性代谢性疾病的重要研究对象。对广西产甜茶的研究对于了解和抢救某些少数民族的历史文化具有重要意义,为别样茶的抗氧化研究奠定了基础,值得进一步探索和开发。     

Synthesis of dimeric phenol derivatives and determination of in vitro antioxidant and radical scavenging activities

In this study, di(2,6-dimethylphenol) (Di-DMP), di(2,6-diisopropylphenol) (Di-DIP, dipropofol) and di(2,6-di-t-butylphenol) (Di-DTP) were synthesized by the reaction of monomeric phenol derivatives with catalytic CuCl(OH). TMEDA and Na₂S₂O₄. Their antioxidant capacity and radical scavenging activity were examined using different in vitro methodologies such as 1,1-diphenyl-2-picryl-hydrazyl (DPPH·) free radical scavenging, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity by ferric thiocyanate, total reducing power by potassium ferricyanide reduction method, superoxide anion radical scavenging, hydrogen peroxide scavenging and ferrous ions chelating activities.     

Non-destructive assessment of flesh firmness and dietary antioxidants of greenhouse-grown tomato (Solanum lycopersicum L.) at different fruit maturity stages

Non-destructive methods have been widely recognized for evaluating fruit quality traits of many horticultural crops and food processing industry. Destructive (analytical) test, and non-destructive evaluation of the quality traits were investigated and compared for ‘Red Rose’ tomato (Solanum lycopersicum L.) fruit grown under protected environment. Fresh tomato fruit at five distinctive maturity stages namely; breaker (BK), turning (TG), pink (PK), light-red (LR), and red (RD) were labeled and scanned using the handheld near infra-red (NIR) enhanced spectrometer at a wavelength range of 285–1200 nm. The labeled tomato samples were then measured analytically for flesh firmness, lycopene, β-carotene, total phenolic content (TPC) and total flavonoids content (TFC). The results revealed that quality traits could be estimated using NIR spectroscopy with a relatively high coefficient of determination (R²): 0.834 for total phenolic content, 0.864 for lycopene, 0.790 for total flavonoid content, 0.708 for β-carotene; and 0.679 for flesh firmness. The accumulation of Lyco and β-Car rapidly increased in tomatoes harvested between the TG and the LR maturity stages. Harvesting tomatoes at BK maturity stage resulted in significantly higher flesh firmness than harvesting at the later maturity stages. Tomato fruits had the lowest TPC and TFC contents at the earliest maturity stage (BK), while they had intermediate TPC and TFC levels at LR and RD maturity stages. NIR spectroscopic measurements of fruit firmness and lipophilic antioxidants in tomato fruit at various maturity stages were partially in accordance with those estimated by destructive (analytical) methods. Based on these findings, we recommend using non-destructive NIR spectroscopy as an effective tool for predicting tomato fruit quality during harvest stage and postharvest processing.     

Synthesis of dimeric phenol derivatives and determination of in vitro antioxidant and radical scavenging activities

In this study, di(2,6-dimethylphenol) (Di-DMP), di(2,6-diisopropylphenol) (Di-DIP, dipropofol) and di(2,6-di-t-butylphenol) (Di-DTP) were synthesized by the reaction of monomeric phenol derivatives with catalytic CuCl(OH). TMEDA and Na2S2O4. Their antioxidant capacity and radical scavenging activity were examined using different in vitro methodologies such as 1,1-diphenyl-2-picryl-hydrazyl (DPPH*) free radical scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity by ferric thiocyanate, total reducing power by potassium ferricyanide reduction method, superoxide anion radical scavenging, hydrogen peroxide scavenging and ferrous ions chelating activities.     

Antioxidant activity of brown alga Saccharina bongardiana from Kamchatka (Pacific coast of Russia). A methodological approach

The present study aims to investigate the levels of polyphenols and antioxidant activity in one of the most important commercial species of seaweeds in Kamchatka, an edible brown seaweed Saccharina bongardiana. Six extracts of S. bongardiana, acetone, methanol, ethanol, and the respective 70 % aqueous solutions, were assessed for total phenol content in order to determine the most efficient extracting solvent. The total phenol content was measured by the Folin–Ciocalteu method and expressed as phloroglucinol equivalents (PGE). The antioxidant tests used were 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, linoleic acid-β carotene oxidation inhibiting assay, and Fe²⁺ ion chelating method. Higher phenolic contents were obtained using aqueous organic solvents, as compared to the respective absolute solvents; 70 % acetone was found to be the most efficient solvent (1.039 mg PGE 100 mg^?1 dry algal powder). High significant correlations were noted between total phenol content and the tested antioxidant activities; so the aqueous organic extracts exhibited the highest antioxidant activities versus DPPH radicals (EC₅₀ values of 0.6–1.1 mg dry weight (DW) mL^?1), linoleic acid-β carotene oxidation (74–78 % at 0.8 mg DW mL^?1), as well as ferrous ions (EC₅₀ values of 5.0–7.9 mg DW mL^?1). Some methodological recommendations regarding the assays used and the expression of results are proposed.     

青橄榄浸膏的提取及其抗氧化活性研究

为优化青橄榄浸膏提取工艺,并探讨其抗氧化性。以茂名盛产的青橄榄为原料,采用超声波辅助乙醇提取法,以总黄酮和总多酚得率为评价指标,考察各因素对青橄榄浸膏提取效果的影响。采用邻苯三酚自氧化法、结晶紫法和DPPH清除能力评价青橄榄浸膏的抗氧化活性。结果显示,浸膏的最佳提取工艺为:乙醇体积分数70%,料液比1∶18 (g∶mL),超声提取温度50℃,时间6 min(超声提取阶段);单纯有机溶剂提取温度60℃,时间45 min(有机溶剂浸提阶段);此条件下总黄酮得率为1. 76%,总多酚得率为15. 53%。终产物浸膏在0. 3 mg/mL浓度下对超氧阴离子自由基抑制率为22. 74%,相当于同等质量浓度的抗坏血酸抑制效果的23. 47%;在0. 02 mg/mL浓度下对羟基自由基的清除率为67. 32%,相当于同等质量浓度的抗坏血酸清除效果的112. 58%;在0. 2 mmol/mL的DPPH溶液体系中,0. 15 mg/mL的浸膏对DPPH的清除率为95. 40%,相当于同等质量浓度的抗坏血酸清除效果的140. 83%;总体来讲,浸膏具有良好的抗氧化能力,虽然对超氧阴离子自由基抑制率弱于抗坏血酸,但羟基自由基的清除率及DPPH清除率均优于抗坏血酸。