Evaluation of in vitro antioxidant and antidiabetic potential of extracts from Phaseolus vulgaris L. seeds (Black turtle beans)

Introduction: Phaseolus vulgaris L also known as common beans or black turtle beans are known worldwide as the most important legume for direct human consumption. Many parts of the plant are known to have important pharmacological potential against many diseases including diabetes. Despite the importance of this legume, P. vulgaris remains an underutilized and under-researched legume in Nigeria. Its therapeutic potential is being overlooked and undermined due to insufficient data on its bioactivity. These bioactive compounds present in some plant derived foods are found as fraction, crude extract, and isolated bioactive compounds that have been screened for antioxidative and antidiabetic potential. Several plant-derived foods and isolated bioactive compounds with potential antidiabetic properties are very limited.Objective: To investigate and estimate the antioxidative and antidiabetic effect of the different solvent extracts of P. vulgaris seed in vitro. Methods: Samples were subjected to antioxidant assays using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity, ferric reducing power and 2,2-azino-bis (3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) Anti-diabetic potential in vitro was estimated by evaluating various solvent extracts on α-amylase and α-glucosidase for any inhibitory effects at doses ranging from (100-500μg/ml). Characterization of possible bioactive constituent in the different solvent extract was done using FTIR spectroscopy.Results: Aqueous extract showed a higher number of total polyphenol (11.3 ± 0.01mg/gGAE) and anthocyanin content of 76.34 ± 1.12 mg/g when compared with the other solvent extract. This was followed closely by the ethanol extract with a value of 7.3±0.01Mg and 74.53 ± 0.24 Mg/g. Ascorbic acid had a significantly higher (P<0.05) activity in the antioxidant assays used. However, among the solvent extracts tested, ethanol extract displayed highest (P<0.05) for ferric reducing power activity, (80.78±0.6mg/ml), ethyl acetate, aqueous and ethanol extracts had similar DPPH activities (12.92±2.30 mg/ml, 12.59±2.33 mg/ml and 12.54±2.30mg/ml) respectively. Dichloromethane, hexane, ethanol and ethyl acetate had similar ABTS activities. (5.69±2.86 mg/ml; 6.92±0.14 mg/ml; 10.10±1.11 mg/ml; 10.76±2.98 mg/ml) respectively. All solvent extracts displayed similar inhibitory activities against α amylase. However, ethyl acetate, aqueous and ethanol extracts showed significantly (P<0.05) higher values for α-glucosidase (3.07±0.61mg/ml; 2.82±0.14mg/ml; 2.60±0.61mg/ml). The Fourier Transform infra-red spectrophotometer (FTIR) of the extracts disclosed that the presence of polyphenol and flavonoids were due to the OH stretching and the terpenes were due to the C-H group. Conclusion: In conclusion, different solvent extracts from the seed of Phaseolus vulgaris have demonstrated low antioxidative but very promising anti –diabetic activities in vitro. The ethanol extract however displayed higher activity than other solvent extracts, FT-IR results of ethanol extracts revealed the presence of flavonoids, anthocyanins and phenolics. This study may further suggest that seeds of Phaseolus vulgaris signify a functional food as well as a nutraceutical in terms of managing of Type 2 diabetes.Keyword: Phaseolus vulgaris, α amylase, α glucosidase, antioxidative

A Concise Review of Current In Vitro Chemical and Cell-Based Antioxidant Assay Methods

Antioxidants remain interesting molecules of choice for suppression of the toxic effects of free radicals in foods and human systems. The current practice involves the use of mainly synthetic molecules as potent antioxidant agents. However, due to the potential negative impact on human health, there is an intensive effort within the research community to develop natural alternatives with similar antioxidant efficacy but without the negative side effects of synthetic molecules. Still, the successful development of new molecules depends on the use of reliable chemical or cell culture assays to screen antioxidant properties. Chemical antioxidant assays include the determination of scavenging ability against free radicals such as DPPH, superoxide anion radicals, hydroxyl radicals, hydrogen peroxide, and nitric oxide. Other antioxidant tests include the ability of compounds to bind and sequester prooxidant metal cations, reduce ferric iron, and attenuate the rate of lipid oxidation. Ex vivo tests utilize cell cultures to confirm entry of the molecules into cells and the ability to quench synthetic intracellular free radicals or to stimulate the increased biosynthesis of endogenous antioxidants. In order to assist researchers in their choice of antioxidant evaluation methods, this review presents background scientific information on some of the most commonly used antioxidant assays with a comparative discussion of the relevance of published literature data to food science and human nutrition applications.

Natural Methoxyphenol Compounds: Antimicrobial Activity against Foodborne Pathogens and Food Spoilage Bacteria, and Role in Antioxidant Processes

The antibacterial and antioxidant activities of three methoxyphenol phytometabolites, eugenol, capsaicin, and vanillin, were determined. The in vitro antimicrobial potential was tested on three common foodborne pathogens (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus) and three food spoilage bacteria (Shewanella putrefaciens, Brochothrix thermosphacta, and Lactobacillus plantarum). The antioxidant assays were carried out for studying the free radical scavenging capacity and the anti-lipoperoxidant activity. The results showed that eugenol and capsaicin were the most active against both pathogens and spoilage bacteria. S. aureus was one of the most affected strains (median concentration of growth inhibition: IC50 eugenol = 0.75 mM; IC50 capsaicin = 0.68 mM; IC50 vanillin = 1.38 mM). All phytochemicals slightly inhibited the growth of L. plantarum. Eugenol was the most active molecule in the antioxidant assays. Only in the oxygen radical absorbing capacity (ORAC) test did vanillin show an antioxidant activity comparable to eugenol (eugenol ORAC value = 2.12 ± 0.08; vanillin ORAC value = 1.81 ± 0.19). This study, comparing the antimicrobial and antioxidant activities of three guaiacol derivatives, enhances their use in future applications as food additives for contrasting both common pathogens and spoilage bacteria and for improving the shelf life of preserved food.

Assessment of total (anti)oxidant status in goat kids

The redox potential of goat serum was assessed by different spectrophotometric assays. Among them, three methods are commonly applied for the evaluation of the oxidative (reactive oxygen metabolites, ROMs, and total oxidant status, TOS) and nitrosative (NO⚫ metabolites, NOx) stress, and four methods for the evaluation of the antioxidant status: the total antioxidant capacity (TAC) based on the ferric reducing ability of plasma (FRAP), the total antioxidant activity (TAA) based on the reduction of the coloured ABTS⚫+ radical cation, the free radical scavenging activity (FRSA) based on the reduction of the purple DPPH⚫, and the total thiol levels (TTLs) based on their interaction with DTNB to form a highly coloured anion. Besides, myeloperoxidase (MPO) and ceruloplasmin oxidase (CP) activities were also assessed. Except for TAA, analytical data showed a great inter-individual variation for both oxidant and antioxidant assays. ROMs were strongly correlated with CP, while TOS with MPO and TAC. Furthermore, a tendency between TOS and FRSA was shown. NOx was correlated with TAC and TAA, and a tendency with TOS was shown. No correlations appeared among the antioxidant assays, even if a tendency between TAC and TAA was evidenced, but TAC was correlated with MPO activity. The observed correlation between ROMs and CP is discussed as a possible analytical interference. The absence of correlation among the antioxidant biomarkers suggests the simultaneous use of a panel of tests to verify any changes in the redox balance, mainly in livestock in which reference values for each biomarker are lacking.

Can Chemical Analysis Predict Wine Aging Capacity?

Oxidation is the limiting factor in wine aging, and recently some famous wines have exhibited unexpected premature oxidation. Antioxidant assays may provide a means to assess a wine’s aging potential by measuring its capacity to chemically reduce reagent components. Correlations between antioxidant activity and wine components have the highest value with flavanols, notable for their catechol and phloroglucinol moieties. Both FRAP and DPPH based methods respond strongly to catechol groups, but these functional groups do not protect wine from oxidation. An ideal assay for wine aging capacity would respond selectively to thiols, phloroglucinol moieties, SO2 and other antioxidants capable of reducing quinones. A definitive test will be to compare the various assays against the shelf life of a number of commercial wines.

In Vitro and In Vivo Antioxidative Activity against Radiation-Induced Damage and the Systematic Chemical Components of Different Extracts of Lagotis brevituba Maxim

Lagotis brevituba Maxim is a perennial species distributed in the highlands of China, which has been used for more than 2000 years as a traditional Tibetan medicinal plant. However, no attention has been paid to the antioxidant activities of Lagotis brevituba Maxim in vitro or in vivo. Thus, this study aimed to evaluate the in vitro and in vivo antioxidant activity of Lagotis brevituba Maxim against radiation-induced damage as well as the systematic chemical components. To explore the relationship between the antioxidant activity and extraction solvent, Lagotis brevituba Maxim was extracted with three different solvents: methanol, water, and acetone. In antioxidant assays in vitro, the water extract had the strongest reducing power, 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity compared with the methanol and acetone extracts. However, the methanol extract was more potent in the β-carotene/linoleic acid cooxidation assay. In antioxidant assays in vivo, mice that were exposed to 6.0 Gy60Co γ-ray whole-body radiation on day 15 after administration of Lagotis brevituba Maxim decreased their level of malondialdehyde (MDA) in a dose-dependent manner compared with the control group, indicating that Lagotis brevituba Maxim had favorable antioxidant activities in vivo. In addition, a total of 44 compounds were tentatively identified by liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS/MS), including 19 flavonoids, 14 phenols, 8 phenylethanoid glycosides, 2 iridoid glycosides, and 1 carbohydrate. We obtained 25 compounds from plants in the genus Lagotis for the first time. These results suggested that Lagotis brevituba Maxim had potent antioxidant activity and could be explored as a novel natural antioxidant.

The Versatility of Antioxidant Assays in Food Science and Safety—Chemistry, Applications, Strengths, and Limitations

Currently, there is a growing interest in screening and quantifying antioxidants from biological samples in the quest for natural and effective antioxidants to combat free radical-related pathological complications. Antioxidant assays play a crucial role in high-throughput and cost-effective assessment of antioxidant capacities of natural products such as medicinal plants and food samples. However, several investigators have expressed concerns about the reliability of existing in vitro assays. Such concerns arise mainly from the poor correlation between in vitro and in vivo results. In addition, in vitro assays have the problem of reproducibility. To date, antioxidant capacities are measured using a panel of assays whereby each assay has its own advantages and limitations. This unparalleled review hotly disputes on in vitro antioxidant assays and elaborates on the chemistry behind each assay with the aim to point out respective principles/concepts. The following critical questions are also addressed: (1) What make antioxidant assays coloured? (2) What is the reason for working at a particular wavelength? (3) What are the advantages and limitations of each assay? and (4) Why is a particular colour observed in antioxidant–oxidant chemical reactions? Furthermore, this review details the chemical mechanism of reactions that occur in each assay together with a colour ribbon to illustrate changes in colour. The review ends with a critical conclusion on existing assays and suggests constructive improvements on how to develop an adequate and universal antioxidant assay.

Antioxidant and Antimicrobial Activity in Flower and Stem of Banana (Musa acuminata ‘Berangan’ and Musa X paradisiaca ‘Nangka’)

Banana plant (Musa spp.) is exploited in many researches as a potential source of therapeutic options to treat diseases. The aim of this study is to evaluate the antioxidant and antimicrobial activity of the banana flower and stem. Two selected Musa spp. banana plants were dried, powdered, and extracted using the Soxhlet method with solvents of increasing polarity, petroleum ether (PE), ethyl acetate (EA), and methanol (ME). The extracts were then subjected to antioxidant assays like DPPH, FRAP, Total Phenolic Count (TPC), and Total Flavonoid Count (TFC). The antimicrobial activity against selected microorganisms was investigated using the agar well diffusion method. The moisture content was found to be higher in banana stems compared to flowers. The banana flower extracts of increasing polarity shown a steady increase in all antioxidant assays, while the banana stem extracts were seen to vary across different antioxidant capacity assays. The highest in DPPH assay was Musa acuminata ‘Berangan’ flower (91.8%) ME extract, FRAP with Musa x Paradisiaca ‘Nangka’ stem (4393.9 mg BHT/g) PE extract, TPC (594.85 mg GAE/g) and TFC (391.01 mg QE/g) with Musa x Paradisiaca ‘Nangka’ stem EA extract. The extracts showed higher antimicrobial activity against S.aureus, followed by E.coli and E.faecalis. The EA extract of Musa x Paradisiaca ‘Nangka’ stem recorded the highest activity across the antioxidant, and antimicrobial assay carried out in this study. In conclusion, both the flower and the stem exhibited good antioxidant and antimicrobial capacity in solvent of increasing polarity.