Anwar Hussein Subratty

Antioxidant and anti–glycation activities correlates with phenolic composition of tropical medicinal herbs

OBJECTIVE To determine the contribution of total phenolic content (TPC) in glycation inhibitory activity of common tropical medicinal food and spices with potential antioxidative properties. METHODS In vitro glucose-bovine serum albumin (BSA) assay was used. Ethanolic extracts of ten common household condiments/herbs (Allium sativum, Zingiber officinale, Thymus vulgaris, Petroselinum crispum, Murraya koenigii Spreng, Mentha piperita L., Curcuma longa L., Allium cepa L., Allium fistulosum and Coriandrum sativum L.) were evaluated for antioxidative activity by 2,2-diphenyl-2-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) and the TPC, flavonoid and tannins content were determined. RESULTS Findings showed good correlation between TPC/DPPH (r = 0.8), TPC/FRAP (r = 0.8), TPC/anti-glycation (r = 0.9), DPPH/anti-glycation (r = 0.6), FRAP/anti-glycation (r = 0.9), Flavonoid/anti-glycation (r = 0.7) and Tannins/anti-glycation (r = 0.8) and relatively fair correlation for TPC/Flavonoids (r = 0.5) and TPC/Tannins (r = 0.5). Results imply that these plants are potential sources of natural antioxidants which have free radical scavenging activity and might be used for reducing oxidative stress. CONCLUSIONS The positive glycation inhibitory and antioxidative activities of these tropical herbs suggest a possible role in targeting ageing, diabetic complications and oxidative stress related diseases.

Antimicrobial Activities and Phytochemical Profiles of Endemic Medicinal Plants of Mauritius

Abstract Medicinal plants are assuming widespread use in the primary health care of individuals and communities. In the current study, we investigated the antimicrobial activities of two endemic plants, Antidesma madagascariense. Lam. and Erythroxylum macrocarpum. O. E. Schulz, which form part of the local pharmacopoeia of Mauritius. Aqueous and methanol extracts of the leaves and twigs of both plants were tested in vitro. against three Gram-negative and five Gram-positive strains of bacteria, including a resistant strain of bacteria. Moreover, they were subjected to antifungal assays against Candida albicans. ATCC 10231 and Aspergillus niger. ATCC 16404, a human and a plant pathogenic microorganism, respectively, known to be good indicators of antifungal activity. It was found that aqueous extracts of both plants possess broad-spectrum antibacterial properties against the test organisms compared to methanol extracts, which gave poor inhibition zones. Moreover, the antibacterial substance within these plants seemed to be most prominent in the leaves and least in the twigs, and the best inhibitory activity was observed for Gram-positive bacteria (Staphylococcus aureus. ATCC 25923). Aqueous extracts of both plants do not possess antifungal properties except the methanol extract against A. niger.. Phytochemical screening of the plants showed the presence of at least tannins, phenols, flavonoids, and alkaloids, which are known antimicorbial compounds. In conclusion, the observed antimicrobial properties would tend to further validate the medicinal properties of these commonly used endemic medicinal plants in Mauritius.

Screening for Alternative Antibiotics: An Investigation into the Antimicrobial Activities of Medicinal Food Plants of Mauritius

The present study was designed to evaluate the antimicrobial activities of 2 endemic medicinal plants; Faujasiopsis flexuosa (Asteraceae) (FF) and Pittosporum senacia (Pittosporaceae) (PS) and 2 exotic medicinal plants, Momordica charantia (Cucurbitaceae) (MC) and Ocimum tenuiflorum (Lamiaceae) (OT) that forms part of local pharmacopoeia of Mauritius and correlate any observed activity with its phytochemical profile. Aqueous and organic fractions of the leaves, fruits, and seeds of these plants were subjected to antimicrobial testing by the disc diffusion method against 8 clinical isolates of bacteria and 2 strains of fungus. It was found that MC, OT, and FF possessed antimicrobial properties against the test organisms. The MIC for MC ranged from 0.5 to 9 mg/mL and that of FF from 2 to 10 mg/mL and the lowest MIC value (0.5 mg/mL) was recorded for the unripe fruits of MC against E. coli. On the other hand, higher concentration of the unripe MC fruit extract of 9 mg/mL was needed to be effective against a resistant strain of Staphylococcus aureus (MRSA). The antimicrobial effect against MRSA was lost upon ripening of the fruits. The methanolic extract of both MC and FF showed highest MIC values compared to the corresponding aqueous extract, which indicates the low efficacy and the need of higher doses of the plant extract. Phytochemical screening of the plants showed the presence of at least tannins, phenols, flavonoids, and alkaloids, which are known antimicrobial phyto-compounds. In conclusion, the observed antimicrobial properties would tend to further validate the medicinal properties of these commonly used endemic medicinal and food plants of Mauritius.

Bitter melon: an exotic vegetable with medicinal values

Purpose – This article focuses on some of the reported medicinal values of bitter melon, an exotic vegetable forming part of the cuisine of various countries.Design/methodology/approach – Available data in the literature strongly support the anti‐hypoglycaemic properties of Bitter melon. A literature view was carried out and the data were used to validate our findings regarding the effects of extracts of Momordica charantia on uptake of sugar.Findings – Our work adds on to the growing evidence of the anti‐diabetic properties of bitter melon.Practical implications – In view of evidence reported in the literature regarding the medicinal properties of vegetables, the importance of vegetables in a well balanced diet should therefore be strongly advocated.Originality/value – This paper adds on to the evidence of the use of Momordica charantia as a medicinal plant in traditional medicine in the control of blood sugar level.

Relationship Between Total Phenolic Content, Antioxidant Potential, and Antiglycation Abilities of Common Culinary Herbs and Spices

Advanced glycation endproducts and oxidative stress contribute to the pathogenesis of diabetic complications. The total phenolic content (TPC), antioxidant, and antiglycation properties of crude ethanolic extracts of 10 common culinary herbs and spices from Mauritius were investigated in vitro. Fluorescence at 370 nm/440 nm was used as an index of albumin glycation. Allium sativum had the highest TPC (3.1 mg GAE/mL), whereas Allium cepa L. showed the highest radical scavenging capacity (72%) and Zingiber officinale had the most potent ferric-reducing antioxidant power (FRAP; 2.99 mg AAE/mL). In contrast, Thymus vulgaris and Petroselinum crispum had the most potent antiglycation activity with IC(50) values of 21.8 and 200 mg/mL, respectively. There was no significant correlation between TPC (r=0.001), FRAP (r=0.161), and the antiglycation activity (r=0.034) for the extracts studied. Therefore, the results showed that antiglycation properties of plant-derived extracts cannot always be attributed to their phenolic content or antioxidant potential.

Antioxidant, antiglycation and cytotoxicity evaluation of selected medicinal plants of the Mascarene Islands

BackgroundMany indigenous plants of Mascarene Islands have been used in folkloric medicine to manage diabetes but few species have received scientific attention. Selected traditional medicinal plants (Antidesma madagascariense Lam. -Euphorbiaceae (AM), Erythroxylum macrocarpum O.E.Schulz -Erythroxylaceae (EM), Pittosporum senacia Putterl -Pittosporaceae (PS), Faujasiopsis flexuosa Lam. C.Jeffrey -Asteraceae (FF), Momordica charantia Linn -Cucurbitaceae (MC) and Ocimum tenuiflorum L -Lamiaceae (OT) were evaluated for their antioxidant, antiglycation and cytotoxic potential in vitro.MethodsGraded concentrations (1.25-100 μg/mL) of the crude methanolic and water extracts and fractions (dichloromethane, ethyl-acetate, n-butanol and water) were evaluated for abilities to scavenge 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH), nitric oxide (NO), superoxide (SO) radicals and to inhibit lipoxygenase and formation of advanced glycation endproduct (AGE) in vitro. The MTT (3-(4, 5-dimethylthazol-2-yl)-2,5-diphenyl tetrazonium bromide) cytotoxicity test was performed on 3T3 cell line.ResultsOnly IC50 for DPPH, SO, NO and lipoxygenase for AM, FF and OT crude extracts and fractions were comparable to ascorbic acid and quercetin activity. Crude aqueous extracts of AM and FF showed IC50 of 4.08 and 3.89 μg/mL respectively for lipoxygenase which was significantly lower (p < 0.05) than quercetin (10.86 ± 0.68 μg/mL). The three crude aqueous extracts of these plants and their n-butanol fractions also showed antiglycation activities (p < 0.05) comparable to aminoguanidine. Increasing concentrations (250-2000 μg/mL) of the six crude extracts (Methanol and water) and their fractions did not inhibit mitochondrial respiration as measured by MTT cytotoxicity assay.ConclusionAM, FF and OT crude extracts and fractions have potent antioxidant and antiglycation properties with no apparent cytotoxicity and might have prophylactic and therapeutic potentials in the management of diabetes and related complications. Our study tends to validate the traditional use of these medicinal herbs and food plants as complementary and alternative medicines.

Experimental evidence for in vitro fluid transport in the presence of a traditional medicinal fruit extract across rat everted intestinal sacs

The present study was designed to investigate the effects of aqueous fruit extract of Momordica charantia (MC), a traditional medicinal plant, on the transport of fluid in vitro. Everted intestinal sacs from rats were mounted in an organ bath containing Krebs solution. We compared the effect of MC extract on water transport with increasing inorganic phosphate concentration with or without d‐glucose in the buffer. In the control experiments, fluid uptake was enhanced significantly (P < 0.05) at high inorganic phosphate concentration (8–10 mm) in the presence of 5.5 mmd‐glucose. Addition of 3.0 mg/mL MC extract to the serosal side inhibits the uptake of fluid significantly (P < 0.05). At high inorganic phosphate concentration (8–10 mm), fluid uptake was not inhibited (P > 0.05) when incubated with 3.0 mg/mL MC fruit extract. It is hypothesized that an increase in inorganic phosphate enhances oxidative phosphorylation thereby increasing the fluid uptake across everted intestinal sacs of rat. These findings seem to indicate that the MC‐induced reduction on intestinal fluid absorption capacity could be mainly the result of an interference with the carrier‐mediated coupled entrance of glucose and Na+ across the brush‐border membrane.

Stimulatory effects of Antidesma madagascariense on D-glucose, L-tyrosine, fluid and electrolyte transport across rat everted intestine, comparable to insulin action in vitro.

Abstract Medicinal plants are believed to be an important source of potential therapeutic agents. This study investigates the effects of Antidesma madagascariense (AM) extract on the transport of D-glucose, L-tyrosine, fluid and electrolytes (Na+ and K+) across rat everted intestinal sacs. These sacs were mounted in an organ bath containing Krebs-Henseleit bicarbonate (KHB) buffer. Experimental findings showed that incubation with graded aqueous AM extracts above 0.375 mg/mL significantly (P<0.05) stimulated the mucosal disappearance and serosal appearance of glucose and fluid. The concentration of glucose accumulated in the intestinal tissues also increased significantly (P<0.05) compared to that found in the controls. Transport of the amino acid L-tyrosine was not significantly enhanced (P>0.05) when incubated with increasing concentrations of AM extract. Effects on electrolyte (K+ and Na+) transport were assessed. Na+ uptake and transport was significantly enhanced (P<0.05) when incubated with 0.75 mg/mL AM extract; however, K+ transport was not significantly enhanced (P>0.05). For comparison, insulin (1 and 2 units/mL) was incubated in the mucosal solution. Aqueous AM extract produced similar stimulatory effects on the transport of glucose, fluid and Na+ as were found with insulin. It is hypothesised that bioactive phytochemicals such as flavonoids, alkaloids, leucoanthocyanins, phenols and saponins from AM leaf extract might interfere with the Na+/glucose carrier, thereby enhancing the transport of glucose, Na+ and fluid across rat everted intestinal sacs. Thus, AM may represent a possible alternative dietary supplement for the treatment of type 2 diabetes.

In vitro Anti-glycation and Anti-oxidant Properties of Synthesized Schiff Bases

A series of mono, bis and mixed Schiff bases (1-7) were synthesised and evaluated for potential anti-glycation and anti-oxidant activities using the bovine serum albumin-glucose assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical assay respectively. All compounds showed significant (p<0.05) antiglycating activities with IC50 values (4.02x10(-24)±0.1-2.88x10(-1)±1.35 mM) which were lower than the standard positive control aminoguanidine (IC50: 1.51x10(-3)±2.11 mM). Moreover, compounds 1-7 were found to possess significant (p<0.05) DPPH radical scavenging properties with SC50 values (1.31x10(-19)±0.05 to 2.25x10(-1)±1.24 mM) lower than the standard ascorbic acid (SC50: 5.50x10(-3)±2.11 mM). Compound 6 was found to be the most potent anti-glycating molecule (IC50 value: 4.02x10(-24)±0.1 mM) while compound 5 was the most potent anti-oxidant molecule (SC50: 1.31x10(-19)±0.05 mM); both being significantly lower (p<0.05) than the respective positive controls used. The present data showed that the number of phenolic OH together with structural changes influence both the anti-glycation and anti-oxidant observed herein. This study provides for the first time a series of potential template molecules for possible pharmaceutical applications that warrant further investigation as potential anti-glycation and anti-oxidant agents which could be of importance in metabolic diseases including diabetes mellitus.

Motives Underlying Healthy and Unhealthy Eating Among University Students in Mauritius

Panoply of influences operates to shape particular food choices. Thus, probing into the drivers of people’s healthy food choices is primordial to addressing the public health issue of obesity. The aim of the current study was to investigate the factors that influence University students’ choice for healthy and unhealthy foods. For the cross-sectional study, data using a structured questionnaire were collected from a stratified sample of 370 students at the University of Mauritius. Both descriptive and inferential statistical tools namely factor analysis, Pearson correlations and independent sample t-tests were used for data analysis. Choice decisions were affected by various factors. Students who attached significantly more importance to health, weight control and natural content ate more healthily as opposed to those who were influenced by the social & physical factor. Decisions to choose foods varied significantly with respect to gender. Girls considered factors such as health, weight control, convenience and attitude to be more important and ate more healthily as opposed to boys (p < 0.05). Health benefits derived from foods were perceived as the predominant food motive for students believed that their current diets were nutritionally adequate. These results are salient for health professionals and suggest that interventions should be geared to increase awareness about the nutritional inadequacy of diets consumed by University students and should specifically target boys. To the best of one’s knowledge, this is the only explicit research on food motives of University of Mauritius students.