Ameenah Gurib-Fakim

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.

Biological activity from indigenous medicinal plants of Mauritius

The Mauritian population has a long tradition in the use of ethno-medicine, and the practice is still strong, especially in the treatment of minor ailments. Such interest stems from an existing culture, and many “tisanes” are still prepared from plant materials and sold in several markets around the island. This paper will focus on the various chemical/biological screening techniques currently being used to evaluate the biological properties of medicinal plant extracts. Particular emphasis will be put on extraction and various screening for biological/pharmacological properties. Due consideration will be given to the pharmacological approaches that utilize different animal models for the in vitro and in vivo screening of medicinal plant extracts.

Medicalethnobotany of some weeds of mauritius and rodrigues

The people of Mauritius and Rodrigues have always used medicinal plants for various ailments, and have for a long time been dependent on surrounding plant resources for their food, shelter, fodder, health care and other cultural purposes. However, encroaching industrialization and the accompanying changes in their lifestyles are responsible for the decrease of practice in the local use of plants for medicine. It is, therefore, felt worthwhile to record the native uses of these plants before the information is lost. The present paper deals with the medicalethnobotany of 53 genera and 94 different species of plants considered as weeds.

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.

Traditional medicinal herbs and food plants have the potential to inhibit key carbohydrate hydrolyzing enzymes in vitro and reduce postprandial blood glucose peaks in vivo.

We hypothesized that some medicinal herbs and food plants commonly used in the management of diabetes can reduce glucose peaks by inhibiting key carbohydrate hydrolyzing enzymes. To this effect, extracts of Antidesma madagascariense (AM), Erythroxylum macrocarpum (EM), Pittosporum senacia (PS), and Faujasiopsis flexuosa (FF), Momordica charantia (MC), and Ocimum tenuiflorum (OT) were evaluated for α-amylase and α-glucosidase inhibitory effects based on starch-iodine colour changes and PNP-G as substrate, respectively. Only FF and AM extracts/fractions were found to inhibit α-amylase activity significantly (P < 0.05) and coparable to the drug acarbose. Amylase bioassay on isolated mouse plasma confirmed the inhibitory potential of AM and FF extracts with the ethyl acetate fraction of FF being more potent (P < 0.05) than acarbose. Extracts/fractions of AM and MC were found to inhibit significantly (P < 0.05) α-glucosidase activity, with IC50 comparable to the drug 1-deoxynojirimycin. In vivo studies on glycogen-loaded mice showed significant (P < 0.05) depressive effect on elevation of postprandial blood glucose following ingestion of AM and MC extracts. Our findings tend to provide a possible explanation for the hypoglycemic action of MC fruits and AM leaf extracts as alternative nutritional therapy in the management of diabetes.

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.

Essential oil composition of Zingiberaceae species from Mauritius

Abstract The chemical composition of the essential oils obtained from the hydrodistillation of the rhizomes of the common ginger (Zingiber officinale) and three ginger-lilies (Hedychium coccineum, H. flavescens and H. coronarium) grown in Mauritius has been investigated by GC and GC/MS. Zingiber officinale oil was characterized by the presence of geranial (16.3%), neral (10.3%), zingiberene (9.5%), β-sesquiphellandrene (6.3%) and ar-curcumene (5.1%). The oils of the ginger lilies were characterized as follows: H. coccineum: (E)-nerolidol (44.4%), trans-sesquisabinene hydrate (24.2%); H. flavescens: linalool (35.0%), 1, 8-cineole (15.3%), β-pinene (14.7%), α-terpineol (14.5%) and α-pinene (5.3%); H. coronarium: α-muurolol (16.8%), α-terpineol (15.9%), 1, 8-cineole (11.2%), an unknown sesquiterpene alcohol (7.0%), α-fenchyl acetate (5.6%), citronellal (5.5%) and (E)-methyl cinnamate (5.1%).

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.

Aromatic Plants of Mauritius: Volatile Constituents of the Leaf Oils of Citrus aurantium L., Citrus paradisi Macfad and Citrus sinensis (L.) Osbeck

ABSTRACT Essential oils obtained from the steam distillation of the leaves of Citrus aurantium L., Citrus paradisi Macfad and Citrus sinensis (L.) Osbeck were analyzed by capillary GC and GC/MS. Seventeen components were identified in the leaf oil of C. aurantium, accounting for 99.03% of the oil. The leaf oil of C. paradisi contained 45 components thereby accounting for 93.1% of the oil, while that of C. sinensis contained 61 components accounting for 86.86% of the total composition. The major components of the leaf oil of both C. aurantium and C. paradisi were linalool (66.1% and 22.9% respectively) while that of C. sinensis had cis-piperitol (26.4%) as the major component.