Medicinal plants from the genus Acalypha (Euphorbiaceae)--a review of their ethnopharmacology and phytochemistry.

ETHNOPHARMACOLOGICAL RELEVANCE: Acalypha is the fourth largest genus of the Euphorbiaceae family with approximately 450-570 species. Several Acalypha species are used as medicinal plants in Africa and in the Mascarene Islands. Almost every part of the plant including the leaves, stem and roots are used as traditional remedies to treat and manage a panoply of ailments. However, there is no updated compilation of traditionally important medicinal plants from the Acalypha genus. The present review therefore, endeavors to provide for the first time an updated compilation of documented ethnopharmacological information in relation to the ethnomedicinal, ethnoveterinary, zoopharmacognosy, phytochemistry and biological activities of medicinal plants from the Acalypha genus which can subsequently open new perspectives for further pharmacological research. MATERIALS AND METHODS: A literature search was performed on Acalypha species using ethnobotanical text books and scientific databases such as Pubmed, Scopus, EBSCO, Google Scholar and other web sources such as records from PROTA, PROSEA, and Botanical Dermatology Database. The Plant List, International Plant Name index and Kew Botanical Garden Plant name databases were used to validate scientific names. RESULTS AND DISCUSSION: Plants from Acalypha genus are traditionally used in the treatment and/or management of diverse ailments such as diabetes, jaundice, hypertension, fever, liver inflammation, schistosomiasis, dysentery, respiratory problems including bronchitis, asthma and pheumonia as well as skin conditions such as scabies, eczema and mycoses. Approximately 124 species were listed in ethnobotanical studies with some botanical description and others mentioned from different web sources. However, only 40 species have been included in the present review due to the unavailability of ethnopharmacological data on the remaining species. Among the 40 cited species, 30 were traditionally used for the treatment and/or management of approximately 70 human diseases or health conditions. Two species, Acalypha alnifolia and Acalypha fruticosa are used as insecticides and sand fly repellent respectively. Only 2 species (Acalypha fruticosa and Acalypha indica) are used in ethnoveterinary practice and have similar human and veterinary applications. In zoopharmacognosy, only Acalypha ornata has been mentioned. Natives from Africa, Central America, North America, Southern China, India, Bangladesh, Papua New Guinea and Mascarenes islands utilize Acalypha species as ethnomedicine. Traditionally used Acalypha species have been reported to possess at least one of the following biological activities: antimicrobial, anti-diabetic, antioxidant, anti-inflammatory, larvidal, pupicidal, hepatoprotective, anticancer, leishmanicidal, antihyperglycemic, antihypertensive, anti-venom, analgesic, anthelmintic, antiemetic, laxative, expectorant, diuretic, post-coital antifertility effects and wound healing. A total of 167 compounds have been identified from 19 species, with 16 from eight species were reported to be bioactive. CONCLUSION: The present review represents 32.3% of species from the Acalypha genus and can be considered as the first compilation of ethnopharmacologically useful plants from this genus. There is a great potential to discover new biologically active phytochemicals from the Acalypha genus because only few species have been studied comprehensively. Therefore, the clinical evaluation of species from this genus is warranted in future studies to confirm the ethnomedicinal claims and for the safety approval of therapeutic applications.

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 IC(50) 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.

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.

Effect of exogenous ATP on Momordica charantia Linn. (Cucurbitaceae) induced inhibition of D-glucose, L-tyrosine and fluid transport across rat everted intestinal sacs in vitro.

Momordica charantia (MC) is a common oriental vegetable with known antidiabetic, laxative and antimicrobial properties. This study investigates the effects of aqueous fruit extract of MC on the transport of d-glucose, l-tyrosine and fluid across rat-everted intestine in vitro. Everted intestinal sacs from rats were mounted in an organ bath containing Krebs-Henseleit bicarbonate buffer. Graded concentrations (1.5-12mg/ml) of MC fruit extract were incubated in the mucosal solution with and without exogenous ATP in the mucosal bathing fluid. The serosal appearance and mucosal disappearance of d-glucose, l-tyrosine and the fluid absorptive capacity of the intestine were significantly inhibited (p<0.05) with increasing graded concentrations of MC. The concentration of d-glucose accumulated or metabolized by the enterocytes in the intestinal tissues were significantly higher (p<0.05) when incubated with MC. Increasing graded concentrations of exogenous ATP (25-200 microM) were incubated with 3.0mg/ml MC to confirm inhibition of the ATP-dependent active transport of d-glucose, l-tyrosine and fluid across rat enterocytes. It was found that increasing concentrations of mucosal ATP from 25 to 100 microM significantly (p<0.05) reverses the MC-depression of the d-glucose, l-tyrosine and fluid uptake across rat everted intestinal sacs. It is hypothesized that bioactive phytochemicals such as saponins in MC fruit extract inhibits the active transport of d-glucose, l-tyrosine and fluid across rat intestine by inhibiting the production of ATP responsible for the active transport of these molecules. It is likely that MC can be a potential alternative drug therapy of postprandial hyperglycaemia via inhibition of glucose uptake across the small intestine.

Screening of traditional antidiabetic medicinal plants of Mauritius for possible alpha-amylase inhibitory effects in vitro.

In this study, seven exotic/indigenous medicinal plants of Mauritius, namely Coix lacryma-jobi (Poaceae), Aegle marmelos (Rutaceae), Artocarpus heterophyllus (Moraceae), Vangueria madagascariensis (Rubiaceae), Azadirachta indica (Meliaceae), Eriobotrya japonica (Rosaceae) and Syzigium cumini (Myrtaceae) were studied for possible effects on starch breakdown by alpha-amylase in vitro. The results showed that only Artocarpus heterophyllus significantly (p < 0.05) inhibited alpha-amylase activity in vitro. To confirm the observed effects, a further biochemical assay was undertaken to investigate the effects of Artocarpus heterophyllus on alpha-amylase activity using rat plasma in vitro. It was found that the aqueous leaf extract significantly (p < 0.05) inhibited alpha-amylase activity in rat plasma. The highest inhibitory activity (27.20 +/- 5.00%) was observed at a concentration of 1000 microg/mL. However, in both cases dose dependency was not observed. Enzyme kinetic studies using the Michaelis-Menten and Lineweaver-Burk equations were performed to establish the type of inhibition involved. In the presence of the plant extract the maximal velocity (Vmax) remained constant (1/150 g / L/s) whereas the Michaelis-Menten constant (Km) increased by 5.79 g / L, indicating that the aqueous leaf extract of Artocarpus heterophyllus behaved as a competitive inhibitor. Results from the present study tend to indicate that Artocarpus heterophyllus could act as a 'starch blocker' thereby reducing post-prandial glucose peaks.

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.