Studies on the possible mechanisms of antidiabetic activity of extract of aerial parts of Phyllanthus niruri.

CONTEXT/OBJECTIVES: The effects of methanol extract of aerial parts of Phyllanthus niruri L. (Euphorbiaceae), an antidiabetic herb, on glucose absorption and storage in diabetes were studied to elucidate the mechanisms of blood glucose lowering and glycemic control in diabetes. METHODS: The effect of chronic oral administration of the extract on glycemic control was evaluated in alloxan diabetic rats using blood glucose lowering and post-prandial glucose suppression activities as well as effects on hemoglobin glycation and body weight. Effects on glucose mobilization and storage were assessed using the weight and glycogen content of liver isolated from treated diabetic rats, while in vitro inhibition of α-amylase and α-glucosidase enzyme activities were used as indices of effect on glucose absorption. RESULTS: Results showed that the extract lowered blood glucose, suppressed postprandial rise in blood glucose following a glucose meal, reduced hemoglobin glycation and increased absolute and relative weights as well as glycogen content of liver in diabetic rats. Treatment with the extract also ameliorated the decrease in body weights caused by the diabetic disease. In vitro, the extract inhibited α-amylase (IC50: 2.15 ± 0.1 mg/mL) and α-glucosidase (IC50: 0.2 ± 0.02 mg/mL) activities. DISCUSSION AND CONCLUSION: These findings suggest that aerial parts of P. niruri may owe their blood glucose lowering properties to inhibition of glucose absorption and enhancement of glucose storage.

Medicinal Plants Used in Wound Care: A Study of Prosopis africana (Fabaceae) Stem Bark.

The effects of the methanol extract of the stem bark of Prosopis africana (Guill., Perrott. and Rich.) Taubert (Fabaceae) on bleeding/clotting and coagulation time, excision and dead space wounds were studied in rats. Also, the extract was subjected to antibacterial, and acute toxicity and lethality (LD(50)) tests. The extract significantly (P<0.05) reduced bleeding/clotting and coagulation time in rats. It also reduced epithelialization period of excision wounds in rats and inhibited the growth of laboratory strains of Staphylococcus aureus, Bacillus subtilis, Salmonella typhi, Pseudomonas aeruginosa and Klebsiella pneumoniae to varying extents. Acute toxicity and lethality (LD(50)) test on the extract established an LD(50) of 774 mg/kg (i.p) in mice while phytochemical analysis gave positive reactions for alkaloids, saponins, tannins, flavonoids, steroids, terpenoids and carbohydrates. The results of this study demonstrate the beneficial effects of the stem bark of P. africana in wound care.

Anticonvulsant and anxiolytic evaluation of leaf extracts of Ocimum gratissimum, a culinary herb.

Anticonvulsant and anxiolytic activities of leaf extracts and fraction of Ocimum gratissimum L. (Lamiaceae) were studied using seizures induced by pentylenetetrazol and open-field tests in mice. The results showed that the extracts and fraction increased the latency of tonic and tonic-clonic seizures and death and elicited 50% protection against mortality. In the open-field test, the extracts and fraction decreased the frequency of line crossing, center square entries, rearing against a wall and grooming, whereas grooming duration and freezing frequency and duration were increased. Acute toxicity test in mice gave an oral LD(50) greater than 5000 mg/kg for the methanol extract. These findings suggest that extracts of this plant possess anticonvulsant and anxiolytic-like properties.

Carica papaya (Paw-Paw) unripe fruit may be beneficial in ulcer.

The anti-ulcer potentials of aqueous (AE) and methanol (ME) extracts of whole unripe Carica papaya fruit were evaluated using ethanol- and indomethacin-induced gastric ulcer models in rats. The effect of the extracts on small intestinal propulsion was also investigated. The extracts significantly reduced the ulcer index in both experimental models (P < .05) compared to the control group. ME showed a better protection against indomethacin-induced ulcers, whereas AE was more effective against ethanol-induced gastric ulcers. The extracts also significantly (P < .05) inhibited intestinal motility, with ME showing greater activity. Oral administration of AE and ME up to 5,000 mg/kg did not produce lethality or signs of acute toxicity in mice after 24 hours. The extracts of unripe C. papaya contain terpenoids, alkaloids, flavonoids, carbohydrates, glycosides, saponins, and steroids. The cytoprotective and antimotility properties of the extracts may account for the anti-ulcer property of the unripe fruit.

Evaluation of the anti-asthmatic property of Asystasia gangetica leaf extracts.

The leaf of Asystasia gangetica T. Adams (Acanthaceae) is used in many parts of Nigeria for the management of asthma. This study was aimed at investigating the anti-asthmatic property of hexane, ethylacetate, and methanol extracts of the leaves of Asystasia gangetica, obtained by successive sohxlet extraction. The results indicated that the extracts did not exhibit contractile or relaxant activity in isolated tissue preparations; however, they inhibited the contraction evoked by spasmogens; the IC(50) were calculated, where possible. The extracts relaxed histamine-precontracted tracheal strips in the following degree of potency-ethylacetate extract>hexane extract=methanol extract. The extracts also exhibited anti-inflammatory activity in the order of magnitude-methanol extract>hexane extract>ethylacetate extract. Acute toxicity test estimated an i.p. LD(50) of 2150 mg/kg in mice for methanol extract while phytochemical screening showed the presence of carbohydrates, proteins, alkaloids, tannins, steroidal aglycones, saponins, flavonoids, reducing sugars, and triterpenoids, with the methanol extract having the highest number of constituents. The study justified the use of the leaf of Asystasia gangetica in the management of asthma in Nigerian folk medicine.