The methanol crude extract of the bark of Psidium guajava (guava) previously displayed interesting cytotoxic effects on a panel of human cancer cell lines. In the present work, we plan to determine the toxicological effects of this guava botanical in Wistar rats. Acute oral toxicity of the extract was carried out by administration of a single dose of 5000 mg/kg body weight to female rats in 14 days. Subacute toxicity was conducted by oral administration of the extract at daily doses of 250 mg/kg, 500 mg/kg, and 1000 mg/kg body weight, respectively, while rats in the control group received no extract. After 28 days of treatment, animals were sacrificed for hematological and biochemical studies. In the acute toxicity study, no mortality or signs of toxicity were recorded; hence, the median lethal dose (LD50) of the Psidium guajava bark extract is greater than 5000 mg/kg body weight. For the subacute toxicity study, significant variations in body weight, relative weight of organs, and biochemical parameters were observed in the animals treated at different doses of the plant extract compared to control animals. Histopathological analyses showed minor liver inflammation in females treated at the highest dose (1000 mg/kg). These results suggest that intake of a single high dose of the Psidium guajava bark extract is nontoxic, but repeat administration could exhibit mild organ toxicity.

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Among the causes of mortality, wound healing remains a major problem that often results from imbalance between prooxidants and endogenous antioxidants in diabetics. The aim of this study was to evaluate the wound healing activity of Gymnema sylvestre in normoglycemic rat, and its antioxidant properties in type 2 diabetic rat. Evaluation of the healing properties of extracts (aqueous and methanol) and fractions (methylene chloride and methanol) G. sylvestre (10% of fraction or extract) were conducted in female normoglycemic rats and 1% fluoxetine was considered positive control using glycerin as a vehicle, while antioxidant assessments were conducted in male diabetic rats. Type 2 diabetes was induced in male rats by a high sucrose diet for 12 weeks followed by daily intraperitoneal injection of dexamethasone (8 mg/kg) for 5 consecutive days. Animals with a blood glucose above or equal to 140 mg/kg after 12 hours of fasting were considered diabetic. For the evaluation of wound healing 5 groups consisting of 3 female rats each were formed. Fluoxetine (1%), aqueous (Aq) and methanol (MeOH) extracts as well as methylene chloride (F1) and methanol (F2) fractions of the plant were administered at 10% via utopian application on wounds of about 2.5 cm in diameter. For the estimation of oxidative stress parameters in the diabetic rat, 7 groups of 5 animals each were formed, with three control groups including two negative control groups (normoglycemic and diabetic) receiving the vehicle orally (DMSO 3%) and a positive control group receiving metformin (Met, 200 mg/kg). The four experimental groups were treated orally with administration of Aq (100 mg/kg), MeOH, F1 and F2 (7.5 mg/kg). The different treatments were administered once a day for 14 consecutive days. Results showed that G. sylvestre promoted wound healing (P>0.05) in the normoglycemic rat with a stronger effect for F2 and MeOH compared to the untreated group. In the diabetic rat, extracts and fractions of G. sylvestre significantly reduced (P<0.001) the MDA level, while F1 significantly increased (P<0.01) the activity of catalase (CAT) and reduced glutathione (GSH) compared to the untreated diabetes group on day one. These results revealed that G. sylvestre exhibited strong wound healing effects and justify the use of this in traditional pharmacopoeia.