Assessment of Biological Activities, Acute and Sub-chronic Toxicity of Liang (Gnetum gnemon var. tenerum) Leaves Powder, a Natural Product.

Gnetum gnemon var. tenerum (Gnetaceae) is a shrub plant native to South-East Asia. In Thailand, Liang leaves are commonly consumed in South of Thailand as vegetable. According to literature, they have an antihyperglycemic capacity because of their rich chlorophyll, fiber, and protein. However, there is need to assess the safety since natural food products are not completely devoid of toxicity. This study aimed to assess the biological activities as well as the acute and sub-chronic oral toxicity of Liang leaves powder (LLP). The evaluation of LLP for acute oral toxicity was performed at dose level 2000 mg/kg body weight in Wistar rats while the sub-chronic oral toxicity of LLP was performed at the effective dose (1.47 g/kg) for antihyperglycemic property according to Organisation for Economic Co-operation and Development (OECD)-425. The results showed that LLP demonstrated anti-inflammatory activities. It also showed no clinical signs of toxic effects and mortality in rats throughout 90 d. Thus, LLP could be classified in GHS category 5 which are of relatively low acute toxicity and then the lethal dose, 50% (LD50) cut off at 5000 mg/kg body weight to infinity (∞). Administration of LLP to the experimental rats significantly increased (p < 0.05) the concentration of triglyceride and increased concentration of creatinine as a result of kidney malfunction was also noticed in the experimental rats. Hematological alteration was not noticed in the treated female rats, but red blood cell, hemoglobin and hematocrit concentrations significantly increased in the treated male rats. The study concludes that sub-chronic administration of 1.47 g/kg LLP is relatively safe.

The Antihyperglycemic Effect of Crude Liang (Gnetum gnemon var. tenerum) Leaves Powder on Wistar Rats.

Chlorophyll and chlorophyllin (CHL) demonstrated antidiabetic activity by inhibiting gluconeogenesis and increasing glucose uptake in rats' muscle cells. Liang leaves contain high amounts of chlorophyll and chlorophyllin and may provide an antidiabetic effect. The antidiabetic activity of chlorophyll and CHL contained in Liang leaves, Cu-chlorophyllin (CCL) Liang leaves treated with CuSO4, and untreated crude Liang leaves (CLL) were compared using commercial chlorophyllin (CHL) as a reference. Twelve Wistar male rats were separated into 4 groups (3 rats/group); the first was a normal one (based line group), the second were the diabetic rats treated with CHL, while the third and the fourth were the diabetic rats treated with 0.97 g/kg of CCL and CLL, respectively. Diabetic rats were induced by a high fructose diet, before being taken to administer commercial CHL, CCL, and CLL for 7 days. Nonfasting blood glucose and body weight were checked daily. After euthanasia, organ weight, biochemical, hematological, and histopathological properties were evaluated. CCL treatment showed no antihyperglycemic activity in the rat model but caused some biochemical abnormalities and thrombocytopenia. Commercial CHL gave a higher reduction of nonfasting blood glucose (NFBG) than Liang leaves powder CCL or CLL but also showed some signs of abnormal biochemical parameters. CLL exhibited an antihyperglycemic effect, with higher body weight and increased HDL/LDL ratio and thus could be a promising alternative natural source for diabetes treatment.