A new ester of fatty acid from a methanol extract of the whole plant of Amaranthus spinosus and its α-glucosidase inhibitory activity.

ABSTRACT

CONTEXT Amaranthus spinosus Linn. (Amaranthaceae), commonly known as "spiny pigweed", is used both in the Indian traditional system and in folk medicine to treat diabetes. OBJECTIVE: The present study evaluates the scientific basis of antidiabetic activity of chloroform fraction of methanol extract of A. spinosus and of an isolated constituent of A. spinosus. MATERIALS AND METHODS: HPLC analysis was performed to determine the purity and the amount of the constituent present in the plant extract. The yeast α-glucosidase inhibition technique was used to determine the antidiabetic activity of A. spinosus. Acarbose was used as a standard. An appropriate therapeutic approach for preventing diabetes mellitus and obesity is to retard the absorption of glucose by inhibition of α-glucosidase. RESULTS: One novel fatty acid with strong α-glucosidase inhibitory activity - (14E, 18E, 22E, 26E) - methyl nonacosa-14, 18, 22, 26 tetraenoate [1] (IC50 value 6.52 µM/mL) and ß-sitosterol [2] were purified. Compound 1 was found to be more potent than the methanol extract. HPLC quantitative analysis revealed that 0.15% of compound 1 and 0.06% of compound 2 were present in the plant extract. CONCLUSION: This novel fatty acid can potentially be developed as a novel natural nutraceutical for the management of diabetes.