Evaluation of α - amylase inhibitory activity and anti-diabetic effect of natural extracts from : Asphodelus microcarpus, Bubonium graveolens and Haplophyllum tuberculatum

Abstract

Medicinal plants represent an essential source for discovering new therapeutic molecules effective against many diseases. In this context, we studied three local plants: Asphodelus microcarpus, Bubonium graveolens et Haplophyllum tuberculatum, known for their positive effect on several diseases. We determined the content of phenolic coumpounds of extracts from these plants, study their inhibitory effect on amylase as well as evaluate their toxicity and their anti-diabetic activity in Wistar rats. The amount of phenolic compounds ranged from 2.88 to 11.97 mg/g gallic acid equivalent, while the amount of flavonoids ranged from 0.48 to 1.5 mg/g quercetin equivalent. The kinetic analysis of the enzymatic reactions showed that phenolic compounds had inhibitory effects on the amylase enzyme at inhibitory concentrations of 50%, with values ranging from 19.78 to 82.01 mg/ml. Asphodelus microcarpus aqueous extract and Bubonium graveolens essential oils extract acute toxicity studies given orally to Wistar rats didn't exhibit lethal toxicity, even at the dose level of 5000 mg/kg. For the antidiabetic study of aqueous extract of Asphodelus microcarpus and essential oils of Bubonium graveolens, the extract was administered orally to normal Wistar rats and diabetic rats induced by alloxan (150 mg/kg). The first procedure consisted of testing the acute effect of the extracts (30 to 120 min), on fasting glycemia of normal rats. While in the second procedure, plant extract effect was tested, in normal and diabetic rats, in daily treatment of 28 days. The results showed significant antihyperglycemic effect, observed in time interval of 30 to 60 min after the administration of the extract. The effect was evident mainly with essential oil extracts, an improvement was noted in the troubles that come with experimental diabetes, as polyphagia, polydipsia, body weight lost, and some deterioration blood parameters deterioration. In the light of these results, we can say that Asphodelus microcarpus and Bubonium graveolens H. scoparia are a medicinal plants with remarkable antihyperglycemic activity, which appeared in our experiments with a reduction of hyperglycemia, induced by oral charge in normal rats. Our study indicates also that the most responsible molecules belong to the family of flavonoids