Phytochemical Screening, median lethal dose and effects of Cassia abbreviata Oliv. crude extracts and fractions on oral glucose tolerance in non-diabetic male Wistar rats

Abstract

Background: Cassia abbreviata plant extracts are used traditionally to treat various ailments including diabetes mellitus. However, very few animal studies have been conducted to investigate potential hypoglycaemic effects locally. We examined phytochemicals, median lethal dose and effects of Cassia abbreviata extracts and fractions on oral glucose tolerance in non-diabetic male Wistar rats. Methods: Qualitative and Lorke’s methods were used to screen for phytochemicals and acute toxicity testing. Rats weighing 160 - 250 g were divided into 4 groups of 3 rats (phase one) and 4 groups of 1 rat (phase two) each for acute toxicity. Main experiments comprised 8 groups (extracts) and 7 groups (fractions) of 6 rats per group. Doses of 762 mgkg-1, 381 mgkg-1, and 190 mgkg-1 for extracts, 381 mg.kg-1 for the fractions, 10 mg.kg-1 for sitagliptin and 10 mL.kg-1 of vehicle were administered. Thereafter, blood glucose levels were assessed using Accu-Chek glucometer. Results: Leaf methanolic extract and ethyl acetate fraction contained more phytochemicals. Acute toxicity test revealed no mortality in all the groups except for leaf ethanolic and methanolic crude extracts in phase two at dose 5000 mg.kg-1. Root bark ethanolic extract 381 mg.kg-1 showed significant hypoglycaemic effect at 60 min and 180 min while 381 mg.kg-1 n-hexane fraction showed significant hypoglycaemic effect only at 180 min. Sitagliptin 10 mg.kg-1 minimally reduced the blood glucose levels at 60 min. Conclusion: More phytochemicals were observed in leaf methanolic extract and ethyl acetate fraction. Both extracts and fractions were considered practically non-toxic following acute toxicity testing. Root bark ethanolic extract and n-hexane fraction revealed better hypoglycaemic effects. Hypoglycaemic bioactivity observed may be due to various mechanisms.