Evaluation of hypoglycemic activities of hydroethanolic leaf extract of <i>Nicotiana tabacum</i> (Solanaceae)

Abstract

The aim of this study was to evaluate the hypoglycemic activities of hydroethanolic leaf extract of Nicotiana tabacum. Acute toxicity was evaluated in Swiss albino mice using graded oral doses of the extract. Hypoglycemic properties of Nicotiana tabacum was assessed using oral glucose tolerance test and on normoglycemic rats that received single doses of the extract at 40 and 80 mg/kg body weight and blood glucose levels estimated at 2, 4 and 6 hours (single dose study). Phytochemical screening of the extract for the presence of secondary metabolites was performed with standard methods. Acute toxicity study revealed a median lethal dose (LD₅₀) of 5.82g/Kg. the single-dose study showed that 40mg/Kg and 80mg/Kg body weight of the extract significantly (p<0.05) reduced blood glucose levels at 2h compared to control (27.35% and 28.37% respectively), while 80mg/kg body weight of the extract significantly (p<0.05) reduced blood glucose level at 6h compared to control (75.40%). The oral glucose tolerance test results also showed a significant reduction (p<0.05) in blood glucose levels. These findings suggest that the extract of Nicotiana tabacum has hypoglycemic properties which may be accounted for by the presence of secondary metabolites in the extracts -flavonoids, alkaloids, phenols and terpenoids.

Key words: Nicotiana tabacum, Diabetes mellitus, Hypoglycemia, Oral glucose tolerance