Novel Anti-diabensity Peptide Alkaloids from Allophylus africanus P. Beauv

Aim: The aim of the study was to characterize and investigate the mechanism of action anti-hyperglycemic and anti-hyperlipidemic constitutents of Allophylus africanus Background: Allophylus africanus P. Beauv is a medicinal plant commonly used in sub-Sahara Africa for treatment metabolic disorders and infectious diseases. Objectives: The objectives of the study were to isolate and characterize anti-hyperglycemic and anti-hyperlipidemic chemical constituents from Allophylus africanus, and to investigate the mechanism of their enzymatic inhibitions. Methods: The chemical constituents were isolated using various column chromatographic techniques. The anti-hyperlipidemic and anti-hyperglycemic properties of the chemical constituents were investigated by measuring their inhibitory effects on porcine pancreatic lipase and α-glucosidase enzymes. Fluorescence quenching constants obtained from Stern−Volmer plots were used to determine the mechanisms of inhibitory action. Results: Twelve compounds of which three were new peptide alkaliods, ethylamino asperphenamate (10), allophylane (11) and allophyline (12) were isolated. The new peptide alkaloids and asperphenamate (9) inhibited porcine pancreatic lipase in a dose dependent manner with IC50 < 90 µM. Also, 9, 12, stigmasta-5, 22-dien-3-O-β-D-glucoside (3) and eudesmenol (5) inhibited α-glucosidase enzymes with IC50 < 165 µM which was lower than that of standard drug, acarbose (432.16 ± 6.52 µM). From the Stern-Volmer plots, 9 and 10 indicated a static quenching while 11 and 12 suggested occurrence of both static and dynamic quenching mechanisms on porcine pancreatic lipase. On α-glucosidase, only 12 exhibited a concurrent static and dynamic quenching mechanism. Conclusion: The anti-diabesity compounds obtained from A. africanus established its potential for treatment of metabolic disorder. Amongst the isolated compounds, three were reported for the first time in nature while others were reported for the first time in the plant