Hypoglycemic and antihyperglycemic effects of phytopreparations and limonoids from Swietenia humilis.

An aqueous extract from the seeds of Swietenia humilis (31.6-100mg/kg bw) lowered (p<0.05) blood glucose levels in normal and nicotinamide-streptozotocin (NA-STZ)-induced hyperglycemic mice. Furthermore, when administered to fructose-fed rats with metabolic syndrome, the decoction showed significant antihyperglycemic, hypoglycemic and hypolipidemic effects, as well as an augmentation of hepatic glycogen. Limonoids 2-hydroxy-destigloyl-6-deoxyswietenine acetate (1), humulin B (2), methyl-2-hydroxy-3-β-isobutyroxy-1-oxomeliac-8(30)-enate (3), methyl-2-hydroxy-3-β-tigloyloxy-1-oxomeliac-8(30)-enate (4), humilinolide G (5), humilinolide C (6), methyl-2-hydroxy-3-β-isobutyoyl-8α,30α-epoxy-1-oxo-meliacate (7), and humilinolide H (8), were isolated from a CH2Cl2-MeOH (1:1) extract of the seeds. Compounds 5 and 8 are analogs of compounds 6 and 7. The structure of 5 was unequivocally established by X-ray analysis. When tested in normal and NA-STZ-hyperglycemic mice, compounds 1, 2, and 4 (3.16-31.6 mg/kg bw) decreased glycemia during an oral glucose tolerance test. The present investigation sustains the contemporary popular uses of S. humilis seeds for treating metabolic disorders, including diabetes and dyslipidemia and demonstrates the potential of the mexicanolides as antihyperglycemic agents.