Limonoids from Meliaceae with lipid peroxidation inhibitory activity.

In this study the antioxidant activity of natural limonoids from Meliaceae swietenolide (1), 3,6-O,O-diacetylswietenolide (2), swietenine (3), swietemahonin G (4) and 2-hydroxyswietenine (5) were investigated along with the semi-synthetic analogues (6-25) of compounds 1, 3-4. Lipid peroxidation (LPO) inhibitory assays revealed 85.6, 13.3, 77.3, 61.2 and 24.6 % inhibition for the natural compounds 1-5. Excellent antioxidant activity was seen for the semi-synthetic analogues 10 (98.3 %), 16-17, 21-22 and 25 (100 %), which were more active than the positive controls BHA (91.3 %) and TBHQ (95.7 %).