Inhibition of Candida rugosa lipase by saponins, flavonoids and alkaloids

Lipase inhibitors have generated a great interest because they could help in the prevention or the therapy of lipase-related diseases. Therefore, the aim of the work was to evaluate by HPLC, and using Candida rugosa lipase as model, the inhibitory effect of several saponins: beta-aescin, digitonin, glycyrrhizic acid (GA) and Quillaja saponin (QS); flavonoids: 3-hydroxyflavone, 5-hydroxyflavone, (+)-catechin and kaempferol; and alkaloids: aspidospermine, papaverine, physostigmine, pilocarpine, raubasine, rescinnamine, reserpine and trigonelline. The inhibition produced by most of these compounds is described here for the first time. Saponins appeared very active, being beta-aescin and digitonin the most active compounds (IC50 = 0.8-2.4 x 10(-5) M). The inhibitory activity of flavonoids was lower than that of saponins (except GA), and (+)-catechin and kaempferol were the most active. Alkaloids was the most heterogeneous group assayed, varying from rescinnamine, with an IC16 similar to that of digitonin, to papaverine and others which showed almost no inhibition. In conclusion, beta-aescin, digitonin, kaempferol or (+)-catechin, strong lipase inhibitors with a low toxicity and present herbal drugs used for lipase-related diseases such as acne or ulcer, are promising candidates for the prevention or the treatment of these diseases. (c) 2006 Elsevier B.V. All rights reserved