Screening of crude drug extracts for prolyl endopeptidase inhibitory activity

Author(s): Fan, W., Kasimu, R., Kadota, S.

Abstract: Prolyl endopeptidase (PEP, EC 3.4.21.26) is an enzyme to play a role in metabolism of proline-containing neuropeptides, such as vasopressin, substance P and thyrotropin-releasing hormone (TRH), which were suggested to be involved with learning and memory processes. Then, specific inhibitor of PEP is expected to have antiamnesic effects, and thus we screened forty-six water- and methanol-extracts from crude drugs selected on the basis of traditional Chinese medicine theory, for Flavobacterium prolyl endopeptidase inhibition. Among them, the water-extracts of Rhodiola sacra (IC50, 0.77 mg/ml) and the methanol-extracts of Lycopodium clavatum (IC50, 1.3 mg/ml), Paeonia lactiflora var. trichocarpa (IC50, 5.7 mg/ml), Paeonia veitchii (IC50, 2.4 mg/ml) and Rhodiola sacra (IC50, 0.67 mg/ml) showed strong inhibitory activity.In addition, we also examined the PEP inhibitory activity of eleven compounds from Salvia deserta, and found that in addition to a catechol group a-hydroxy-para-quinone group may be related to the PEP inhibition.

Keyword(s): Screening

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