Studies on biological activities of melanin from marine animals. II. Purification of melanin from Octopus vulgaris Cuvier and its inhibitory activity on gastric juice secretion in rats.

Abstract

Octopus melanin obtained from ink bags of O. vulgaris inhibited gastric secretion in rats in the same way as that from Ommastrephes bartrami. The MW of this melanin fraction (which has an indole skeleton) was .apprx. > 200,000 by gel filtration on Sephadex G-200 and the Octopus melanin fraction (Fr. OM) released several kinds of proteins in the presence of SDS [sodium dodecyl sulfate]. The chemical composition of Fr. OM was melanin pigment 79%, protein 17.5% and sugar 1.7%, so Fr. OM was considered to be a melanoprotein. Fr. OM significantly reduced gastric secretion in rats at the dose of 1 mg/kg, i.p. and also prevented both ulcer formation in pylorus-ligated rats and aspirin-induced ulcer.