Choline esters, their precursors and metabolites in the hypobranchial gland of prosobranchiate molluscs, Concholepas concholepas and Thais chocolata

Are the Traditional Medical Uses of Muricidae Molluscs Substantiated by Their Pharmacological Properties and Bioactive Compounds?

Marine molluscs from the family Muricidae hold great potential for development as a source of therapeutically useful compounds. Traditionally known for the production of the ancient dye Tyrian purple, these molluscs also form the basis of some rare traditional medicines that have been used for thousands of years. Whilst these traditional and alternative medicines have not been chemically analysed or tested for efficacy in controlled clinical trials, a significant amount of independent research has documented the biological activity of extracts and compounds from these snails. In particular, Muricidae produce a suite of brominated indoles with anti-inflammatory, anti-cancer and steroidogenic activity, as well as choline esters with muscle-relaxing and pain relieving properties. These compounds could explain some of the traditional uses in wound healing, stomach pain and menstrual problems. However, the principle source of bioactive compounds is from the hypobranchial gland, whilst the shell and operculum are the main source used in most traditional remedies. Thus further research is required to understand this discrepancy and to optimise a quality controlled natural medicine from Muricidae.

Choline esters and biogenic amines in the hypobranchial gland of 55 molluscan species of the neogastropod Muricoidea superfamily

As many as 55 neogastropod molluscs, all belonging to the Muricoidea superfamily, have been investigated for occurrence and contents, in their hypobranchial gland (HG), of choline esters and, subordinately, biogenic amines. Very high amounts of esters, strictly localized in the median area of the HG, were found in all dye-secreting molluscs. The choline esters were represented by murexine, dihydromurexine and senecioylcholine. A fourth ester, acryloylcholine, occurred in the HG of a single, non dye-secreting mollusc. All the compounds displayed potent neuromuscular blocking actions in all examined vertebrate and invertebrate species, as well as potent nicotinic actions. Muscarinic effects were either lacking or unimportant. In addition to choline esters the HG occasionally contained known and hitherto unknown biogenic amines: tyramine, octopamine, 5-hydroxytryptamine, histamine, urocanylhistamine and imidazole-propionylhistamine. The interest of extending the search of bioactive compounds to carnivorous, predatory molluscs other than those described in this paper and, more, extensively, to any molluscan species provided with 'venomous' glands or apparatuses, is emphasized.