Screening for molluscicidal activity in crude drugs

Area of Science:

• Pharmacology
• Natural Products Chemistry
• Parasitology

Background:

• Schistosomiasis japonica remains a significant public health concern, particularly in Japan.
• Control strategies often target the intermediate snail host, Oncomelania nosophora.
• Identifying novel and effective molluscicides from natural sources is crucial for integrated control programs.

Purpose of the Study:

• To screen crude drug and medicinal plant extracts for molluscicidal activity against Oncomelania nosophora.
• To identify active compounds from promising plant sources.
• To investigate the structure-activity relationship of key compounds.

Main Methods:

• Thirty-four crude drug and medicinal plant extracts were prepared and screened for activity against Oncomelania nosophora.
• The methanolic extract of Anemarrhenae Rhizoma demonstrated significant molluscicidal effects.
• Chemical isolation and characterization of active saponins, including timosaponin A-III and markogenin-3-O-beta-D-glucopyranosyl (1-2)-O-beta-D-galactopyranoside, were performed.

Main Results:

• The methanolic extract of Anemarrhenae Rhizoma exhibited strong molluscicidal activity.
• Timosaponin A-III, a major saponin in Anemarrhenae Rhizoma, displayed potent activity against Oncomelania nosophora.
• Markogenin-3-O-beta-D-glucopyranosyl (1-2)-O-beta-D-galactopyranoside, despite sharing a similar glycosidic linkage, was found to be inactive.

Conclusions:

• Anemarrhenae Rhizoma is a potential source of natural molluscicides for controlling Oncomelania nosophora.
• Timosaponin A-III is a promising lead compound for developing new agents against Schistosoma japonicum intermediate hosts.
• The specific glycosidic structure of saponins plays a critical role in their molluscicidal efficacy.