A high-performance molluscicidal ingredient against Oncomelania hupensis produced by a rhizospheric strain from Phytolacca acinosa Roxb

BACKGROUND: Snail (Oncomelania hupensis) control is an important and effective preventive strategy in schistosomiasis control programs, and screening microbial molluscicidal agents is one of the most promising categories in biomolluscicides. OBJECTIVE: To purify and identify the molluscicidal ingredient (MI) obtained from strain SL-30's exocellular broth. MATERIALS AND METHODS: The active extracts extracted from SL-30's exocellular broth was purified on a silica gel column guided by molluscicidal activity assay against Oncomelania hupensis, then the MI was obtained. NMR spectroscopy and LC-MS/MS analysis was used to identify the molecular structure of the MI. RESULTS: Molluscicidal activity bioassay showed that the MI exhibited significant molluscicidal activity with the LC(50) values of 0.101, 0.062, and 0.022 mg/L, respectively, in the case of exposure period of 24 h. From (1)H NMR, (13)C NMR, (1)H-(1)H COSY, and (1)H-(13)C HSQC spectra, partial important structure fragment was obtained, and the relative molecular weight of the MI showed 326 according to LC-MS analysis. Then, on these grounds, it was indicated that the molecular structure of the MI had a higher similarity to Gliotoxin with the molecular formula of C(13) H(14)N(2)O(4)S(2). The quasi-molecular ion of m/z 325.45 was further analyzed by MS(2) as the parent ion, and two daughter ions obtained at m/z 295.11 [M-CH(2)OH]- and m/z 261.08 [M-CH(2)OH -2S]– CONCLUSION: The MI was finally confirmed as Gliotoxin.