Antifungal, antiprotozoal, cytotoxic and piscicidal properties of justicidin B and a new arylnaphthalide lignan from Phyllanthus piscatorum

Abstract

Using activity against Candida albicans as a lead, the bioactivity-guided fractionation of the CH2Cl2 ext. of P. piscatorum led to the isolation of the arylnaphthalide lignan justicidin B (I), which was found to be present in high amts., and a new C-11 hydroxylated deriv. that we named piscatorin (II). We provide evidence that I is the main active principle of P. piscatorum, showing the same biol. effects that were found for the raw exts. I inhibited the growth of the pathogenic fungi Aspergillus fumigatus, Aspergillus flavus, and Candida albicans, but was not effective against Cryptococcus neoformans and Blastoschizomyces capitatus. I also exhibited strong activity against the trypomastigote form of Trypanosoma brucei rhodesiense and moderate activity against Trypanosoma cruzi. Testing against Plasmodium falciparum showed only weak activity. This is the 1st report on the in vitro fungicidal and antiprotozoal effects of justicidin B. In addn., both compds. exhibited a non-specific cytotoxicity in neoplastic and primary cell cultures. No antibacterial effects were detected. Both compds. were piscicidal against zebra fish and it is shown for the 1st time that I and II are the piscicidal principles of P. piscatorum, exhibiting a potency that is comparable to rotenone.