Alternariol,a dibenzopyrone mycotoxin ofAlternaria spp., is a new photosensitizing and DNA cross-linking agent

Summary The mycotoxin alternariol (3,4,5-trihydroxy-6-methyldibenzo [a] pyrone) but not alternariol monomethyl ether (3,4-dihydroxy-5-methoxy-6-methyldibenzo [a] pyrone) is phototoxic toEscherichia coli in the presence of near UV light (320–400 nm). The phototoxicity bioassays with a DNA repair-deficient mutant ofE. coli suggested that DNA may be the molecular target for photo-induced toxicity of alternariol. Interactions between alternariol and double-stranded, supercoiled DNA suggest that alternariol interacts with DNA by intercalation. No DNA breakage was detected in this system; however, alternariol forms a complex and cross-links double-stranded DNA in near UV light. These results suggest that alternariol is a new phototoxic, DNA-intercalating agent and is a DNA cross-linking mycotoxin in near UV light.Acknowledgment. Dr Albert Stoessl (Agriculture Canada, London, Ontario, Canada) generously provided a mixture of alternariol and alternariol monomethyl ether, and made many helpful suggestions. Dr Ashwood-Smith (University of Victoria, Victoria, British Columbia, Canada) kindly supplied the microorganisms through Dr G.H.N. Towers (University of British Columbia, Vancouver). We gratefully acknowledge the gifts. It is a pleasure to acknowledge the able assistance of Mr S. Tallevi.     

红树林真菌E33代谢产物的分离及衍生物制备

从南海红树林麒麟菜内生真菌E33中分离到6个化合物,其中alternariol monomethyl ether(1),alterna-riol(2),dehydroaltenusin(3)为首次从海洋红树林真菌里得到,通过酯化反应制备了化合物1的新衍生物7-hy-droxy-9-methoxy-1-methyl-6-oxo-6H-benzo[c]chromen-3-ylacetate(4),这4个化合物对hepG2细胞显示了微弱的细胞毒活性。     

南海红树林内源真菌#2240的四个格链孢酚类衍生物次级代谢产物研究

通过人工发酵培养,利用层析技术,首次从南海红树林内源真菌#2240的培养液中分离得到4个格链孢酚类衍生物次级代谢产物,它们分别是：4-甲氧基-10-乙酸格链孢酚酯（化合物1）、格链孢酚（化合物2）、4-甲氧基格链孢酚（化合物3）、4,10-二甲氧基格链孢酚（化合物4）.其结构通过谱图分析（包括1H、13C NMR,DEPT,HMQC,HMBC,HREIMS,UV及IR等）和相关文献得以确定.初步药理实验表明,化合物2和3对KB和KBv200癌细胞具有较强活性,IC50值分别为3.17、3.12μg/mL和4.82、4.94μg/mL,化合物1和4对上述两种癌细胞的抑制活性较弱,IC50值均超过50μg/mL.并且从生源途径角度也初步探索了上述四个化合物之间的相互关系.