Screening of Brazilian plants for antimicrobial and dnadamaging activities: I. Atlantic rain forest . Ecological station juréia-itatins

I. Atlantic Rain Forest . Ecological Station Juréia-Itatins) Crude extracts from 88 plant species occurring in São Paulo State (Brazil), collected in an Atlantic Forest region, have been screened for antimicrobial and DNA-damaging activities. Of the 114 extracts assayed for antibacterial activity, only the extracts from leaves and stems of Aspidosperma ramiflorum (Apocynaceae) showed a slight activity against Escherichia coli. In the antifungal assay with Candida albicans, no active extract was observed, while in the bioautography assay with Cladosporium sphaerospermum and C. cladosporioides 12% were active. However, only the extract of Psychotria mapoureoides (Rubiaceae) stems showed a strong inhibition of both fungi. The DNA-damaging assay with mutant strains of Saccharomyces cerevisiae resulted in 17.5 % of active extracts. The majority (55 %) of the active extracts showed selectivity for the DNA-repair mechanism of topoisomerase II and only 20 % showed a selective response for the mechanism of topoisomerase I.