Abstract: | Aiming to identify new sources of bioactive secondary metabolites, we isolated 82
endophytic fungi from stems and barks of the native Brazilian tree Caesalpinia
echinata Lam. (Fabaceae). We tested their ethyl acetate extracts in several in vitro
assays. The organic extracts from three isolates showed antibacterial activity
against Staphylococcus aureus and Escherichia coli minimal inhibitory concentration
(MIC) 32-64 μg/mL]. One isolate inhibited the growth of Salmonella typhimurium (MIC
64 μg/mL) and two isolates inhibited the growth of Klebsiella oxytoca (MIC 64 μg/mL),
Candida albicans and Candida tropicalis (MIC 64-128 μg/mL). Fourteen extracts at a
concentration of 20 μg/mL showed antitumour activities against human breast cancer
and human renal cancer cells, while two isolates showed anti-tumour activities
against human melanoma cancer cells. Six extracts were able to reduce the
proliferation of human peripheral blood mononuclear cells, indicating some degree of
selective toxicity. Four isolates were able to inhibit Leishmania (Leishmania)
amazonensis and one isolate inhibited Trypanosoma cruzi by at least 40% at 20 μg/mL.
The trypanocidal extract obtained from Fusarium sp. {"type":"entrez-nucleotide","attrs":{"text":"KF611679","term_id":"560187972","term_text":"KF611679"}}KF611679] culture was subjected
to bioguided fractionation, which revealed beauvericin as the compound responsible
for the observed toxicity of Fusarium sp. to T. cruzi. This depsipeptide showed a
half maximal inhibitory concentration of 1.9 μg/mL (2.43 μM) in a T. cruzi cellular
culture assay. |