Antifungal Activities of Compounds Produced by Newly Isolated Acrocarpospora Strains

Abstract

In our continued search for bioactive metabolites from cultures of rare Actinobacteria resources from all over Taiwan and various natural ecological environments, an active antimicrobial strain of Acrocarpospora punica 04107M was collected in Taitung County in Taiwan and prepared from soil. The bioassay-guided fractionation of the BuOH extract of a culture broth from A. punica 04107M led to the isolation of five previously undescribed compounds: Acrocarposporins A−E (Compounds 1−5). All the constituents were confirmed by HRESIMS and 1D- and 2D-NMR spectroscopy. Their antifungal activity was also evaluated. Our results showed that four constituents (Compounds 1, 2, 4, and 5) possessed mild antifungal activity against Aspergillus niger, Penicillium italicum, Candida albicans, and Saccharomyces cerevisiae. It is worth mentioning that the chemical composition of Acrocarpospora punica 04107M has never been studied. This is the first report on diterpenoid metabolites from the genus Acrocarpospora.

Keywords: Acrocarpospora punica 04107M; Streptosporangiaceae; antifungal activities; diterpenoid.

Figure 1

Neighbor-joining tree based on nearly complete 16S rDNA sequences showing the phylogenetic position of strain 04107M within the Acrocarpospora species. Numbers at the nodes indicate the percentage of 1000 bootstrap resampling procedures and only values over 50% are given. Bar: 0.01 substitutions per nucleotide position.

Figure 2

Compounds 1–5, isolated from Acrocarpospora punica 04107M.

Figure 3

Key COSY (¹H→¹H) and HMBC (¹H→¹³C) correlations of Compounds 1–5.

Figure 4

Key NOESY correlations (↔) of Compounds 1–5.