Undescribed Metabolites from an Actinobacteria Acrocarpospora punica and Their Anti-Inflammatory Activity

In an effort to explore bioactive anti-inflammatory compounds from natural Actinobacteria resources from all over Taiwan and various ecological environments, an active strain of Acrocarpospora punica was collected at Taitung County in Taiwan, prepared from soil origin. A bioassay-guided fractionation of the BuOH extract of a culture broth of a new strain of the actinomycete Acrocarpospora punica led to the isolation of five previously undescribed compounds: acrocarpunicains A-F (1-6). The structures were elucidated by 1D and 2D Nuclear Magnetic Resonance (NMR) spectroscopy and mass spectrometry. Furthermore, the isolated compounds were subjected to in vitro testing to evaluate their anti-inflammatory activity. Of these isolates, acrocarpunicains A (1), B (2), C (3) and F (6) showed NO inhibitory activity with IC₅₀ values of 9.36 ± 0.25, 10.11 ± 0.47, 5.15 ± 0.18, and 27.17 ± 1.87 μM, stronger than the positive control, quercetin (IC₅₀ = 35.95 ± 2.34 μM). To the best of our knowledge, this is the first report on azaphilone and phenanthrene-type metabolites from the genus Acrocarpospora.