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Cyclizidine-Type Alkaloids from Streptomyces sp. HNA39
- Jiang, Yong-Jun, Li, Jia-Qi, Zhang, Hao-Jian, Ding, Wan-Jing, Ma, Zhong-Jun
- Journal of natural products 2018 v.81 no.2 pp. 394-399
- Streptomyces, alkaloids, chlorine, cytotoxicity, inhibitory concentration 50, protein kinases
- Eight new cyclizidine-type alkaloids (1–8) and one known alkaloid (9) were identified from the chemical investigations of a marine-derived actinomycete, Streptomyces sp. HNA39. Among these alkaloids, compounds 3, 7, and 8 contain a chlorine atom, and the known alkaloid, (+)-ent-cyclizidine (9), is now first reported as a natural product. Their structures were elucidated by extensive NMR-spectroscopic analysis and HRESIMS data. The absolute configurations of all of the compounds were established by ECD calculations. Cytotoxicity evaluations of all of the compounds showed that compound 2 exhibited significant activity against the PC3 and HCT116 human-cancer-cell lines with IC₅₀ values of 0.52 ± 0.03 and 8.3 ± 0.1 μM, respectively. Interestingly, compounds 2, 5, 7, and 8 exhibited moderate inhibition against the ROCK2 protein kinase with IC₅₀ values from 7.0 ± 0.8 to 42 ± 3 μM.