Seven new metabolites, including one thiolactone (1), along with one revised thiolactone (2), two Δ8,9-steroids (4–5), and three 4,5-diol derivatives (7–9), were isolated from the Meira sp. 1210CH-42, together with two known compounds (3 and 6). In 2023, we reported the first marine-derived Meira sp. 1210CH-42, which was isolated from a seawater sample collected in the Chuuk Islands, Federated States of Micronesia [1]. Preliminary screening indicated that the Meira sp. 1210CH-42 strain exhibited significant bioactivity. Therefore, we mass-cultured the strain, and as a result, we could isolate bioactive secondary metabolites from the 1210CH-42 strain. Their structures were elucidated based on the detailed analysis of 1D and 2D NMR, HR-ESIMS spectroscopic data, and ECD calculations. The biological activities of the compounds were assessed, including antioxidant, α-glucosidase inhibitory, and cytotoxic effects. Interestingly, these compounds demonstrated potent α-glucosidase inhibitory activity with IC50 values ranging from 86.0 to 279.7 μM, compared to acarbose (IC50 = 301.9 ~ 418.9 μM) [1-2].

[Acknowledgments: This work was supported by the Korea Institute of Marine Science and Technology Promotion (KIMST) funded by the Ministry of Oceans and Fisheries, Korea (grant No.: 20220027) and by the Korea Institute of Ocean Science and Technology (grant numbers: PEA0121 and PEA0211); H.J. Shin is the Investigator.]