| Summary: | A talented endophytic <i>Streptomyces</i> sp. PH9030 is derived from the medicinal plant <i>Kadsura coccinea</i> (Lem.) A.C. Smith. The undescribed naphthoquinone naphthgeranine G (<b>5</b>) and seven previously identified compounds, <b>6</b>–<b>12</b>, were obtained from <i>Streptomyces</i> sp. PH9030. The structure of <b>5</b> was identified by comprehensive examination of its HRESIMS, 1D NMR, 2D NMR and ECD data. The inhibitory activities of all the compounds toward α-glucosidase and their antibacterial properties were investigated. The α-glucosidase inhibitory activities of <b>5</b>, <b>6</b>, <b>7</b> and <b>9</b> were reported for the first time, with IC<sub>50</sub> values ranging from 66.4 ± 6.7 to 185.9 ± 0.2 μM, as compared with acarbose (IC<sub>50</sub> = 671.5 ± 0.2 μM). The molecular docking and molecular dynamics analysis of <b>5</b> with α-glucosidase further indicated that it may have a good binding ability with α-glucosidase. Both <b>9</b> and <b>12</b> exhibited moderate antibacterial activity against methicillin-resistant <i>Staphylococcus aureus</i>, with minimum inhibitory concentration (MIC) values of 16 μg/mL. These results indicate that <b>5</b>, together with the naphthoquinone scaffold, has the potential to be further developed as a possible inhibitor of α-glucosidase.
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