Phytochemical investigation and chromatographic separation of extracts from one new actinobacteria strain Amycolatopsis taiwanensis that was isolated from soil of Yilan township, in the north of Taiwan, led to the isolation of nine new compounds, amycolataiwanensins A–I (1–9, resp.), and one new natural product, namely amycolataiwanensin J (10). The structures of the new compounds were unambiguously elucidated on the basis of extensive spectroscopic-data analysis (1D- and 2D-NMR, MS, and UV) and comparison with literature data. The effect of some isolates on the inhibition of NO production in lipopolysaccharide-activated RAW 264.7 murine macrophages was evaluated. Of the isolates, 3, 5, 7 and 8 exhibited potent anti-NO production activity, with IC₅₀ values of 17.52, 12.31, 17.81 and 13.32 μM, respectively, compared to that of quercetin, an iNOS inhibitor with an IC₅₀ value of 35.94 μM. This is the first report on indole metabolite from the genus Amycolatopsis.

Phytochemical investigation and chromatographic separation of extracts from the actinobacteria strain Saccharomonospora piscinae that was isolated from dried fishpond sediment of Kouhu township, in the south of Taiwan, led to the isolation of three new compounds, saccharpiscinols A–C (1–3, respectively), and three new natural products, namely (2S)-5,7,3′,4′-tetrahydroxy-6,8-dimethylflavanone (4), methyl-4-hydroxy-2-methoxy-6-methylbenzoate (5), and (±)-7-acetyl-4,8-dihydroxy-6-methyl-1-tetralone (6). Compounds 4–6 were reported before as synthesized products, herein, they are reported from nature for the first time. The structures of the new compounds were unambiguously elucidated on the basis of extensive spectroscopic data analysis (1D- and 2D-NMR, MS, and UV) and comparison with literature data. The effect of some isolates on the inhibition of NO production in lipopolysaccharide-activated RAW 264.7 murine macrophages was evaluated. Saccharpiscinol A showed inhibitory activities against LPS-induced NO production.

The cultivation of one actinobacteria strain, Herbidospora yilanensis, was isolated from sediment samples collected from Yilan County City in Taiwan, resulting in the isolation of five previously undescribed compounds: herbidosporayilanensins A–E (1–5), and four compounds isolated from nature for the first time: herbidosporayilanensins F–I (6–9). Their structures were elucidated by spectroscopic analyses, including 1D- and 2D-NMR experiments with those of known analogues, and on the basis of HR-EI-MS mass spectrometry, their antimycobacterial activities were also evaluated.

Background: Melanoma is an aggressive malignancy characterized by rapid proliferation and the potential to develop resistance to conventional therapies. Tetrahydrocurcumin (THC), a metabolite of curcumin, has demonstrated various biological activities; however, its effects on melanoma cell proliferation and cell cycle regulation remain insufficiently characterized. Methods: This study investigated the antiproliferative effects of THC and the associated molecular changes in human melanoma A375 and C32 cells. Cell viability was assessed using the CCK-8 assay, while Ki-67 immunofluorescence was used to evaluate cellular proliferation. Apoptosis was examined by Annexin V/propidium iodide staining, and cell cycle distribution was analyzed by flow cytometry. The expression of cell cycle-related proteins was evaluated by Western blotting. Results: THC treatment inhibited the viability of A375 and C32 cells in a dose- and time-dependent manner, with 24-h IC₅₀ values of 158.1 μM and 154.8 μM, respectively. Consistently, Ki-67 expression decreased following THC treatment, supporting its antiproliferative effect. However, Annexin V/propidium iodide analysis did not reveal a significant increase in apoptosis under the tested conditions, suggesting that growth inhibition was not primarily associated with the induction of apoptosis. Flow cytometric analysis demonstrated an increased proportion of cells in the G2/M phase, accompanied by a reduction in the G1-phase population. At the molecular level, THC treatment was associated with increased Cyclin B1 and CDK1 expression, together with alterations in other cell cycle regulatory proteins. These findings suggest that THC suppresses melanoma cell growth and promotes G2/M-phase accumulation, potentially through dysregulation of cell cycle progression. Further investigation of Cyclin B1–CDK1 complex activity and the phosphorylation status of CDK1 is required to clarify the underlying molecular mechanism. Conclusion: This study identifies THC as a potential inhibitor of melanoma cell proliferation and provides a basis for further investigation of its effects on cell cycle regulation.