Spiroconyone B and C, Two Rearranged Cholestane Steroids with Spiro[4.5]decane and Oxaspiro[4.5]decane Scaffolds from
Ran-Ran Zhang1,2, Zhen Lu1, Qiang-Qiang Shi3
1Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, P. R. China.
None:
Spiroconyone B (1) and C (2), two unique steroids bearing rare spiro[4.5]decane and oxaspiro[4.5]decane scaffolds, along with four analogues (3-6) were isolated from the sea star Patiria pectinifera. Structures were established by comprehensive spectroscopic analysis, quantum-chemical nuclear magnetic resonance calculations, electronic circular dichroism data, and single-crystal X-ray diffraction. Compounds 1, 4, and 5 exhibited cytotoxicity toward HL-60 cells with IC50 values of 7.6 ± 0.3, 3.6 ± 0.1, and 6.0 ± 0.5 μM, respectively. Flow cytometry indicated that 4 induced G2/M phase arrest, and annexin V/PI assays showed dose-dependent increases in the level of total apoptosis for 1 and 4. Western blotting revealed downregulation of cyclin B1 and cdc2 (CDK1) by 4; both 1 and 4 decreased Bcl-2 and increased Bax, consistent with mitochondria-mediated apoptosis. Network pharmacology, supported by mechanistic assays, further suggested the engagement of the PI3K/Akt pathway by 4.
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