Two new rare 30-norisodinosterol derivatives, 23,24-dimethylcholest-16-ene-3β,5α,6β,11α,20( R )-pentol 3-monoacetate ( 1 ) and 23,24-dimethylcholest-16-ene-3β,5α,6β,20( R )-tertrol 3-monoacetate ( 2 ), along with a known steroid, 3β,5α,6β,11α,20β-pentahydroxygorgosterol ( 3 ), were identified from Xenia umbellata . The structures of the isolated compounds were determined by analyses of the measured spectra (1D and 2D nuclear magnetic resonance, mass spectrometry, and infrared). The biosynthetic pathway of the new norisodinosterols was proposed. Compound 1 exhibited potent cytotoxicity against HepG2, PC-3, and HT-29 with IC 50 values of 4.70 ± 0.2, 5.60 ± 0.6, and 4.00 ± 0.4 μg/mL, respectively. On the contrary, compound 3 showed less potent cytotoxicity against HepG2 with IC 50 value of 22.20 ± 1.0 μg/mL. Two DNA-binding dyes have been used for the morphological detection of viable, apoptotic, and necrotic cells. The early apoptotic cell death was observed in all types of treated tumour cells. The late apoptotic cells are highly present in HepG2 cells with compound 3 compared with other cancer cells except for compound 1 . The anti-proliferative activity of compounds 1 and 3 warranted further investigation. Graphical abstract

中文翻译：

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伞形异形菌的稀有降鸟异甾醇衍生物：分离和抗增殖活性

两种新的稀有的30-去甲异甾醇衍生物23,24-methylcholest-16-ene-3β，5α，6β，11α，20（R）-戊醇3-单乙酸酯（1）和23,24-二甲基胆甾16-ene-3β从Xenia umbellata中鉴定出，5α，6β，20（R）-叔三醇3-单乙酸酯（2）以及已知的类固醇3β，5α，6β，11α，20β-五羟基g固醇（3）。通过分析测得的光谱（1D和2D核磁共振，质谱和红外光谱）确定分离出的化合物的结构。提出了新的去甲异麦角甾醇的生物合成途径。化合物1对HepG2，PC-3和HT-29表现出强大的细胞毒性，IC 50值分别为4.70±0.2、5.60±0.6和4.00±0.4μg/ mL。相反，化合物3对HepG2的杀伤力较小，IC 50值为22.20±1.0μg/ mL。两种DNA结合染料已用于活细胞，凋亡和坏死细胞的形态学检测。在所有类型的治疗肿瘤细胞中均观察到早期凋亡细胞死亡。与化合物3以外的其他癌细胞相比，晚期凋亡细胞在具有化合物3的HepG2细胞中高度存在。化合物1和3的抗增殖活性值得进一步研究。图形概要