Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH, 43210, USA.
World Botanical Associates, P.O. Box 81145, Bakersfield, CA, 93380, USA.
Phytochemistry. 2020 Dec;180:112521. doi: 10.1016/j.phytochem.2020.112521. Epub 2020 Oct 21.
Three undescribed stictanes, nieblastictanes A-C, two flavicanes, nieblaflavicanes A and B, together with three already reported stictanes, along with the known compounds (+)-usnic acid, sekikaic acid, divaricatic acid, and divaricatinic acid methyl ester were isolated from an ethyl acetate extract of the western North American lichen Niebla homalea. The structures of the new and known compounds were established by spectroscopic methods including nuclear magnetic resonance spectroscopy, mass spectrometry and electronic circular dichroism. Among the compounds isolated, usnic acid exhibited moderately potent antiproliferative activities against the A2780 ovarian (IC 3.8 μM) and MCF-7 breast cancer (IC 6.8 μM) cell lines. A plausible mode of formation of the chlorine-containing compound nieblastictane C is provided and the contribution of the isolated compounds to the chemotaxonomy of United States lichen species of the genus Niebla is also discussed.
从北美西部的地衣 Niebla homalea 的乙酸乙酯提取物中分离得到三种未描述的石松烷，nieblastictanes A-C，两种 flavicanes，nieblaflavicanes A 和 B，以及三种已报道的石松烷，以及已知化合物 (+)-usnic acid，sekikaic acid，divaricatic acid 和 divaricatinic acid methyl ester。新化合物和已知化合物的结构通过包括核磁共振波谱、质谱和电子圆二色性在内的光谱方法确定。在所分离的化合物中，usnic acid 对 A2780 卵巢（IC 3.8 μM）和 MCF-7 乳腺癌（IC 6.8 μM）细胞系表现出中等强度的抗增殖活性。提供了含氯化合物 nieblastictane C 的形成的可能模式，并讨论了分离化合物对美国 Niebla 属地衣种化学分类学的贡献。
