Cytotoxic steroidal saponins from Panicum turgidum Forssk

• Published in: Steroids 2017-09, Vol.125, p.14-19
• Main Authors: Zaki, Ahmed A., Ali, Zulfiqar, Wang, Yan-Hong, El-Amier, Yasser A., Khan, Shabana I., Khan, Ikhlas A.
• Format: Article
• Language: English
• Subjects: Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacology; Cell Line, Tumor; Cholestan; Cytotoxicity; Humans; Inhibitory Concentration 50; Panicum - chemistry; Panicum turgidum; Poaceae; Saponins - chemistry; Saponins - pharmacology; Spirostan; Steroidal glycosides; Steroids - chemistry
• ISSN: 0039-128X; 1878-5867
• DOI: 10.1016/j.steroids.2017.06.003

[Display omitted] •Seven steroidal saponins were isolated from Panicum turgidum.•Three bidesmosidic cholestane-type and one spirostane-type steroidal glycosides were found new.•Spirostane-type steroidal glycosides showed cytotoxicity. Three new bidesmosidic cholestane-type steroidal glycosides, 16-O-β-d-glucopyranosyl-cholest-5-en-3β,16β-diol-22-one-3-O-α-l-rhamnopyranosyl-(1→2)-O-[(β-d-glucopyranosyl(1→4)]-O-β-d-glucopyranoside (1), 16-O-β-d-glucopyranosylcholest-5-en-3β,16β-diol-22-one-3-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-glucopyranoside (2), and 16-O-β-d-glucopyranosylcholestan-3β,16β-diol-6,22-dione-3-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-glucopyranoside (3) were isolated from a methanolic extract of Panicum turgidum. In addition four known compounds, pennogenin 3β-O-α-l-rhamnopyranosyl-(1→2)-O-[α-l-rhamnopyranosyl-(1→4)-O-α-l-rhamnopyranosyl-(1→4)]-O-β-d-glucopyranoside (4), yamogenin 3β-O-α-l-rhamnopyranosyl-(1→2)-O-[α-l-rhamnopyranosyl-(1→4)]-O-β-d-glucopyranoside (5), yamogenin 3β-O-α-l-rhamnopyranosyl-(1→2)-O-[α-l-rhamnopyranosyl-(1→4)-O-α-l-rhamnopyranosyl-(1→4)]-O-β-d-glucopyranoside (6), and pennogenin 3β-O-α-l-rhamnopyranosyl-(1→2)-O-[α-l-rhamnopyranosyl-(1→4)]-O-β-d-glucopyranoside (7) were also isolated and characterized. Their structures were established using extensive spectroscopic methods including 1D and 2D NMR and HRESIMS. The isolated compounds were screened for cytotoxicity towards a panel of mammalian cell lines and 4–7 were found to be cytotoxic.