Kleinhospitine E and Cycloartane Triterpenoids from Kleinhovia hospita

• DOI: 10.1021/acs.jnatprod.8b00211
• Publication Date: 2018-07-16T12:54:24Z
• Authors: Abdul Rahim; Yohei Saito; Katsunori Miyake; Masuo Goto; Chin-Ho Chen; Gemini Alam; Susan Morris-Nats...; Kuo-Hsiung Lee; Kyoko Nakagawa-Goto
• Keywords: Magnetic Resonance Spectroscopy; Molecular Structure; Anti-HIV Agents; Plant Extracts; Antineoplastic Agents, Phytogenic; 01 natural sciences; Triterpenes; 3. Good health; 0104 chemical sciences; Cell Line, Tumor; Humans; Drug Screening Assays, Antitumor; Malvaceae

A novel cycloartane triterpenoid alkaloid, kleinhospitine E (1), six new triterpenoids (2–7), three known (8–10), and taraxerone (11) were isolated from a methanol extract of Kleinhovia hospita. Their structures elucidated by 1D- 2D-NMR spectroscopy as well HRMS analysis. The absolute configurations all compounds determined their ECD spectra comparison with theoretical values. Kleinhospitine (1) is the first alkaloid possessing an unusual γ-lactam oxopropylidene side chain. Compounds 2, 3, 6 assigned 9α,10α-cyclopropyl ring, which found rarely among naturally occurring compounds, while 4 5 established isomers compound 3 containing 21,23-diacetal Biological evaluation revealed that 9 exhibited more potent antiproliferative activities against multidrug-resistant tumor cell line compared its parent chemosensitive line. Furthermore, submicromolar anti-HIV activity.