A phenanthridin-6(5H)-one derivative and a lanostane-type triterpene with antibacterial properties from Anonidium mannii (Oliv). Engl. & Diels (Annonaceae)

• Published in: Natural product research 2021-11, Vol.35 (21), p.4041-4050
• Main Authors: Ngangoue, Marcelle Oliviane, Ngameni, Bathelemy, Ambassa, Pantaleon, Chi, Godloves Fru, Wamba, Brice Elvis Nougan, Ombito, Japheth Omollo, Bojase, Gomotsang Moleta, Fotso, Ghislain Wabo, Kuete, Victor, Ngadjui, Bonaventure Tchaleu
• Format: Article
• Language: English
• Subjects: Anonidium mannii; antibacterial activity; lanostane-type tritepene; phenanthridin-6(5H)-one alkaloid
• ISSN: 1478-6419; 1478-6427
• DOI: 10.1080/14786419.2020.1758094

The chemical investigation of Anonidium mannii root extract by column chromatography techniques led to the isolation of eight compounds among which two previously unreported compounds; a lanostane-type triterpene, lanosta-7,9(11),23-triene-3β,15α-diol 1 and an alkaloid, 9-hydroxy-8-methoxyphenanthridin-6(5H)-one 2 along with six known compounds: lanosta-7,9(11),24-triene-3β,21-diol 3, oxoanolobine 4, 3, 4-dihydroxybenzoic acid 5, stigmasterol 6, β-sitosterol 7 and 3-O-β-D-glucopyranosyl-β-stigmasterol 8. Their structures were established from spectral data, mainly HR-ESIMS, 1 D and 2 D NMR and by comparison with literature data. The crude root and stem bark extracts (AMR and AMB) and the isolated compounds (1-8) were tested against nine Gram-negative bacteria using rapid p-iodonitrotetrazolium chloride ≥97% (INT) microdilution technique. It was found that AMR, AMB and compound 5 were active against the nine tested bacteria with MIC values ranging from 64 to 1024 µg/mL. Compounds 1-4 had selective antibacterial activities whilst 6-8 were not active.