TITLE:
Triterpenoids and Semisynthetic Derivatives with Antimicrobial Activities from the Leaves of Caloncoba glauca (Flacourtiaceae)
AUTHORS:
James D. Simo Mpetga, Arno R. Nanfack Donfack, Jean-De-Dieu Tamokou, Irene Chinda Kengne, Pierre Tane, Xiao-Jiang Hao, Mathieu Tene
KEYWORDS:
Caloncoba glauca, Triterpenoids, Chemical Derivatizations, Antimicrobial Activity, Structure-Activity Relationship
JOURNAL NAME:
Advances in Biological Chemistry,
Vol.11 No.4,
July
23,
2021
ABSTRACT: Chemical investigation of the MeOH extract from the
leaves of C. glauca yielded nine known triterpenoids (1-9)
belonging to the cycloartane and friedelane series. Two of these
compounds namely glaucartanoic acid A (1) and 3β,21β-dihydroxy-30-nor-(D:A)-friedoolean-20(29)-en-27-oic
acid (5) were subjected to chemical derivatizations and afforded five
new derivatives: diacetylglaucartanoic acid A (1a),
24-acetylglaucartanoic acid A (1b), glaucartanoic acid A methyl ester (1c),
24-methoxyglaucartanoic acid A methyl ester
(1d), and 3β,21β-diacetoxy-30-nor-(D:A)-friedoolean-20(29)-en-27-oic acid (5a). Their structures were assigned based on their NMR and MS data
and by comparison with literature values.
The MeOH extract, isolated compounds and some new semi-synthetic
derivatives were subjected to in vitro antimicrobial assays
against a panel of pathogenic microorganisms, including Gram-positive
and Gram-negative bacteria, and fungi using broth microdilution method. The
MeOH extract displayed activity towards all the tested pathogenic bacterial and fungal strains with good
activity (MIC against Staphylococcus aureus ATCC25923 and Shigella flexneri SDINT. Compounds 3 and 5 showed the most potent antimicrobial effect.