Jean Rodolphe Chouna; Raymond Ngansop Nono; Pépin Nkeng-Efouet-Alango;
Antimicrobial’s resistances cause failure of empirical treatments, aggravates morbidity, increases mortality, and has negative impact on the costs of care because of ineffective antimicrobials treatment. In order to bring our modest contribution to this problem, we are investigating the trunk bark of Lasianthera africana a tropical plant from the Icacinaceae family. Its leaves are used in traditional medicine for the treatment of internal heat, urinary tract infection and enteric diseases. Its fruits are also used for treatment of asthma, hypertension, skin diseases and wounds healing. The goal of this work is to isolate the bioactive compounds and standardize this plant. Thus, the trunk barks were macerated using Ethanol then, the extraction protocol of alkaloid were done. Preliminary phytochemical investigation of the Ethanol extract allowed us to the isolation of ten known compounds to know: Melianodiol, Grandifotane A, Epicatechin, Betulinic acid, Betulin, tetracosanoic acid, β-sitostérol + Stigmasterol, β-sitostérol 3-O-β-D-glucopyranoside + Stigmasterol 3-O-β-D-glucopyranoside, stigmastane-3,6-dione, Di (2-ethylhexyl)phthale and one new hemisynthetic derivative: 21,23,24-triacetoxy-21,23-epoxytirucall-7-en-3- one. The antimicrobial activity of extracts, fractions and some compounds were evaluated against five gram+ strains using liquid microdilution method (Klebsiella pneumonia (clinical isoate), Klebsiella pneumonia (NR41388), Staphylococcus areus (clinical isoate), Staphylococcus areus (ATCC 25923), Streptococcus pneumonia (ATCC491619)). According to this test, the fraction E (MIC = 3.9) from the acid extract of methylene chloride showed a significant activity against S. aureus ATCC 25923. Furthermore, compounds like Epicatechin and Melianodiol showed respectively a good and moderated activity against S. aureus ATCC 25923 (MIC= 7.8; 62.5). This study will contribute both to the chimiotaxonomic knowledge of this plant and its bioactive compounds.
Key words: Lasianthera africana, Icacinaceae, antimicrobial activity
