Roland Tchuenteu Tchuenguem2,; Boris Yotta Kianfé1; Beaudelaire Kemvoufo Ponou1; Rémy Bertrand Teponno1,; Léon Azefack Tapondjou1;
The genus Helichrysum belongs to the Asteraceae family and includes about 500 species distributed in the arid zone, generally on the mountain. Plants of this genus are recognized by their aromaticity and their therapeutic properties. Helichrysum odoratissimun is a plant species whose main stem can reach more than one meter in height. It is commonly used in traditional medicine for the treatment of digestive disorders, cold and cough. The present study was designed to evaluate the antimicrobial activity of extracts, fractions, and compounds from Helichrysum odoratissimun. The in vitro antibacterial and antifungal activities of the crude EtOH extract and its n-BuOH and EtOAc fractions as well as compounds 1-8 were evaluated using the broth microdilution method. The EtOAc fraction showed the most potent activity against Pseudomonas aeruginosa (ATCC74117) and Candida albicans (ATCC 9028) with minimum inhibitory concentration (MIC) values at 16 µg/mL and 32 µg/mL, respectively. Otherwise, the n-BuOH fraction showed the significant effect against Candida albicans (ATCC 9028) with a MIC value of 64 µg/ml. Based on these results, the EtOAc and n-BuOH fractions were purified using varying chromatographic methods to afford 5,8-dihydroxy-3,6,7-trimethoxyflavone (1), 5,4´-dihydroxy-7-methoxyflavanone (2), methylinositol (3), quercetin (4), quercetin-3-methoxy-7-O-β-D-glucopyranoside (5), 3-hydroxydihydrobenzofurane (6), 4,5-di-p-trans-coumaroyl quinic acid (7), kaempferol (8), β-sitosterol- 3-O-β-D-glucopyranoside (9), and oleanolic acid (10), Their structures were established using extensive spectroscopic and spectrometric analysis as well as comparison with published data. Among the isolated compounds, 5,8-dihydroxy-3,6,7-trimethoxyflavone, 5,4´-dihydroxy-7-methoxyflavanone and quercetin showed moderate activity against Candida albicans with MIC values of 64, 64 and 32 µg/mL, respectively. These results are in agreement with the use of H. odoratissimun in traditional medicine against infectious diseases such as cough, cold and digestive disorders. Thus the ethyl acetate fraction of this plant could further be submitted for more investigations as lead for infectious diseases.
Keywords: Helichrysum-odoratissimun, Asteraceae, Antimicrobial-activity, Isolation, Structure-elucidation
