Sakava Paul, Tagatsing Fotsing Maurice, Zeuko’o Menkem Elisabeth, Talla Emmanuel, Laurent Sophie, Celine Hénoumont, Vander Elst Luce, Awantu Fusi Angelbert, Atchadé Alex de Théodore and Mbafor Tanyi Joseph
The objective of this study was the isolation, the structure elucidation and the identification of chemical constituents from the n-hexane, the ethyl acetate (EtOAc) and the methanol (MeOH) extracts of a cameroonian propolis sample collected from Ngaoundal. Thirteen secondary metabolites belonging to cycloartane, ursane and oleananetype triterpenes were isolated and their structures were established by chemical tests and detailed spectroscopic analysis as cycloart-23(E)-en-3β,25-diol (1), cycloarta-7(E),23(E)-diene-3β,25-diol (2), cycloarta-23(E),25(26)-diene3β-ol (3), 25-pentoxy cycloart-23(E)-en-3β-ol (4), cycloartenol (5), 3β-hydroxyolean-12-en-18β-28-oic acid (oleanolic acid) (6), 3α-hydroxyoleanolic acid (3-Epi-oleanolic acid (7), 3β-hydroxyurs-12-en-18β-28-oic acid (ursolic acid) (8), 3α-hydroxyursolic acid (3-Epi-ursolic acid) (9), β-amyrin (10), α-amyrin (12), 3-Epi-β-amyrin (11) and 3-Epi-α-amyrin (13). To the best of our knowledge, compounds 2 and 4 are here described for the first time, while compounds 1, 3, 6, 7, 9, 11 and 13 are here reported for the first time in a propolis sample. Their presence in this propolis provides valuable chemotaxonomic information about the plants from which the bees collected resins. The plants origin of this propolis could be Mangifera indica (mango), Orthosiphon stamineus, Boswellia sacra, Boswellia neglecta and Melipona beecheii, Ficus exasperate, Byrosonima fagifolia, Byrosonima crassifolia, Lavandula officinalis, Euphorbia dendroides, Pachysandra terminalis, Melandrium firmum. The n-hexane crude extract (EAP4) was active against S. aureus 209 (MIC: 184 mg/ml) and Candida albicans 62I (MIC: 92 mg/ml). Compounds 1 and 3 exclusively exhibited antimicrobial activity against Salmonella spp (MIC: 0.1-0.2 mg/ml). The MIC values of 1 and 3 were greater than that of the standard drug (Amoxicillin): 0.1-0.2 mg/ml versus 0.4 mg/ml.