METHODS AND RESULTS:
Chemical investigation of a sample of propolis originating from North-Western Cameroon led to the isolation of thirteen alk(en)ylphenols (1-13) (inseparable mixture) along with α-amyrin (14), β-amyrin (15), lupeol (16), cycloartenol (17), mangiferonic acid (18), ambonic acid (19), Mangiferolic acid (20), ambolic acid (21), isoMangiferolic acid (22) and nine alk(en)ylresorcinols (23-31) (inseparable mixture). All compounds were identified following analysis of their spectroscopic data and comparison with previously published reports. Compounds (8), (12), (13) and (30) are new natural products. GC-MS analysis carried out on the alk(en)ylphenol and alk(en)ylresorcinol mixtures (dimethyl disulphide trimethylsilyl derivatives) revealed the presence of saturated and mono-unsaturated compounds with side chain lengths ranging from C11 to C19 and C15 to C19, respectively. The position of the double bond in mono-unsaturated derivatives was established from the characteristic fragments resulting from the cleavage of the bond between the two methylthio-substituted carbons. The most abundant compound in each mixture was 3-(12'Z-heptadecenyl)-phenol (10) and 5-(12'Z-heptadecenyl)-resorcinol (29).
CONCLUSIONS:
This study is the first to report the presence of triterpenes (except for lupeol) and phenolic lipids, including eighteen compounds previously unreported in bee glue, in an African sample. |
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