A quantitative study of the phenolic constituents of wild and cultivated leaves of Sclerocarya birrea(Anacardiaceae) was carried out by HPLC-UV/PDA and LC-MS. Phytochemical analysis of the methanol extract of wild plants led to the isolation of one new flavonol glycoside, quercetin 3-O-alpha-l-(5' '-galloyl)-arabinofuranoside (1), and eight known phenolic compounds; two epicatechin derivatives were also isolated from the same extract of the cultivated species. The antioxidant activity of all isolated compounds was determined by measuring free radical scavenging effects using the Trolox equivalent antioxidant capacity assay and the coupled oxidation of beta-carotene and linoleic acid (autoxidation assay).

RAPDs and chloroplast microsatellites were used to quantify the genetic variation of Vitellaria paradoxa (an economically important tree species in sub-Saharan Africa, north of the equator) and to analyse the geographic distribution of diversity in relation to the refuge theory. A total of 13 locations were sampled in eight countries, covering most of the natural range from Senegal to Uganda. A total of 67 polymorphic and 15 monomorphic RAPD loci were detected in 179 individuals. No relationship was identified between diversity and longitude or latitude. An unrooted neighbourjoining tree suggested a western group and an eastern group, representing 7% (P ¼ 0.000) of the total variation. A Mantel test suggested that genetic distances between populations were correlated to geographic distances (R ¼ 0.88, P ¼ 0.001). The three-chloroplast microsatellite primers, assayed in 116 individuals, revealed 10 different alleles and seven chlorotypes. Most of the populations comprised a single haplotype. It is proposed from these results that the difference between western and eastern populations results from putative refugia separated by the current 'Dahomey Gap' (a semiarid zone that meets the coast around the Ghana-Togo-Benin-Nigeria borders), an area that may have been exceptionally dry during glacial periods. In addition, it is suggested that the haplotype distribution and frequency in the western populations could be due to the more recent impact of humans, particularly shea tree selection and dispersal during traditional agroforestry.

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