Chemotaxonomic Significance of Flavonoids in Some Species of Galium (Rubiaceae) from Libya

The flavonoid profiles of five Libyan Galium L. (Rubiaceae) species collected from different localities and habitats were investigated. Fourteen flavonoid compounds were isolated and identified using the direct comparison of chromatographic and UV spectral analyses with standard samples. The flavone compounds were identified as apigenin (1) and its 7-glycoside (2); luteolin 7-diglycoside (3), diosmetin (4) and its 7-monoglycoside (5), as well as its 7-diglycoside (6). In addition, the detected flavonol compounds were kaempferol 3-glycoside (7), 3-diglycoside (8) and 3,7-diglycoside (9); quercetin (10) and its 3-glycoside (11), 3-rutinoside (12), 3,7-diglycoside (13), and 3-diglycoside- 7-glycoside (14). The chemotaxonomic relationships of the studied species of Galium and their significance were also discussed.