Hook. (20 kg) was extracted three times with ethanol under reflux. After evaporation of the solvent in vacuo, the concentrated extract was suspended in water and extracted successively with EtOAc and n-BuOH. The n-BuOH extract (150 g) was chromatographed over a silica-gel column separately with gradient elution by chloroform-methanol (20:1-7:3). There were flavonoids in the chloroform-methanol (8:2-7:3) fractions. All the fractions were combined to obtain 1.8 g flavonoids, and the flavonoids were chromatographed over RP-18 with water-methanol (6:4) and Sephadex LH-20 with methanol to afford compounds 1-5. These compounds were identified using UV, MS, and NMR spectrum, chemical transformations, and comparison with authentic samples and were isolated from L. pinceana for the first time. Kaempferol 3-O-α-L-rhamnoside (1), C 21 H 20 O 10 , mp 172-174°C. Negative FAB-MS m/z (%): 431 (M-1, 100), 325 (18), 311 (9), 285 (55).
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