Flavonoids from Acacia Tortilis (original) (raw)

The genus Acacia comprising over 500 species, found in the warmer, drier parts of the World, chiefly in Arabia, Australia and Africa. 1 In India, there are about 22 indigenous species, distributed throughout the plains. Some of the Acacia species are of considerable value for reafforestation and reclamation of waste land. They are the good sources of tannin, gum and timber. 1 Acacia tortilis (Syn: A. raddiana Savi) (Leguminosae) was found to be a very useful source of protein. 2 The acid digest of cell wall constituents fibres and cellulose found in the leaves provide nutrients for the animals as fodder. 3 It is also used for the relaxation of smooth muscle. 4 Earlier investigations of this plant described the isolation of apigenin glycoside, 5 quercetin glycoside and isorhaminetin glycoside from leaves, 6 and n-hexacosanol, betulin, α-, β-amyrin and β-sitosterol from the stem bark. 7 Medicinal properties and scanty work on this plant stimulated our interest to carry out its comprehensive investigation. We now report here the isolation and characterisation of a novel flavonoid 5,7-dihydroxy-4-p-methyl benzyl isoflavone 4a, along with the three known flavonoids, apigenin, luteolin and quercetin from the leaves of Acacia tortilis. The dried and powdered leaves of Acacia tortilis (3 kg) procured from Yeman, were exhaustively extracted with light petroleum ether (60-80), benzene and finally with methanol respectively. The methanol extract was concentrated by heating over a boiling water bath under reduced pressure, and a brown gummy mass was obtained. It gave a positive colour test for flavonoids. 8 TLC examination in benzene-pyridine-formic acid (BPF, 36:9:5) and toluene-ethylformate-formic acid (TEF, 5:4:1) systems showed it to be a mixture of several compounds. The brown gummy mass was purified by reflux-ing it with petroleum ether, benzene and chloroform. The semi-solid mass left behind was chromatographed over silica gel column. Fractional elution with benzene-ethylacetate