The potential of wattle tannin extracts for fine use

As a contribution to the fine use of wattle tannin, four fractions, purified tannin (Tp), ether extracts (Te), ethyl acetate extracts (Ta) and water fraction (Tw), were obtained by the methods of precipitation and liquid-liquid extraction of commercial wattle tannin. The number average molecular weights (M(n)) of Tp, Te, Ta and Tw were determined as 2660, 440, 980 and 2050 Da, respectively. The biological activities including protein precipitation, enzyme inhibition and antibacterial potency of each fraction were studied and compared. The results indicated that the molecular weight of each fraction is directly associated with its biological activities. The fraction of Tw showed the strongest capacity to precipitate protein and Ta showed the strongest capacity to inhibit enzyme activities, while Ta and Te showed better antibacterial potency.