Polygalloyltannin isolated from the roots of Acacia nilotica Del. (Leguminoseae) is effective against Plasmodium berghei in mice

Crude methanolic root extracts of Acacia nilotica Del. (Leguminoseae) demonstrated significant activity against chloroquine sensitive strain of Plasmodium berghei in mice. Purified extracts showed only a single fraction with significant antiplasmodial effects using bioguided essay techniques. The active A. nilotica isolate was highly polar dissolving readily in methanol, appeared as a single spot in different TLC conditions and was positive for tannins, melting with decomposition between 224 229°C. Its H NMR spectra exhibited large signals at S 6.90 7.58 and 4.70 5.00. The Mass spectra (ES1 Msn) of the isolate gave a large M 1 signal of m/z 1395 consistent with the molecular formula C62H43O38. Others at 1243, 1091, 939, 787, 635, 453 and 331 that differ by m/z 152 were accounted for by the progressive loss of a galloyl (C7H4O4) moiety. A polygalloyltannin structure containing a central glucosyl moiety corresponding with 1, 3, 6 – digalloyl – 2, 4 monogalloyltannin was hence postulated.