Inhibition of galectin-3 mediated cellular interactions by pectic polysaccharides from dietary sources

Pectic polysaccharides from dietary sources such as Decalepis hamiltonii-swallow root ( SRPP), Hemidesmus indicus ( HPP), Nigella sativa-black cumin ( BCPP), Andrographis serpyllifolia-(APP), Zingiber officinale ginger ( GRPP) and, citrus pectin (CPP) were examined for galectin inhibitory activity. Inhibition of ( a) galectin-3 of MDA-MB-231 cells induced hemagglutination of red blood cells; ( b) galectin-3 mediated interaction between normal/metastatic human buccal cells ( NBC)/( MBC) and; ( c) invasion of MDA-MB-231 and MBC in the invasive chamber was assessed. Results indicated that SRPP inhibited hemagglutination at Minimum Inhibitory Concentration ( MIC) of 1.86 mu g ml(-1) equivalent of carbohydrate as apposed to those of BCPP ( 130 mu g ml(-1)), APP ( 40 mu g ml(-1)), HPP ( 40 mu g ml(-1)) and CPP ( 25 mu g ml(-1)). GRPP even at concentration > 1 - 6 mg ml(-1) did not inhibit agglutination. Also SRPP showed similar to 15 and 2 fold potent anti hemagglutination activity relative to that of galectin-3 specific sugars galactose ( MIC-27.1 mu g ml(-1)) and lactose ( MIC-4.16 mu g ml(-1)) respectively. Further, SRPP at 10 mu g ml(-1) inhibited agglutination of NBC by galectin-3 of MDA-MB-231 cells. Modified swallow root pectic polysaccharide ( MSRPP) of 50 kDa retained anti hemagglutination activity ( MIC of 1.03 mu g ml(-1)) and inhibited MDA-MB-231 and MBC invasion by 73 and 50% with an IC50 of 136 and 200 mu g ml(-1) respectively. Both SRPP and MSRPP induced apoptosis up to 80% at 100 mu g ml(-1) concentration by activating similar to 2 and 8 folds of Caspase-3 activity. Sugar composition analysis and its correlation with the galectin inhibitory property indicated that pectic polysaccharides with higher arabinose and galactose content-arabinogalactan inhibited hemagglutination significantly.