Haemolytic and antimicrobial activities of saponin-rich extracts from guar meal

Saponin-rich GM extract was prepared by refluxing 25 g of GM with 250 ml of EtOH/H2O (1:1, v/v) for 3 h then filtering and distilling EtOH at 50 °C. The refluxed extract was partitioned with equal volume of BuOH obtaining crude saponin-rich GM extract with 4.8 ± 0.6% DM of GM that was purified by RP-HPLC eluting 20%, 60% and 100% MeOH fractions with 2.04 ± 0.32%, 0.91 ± 0.16% and 1.55 ± 0.15% DM of crude saponin-rich GM extract, respectively. Further purification of 100% MeOH fraction using NP-HPLC eluted four peak sub-fractions at 16, 39, 44 and 46 min. All saponin-rich GM fractions eluted were evaluated for both haemolytic and antimicrobial activities using 96-well plates in eight concentrations. Results indicated that only 100% MeOH fraction and its 16 min peak sub-fraction exhibited both haemolytic and antibacterial activities against Staphylococcus aureus, Salmonella Typhimurium and Escherichia coli, but 20% and 60% MeOH fractions stimulated Lactobacillus spp. growth.