Effect of date fruits, Phoenix dactylifera L., on the hemolytic activity of streptolysin O

The effect of date fruit Phoenix dactylifera (Arecacaea) extracts on Streptococcus pyogenes was examined in vivo and in vitro. It was found that incubation for 24 h with date fruit extract at 5, 10 and 20% dilution effectively slowed the growth of S. pyogenes to 30.8, 64.7 and 88.5%, respectively. Date extract (DE) neutralized the hemolytic activity of the streptococcal exotoxin, streptolysin O, at very low concentrations. Inhibition of 96% was obtained at 1:262144 DE dilution. The inhibitory substance was found to be steroidal in nature and not proteinaceous as deproteinization of DE did not decrease its inhibitory effect. The results indicated that the neutralization property of this factor is most probably due to erythrocyte membrane stabilization and inhibition of streptolysin O enzyme. Date intake did not affect the titer of antistreptolysin O antibodies.