Anti-complementary activity of Crataegus sinaica

The 80% and 70% acetone extracts from fruits and leaves of Crataegus sinaica Boiss (Rosacea) and the ethyl acetate-, butanol-, and water-fractions obtained from these initial extracts as well as the isolated compounds, quercetin 1. 1., hyperoside (quercetin 3-O-galactoside) 2. 2., rutin (quercetin 3-O-rutinoside) 3. 2., vitexin 4. 1., rhamnosylvitexin 5. 3., monoacetylrhamnosylvitexin 6. 3., epicatechin 7. 4., procyanidin B-5 8. 4., proanthocyanidin A-2 9. 5., procyanidin B-2 10. 4., and procyanidin C-1 11. 4., were tested for their influence on the classical (CP) and alternative (AP) pathways of complement-mediated hemolysis. All extracts and fractions showed a strong anti-complementary effect in a dose-dependent way which was more pronounced on the CP than on the AP. The results indicated that the pure proanthocyanidins were active on the CP. Procyanidin C-1 and proanthocyanidin A-2 were the most active on the CP and also showed activity on AP, whereas the flavonoids isolated were generally less active. However, rutin, showed a strong activity, quercetin and rhamnosylvitexin a moderate activity on the CP. This is the first report on the chemical constituents and complement-modulating activity of C. sinaica and on the occurrene of proanthocyanidin A-2 9. in hawthorn.