IN-VITRO AND IN-VIVO INVESTIGATIONS ON TH E CARDIOPROTECTIVE EFFECTS OF OLIGOMERIC PROCYANIDINS IN A CRATAEGUS EXTRACT FROM LEAVES WITH FLOWERS

Cardioprotective effects of a standardized extract from leaves with fl owers of Crataegus (WS-1442; content of oligomeric procyanidins [OPC]: 18.75%) have recently been demonstrated in an ischemia-reperfusion mo del in rats. Further studies were now conducted to clarify the mechani sm of action and to identify active constituents involved in these eff ects of WS-1442. Exhausting partitioning between ethyl acetate/water a nd successive ultrafiltration of the aqueous layer led to the quantita tive recovery of three fractions, which were tested for their in vitro radical scavenging (RS) and human neutrophil elastase (HNE) inhibitor y activity. The lipophilic ethylacetate-soluble fraction A, enriched i n flavone derivatives and constituting 14.9 % of WS-1442, was as activ e as WS-1442 in inhibiting HNE. However, its RS activity was only abou t half that of the primary extract. Although 67.9 % of WS-1442 was rec overed in a water-soluble low molecular weight fraction B, this fracti on displayed only weak RS and HNE inhibiting activity. In contrast, th e RS and HNE inhibiting potencies of an essentially flavone-free and O PC-rich fraction C (21.3 % of WS-1442) were significantly higher (inhi bition of lipid peroxidation: IC50 0.3 mu ml; inhibition of HNE: IC50 0.84 mu g/ml) as those of WS-1442. The RS and HNE inhibitory activitie s of the extract and those of its fractions correlated well with their OPC-content but not with their concentration of flavonols. These resu lts demonstrate that OPCs of Crataegus extracts possess stronger radic al scavenging activities than flavone derivatives or other constituent s. In addition, the oligomeric components are potent inhibitors of HNE . Oral administration of 20 mg/kg/d of the OPC-rich fraction C to rats afforded similar protection against ischemia-reperfusion induced path ologies as treatment with WS-1442 at a dose of 100 mg/kg/d. These obse rvations indicate that radical scavenging and elastase inhibitory acti vities could indeed be involved in the observed cardioprotective effec ts of WS-1442, and demonstrate that OPCs are major orally active const ituents of WS-1442. Thus, Crataegus extracts used therapeutically for cardiovascular diseases should be analyzed and standardized for their OPC-content.