PHYTOCHEMICAL STUDY AND ANTIINFLAMMATORY PROPERTIES OF LOBELIA-LAXIFLORA L

Three new piperidine alkaloids were isolated from stems, leaves and fl owers of Lobelia laxiflora L. (Campanulaceae). The structures of racem . cis-8,10-diethyl-3,4-dehydrolobelidiol (1), racem. trans-8-ethyl-10- phenyl-3,4-dehydrolobelidiol (2) and racem. cis-8-ethyl-10-phenyl-3,4- dehydrolobelidiol (3) were established by spectral analyses. The resid ues obtained from the ethanol extracts from stems (S), leaves (L), and flowers (F) were applied in carrageenan (Car)- and cobra venom (CV)-i nduced acute inflammation in mice. A suppression of paw edema formatio n at a dose of 100 mg kg(-1) was established. In this study the antiin flammatory potential of Lobelia l. was regarded in connection with the complement system. The sequential activation and assembly into functi onal units of complement components can proceed via two different path ways, named classical (CP) and alternative (AP). The ability of the re sidues, nonalkaloid fractions, alkaloid fractions and the three alkalo ids at a concentration from 0.125 to 1.0 mg ml(-1) to inhibit compleme nt activation and thus to prevent inflammatory process was estimated i n vitro in human serum via both pathways. All of them inhibited comple ment activity with a predominant action on CP.