Gallic acid was found to possess antiinflammatory activity towards zymosan-induced acute food pad swelling in mice. In vitro studies on the mode of action of gallic acid revealed that this compound interferes with the functioning of polymorphonuclear leukocytes (PMNs). Scavenging of superoxide anions, inhibition of myeloperoxidase release and activity as well as a possible interference with the assembly of active NADPH-oxidase may account for the inhibition of inflammatory process by gallic acid. Structure-activity relationship analysis showed that the o-dihydroxy group of gallic acid is important for the inhibitory activity in vitro.

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SUMMARYLicorice, the root extract of Glycyrrhiza glabra L., is used as a medicine for various diseases. Antiinflammatory as well as anti-allergic activities have been attributed to one of its main constituents, glycyrrhizin. These activities are mainly ascribed to the action of the aglycone, b-glycyrrhetinic acid. b-Glycyrrhetinic acid has a steroid-like structure and is believed to have immunomodulatory properties. To determine whether interference with complement functions may contribute to the immunomodulatory activity of b-glycyrrhetinic acid, its effects on the classical and alternative activation pathways of human complement were investigated. We found that b-glycyrrhetinic acid is a potent inhibitor of the classical complement pathway (IC 50 =35 m), whereas no inhibitory activity was observed towards the alternative pathway (IC 50 >2500 m). The anticomplementary activity of b-glycyrrhetinic acid was dependent on its conformation, since the a-form was not active. It was also established that naturally occurring steroids, e.g. hydrocortisone and cortisone, did not inhibit human complement activity under similar conditions. Detailed mechanistic studies revealed that b-glycyrrhetinic acid acts at the level of complement component C2.

From the latex of Jatropha curcas L. (Euphorbiaceae) a novel cyclic octapeptide was isolated, which we named curcacycline A. The compound was found to contain one threonine, one valine, two glycine, and four leucine residues. By two-dimensional ~H-NMR spectroscopy (HOHAHA and ROESY), its sequence was determined to be GiyLLeu2-Leu3-Gly4-ThrS-Val6-LeuT-Leu sGly% Curcacycline A displays a moderate inhibition of (i) classical pathway activity of human complement and (ii) proliferation of human T-cells.and two-dimensional 1H-NMR spectroscopy (HOHAHA and ROESY). Experimental Plant materialJatropha curcas L. plants grown as hedges in Jepara (near Kudus, Java, Indonesia) were identified. Crude latex was obtained by cutting off leaf stalks, adding a few drops of EtOH to prevent the latex from excessive foaming. The latex was stored at -20°C until use.

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