Topical anti-inflammatory activity of extracts and compounds from Hypericum perforatum L

Three preparations of Hypericum perforatum L. (a hydroalcoholic extract, a lipophilic extract and an ethylacetic fraction) and the pure compounds hypericin, adhyperforin, amentoflavone, hyperoside, isoquercitrin, hyperforin dicyclohexylammonium (DHCA) salt and dicyclohexylamine were evaluated for their topical anti‐inflammatory activity. H. perforatum preparations provoked a dose‐dependent reduction of Croton‐oil‐induced ear oedema in mice, showing the following rank order of activity: lipophilic extract > ethylacetic fraction > hydroalcoholic extract (ID50 (dose that inhibited oedema by 50%) 220, 267 and >1000 μg cm−2, respectively). Amentoflavone (ID50 0.16μmol cm−2), hypericin (ID50 0.25μmol cm−2), hyperforin DHCA salt (ID50 0.25μmol cm−2) and adhyperofrin (ID50 0.30μmol cm−2) had anti‐inflammatory activity that was more potent or comparable to that of indometacin (ID50 0.26 μmol cm−2), whereas isoquercitrin and hyperoside were less active (ID50 about 1μmol cm−2). As dicyclohexylamine alone was inactive, the effect of hyperforin DHCA salt can be attributed completely to the phloroglucinol moiety. The pharmacological activity and phytochemical profile of the tested extracts and fraction suggest that different constituents are involved in the topical antiphlogistic property of H. perforatum in‐vivo.