PGE2 as a measure of anti‐inflammatory activity in Hypericum perforatum extracts and pure constituents

Abstract

Recent reports provide evidence that Hypericum perforatum (Hp) may possess anti-inflammatory properties. We assessed the anti-inflammatory activity of extracts and constituents using RAW264.7 macrophage cells stimulated with lipopolysaccharide (LPS) and prostaglandin E2 (PGE2) was measured after 8 hours. Extracts made from commercial source Frontier Herb exhibited reductions in PGE2 regardless of extraction procedure used; Iowa State Plant Introduction Station material revealed that only certain soxhlet chloroform extractions reduced PGE2. Of the flavonoids, rutin showed no reduction in PGE2 at concentrations up to 20 uM, quercetin showed a reduction in PGE2 at 5 uM (p=.0001) and a potent reduction in PGE2 from 10 to 40 uM (p<.0001) while quercetrin showed a reduction in PGE2 at 20 uM (p=.0197). The phloroglucinol hyperforin showed a reduction in PGE2 at 2 uM (p=.0297). The napthodianthrones hypericin (2 uM and 5 uM) and pseudohypericin (0.5 uM and 2 uM) showed no effect on PGE2 levels when assayed in the dark; light-activated hypericin showed no effect on PGE2; but 2 uM light-activated pseudohypericin showed a reduction in PGE2 (p<.0119). There was a significant increase in PGE2 production of 2 uM and 5 uM hypericin without LPS in light-activated versus dark conditions, warranting further study of the napthodianthrones’ effect on inflammation. Future work includes isolating and identifying constituents responsible for activity, but it is likely interactions of compounds accounting for the anti-inflammatory activity of extracts. Supported by grant ES012020 from NIEHS and ODS, NIH.