Hydroalcoholic plant extracts with anti-inflammatory activity.

The aim of the present study was to investigate if standardized hydroalcoholic plant extracts such as Calendula officinalis, Hypericum perforatum, Plantago lanceolata and Glycyrrhiza glabra can suppress in cell-free systems the activities of 5-lipoxygenase (5-LO) and cyclooxygenase-2 (COX-2), key enzymes in the formation of proinflammatory eicosanoids from arachidonic acid (AA). Studies were undertaken to compare the above mentioned plant extracts to a known NSAID (nimesulide) in their ability to inhibit both cyclooxygenase (COX-2) and lipoxygenase (5-LO) activities in cell-free systems. We report on 2 vegetal extracts (Hypericum perforatum and Glycyrrhiza glabra) that inhibit 5-LO activity and 2 vegetal extracts (Plantago lanceolata and Glycyrrhiza glabra) that inhibit COX-2 activity. In this study, we demonstrate for the first time that Glycyrrhiza glabra extract efficiently suppresses both eicosanoids and leukotrienes formation in cell-free systems, implying that this extract directly acts as a dual inhibitor of 5-LO and COX-2 activities. With regard to the properties of dual COX-2/5-LO inhibitors, Glycyrrhiza glabra extract might be a potential drug possessing anti-inflammatory activity devoid of the most troublesome (gastric) side effects seen for drugs used as COX-2 and 5-LO inhibitors. Hypericum perforatum, Plantago lanceolata and Glycyrrhiza glabra extracts can be added to an already impressive list of these species that have anti-inflammatory activity.