Pharmacological basis of the use of Acorus calamus L. in inflammatory diseases and underlying signal transduction pathways

Acorus calamus L. is used as anti-inflammatory remedy in traditional system of medicine in Pakistan and India. This study was designed to explore the anti-inflammatory mechanism of Acorus calamus L. and its underlying signaling pathways. Aqueous, butanolic and n-hexane fractions of Acorus calamus were tested against cyclooxygenase (COX) and lipoxygenase (LOX) mediated eicosanoids production by arachidonic acid (AA). Butanolic fraction of Acorus calamus, but not the aqueous and n-hexane fractions, inhibited the COX mediated production of thromboxane B2 (TXB2) and liopxygenase product 1 (LP1) -a metabolite of LOX pathway. 12-(hydroxyeicosatetraenoic acid) HETE- another product of the LOX pathway was unaffected by all three fractions. Butanolic fraction of Acorus calamus showed strong inhibition against AA-induced platelet aggregation. Investigation of the underlying signaling pathways revealed that butanolic fraction inhibited phospholipase C (PLC) pathway in platelets, most probably acting on protein kinase C (PKC). Aqueous and n-hexane fractions of Acorus calamus were not effective against any platelet agonist. This study shows that butanolic fraction of Acorus calamus possesses components that inhibit AA metabolism and platelet aggregation through multiple pathways.