OBJECTIVETo study the screening of essential oils of Skimmia laureola leaves (SLO) for acute toxicity, antinociceptive, antipyretic and anticonvulsant activities in various animal models.

METHODSSLO were extracted using modified Clevenger type apparatus. Acute toxicity test was used in mice to observe its safety level. Antinociceptive activity of SLO was evaluated in acetic acid induced writhing and hot plate tests. Yeast induced hyperthermic mice and pentylenetetrazole induced convulsive mice were used for the assessment of its antipyretic and anticonvulsant profile respectively.

RESULTSSubstantial safety was observed for SLO in acute toxicity test. SLO showed a high significant activity in acetic acid induced writhing test in a dose dependent manner with maximum pain attenuation of 68.48% at 200 mg/kg i.p. However, it did not produce any relief in thermal induced pain at test doses. When challenged against pyrexia evoked by yeast, SLO manifested marked amelioration in hyperthermic mice, dose dependently. Maximum anti-hyperthermic activity (75%) was observed at 200 mg/kg i.p. after 4 h of drug administration. Nevertheless, SLO had no effect on seizures control and mortality caused by pentylenetetrazole.

CONCLUSIONSIn vivo studies of SLO showed prominent antinociceptive and antipyretic activities with ample safety profile and thus provided pharmacological base for the traditional uses of the plant in various painful conditions and pyrexia. Additional detail studies are required to ascertain its clinical application.

Analgesics ; pharmacology ; Animals ; Anticonvulsants ; pharmacology ; Antipyretics ; pharmacology ; Body Temperature ; drug effects ; Female ; Male ; Mice ; Oils, Volatile ; pharmacology ; toxicity ; Plant Leaves ; chemistry ; toxicity ; Rutaceae ; chemistry ; Toxicity Tests

Our recent studies have shown that co-activation of Gq and Gi proteins by 5-hydroxytryptamine (5-HT) and adrenaline show synergism in human platelet aggregation. This study was conducted to examine the mechanism(s) of synergistic interaction of 5-HT and platelet activating factor (PAF) in human platelets. We show that PAF, but not 5-HT, increased platelet aggregation in a concentration-dependent manner. However, low concentrations of 5-HT (2 microM) potentiated platelet aggregation induced by subthreshold concentration of PAF (40 nM) indicating a synergistic interaction between the two agonists and this synergism was blocked by receptor antagonists to either 5-HT or PAF. 5-HT also potentiated the effect of PAF on thromboxane A2 (TXA2) formation and phosphorylation of extracellularly regulated mitogen-activated protein kinases (ERK1/2). The synergism of 5-HT and PAF in platelet aggregation was inhibited by calcium (Ca2+) channel blockers, verapamil and diltiazem, phospholipase C (PLC) inhibitor, U73122, cyclooxygenase (COX) inhibitor, indomethacin, and MEK inhibitor, PD98059. These data suggest that synergistic effect of 5-HT and PAF on human platelet aggregation involves activation of PLC/Ca2+, COX and MAP kinase pathways.
Diltiazem/pharmacology ; Dose-Response Relationship, Drug ; Drug Synergism ; Estrenes/pharmacology ; Flavones/pharmacology ; Human ; In Vitro ; Indomethacin/pharmacology ; Kinetics ; Mitogen-Activated Protein Kinases/metabolism ; Phosphorylation/drug effects ; Platelet Activating Factor/*pharmacology ; Platelet Activation/drug effects ; Platelet Aggregation/*drug effects/physiology ; Pyrrolidinones/pharmacology ; Serotonin/*pharmacology ; Thromboxane A2/biosynthesis ; Verapamil/pharmacology

Our recent studies have shown that co-activation of Gq and Gi proteins by 5-hydroxytryptamine (5-HT) and adrenaline show synergism in human platelet aggregation. This study was conducted to examine the mechanism(s) of synergistic interaction of 5-HT and platelet activating factor (PAF) in human platelets. We show that PAF, but not 5-HT, increased platelet aggregation in a concentration-dependent manner. However, low concentrations of 5-HT (2 microM) potentiated platelet aggregation induced by subthreshold concentration of PAF (40 nM) indicating a synergistic interaction between the two agonists and this synergism was blocked by receptor antagonists to either 5-HT or PAF. 5-HT also potentiated the effect of PAF on thromboxane A2 (TXA2) formation and phosphorylation of extracellularly regulated mitogen-activated protein kinases (ERK1/2). The synergism of 5-HT and PAF in platelet aggregation was inhibited by calcium (Ca2+) channel blockers, verapamil and diltiazem, phospholipase C (PLC) inhibitor, U73122, cyclooxygenase (COX) inhibitor, indomethacin, and MEK inhibitor, PD98059. These data suggest that synergistic effect of 5-HT and PAF on human platelet aggregation involves activation of PLC/Ca2+, COX and MAP kinase pathways.
Diltiazem/pharmacology ; Dose-Response Relationship, Drug ; Drug Synergism ; Estrenes/pharmacology ; Flavones/pharmacology ; Human ; In Vitro ; Indomethacin/pharmacology ; Kinetics ; Mitogen-Activated Protein Kinases/metabolism ; Phosphorylation/drug effects ; Platelet Activating Factor/*pharmacology ; Platelet Activation/drug effects ; Platelet Aggregation/*drug effects/physiology ; Pyrrolidinones/pharmacology ; Serotonin/*pharmacology ; Thromboxane A2/biosynthesis ; Verapamil/pharmacology