Background: Cupressus arizonica Greene is a coniferous tree with great importance in fragrance and pharmaceutical industries. Essential oils from C. arizonica (EC) have shown potential antioxidant, and anti-microbial activities. This study aimed at investigating the anti-nociceptive and anti-inflammatory effects/mechanisms of EC.
Methods: The EC was evaluated for anti-nociceptive and anti-inflammatory activities on male Wistar rats using a formalin test and carrageenan-induced paw edema, respectively. Also, we pre-treated some of the animals with naloxone and flumazenil in the formalin test to find out the possible contributions of opioid and benzodiazepine receptors to EC anti-nociceptive effects. Finally, gas chromatography/mass spectrometry (GC/MS) analysis was used to identify the EC's constituents.
Results: EC in intraperitoneal doses of 0.5 and 1 g/kg significantly decrease the nociceptive responses in both early and late phases of the formalin test. From a mechanistic point of view, flumazenil administration 20 minutes before the most effective dose of EC (1 g/kg) showed a meaningful reduction in the associated antinociceptive responses during the early and late phases of the formalin test. Naloxone also reduced the anti-nociceptive role of EC in the late phase. Furthermore, EC at the doses of 1, 0.5, and 0.25 g/kg significantly reduced paw edema from 0.5 hours after carrageenan injection to 4 hours. GC/MS analysis showed that isolated EC is a monoterpene-rich oil with the major presence of α-pinene (71.92%), myrcene (6.37%), δ-3-carene (4.68%), β-pinene (3.71%), and limonene (3.34%).
Conclusions: EC showed potent anti-nociceptive and anti-inflammatory activities with the relative involvement of opioid and benzodiazepine receptors.
Keywords: Analgesics; Anti-Inflammatory Agents; Antioxidants; Cupressus; GABA-A.; Gas Chromatography-Mass Spectrometry; Inflammation; Oils; Opioid; Pain Measurement; Rats; Receptors; Volatile; Wistar.