CHEMICAL COMPOSITION AND ANTINOCICEPTIVE ACTIVITY OF ESSENTIAL OIL FROM Myrcia rostrata DC. (MYRTACEAE) IN ANIMAL MODELS

There are approximately 300 Myrcia DC. species in Brazil. The antimicrobial, anti-inflammatory and antinociceptive activities of some of these species have been described in the literature. The present study aimed to analyze the chemical composition and evaluate the antinociceptive activity of essential oil from fresh Myrcia rostrata DC. leaves. The oil was obtained by hydrodistillation in a Clevenger-type apparatus and chemical analysis was conducted by GC/FID and GC/MS. The acute oral toxicity and the rota rod tests were executed beforehand. The nociceptive tests (acetic acid-induced writhing, formalin and hot plate) were performed with the oil at doses of 75, 150 or 300 mg kg-1. Of the constituents identified, 95.24% were sesquiterpenes, carotol (17.68%) being the major compound. The essential oil caused no obvious signs of toxicity, nor did it affect the motor coordination of the animals. In conclusion, the animals that received the oil, especially at 300 mg kg-1, demonstrated a lower number of writhes (1.62 versus 27.88±2.75), a decrease in paw-licking time in both phases of the formalin test, and increased latency on the hot plate when compared to the control group.

巴西境内约有300种南美稔属（Myrcia DC.）物种。该属部分物种的抗菌、抗炎及镇痛活性已在相关文献中被报道。本研究旨在分析新鲜喙状南美稔（Myrcia rostrata DC.）叶片精油的化学成分，并评价其镇痛活性。该精油通过克莱文杰型（Clevenger-type）水蒸气蒸馏装置提取，化学成分分析采用气相色谱-火焰离子化检测器（GC/FID）与气相色谱-质谱联用（GC/MS）完成。本研究预先开展了急性经口毒性试验与转棒疲劳实验。镇痛活性评价采用醋酸扭体、福尔马林与热板三种实验范式，给药剂量分别为75、150及300 mg·kg⁻¹。在已鉴定的化学成分中，95.24%为倍半萜类化合物，其中香紫苏醇（carotol）占比最高，达17.68%。该精油未表现出明显毒性，亦未对受试动物的运动协调能力造成影响。综上，与对照组相比，给药组动物（尤其是300 mg·kg⁻¹剂量组）的扭体次数显著降低（1.62 vs 27.88±2.75），福尔马林实验两个阶段的舔爪时长均有所缩短，且热板实验中的痛觉潜伏期显著延长。