Atividade antiedematogênica e antinociceptiva do óleo essencial de Pectis elongata Kunth (ASTERACEAE) quimiotipo citral

Abstract

The species Pectis elongata Kunth, known in Pará as cumin or little lemon, is an easy-to-grow herbaceous plant, sold freely at fairs in Santarém and used by traditional communities as a spice and to treat pain and inflammation. Studies of the chemical composition of its essential oil revealed the presence of two distinct chemotypes: limonene plus peryl aldehyde and citral (neral and geranial), whose anti- inflammatory and analgesic actions are already well established in the literature. The main hypothesis investigated in this research is that the essential oil obtained from P.elongata Kunth (EOPe) can serve as an alternative to standard therapy for pain and inflammation, minimizing adverse reactions such as gastrointestinal complications caused by the prolonged use of conventional drugs and that the presence of the chemotype, citral, with pronounced anti-inflammatory and analgesic action, in addition to having a gastroprotective effect, can help with adherence to treatment. For this, the objective of this work was to determine the EOPe chemotype of specimens collected in Santarém, Pará, and to evaluate its possible antiedematogenic (inflammation) and antinociceptive (pain) effect. The anti-inflammatory activity was induced by λ- carrageenan in a paw edema model in rats and the analgesic activity by formalin in mice. For this, a total of 36 rats and 36 mice were used, arranged in 6 groups, containing 6 animals each. For validation of tests, indomethacin and morphine were used as positive control (paw edema and formalin test, respectively), distilled water as the negative control, and mineral oil as solvent control. The oil yield after extraction was 1%. The chemical composition analysis showed the presence of the citral chemotype, representing 89.29% of the sample. In the antinociceptive activity test, EOPe showed analgesic activity only at a dose of 400 mg/kg, both in the neurogenic phase (78.22%) and in the inflammatory phase (58.03%), reducing pain behavior (licking and biting) of mice. The paw edema test in rats showed anti-inflammatory activity in reducing edema at doses of 200 mg/kg and 400 mg/kg, with maximum reduction values (70.2% and 70.5%, respectively) in the 1st hour of the experiment, followed by the 24th hour, with a reduction of (52.8% and 58.1%). Based on the results obtained, it is possible to suggest that EOPe, citral chemotype, has analgesic properties, inhibiting central and peripheral pain, in addition to promoting a reduction in paw edema, and showing anti-inflammatory potential.