The influence of seasonality on the content of goyazensolide and on anti-inflammatory and anti-hyperuricemic effects of the ethanolic extract of Lychnophora passerina (Brazilian arnica).

Abstract

Ethnopharmacological relevance: Lychnophora passerina (Mart ex DC) Gardn (Asteraceae), popularly known as Brazilian arnica, is used in Brazilian folk medicine to treat pain, rheumatism, bruises, inflammatory diseases and insect bites. Aim of the study: Investigate the influence of the seasons on the anti-inflammatory and anti-hyperuricemic activities of ethanolic extract of L. passerina and the ratio of the goyazensolide content, main chemical constituent of the ethanolic extract, with these activities. Materials and methods: Ethanolic extracts of aerial parts of L. passerina were obtained from seasons: summer (ES), autumn (EA), winter (EW) and spring (EP). The sesquiterpene lactone goyazensolide, major metabolite, was quantified in ES, EA, EW and EP by a developed and validated HPLC-DAD method. The in vivo antihyperuricemic and anti-inflammatory effects of the ethanolic extracts from L. passerina and goyazensolide were assayed on experimental model of oxonate-induced hyperuricemia in mice, liver xanthine oxidase (XOD) inhibition and on carrageenan-induced paw edema in mice. Results: HPLC method using aqueous solution of acetic acid 0.01% (v/v) and acetonitrile with acetic acid 0.01% (v/v) as a mobile phase in a gradient system, with coumarin as an internal standard and DAD detection at 270 nm was developed. The validation parameters showed linearity in a range within 10.0–150.0 μg/ml, with intraday and interday precisions a range of 0.61–3.82. The accuracy values of intraday and interday analysis within 87.58– 100.95%. EA showed the highest goyazensolide content. From the third to the sixth hour after injection of carrageenan, treatments with all extracts at the dose of 125 mg/kg were able to reduce edema. Goyazensolide (10 mg/kg) showed significant reduction of paw swelling from the second hour assay. This sesquiterpene lactone was more active than extracts and presented similar effect to indomethacin. Treatments with ES, EA and EP (125 mg/kg) and goyazensolide (10 mg/kg) reduced serum urate levels compared to hyperuricemic control group and were able to inhibit liver XOD activity. One of the mechanisms by which ES, EA, EP and goyazensolide exercise their anti-hyperuricemic effect is by the inhibition of liver XOD activity. Goyazensolide was identified as the main compound present in ES, EA, EW and EP and it is shown to be one of the chemical constituents responsible for the anti-inflammatory and anti-hyperuricemic effects of the ethanolic extracts. Conclusion: The anti-inflammatory and anti-hyperuricemic activities of the ethanolic extracts from L. passerina were not proportionally influenced by the variation of goyazensolide content throughout the seasons. The involvement of goyazensolide on in vivo anti-inflammatory and anti-hyperuricemic activities of L. passerina extracts was confirmed, as well as the possibility of participation of other constituents on these effects. This study demonstrated that the aerial parts of L. passerina may be collected in any season for use as anti-inflammatory agent. For use in hyperuricemia, the best seasons for the collection are summer, autumn and spring. The ethanolic extract of L. passerina and goyazensolide can be considered promising agents in the therapeutic of inflammation, hyperuricemia and gout.