Persea americana Mill. crude extract exhibits antinociceptive effect on UVB radiation-induced skin injury in mice

Persea americana, popularly known as avocado, has been empirically used as analgesic and anti-inflammatory including in the skin disorder treatment. Species of the genus Persea also show a photoprotective effect against UVB radiation. We investigated the antinociceptive and anti-inflammatory effects from a topical formulation containing the P. americana leaf extract in a UVB irradiation-induced burn model in mice and performed a gel-formulation stability study. The antinociceptive and anti-inflammatory effect was evaluated through mechanical allodynia, paw oedema, and inflammatory cell infiltration. Phenolic compounds were quantified by UHPLC–MS/MS. The gel-formulation stability study was performed analyzing organoleptic characteristics, pH, and viscosity. P. americana (3%) gel was able to prevent the UVB irradiation-induced mechanical allodynia on the 2nd and 3rd day after irradiation with maximum inhibition of 60 ± 12% at 2nd day. Such effect may be attributed, at least in part, due the presence of (+)-catechin (302.2 ± 4.9 μg/g) followed by chlorogenic acid (130 ± 5.1 μg/g) and rutin (102.4 ± 0.9 μg/g) found in the extract. The gel was not able to prevent the inflammatory parameters such as edema and leukocyte infiltration induced by UVB irradiation. No changes important were detected in the stability study, mainly in low temperature. Our results suggest that P. americana gel-formulation, which presented stability, ensuring its quality and the therapeutic effect, could be an interesting strategy for the treatment of the pain associated with sunburn; this effect could be attributed to its biological constituents, especially catechin, chlorogenic acid, and rutin.