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The monoterpenes are the main constituents of most essential oils and p-cymene is a monoterpene commonly found in various species of aromatic herbs, which has been reported for anti-inflammatory, antinociceptive, and antimicrobial activities. However, there is no report concerning its pharmacological activity on the vascular smooth muscle. The aim of current work was to investigate the effects of p-cymene in isolated rat aorta and also study its mechanism of action. In this work, we show that p-cymene has a relaxant effect, in a dose-dependent way, on the vascular smooth muscle, regardless of the presence of the endothelium. Using a nonselective potassium channel blocker, the CsCl, the relaxant effect of p-cymene was attenuated. In the presence of more selective potassium channels blockers, such as TEA or 4-AP, no change in the relaxant effect of p-cymene was evidenced, indicating that BKCa and KV channels are not involved in that relaxant effect. However, in the presence of glibenclamide or BaCl2, KATP and Kir blockers, respectively, the relaxant effect of p-cymene was attenuated. The data presented indicate that p-cymene has a relaxing effect on rat aorta, regardless of the endothelium, but with the participation of the KATP and Kir channels.

In this paper, we report the influence of the extraction process on the flavonoid content obtained from leaves of C. quercifolius and its antioxidant activity. A factorial design 2² was performed, using temperature and agitation as independent variables. Qualitative and quantitative analyzes of the extracts were performed by HPLC-DAD. Rutin and apigenin were identified in the extracts and chosen as analytical markers. Pareto chart and Surface response plots suggested that rutin content was increased up to 3.93 times when temperature was employed during the extraction process. However, apigenin content was significantly reduced in the method whose temperature or agitation were used (p<0.05). A higher antioxidant activity was observed in extracts whose rutin extraction was favored, suggesting that this flavonoid contributes at least in part to the antioxidant potential of the species.

There is a growing need for research of photoprotective molecules from natural sources. Flavonoids have shown significant absorption in ultraviolet A (UVA), ultraviolet B (UVB) region, due to their chemical structure with conjugated double bonds, and may be used as ingredients in cosmetics formulations for skin protection. This systematic review reports what has been researched over the past decade on flavonoid and photoprotective activity, as well as some mechanisms of action by which these metabolites act. The search was conducted in three databases (Science Direct, PubMed and Scopus) using the descriptors "flavonoid", "photoprotection" and "sunscreen" combined, published between January 2006 and January 2016. Twenty-two articles were selected and 17 flavonoids were cited. The data reviewed here indicate that flavonoids are potential in the fight against UVA and UVB radiation and which may be used as adjuvants in photoprotective formulations.

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