Secondary metabolite production by plants is influenced by external environmental factors that can change depending on the seasons, which makes it important to know how the plant, through its metabolism, is able to adapt to these variations. Mentha x villosa and Plectranthus amboinicus present in their chemical composition polyphenols, and through previous studies, it has been seen that these two species present promising in vitro photoprotective activity. The aim of this study was to evaluate seasonal alterations in photoprotective and antioxidant activities and the influence of factors such as precipitation levels and sun radiation incidence. Thus, polyphenol quantification, cromatographics (HPLC-DAD) and multivariate (PCA) analyses of extracts of the two species through twelve months were done. It was observed that the best months for photoprotective and antioxidant activities were September for M. villosa and July for P. amboinicus (SPF = 14.79). It was possible to conclude that solar radiation more clearly influences the production of phenolics and the increase of SPF in M. villosa, in addition to favoring the antioxidant activity of the two species, while precipitation seems to have no influence.

Overexposure to sunlight has harmful effects on the skin and can cause erythema and skin cancer. Photoprotective agents are important for preventing exposure to sunlight and are present in the composition of sunscreens. Globally, the use of filters based on natural products has gained interest in scientific studies; in addition to their sunscreen properties, these products demonstrate antioxidant, healing, and moisturizing activity. These favor adequate sun protection due to the wide spectrum of activities and are environmentally friendly. Plectranthus amboinicus (Lour.) Spreng., Lamiaceae, is used in traditional medicine to treat several conditions and is commonly known as "hortelã-da-folha-grossa" in Brazil. This species presents phenolic compounds, including rosmarinic acid, and has been studied for photoprotection and antioxidant activity. The aim of this study was to evaluate the photoprotection potential and antioxidant activity, and to develop analytic methodology for extract standardization and validation. Thus, maximum absorbance, sun protection factor, DPPH radical scavenging activity, and total phenolic contents of P. amboinicus crude ethanolic extract were determined, and an HPLC analytical methodology was developed and validated to quantify rosmarinic acid. Analyses revealed that the extract presented good photoprotection (SPF = 12.63), promising antioxidant activity (EC 50 = 112.39 μg/ml), total phenolic content (142.39 ± 1.12 mg GAE/g), and rosmarinic acid concentrations (22.5 μg/ml). In addition, an HPLC analytical method was validated for marker quantification. These results show that the extract has potential photoprotective and antioxidant activity, and this favors the isolation of a final product with protective characteristics that encompass broad spectrum action and biological protection.

Riparin I is an alkamide with potential anxiolytic activity in preclinical studies. The characterization and understanding of solid-state properties play an importance role in drug development. For this work, the solid state of five riparin I batches (RIP-1, RIP-2, RIP-3, RIP-4, and RIP-5), obtained by the same synthesis process, were characterized by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), DSC-photovisual, Thermogravimetry (TG), Fourier Transform Infrared (FTIR), Pyrolysis (Pyr-GC/MS), X-ray Powder Diffraction (PXRD), and Solid-State Nuclear Magnetic Resonance (ssNMR) techniques. Batches of riparin I with different crystal habits resulting in crystallization impurities were observed, which can be attributed to the presence of triethylamine. The main differences were observed by DSC, PXRD, and ssNMR analysis. DSC curves of RIP-2 and RIP-3 presented endothermic peaks at different temperatures of fusion, which can be attributed to the mixture of different crystalline forms. PXRD and ssNMR results confirmed crystallinity differences. The results offer evidence of the importance of controlling the reproducibility of the synthesis in order to obtain the adequate morphology for therapeutic efficacy and avoiding future problems in quality control of riparin I products.