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Infections caused by microorganisms of the Candida genus represent a major cause of morbidity and mortality among the population. Therefore, this study aimed at evaluating the antifungal activity and toxicity of resveratrol-analog Schiff bases. Faced with Candida albicans ATCC 10,231, the broth microdilution method was used, along with amphotericin B as the reference drug. The toxicity was evaluated in human keratinocyte cells and against Artemia salina. All analogs were active against the microorganism and caused structural changes in the yeast. The minimum inhibitory concentration was lower for analog A (156.3 µg mL−1), followed by B (312.5 µg mL−1), C (312.5 µg mL−1) and D (625 µg mL−1); while the minimum fungicidal concentration was lower for A (1,250 µg mL−1), B (1,250 µg mL−1) and D (1,250 µg mL−1), followed by C (2,500 µg mL−1). In keratinocytes, the compounds presented cell viability between 50.9 and 93%. Against A. salina, the compounds presented moderate cytotoxic activity. The compound with the nitro group, an electron withdrawing group, in the para position presented better antifungal activity. Resveratrol analogs can be promising in the development of new antifungal agents. Keywords: Resveratrol analogs, Schiff bases, Candida albicans, Antifungal activity, Toxicity

Plant species are sources of active compounds that can fight and/or prevent damage caused by reactive oxygen species, which enables the development of natural products that can help to prevent premature aging caused by exposure to solar radiation. This study assessed the antioxidant and photoprotective activities of six dried extracts of plants from the Brazilian Amazon biome. Plant extracts were prepared in 70% (v/v) ethanol by dynamic maceration for 72h in the dark, and then filtered, concentrated and lyophilized. The extracts were subjected to a phytochemical screening. The antioxidant activity was measured using a 2,2-diphenyl-1-picrylhydrazyl assay and the photoprotection assay was performed using the diffuse transmittance technique. The data obtained from the antioxidant activity assay was evaluated by Student's t-test for independent samples, with the aid of Statistical Package for Social Sciences v.14.0 for Windows software. The flavonoids represent a special metabolites class present in all analyzed extracts. The antioxidant activity (μgmL(-1)) decreased in the following order: Aniba canelilla (1.80±0.16), Brosimum acutifolium (2.84±0.38), Dalbergia monetaria (5.46±0.17) or Caesalpinia pyramidalis (6.45±1.18), Arrabidaea chica (15.35±0.86), and Aspidosperma nitidum (99.14±2.3). Only D. monetaria showed a considerable sun protection factor allowing for labeling (6.0±0.3). The D. monetaria extract was considered the most promising sample because it had optimal antioxidant and photoprotective activities against solar radiation, considering the limit established by regulatory agencies. These extracts with antioxidant potential can be used in photoprotective formulations, providing synergistic photoprotective effect or elevating the adeed value of the product. Additionally, these formulations are attractive to a population who searchs for products made with natural ingredients.

Onychomycosis is a fungal infection of the nail caused by high densities of filamentous fungi and yeasts. Treatment for this illness is long-term, and recurrences are frequently detected. This study evaluated in vitro antifungal activities of 12 organic compounds derived from amino alcohols against standard fungal strains, such as Trichophyton rubrum CCT 5507 URM 1666, Trichophyton mentagrophytes ATCC 11481, and Candida albicans ATCC 10231. The antifungal compounds were synthesized from p-hydroxybenzaldehyde (4a-4f) and p-hydroxybenzoic acid (9a-9f). Minimum inhibitory concentrations and minimum fungicidal concentrations were determined according to Clinical and Laboratory Standards Institute protocols M38-A2, M27-A3, and M27-S4. The amine series 4b-4e, mainly 4c and 4e compounds, were effective against filamentous fungi and yeast (MIC from 7.8 to 312 µg/mL). On the other hand, the amide series (9a-9f) did not present inhibitory effect against fungi, except amide 9c, which demonstrated activity only against C. albicans. This allowed us to infer that the presence of amine group and intermediate carbon number (8C-11C) in its aliphatic side chain seems to be important for antifungal activity. Although these compounds present cytotoxic activity on macrophages J774, our results suggest that these aromatic compounds might constitute potential as leader molecules in the development of more effective and less toxic analogs that could have considerable implications for future therapies of onychomycosis.