Potencial de Stachys byzantina K. Koch (peixinho-da-horta) no tratamento da hiperpigmentação e como paliativo do envelhecimento da pele

Abstract

The nature is a remarkable source of bioactive compounds with therapeutic potential, which have been significantly contributing to treat diseases. However, simultaneously to the development of new natural products, the incidence of cutaneous disorders is increasing, affecting a substantial part of the global population. Dermatological diseases are estimated to be the fourth most common cause of all human diseases. Furthermore, skin aging is associated with an increase of enzymes expression, including collagenase, elastase, and hyaluronidase in skin tissue. The fragmentation of the extracellular matrix induces the expression of proinflammatory genes, resulting to the loss of skin integrity and elasticity. In this context, the primary objective of this study was to evaluate the cosmetic potential of S. byzantina aerial parts in reducing the impact of hyperpigmentary disorders and skin aging. This study investigated the ethanolic extract (EE) of this plant and its fractionation was carried out using solvents with different polarities to obtain the hexane fraction (PHEX), the dichloromethane fraction (PDCM), the ethyl acetate fraction (ACT) and the hydroethanolic fraction (HID). Subsequently, the potential of these fractions to inhibit the tyrosinase enzyme activity was determined, and the most promising plant-derived fraction was also evaluated for its potential to inhibit hyaluronidase and elastase enzymes. Phytochemical screening was conducted using thin-layer chromatography, and antioxidant capacity was assessed using different methodologies: 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, β-carotene/linoleic acid, Griess reaction, and oxygen radical absorbance capacity (ORAC) assays. Highperformance liquid chromatography coupled to UV detection analyses (HPLC-UV) were performed. The levels of phenols and flavonoids, as well as the identification and quantification of chlorogenic acid, were determined. The antiglycation potential was also evaluated using a glycation test, using glucose as a reducing sugar. The sun protection factor (SPF) was also calculated. Cell viability was assessed using the MTT assay. All fractions were able to inhibit the tyrosinase enzyme at different levels. PDCM was the sample with the highest inhibition, with IC50 of 63,5 ± 10,9 µg/mL. The PDCM compound with the higher HPLC-UV absorption, along with two other compounds, was found to bind to the catalytic site of tyrosinase, which suggested a competitive inhibition of this enzyme. Therefore, PDCM was selected for further tests, in addition to the EE. PDCM also inhibited the hyaluronidase enzyme with IC50 of 369 ± 11.642 μg/mL and inhibited the elastase enzyme by 40% at 500 μg/mL. EE showed IC50 of 4.58 ± 0.29 μg/mL in DPPH assay, whereas PDCM showed IC50 of 3.33 ± 0.13 μg/mL. EE exhibited IC50 of 25.64 ± 2.1 μg/mL and PDCM showed IC50 of 5.58 ± 1.49 μg/mL in βcarotene/linoleic acid assay. EE and PDCM showed IC50 of 88.89 ± 10.6 μg/mL and 175.3 ± 20.8 μg/mL in nitric oxide inhibition assay, respectively. Both samples were able to protect fluorescein from oxidation at a 3.125 μg/mL in ORAC assay. They also inhibited the glycation process at 350 μg/mL. The phenolic content for EE was 222.37 ± 7.44 (mgEAT/g), whereas for PDCM, it was 116.30 ± 6.73 mgEAT/g. The flavonoid content for EE was 84.52 ± 4.32 (mgEQ/g), and for PDCM it was 66.38 ± 13.57 mgEQ/g. Both EE and PDCM exhibited an SPF higher than the requested by the regulatory agencies. There was no citotoxicity to L929, HaCaT, THP-1, HEK-293, MDA-MB-231, and MCF-7 cells at concentrations equal to or less than 50 μg/mL for both samples. In conclusion, PDCM demonstrated promising cosmetic potential, not only to treat hyperpigmenting disorders, but also for delaying the impacts caused by free radicals in skin aging.