Synthesis of Resorcinol Derivatives and their Effects on Melanin Production

Determination of 4-n-butylresorcinol by fluorescence derivatization based on dopamine

4-n-butylresorcinol (4nBR) is a frequently utilized as whitening ingredients in skincare cosmetics. Compared with other whitening ingredients, it can effectively inhibit tyrosinase with lower toxicity and superior inhibition efficacy. Under alkaline conditions, an induced oxidative coupling reaction can occur between 4nBR and dopamine (DA) to generate strong fluorescent substance azamonardine with an intense emission band centering at 476 nm when excited at 440 nm. This phenomenon can be used to establish a fluorescence analysis method for 4nBR. The results indicated that the linear range of the method was 1.0-24.0 nmol L-1, and the detection limit was as low as 0.25 nmol L-1. The method showed high sensitivity, good selectivity, mild experimental conditions and low cost. The proposed method was successfully used to detect 4nBR in cosmetics, and the results were consistent with those of HPLC. The spiking recoveries were between 98.2% and 108 %.

Novel Synthesized Tyrosinase Inhibitors: A Systematic Patent Review (2012-Present)

Tyrosine is an enzyme responsible for melanin production. Its abnormal accumulation in different parts of the body is known as hyperpigmentation. Tyrosinase inhibitors have been used as one of the main approaches to treat these kinds of cosmetic and medical issues. This review aimed to discuss the advances in patents for this class of inhibitors, focusing on synthetic ones, by studying recent patent applications (2012-2022). We performed a screening using the European Patent Office's Espacenet database, from which 15 inventions were selected and fully studied. China has more patent applications, all of them were focused on synthetic methods and the majority declared at least two additional applications as antibrowning agents for fruits and vegetables, biological pesticides, and medicine to treat diseases like Parkinson's or melanoma. The strategies employed by the investigators focused on the examination of previous literature, which oriented on the type of structures that have been found to show good inhibitory activity; the study also examined aspects of their reaction mechanisms and information about the structureactivity relationship. For some groups of inhibitors, such as benzaldehyde and anthraquinone derivatives, the data were meaningful and extensive. In contrast, arginyl and troponoids compounds were difficult to analyze due to the limited research works.

Effects of 4-hexylresorcinol administration on the submandibular glands in a growing rat model

Background

4-Hexylresorcinol (4HR) is a food additive and class I histone deacetylase inhibitor. In this study, we examined the effects of 4HR administration on the submandibular gland in a growing rat model.

Methods

Four-week-old rats were used in this study. The experimental group (nine males and eight females) received 12.8 mg/kg of 4HR weekly for 12 weeks. Ten rats (five males and five females) were used as controls. The submandibular glands of rats were collected 12 weeks after the first administration of 4HR. The weight of the glands was measured. Histological analysis, immunoprecipitation-high-performance liquid chromatography (IP-HPLC), and western blotting were performed.

Results

The weights of the rat submandibular glands were higher in the experimental groups than in the control group, especially in male rats (P < 0.05). The vascular endothelial growth factor (VEGF) and testosterone in the submandibular glands were more highly expressed in 4HR-treated male rats than in untreated rats, as detected by both western blotting and immunohistochemistry. The IP-HPLC results demonstrated that the expression levels of Ki67, epidermal growth factor, and testosterone in the submandibular glands were higher in 4HR-treated male rats than in untreated rats.

Conclusions

This study demonstrated that the systemic administration of 4HR increased the weight of submandibular glands in male rats. In addition, the testosterone and VEGF expression levels in the submandibular glands increased owing to 4HR administration.