Study on the Chemical Composition and Tyrosinase Inhibition Activity of Vashancone
Castanopsis ceratacantha, also known as Castanopsis fargesii and Castanopsis Mount Huangshan, is mainly distributed in Yunnan, Guizhou and southwest Sichuan. It is widely used in folk medicine to stop bleeding, thirst, diarrhea (nuts), chronic ulcers and other diseases. At present, there is no relevant literature at home and abroad on the chemical composition and biological activity research of Aconitum carmichaelii. Our research group conducted a preliminary chemical composition study on the ethanol extract of Aconitum carmichaelii leaves, and found that the leaves contain novel triterpenoid tannic compounds. These compounds are one of the few compounds discovered so far, which are generated by esterification reaction of pentacyclic triterpenoids and unique polyphenols. Currently, they have only been isolated from Aconitum plants. Has good antioxidant, anticancer, and lipid-lowering activities. In order to elucidate the material basis of Aconitum carmichaelii and discover new triterpenoid tannic compounds, this experiment systematically isolated and purified the 80% ethanol extract of Aconitum carmichaelii. Tyrosinase (also known as polyphenol oxidase) is related to the synthesis of pigments in the body, directly affecting the synthesis of melanin. It is the rate limiting enzyme for melanin synthesis and has various important physiological functions in the body, especially in skin whitening, antioxidant effects, etc. It is also related to the occurrence and treatment of pigment disorders and malignant melanoma. The main site of action of tyrosinase in the process of melanin formation is hydroxyl, and the ethanol extract of Aconitum carmichaelii mainly contains tannins, among which compounds containing multiple unique polyphenolic structures are the main ones, which have good antioxidant and anticancer activities. Whether they have tyrosinase inhibitory activity has not been reported yet. This experiment screened the tyrosinase inhibitory activity of multiple characteristic tannin compounds isolated, in order to find natural compounds with better activity.

Seventeen compounds were isolated from the 80% ethanol extract of the leaves of Aconitum carmichaelii, mainly tannins containing multiple unique polyphenolic structures. According to existing literature, they are mainly found in Aconitum plants. The presence of triterpenoid tannic compounds in most cone plants may be related to their habitat and secondary metabolic pathways. The liquid chromatography detection of the 80% ethanol extract of the leaves of Huashan cone showed the presence of novel triterpenoid tannic compounds, but they were not obtained during the systematic separation and purification process. It is possible that these compounds were not effectively enriched during the separation process, and the means of separation and purification need to be further improved. At present, there are few reports on the biological activity of novel triterpenoid tannic compounds, and only preliminary studies have been conducted in anti-cancer, antioxidant, and lipid-lowering aspects. This paper did not isolate novel triterpenoid tannic compounds from the 80% ethanol extract of Aconitum carmichaelii leaves, but obtained a large number of compounds containing unique polyphenolic structures. Based on the structure-activity relationship, 9 characteristic compounds containing multiple unique polyphenolic structures were screened for their tyrosinase inhibitory activity. The results showed that compound 14 had stronger enzyme inhibitory activity than the positive drug, which may be related to the presence of more phenolic hydroxyl groups in the compound. Tannin compounds have rich biological activity, and the biological activity and mechanism of action of this particular tannin compound need further exploration and research.