Active compounds in Pu erh large leaf tea that stimulate melatonin receptors
Depression, anxiety, and sleep disorders are common central nervous system diseases, and modern pharmacological research suggests that their onset is related to a decrease in the levels of neurotransmitters such as melatonin (MT) and serotonin, as well as a decline in receptor function. Therefore, receptor models of these neurotransmitters are often applied in the development of antipsychotic drugs, among which MT1 receptor agonists such as circadin, ramelteon, agomelatine, etc. have been clinically used for the treatment of central nervous system diseases such as depression.
Tea is processed from the tender leaves or buds of Camellia plants in the family Theaceae, and has a long history of medicinal and edible use. Modern pharmacological research has shown that tea has many pharmacological activities such as stimulating the central nervous system, diuresis, antioxidant, antiviral, and blood pressure lowering. Tea polyphenols are generally considered the material basis of tea activity. However, the material basis of tea’s anti psychotic activity is not very clear, and there are few reports on the effects of tea on melatonin receptor function.

In order to further elucidate the material basis of the anti psychotic activity of tea leaves, this study found that the ethyl acetate portion of fresh leaf extract from Puer tea (Camellia sinensis) had a significant stimulating effect on melatonin receptors. Based on the melatonin receptor stimulating activity testing model, under the guidance of activity tracking, silica gel column chromatography and high-performance liquid chromatography were comprehensively used to track and separate the active parts of the tea leaves. The calcium flow detection method was used to test the stimulating effect of the isolated compounds on melatonin receptors on HEK293 cell models, in order to provide more theoretical basis for the further development and utilization of tea leaves and the research and development of new anti psychotic drugs.

 

Modern pharmacological research has shown that the receptor function of melatonin is closely related to the onset and treatment of mental illnesses such as depression and anxiety; Tea has pharmacological activity that excites the central nervous system, but its active substance basis is not very clear. Therefore, in order to further elucidate the material basis of tea’s anti psychotic activity, this study used the melatonin receptor MTT assay to test the model. Under the guidance of activity tracking, 9 polyphenolic compounds were isolated from the active parts of Pu’er large leaf tea. Their chemical structures were identified by HR-ESI-MS and NMR analysis and compared with literature data. Compounds 1 and 2 are the first discovered flavonol pyran derivatives from Camellia genus, enriching the chemical information of tea leaves.

The activity test results showed that all 9 compounds obtained in this study have certain excitatory effects on the melatonin MT1 receptor, and the excitatory effect on the melatonin MT1 receptor is generally higher than the corresponding excitatory effect on the melatonin MT2 receptor. Of particular note is the high content of compound (-) – catechin (3), which is one of the major components of tea and has high excitatory activity on both melatonin MT1 and MT2 receptors. It is likely to be the main active substance in tea that regulates MT receptors and exerts antipsychotic activity. Its mechanism of action deserves further investigation.