Studies On Secondary Metabolites Of Two Medicinal Fungi And Their Tyrosinase Inhibitory Activity

The secondary metabolites of fungi are extremely abundant and are one of the sources of active natural products.The regulation of fungal liquid fermentation is an important means to obtain novel structural compounds.In order to search for new natural and safe compounds with high anti-tyrosinase activity,in this paper,two medicinal fungi were selected to study their secondary metabolites and tyrosinase inhibitory activity.In this study,The liquid fermentation production of two medicinal fungi was carried out by adding exogenous chemicals.Thirteen compounds were isolated from the fermentation liquid of two fungi by the chromatography techniques including silica gel CC(column chromatography),ODS CC,Sephadex LH-20 CC,and HPLC.The structures of 8 compounds were identified by spectroscopy methods including MS,HRMS,¹H-NMR,¹³C-NMR,HMBC,COSY and X-ray single crystal diffraction technique.The compounds which have the inhibitory activity against mushroom tyrosinase diphenolase activity was screened by L-dopa oxidation experiments.The details are as follows:A histone deacetylase inhibitor,sodium butyrate,was added to the liquid medium of Shiraia bambusicola with the concentration of 100 m M.After 8 days of fermentation,8 compounds(1-8)were isolated from the fermentation broth of Shiraia bambusicola,and the structure of 4 compounds were identified,.which were6-methylsalicylic acid(1)and methyl asterrate(2),3,6,8-trihydroxy-1–methyl orrosanone(3)and asterric acid(6),respectively.Compounds 1,2 and 6 were all isolated from Shiraia bambusicola for the first time.Further experiments on mushroom tyrosinase inhibition activity indicated that compounds 2,3 were mixed tyrosinase inhibitors and had significant inhibitory effect on mushroom tyrosinase.The half maximal inhibitory concentration(IC₅₀)of compounds 2,3 were 57.56,51.93?M,respectively.Compound 1 was a competitive tyrosinase inhibitor with a weak inhibitory activity against mushroom tyrosinase with an IC₅₀ value of 109.13?M.The compound,2-aminobenzyl alcohol,was added to the liquid medium of Dictyophora indusiata with the concentration of 0.5 g/L,and after fermentation for 7days,5 compounds(9-13)were isolated from the fermentation broth of Dictyophora indusiata.Among them,the structure of 4 compounds(10-13)was identified,which were 1,3-dihydroxy-2,4-dimethylbenzene(10),2-(2'-aminobenzylamino)benzyl alcohol(11),(2-((2-((2'-aminobenzyl)amino)benzyl)amino)phenyl)methanol(12),(2-((2-((2-((2'-aminobenzyl)amino)benzyl)amino)benzyl)amino)phenyl)methanol(13)respectively.Compounds 11-13 are dimers,trimers,and tetramers of 2-aminobenzyl alcohol,respectively,of which compounds 12 and 13 are novel compounds.Mushroom tyrosinase inhibitory activity experiments indicated that compound 9 and13 were able to inhibit mushroom tyrosinase,both of which were competitive inhibitors against mushroom tyrosinase with IC₅₀ of 109.81 and 69.89?M,respectively.This study provides new ideas and basis for obtaining new natural products,and provides a certain theoretical basis for the development and application of anticancer drugs,whitening products and food preservatives.