| Flos populi is an important traditional Chinese medicine prepared from the male inflorescence of Populus tomentosa Carr. or Populus canadensis Moench(Salicaceae family). Recorded in 1977 by Chinese Pharmacopoeia; Flos populi is rich in resources and diversity of chemical composition. Flos populi contains glycoside, cardiotonic glycoside, flavonoids and phenols. Traditionally, it is employed for detoxication and relief of fever. In Compendium of Materia Medica, extracts of Chinese white poplar bark was used to cure dysentery. Currently, Flos populi is mainly used for the treatment of various inflammatory diseases and anti diarrhea in East Asian countries.Phytosterol is a kind of active trace components existing in natural plants, known as the "key of life", mainly including the stigmasterol, beta-sitosterol, ergosterol, a steroid nucleusstructure similar to cholesterol. Phytosterol has the functions of reducing blood fat, anti-inflammatory, antitumor, antioxidant activity of a variety of and the biological activity, has been utilized, must include: used in the production of steroid drugs; by plant sterolslower cholesterol and other characteristics to the development of nutritional and functionalfood; as the surface active agent used in cosmetics, lipstick. There have been no reports about the plant sterols in poplar flower, the experiment of Flos populi in 3 sterols including stigmasterol, ergosterol and beta-sitosterol were derivatization, providing the reference for further research of Yang Shuhua and exploitation of sterol ester. The content of amino acidin Flos populi, activity of Flos populi alcohol extraction, hypolipidemic, poplar flowerstigmasterol, ergosterol, beta-sitosterol derivative and synthesis of phytosterol ester derivative of ACE activity were studied in detail, the main research contents and results are as follows:(1) To determine the contents of 21 free and hydrolyzed amino acids from Flos Populi Tomentosae by pre-column derivatization RP-HPLC. The samples were derived with phenylisothiocyanate(PITC) and HPLC method was adopted. Gradient elution chromatography was applied to determine free and hydrolyzed amino acids contents in Flos Populi Tomentosae. The Results demonstrated that The 21 amino acids showed a good linearity in the ranges of 0.0019?2.7 μmol·mL-1 with the correlation coefficients over 0.999. The average recoveries of free amino acids were 88.25%?100.04% with relative standard deviation of 0.57%?2.73%(n=6); and the average recoveries of total amino acids were 90.21%?100.01% with relative standard deviation of 0.52%?2.32%,(n=6). The method is sensitive, accurate and reproducible, and it is suitable for the determination of amino acids in many other samples.(2) The present study was undertaken to evaluate antihyperlipidemic and in vitro antioxidant activity of ethanolic extract of Flos Populi(EFP). The results showed that EFP contains 78.5% flavonoids and 10.4% phenolics and it showed free radical scavenging activity on 2,2-diphenyl-picrylhydrazyl(DPPH)(IC50 36.40 ± 0.62 μg/mL) and high reducing power(EC50 206.32±1.6l μg/mL) under in vitro chemical assays. And no matter prophylactic administration or remedial administration, in high fat diet induced hyperlipidemic mice, oral treatment with EFP produced a decrease in the levels of serum total cholesterol(TC), triglycerides(TG), low-density lipoprotein-cholesterol(LDL-C), and increase in high-density lipoprotein-cholesterol(HDL-C). In a word, in high fat diet-fed hyperlipidemic mice, EFP(100, 200 and 400 mg/kg) significantly altered the plasma lipids levels to near normal. These results support a potential effect of EFP in cardiovascular disease.(3) Study the preparation of phytosterol organic acids derivatives. By the principle of esterifition synthesis using EDCI and DMAP, stigmasterol, ergosterol and beta-sitosterol reacted with different organic acids including, Phenylalanine, Malonic acid, Succinate, Furoic, Salicylic acid, Sorbic acid, 2- Naphthoic acid, Thiazole-2- formic acid, 2-Tetrahydrofuroic acid and Indole-3-carboxylic acid to afford compounds was prepared; the chemical structures are defined by UV, IR, 1HNMR and 13 NMR, respectively.(4) ACE inhibitory activities of the phytosterol esters were evaluated. The inhibitory of 30 phytosterol esters activity of ACE was detected by HPLC. And the results show that most of them(2-Tetrahydrofuroic acid ergosterol esters, 2-Naphthoic acid ergosterol esters, Phenylalanine ergosterol esters, Malonic acid ergosterol esters, Succinate ergosterol esters, Furoic ergosterol esters, Thiazole-2- formic acid ergosterol esters et. al) have stronger ACE inhibitory activities than phytosterol excepting stigmasterol esters. This novel ACE inhibitory activity offers an intriguing solution for naturally ACE inhibitors and will have great potential application as ACE inhibitors in medicine and food industry. The methods developed in this study will be valuable for development of other phytosterol esters. |
