Studies On The Quality Control Of Peanut Hull And Absorption Of Its Effective Component-luteolin

Peanut is the legume of Arachis hypogaea L.from Leguminosae family, peanut hull is its sheel. Peanut hull is very abundant in China, and wide applied in the field of medicine, industry, agriculture and health food.Peanut hull is a medical herb in civilian, which can be applied to treatment of asthma, excessive phlegm, hypertension. Luteolin, the representative flavonoids in peanut hull has the effects of reducing blood pressure, blood-fat, extension aeteria coronaria, antioxidant, preventing cough, eliminating phlegm, antibiosis, anti-inflammatory, reinforcement immunization and anti-tumor.Studies indicate the physiological activities of peanut hull are related to its contained flavonoids closely, therefore, the purpose of the present study was todetermine the content of luteolin--the main flavonoids in peanut hull, the site ofintestines where luteolin was absorbed and the absorption mechanism. Moreover, the absorption parameters in small intestine and the pharmacokinetic parameters of luteolin and peanut hull extract contained luteolin were compared, respectively. The results will provide information for development and utilization of peanut hull.1. Determination of flavonoids in peanut hullObjectives: To develop the methods for determination of the total flavonoids and luteolin in peanut hull and applied the developed methods to evaluate the quality of peanut hull from different regions.Methods: AICI3 colorimetry was used to determine the contents of the total flavonoids in peanut hull, with luteolin as the reference substance. The content of luteolin was determined by HPLC, Agilent Zorbax SB C18 column (250mm x4.6mm, 5um) was used as analytical column, the column temperature was 30°C, the mobile phase was the mixture of methanol and phosphoric acid solution(58:42, v/v), the detective wavelength was 35Onm. The contents of total flavonoids and luteolin of peanut hull from different regions were compared by the established methods.Results: The linear range of total flavonoids was in the range of 1.04~10^g-mL'1, r=0.9992, the average recovery was 100.3% with the RSD=1.7%(n=9). The content range of total flavonoids of peanut hull from different plant regions was from 0.23% to 0.62%. The linear range of luteolin was 2.233-71.46μg?mL'1, r=0.9999, the average recovery was 100.7% with the RSD=2.6% (n=9) . The content range of luteolin was within 0.17%~0.39%.Conclusions: The methods are simple, accurate, sensitive and repeatable, which can be used for quality control of peanut hull. The contents of the total flavonoids and luteolin were different among peanut hull from different plant regions.2. Absorption of effective component from peanut hull in rat intestineObjectives: To study the absorption extensive and mechanism of luteolin and peanut hull extract.Methods: The absorption kinetics and absorption site were investigated using in situ single-pass intestinal perfusion model in the rat by determination of the concentration change of luteolin in perfusate with HPLC method. The energy inhibitor—2,4-dinitrophenol(DNP) was used to proved the absorption mechanism.Results: In the range of 2.556-10.22μg?mL"1 of luteolin, the intestinal absorption rates constant was not significant difference, and the constant of absorption did not change when DNP was applied. The results indicated that the intestinal absorption pattern of luteolin was passive diffusion. According to the absorption parameters, luteolin could be well absorbed at all segments of intestine in rats, which meant there was no special absorption site. Therefore, according to Biopharmaceuticals Classification System (BCS), luteolin could be defined as Class II drug and was a good candidate for a sustained-release system. The intestinal absorption of luteolin from peanut hull extract was better than that of pure luteolin, which indicated that concomitant components in extract promoted the absorption of luteolin.Conclusions: Luteolin is absorbed in intestines in passive diffusion manner, and can be defined as Class II drug in BCS (Biopharmaceuticals Classification System). The other components in peanut hull extract can promote the absorption of luteolin.3. Study on pharmacokinetics of peanut hull extract and pure luteolinObjectives: To compare pharmacokinetic paremeters of pure luteolin andpeanut hull extract in rats.Methods: The rats were orally administration of luteolin monomelic form and peanut hull extract, the luteolin in plasma was determined by HPLC. The concentration-time data were fitted using 3P87 pharmacokinetic program.Results : The concentration-time profiles of luteolin was fitted with two-compartment model. The r(peak)Of monomelic form and peanut hull extract were 1.02h and 0.52h, respectively, the C(max) were 1.97μg?mL"1 and 8.34μg?mL■1 respectively. The results demonstrated that luteolin was quickly absorbed in vivo of rat. The pharmacokinetic parameters, ?i/2(a), A/2(p) ,7o>eak),CZ(S)of pure luteolinshowed no significant difference with peanut hull extract, however, the C(maX) and AUC of peanut hull extract were obviously greater than those of luteolin monomeric form.Conclusions: Luteolin is rapid absorbed, distributed and eliminated in vivo of rat. The other ingredients in peanut hull extract promote the absorption of luteolin.