Research On The MetaboliteIdentification Of Luteolin In Rats By HPLC-MS/MS

The flavonoids luteolin represent a large family of Chinese herbs including Herba taraxaci, polygonum cuspidatatum,Lonicera japonica and so on. It shows anti-cancer, antiallergic, anti-inflammatory, free radical scavenging, and anti-diabetic activities.I, II phase of luteolin on catalytic enzymes, and the effect of the three phase transport proteins is helpful to the study of the clinical application of flavonoids.It can provide theoretical basis for the modernization of traditional Chinese medicine.The stability of luteolin in biological samples were investigated in vitro by HPLC-HR-MS. The degradation rate constants of luteolin in several media, including buffered aqueous solutions at different pHs (7.8-8.0、7.4、4.5) and at different temperature (25℃、35℃>、45℃) were obtained. The degradation rate constants of luteolin in biological fluids such as urine at different pHs (8.5、 4.5) and at different temperature (25℃n、35℃ 、45℃) were obtained. The degradation of luteolin followed pseudo-first order kinetics. The degradation was temperature-dependent and pH-dependent.The first-order constants of luteolin in alkaline solution, neutral solution and urine samples were 0.4216h-1(r=0.9923), 0.1395 h-1 (r=0.9740) and 0.0889 h-1 (r=0.9279). But the luteolin was relatively stable at acidic conditions (pH4.5). It was found that low temperatures and acidification (pH4.5) can stabilize luteolin in biological samples, and the acidification condition is the optimal method for collecting biological samples.We identificated the metabolite of luteolin by data-dependent accurate mass spectrometric analysis and multiple data-mining techniques.Luteolin CMCNa solution was given to rats at the dose of 20 mg/kg, then urine, feces and bile samples were collected to be analyzed by HPLC-MS/MS-UV and multiple post-acquisition data-mining techniques, including extracted ion chromatography (EIC), precursor-ion filter (PIF) and neutral-loss filter (NLF). The present study showed that twenty-two metabolites were detected, and eighteen of them were first investigated. As a result,1 phase Ⅰ,21 phase Ⅱ metabolites of luteolin were found in rat urine. Only 2 metabolites of luteolin were found in rat feces and 4 phase Ⅱ metabolites of luteolin were found in rat bile. The results in this study showed the main metabolic pathways of luteolin are methylation, and can form glucuronides, sulfates and glucose in subsequent phase Ⅱ processes.