The Influence Of PH On Extraction Of The Effective Compounds From Lotus Leaves, And Its Characterization

Lotus leaves have been used for traditional medicine in china. The main purpose of this study was researching the influence of pH of solvent on extraction of flavonoids and alkaloids from Lotus leaves, and its isolation, characterization, qualitative and quantitative analysis.Firstly, the determination method of total phenolics and alkaloids in extracts was tested, and determined the influence of pH of extraction solvent on total phenolics and alkaloids. The results showed that: in the case of measuring the components of total phenolics and alkaloids in the extracts, phenolics should be extracted first, and alkaloids were next in order to avoid losses of the compounds.Secondly, lotus leaves were extracted with water of various pH, and measured its total phenolics and alkaloids with folin-ciocalteau and bromocresol green(BCG) reagent respectively. Flavonoids and alkaloids were extracted from a lotus leaves powder. Firstly, the lotus leaves powder was decocted with alkaline water of pH8.0, filtrated and separated from the extraction, and decocted with acid water pf pH2.0. The extractions were concentrated, and adsorbed with AB-8 macroporous resin. The alkaline extraction was isolated from polyamide resin, and eluted on Sephadex LH-20 with water-methanol gradient system, then analyzed with LC-MS and three flavonoids were obtained. The acid extraction was extracted with CHCl3 after being adjusted to pH2.0, 5.0, and 9.0, respectively. Finally, the CHCl3 fractions were isolated on Sephadex LH-20, then analyzed with LC-MS and four alkaloids were obtained. Quercetin 3-O-α-L-arabinopyranosyl(1→2)-β-D-galactopyranoside and compoundⅤwere isolated from lotus leaves for the first time.Finally, contents of the compounds in the extracts were measured by HPLC, contents of Quercetin 3-O-α-L-arabinopyranosyl(1→2)-β-D-galactopyranoside, isoquercitrin and quercetin in pH8.0 extract were 158.39, 131.68, 93.69μg/mL (extract) respectively. Contents of N-nornuciferine, compoundⅤ, roemerine and nuciferine were 202.77, 53.67, 37.22, 10.48μg/mL (extract) respectively.