Separation of flavonoid and alkaloid using collagen fiber adsorbent

Flavonoids and alkaloids are two major classes of plant compounds with biological activities, and they usually coexist in many medicinal herbs. In this study, a novel collagen fiber adsorbent (CFA) was prepared, and its application for adsorption chromatography separation of flavonoids and alkaloids was systematically investigated. The typical flavonoids, rutin and baicalin, and the typical alkaloids, matrine and caffeine, were selected as probe molecules for the investigations. The batch adsorption behaviors of these compounds on CFA in different solvents indicated that hydrogen bond plays a predominant role for the adsorption of flavonoid and alkaloid in pure ethanol, while the hydrophobic interaction plays a predominant role for the adsorption in water. In column chromatography separation, flavonoids were completely separated from alkaloids by a stepwise elution process with pure ethanol followed by aqueous ethanol solution. The two flavonoids, rutin and baicalin, were also well separated although the two alkaloids, matrine and caffeine, were washed out together. The optimal loading volume of sample solution (10 mg/mL) for the separation was determined as 0.66 mL/g CFA. Under these conditions, flavonoid and alkaloid were effectively separated with a recovery higher than 90% in 8 times repeated applications.