Solid phase extraction and characterization of rutin from Labisia pumila var. Alata

Abstract

Rutin is one of the glycosylated flavonoids which is widely investigated by researchers from buckwheat samples due to its biological activities, including antioxidant activity. Interestingly, rutin was also found in L. pumila var. Alata extract, particularly from the leaves of the plants (0.85 mg of rutin/ g of leaves). This study focused on the optimization of methanolic solvent system for rutin elution from the crude extract of Labisia pumila var. Alata using C18 reversed phase solid phase extraction (SPE). The rutin fraction was identified and characterised by using thin layer chromatography (Rf 0.49) and UV-Vis spectrophotometry (285 nm). The presence of rutin was further confirmed and quantified by using a liquid chromatography integrated with tandem mass spectrometer based on rutin ion transition (m/z 609 > 301) in the negative mode of targeted analysis. Methanolic extraction (60% methanol) was found to increase the rutin content (0.14% w/w) in the crude extract. Fractionation of the crude extract using 80% methanol as the solvent system had further increased the rutin content to 1.31% w/w. The fractionation was carried out in a laboratory scale SPE system using C18 packed column with the minimum volume of solvent usage (20 mL) with high yield of recovery (76.88%). The rutin fraction (IC50 800 ppm) also exhibited 9.5 times lower scavenging activity than ascorbic acid (IC50 84 ppm) and 6.6 times lower scavenging activity than standard rutin (IC50 122 ppm). However, it showed 1.9 times higher scavenging activity than crude extract (IC50 1500 ppm). A three-layer artificial neural network (ANN) model was developed to predict the yield of rutin based on the polarity of solvent system and volume of eluent. This ANN model produced a good prediction of the experimental data with a correlation coefficient of (R2) 0.9998 and 1.0 for training and testing data, respectively. As a conclusion, a laboratory scale SPE system for rutin elution from the crude extract of L. pumila var. Alata has been established in the current study.