Optimization of Extraction Conditions of Phytochemical Compounds and Anti-Gout Activity of Euphorbia hirta L. (Ara Tanah) Using Response Surface Methodology and Liquid Chromatography-Mass Spectrometry (LC-MS) Analysis.

Fazleen Izzany Abu Bakar,Sri Fatmawati,Norazlin Abdullah,Mohd Fadzelly Abu Bakar,Susi Endrini

doi:10.1155/2020/4501261

Abstract

Gout is a common disease affected most of the people due to the elevation of uric acid in the blood. Flavonoid and phenolic compounds are reported to exert the anti-gout activity of medicinal plants. Hence, this study aimed at optimizing the extraction conditions of phenolic and flavonoid compounds as well as the anti-gout (xanthine oxidase inhibitory activity) in vitro of Euphorbia hirta using response surface methodology (RSM). The plant part used was the whole plant excluding roots. The effects of three independent variables (extraction time, X1; extraction temperature, X2; and solid-to-liquid ratio, X3) on three response variables (total flavonoid content, Y1; total phenolic content, Y2; and xanthine oxidase inhibitory activity, Y3) were determined using central composite design (CCD) while phytochemical profiling of the extracts was determined by liquid chromatography-mass spectrometry (LC-MS). Quadratic models produced a satisfactory fitting of the experimental data with regard to total flavonoid content (r2 = 0.9407, p < 0.0001), total phenolic content (r2 = 0.9383, p < 0.0001), and xanthine oxidase inhibitory activity (r2 = 0.9794, p < 0.0001). The best extraction conditions observed for total flavonoid content, total phenolic content, and xanthine oxidase inhibitory activity were at a temperature of 79.07°C for 17.42 min with solid-to-liquid ratio of 1 : 20 g/ml. The optimum values for total flavonoid, total phenolic, and xanthine oxidase inhibitory activity were 67.56 mg RE/g, 155.21 mg GAE/g, and 91.42%, respectively. The main phytochemical compounds in the optimized E. hirta extract are neochlorogenic acid, quercetin-3β-D-glucoside, syringic acid, caffeic acid, ellagic acid, astragalin, afzelin, and quercetin. As conclusion, this study clearly demonstrated the best conditions to obtain higher xanthine oxidase inhibitory activity and phytochemical compounds which can be further used for the development of anti-gout agents.

Highlights

Euphorbia hirta L. or locally known as Ara tanah or Gelang susu in Malaysia is from the family of Euphorbiaceae. e genus of Euphorbia is considered to be the largest in the Euphorbiaceae family with about 1600 species and it is native to tropical and subtropical regions of Asia, Africa, and Central as well as South America [1]. is plant was found to possess potent antimicrobial [2], antidiarrhoeic [3], antihyperglycemic [4], anti-inflammatory [5], and anticancer [6] activities
Fitting the models are crucial in interpreting the accuracy of the response surface methodology (RSM) mathematical models for prediction of the Total Flavonoid Content (TFC), Total Phenolic Content (TPC), and Xanthine oxidase inhibitory activity (XO) inhibitory activity of E. hirta extract
In terms of coded values, the predicted responses for the TFC, TPC, and XO inhibitory activity could be expressed by the second-order polynomial equation via multiple regression analysis: YTFC 60.46 + 1.54X1 + 1.11X2 + 2.64X3 − 2.28X1X2 + 1.28X1X3 + 1.28X2X3 − 1.72X21 − 5.73X22 + 2.84X23, (2)

Summary

Introduction

Euphorbia hirta L. or locally known as Ara tanah or Gelang susu in Malaysia is from the family of Euphorbiaceae. e genus of Euphorbia is considered to be the largest in the Euphorbiaceae family with about 1600 species and it is native to tropical and subtropical regions of Asia, Africa, and Central as well as South America [1]. is plant was found to possess potent antimicrobial [2], antidiarrhoeic [3], antihyperglycemic [4], anti-inflammatory [5], and anticancer [6] activities. Euphorbia hirta L. or locally known as Ara tanah or Gelang susu in Malaysia is from the family of Euphorbiaceae. E genus of Euphorbia is considered to be the largest in the Euphorbiaceae family with about 1600 species and it is native to tropical and subtropical regions of Asia, Africa, and Central as well as South America [1]. The decoction or infusion of this plant has been used widely by practitioners of traditional medicine in treating asthma, kidney stones, heartburn, diarrhea, coughs, and menstrual problems [7]. In 2007, three compounds from the methanolic extract of E. hirta, namely, afzelin, quercetin, and myricetin which showed potent inhibition against malaria have been successfully isolated [8]

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Conclusion