Malaysian Journal of Analytical Sciences, Vol 24 No 4 (2020): 503 - 510 503 ANTIOXIDANT AND XANTHINE OXIDASE INHIBITORY ACTIVITY OF Euphorbia hirta LEAVES CRUDE EXTRACT (Antioksidan dan Aktiviti Perencatan Xantina Oksidase Bagi Ekstrak Mentah Daun Euphorbia hirta) Ahmad Anas Nagoor Gunny 1 *, Thum Carmen 1 , Mohd Hishamuddin Che Mat 2 , Ahmad Azudin Nordin 2 , Azalina Mohamed Nasir 1 1 Department of Chemical Engineering Technology, Universiti Malaysia Perlis, Uniciti ALAM Campus, 02100 Padang Besar, Perlis, Malaysia 2 Institute of Sustainable Agrotechnology, Universiti Malaysia Perlis, Sg. Chuchuh Campus, 02100 Padang Besar, Perlis, Malaysia *Corresponding author: ahmadanas@unimap.edu.my Received: 20 November 2019; Accepted: 30 May 2020; Published: 11 August 2020 Abstract Today, exposure to free radicals and gout cases have been a concern, showing several health effects from synthetic medications and clinical drugs for antioxidant effect and xanthine oxidase inhibition effect, respectively; all of which lead to the discovery of natural inhibitors from medicinal plants. In this study, a green solvent known as the deep eutectic solvent is synthesised to replace conventional solvents for the extraction of free radical inhibitors and xanthine oxidase inhibitors from a medicinal plant that has shown many health benefits and is widely used in traditional medicine, the Euphorbia hirta. The leaves extract from Euphorbia hirta showed the highest inhibition (87.95 ± 0.0061%) on free radical assays. The IC50 for free radical inhibition of the leaves extract is 10.56 ± 0.58 μg/mL. The IC50 value for xanthine oxidase inhibition of allopurinol was the lowest, which was at 6.94 ± 0.32 μg/mL; while the leaves extract of Euphorbia hirta exhibited value at 9.40 ± 0.13 μg/mL. The correlation value between the antioxidant effect and the xanthine oxidase inhibition of the leaves extract was 0.960, which indicated that there is a strong relationship between the two said parameters. From the Lineweaver-Burk plot and solver function analysis, the mode of enzyme inhibition was a non-competitive inhibition. Keywords: antioxidant, deep eutectic solvent, Euphorbia hirta, gout treatment, xanthine inhibitor Abstrak Pendedahan kepada radikal bebas dan kes-kes gaut telah menjadi kebimbangan pada hari ini di mana ubat sintetik untuk kesan antioksidan dan kesan perencatan xantina oksidase dari ubat klinikal telah menunjukkan beberapa kesan dalam kesihatan yang membawa kepada penemuan perencatan semulajadi dari tumbuhan perubatan. Dalam kajian ini, pelarut hijau yang dikenali sebagai pelarut eutektik dalam telah disintesis untuk menggantikan pelarut konvensional untuk pengekstrakan perencatan radikal bebas dan perencatan xantina oksidase dari tumbuhan perubatan yang telah menunjukkan banyak manfaat kesihatan dan digunakan secara meluas dalam ubat tradisional, Euphorbia hirta. Ekstrak daun dari Euphorbia hirta menunjukkan perencatan tertinggi (87.95 ± 0.0061%) pada asai radikal bebas. Nilai IC50 untuk perencatan radikal bebas daripada ekstrak daun ialah 10.56 ± 0.58 μg/mL. Nilai IC50 untuk perencatan xantina oksidase terhadap alopurinol adalah paling rendah pada 6.94 ± 0.32 μg/mL manakala ekstrak daun