Available free online at www.medjchem.com Mediterranean Journal of Chemistry 2023, 13(1), 13-20 *Corresponding author: Mohd Adzim Khalili Rohin Received November 30, 2022 Email address: mohdadzim@unisza.edu.my Accepted January 5, 2023 DOI: http://dx.doi.org/10.13171/mjc02301131663rohin Published January 13, 2023 Study on phenolic content, flavonoid content, and antioxidant capacity of extracts from Lansium parasiticum (Osbeck) Nurul Fatihah Muhamad Pithonah 1 , Mohd Adzim Khalili Rohin 1, * , Nor Aishah Fatiha Jailani 1 , Norhaslinda Ridzwan 1 , Mimie Noratiqah Jumli 1 , Norhayati Abd Hadi 1 , Ruziana Ishak 2 , and Atif Amin Baig 3 1 School of Nutrition & Dietetics, Faculty of Health Sciences, Universiti Sultan Zainal Abidin, Gong Badak Campus, Maimunah Block, 21300 Kuala Nerus, Terengganu Darul Iman, Malaysia 2 School of Health & Life Sciences, Teesside University, Middlesbrough, Tees Valley, TS1 3BX, United Kingdom 3 University Institute of Public Health, School of Allied Health Sciences, University of Lahore, Pakistan Abstract: Lansium parasiticum (Osbeck) or its synonym Epicharis parasitica is from the Meliaceae family and has traditionally been used for various medical applications. This study aimed to determine the total phenolic content, total flavonoid content, and antioxidant activity of different duku extracts. A total of four different solvents, 50% ethanol, 100% aqueous, 100% acetone, and 100% chloroform, were used to extract duku flesh. The total phenolic and flavonoid content was determined using the Folin-Ciocaltealuminumminium chloride colorimetric method. The DPPH and ABTS method evaluated the antioxidant activity. The result showed that 50% ethanol presented the highest extraction yield, 10.81% ± 0.004. It is also revealed that aqueous extract exhibited the highest amount of total phenolic content of 152.910 mg GAE/100 g ± 22.143, total flavonoid content of 1669.723 ± 370.091 mg QE/100 g, and antioxidant activity DPPH of 68.51 % ± 2.730 and ABTS of 6.063 U/ml ± 0.721 compared to other extracts. The correlation between total phenolic content and ABTS (r = 0.719, p = 0.029) showed a statistically significant result. Therefore, the extracts of this fruit have promising potential as cheap sources of future natural antioxidant agents in the food industry. Researchers will further these results for future in-vitro or in-vivo biological studies. Keywords: Antioxidant; Duku; DPPH; Flavonoid; Phenolic. 1. Introduction Lansium parasiticum (Osbeck) or its synonym Epicharis parasitica have two distinct forms of fruits: duku and langsat 1 . These fruits grow like berries with cauliferous habits, which means these fruits grow directly from the tree's stem. Duku and langsat were primarily found in western South-East Asia countries such as Malaysia, Indonesia, Thailand, Vietnam, and the Philippines 2 . In Indonesia, it is identified as langsat, duku, or kokosan; in the Philippines, it is known as lansones 3 ; in Thailand, it is known as long-kong, and in Vietnam, it is known as bon-bon fruits 4 . Traditionally, each duku plant had been used as a potential medical application. The bark of the duku tree has been used as an astringent, and its decoction has been used for dysentery, anti-fertility and malaria. 5,6 . In Borneo, Dayak community utilized fruit peels as talc powder for sunburn 7 . While the pulverized seeds of duku mixed with water are consumed as a vermifuge and febrifuge for children 8 . In the Philippines, the pounded seeds of duku decoction are used for deworming and ulcers 9 . Through considerable previous research, very few reports are available on the antioxidant content ability of phenolic acids and flavonoids of duku fruits 10,11 . Among these few reports, Lim et al., 12 observed that langsat fruits give the fourth highest total phenolic content among tropical fruits after guava, papaya, and star fruit, which eventually provide the potential as a higher secondary antioxidant that is measured by the iron (II) chelating experiment. It is known that bioactive compounds in plant-based materials could perform as defensive mechanisms against oxidative stress by diligently being consumed as antioxidants by humans 13 . Therefore, this study aims to investigate the phenolic and flavonoid contents and antioxidant capacity of L. parasiticum extracts. 2. Experimental