Anti-Inflammatory and Antioxidant Activity of Syzygium polyanthum (Wight) Walp.

Sains Malaysiana 51(5)(2022): 1475-1485 http://doi.org/10.17576/jsm-2022-5105-17

ABSTRACT Syzygium polyanthum has been used as folk medicine to treat ailments related to oxidative stress and inflammation. In this study, the anti-inflammatory and antioxidant activity of stem bark and root bark of the plant were investigated. The experiments that have been carried out were estimation of total phenolic and total flavonoid in the methanol extracts and fractions of both parts, isolation and structure elucidation of chemical compounds, anti-inflammatory activity evaluation based on inhibition of prostaglandin E2 production in the LPS-induced human whole blood using radioimmunoassay technique as well as antioxidant activity based on assays by using free radical scavenging DPPH and FRAP. Results showed high amounts of phenolics and flavonoids in both parts of S. polyanthum. Seven compounds were succesfully isolated from the stem bark and identified as stigmasterol (1), 8-hydroxy-6-methoxy-3-pentylisocoumarin (2), 3,3’-di-O-methylellagic acid (3), methylgallate (4), asiatic acid (5), arjunolic acid (6), and daucosterol (7). The ethyl acetate fraction of the root bark showed potent inhibitory activity on the production of PGE2 (IC50 3.03 ± 0.83 μg/mL). The methanol extract of the stem bark displaying promising DPPH scavenging activity (SC50 = 2.82 ± 0.1 μg/ mL) and FRAP activity (7.02 ± 0.1 μg/μg of equivalent trolox amount). Compounds 1, 5, 6 and 7 showed pronounced inhibitory activity on the PGE2 production with IC50 ranging from 0.052 to 1.25 μM. Meanwhile, compound 4 exhibited antioxidant activity toward DPPH (SC50 10.60 μM) and FRAP (20.5 ± 1.0 μg/μg). The study concluded that S. polyanthum as a potential source for therapeutic agents with anti-inflammatory and antioxidant activities.

INTRODUCTION Inflammation is a complex reaction of vascularized tissue to local injury as results of immune response to endogenous and exogenous invades. The aim of inflammation is for limiting tissue damage and infection as well as initiating repair (Vane & Botting 1996). It is a general immune reaction, however, in the condition with aberrant inflammatory response, the reaction resulting in even more damage. Two classes of inflammation have been classified based on the duration of the reaction that are acute inflammation and chronic inflammation. The latter have been proven to exist in the development of a variety of diseases such as bone and joint inflammatory diseases, cardiovascular diseases, diabetic complications, cancers, neurological disorders, pulmonary diseases, autoimmune disorders and metabolic, and endocrine disorders (Arulselvan et al. 2016). Researches have also shown the correlation between oxidative stress and inflammation to activate and accelerate the diseases process (Willcox et al. 2016). Oxidative stress is caused by a diminished antioxidant defence and/or increased production of reactive species (Halliwell 2007). The search for active agents for treatment of diseases and the process related to inflammation and oxidative stress has increased dramatically on natural sources including plants (Azab et al. 2016; López-Alarcón & Denicola 2013). The attention has been made due to many evidences of unwanted side effects by modern medicines (Attiq et al. 2018). Studies have also suggested synergistic effects of natural products such as in herbal preparations and neutraceuticals to support better health for mankind (Alok et al. 2014; Shahidi & Zhong 2015).

Plants from the family Myrtaceae have long been used in traditional medicines to treat diseases related to inflammation and oxidative stress (Quattrocchi 2012). The family is comprised of about 145 plant genera with 5,970 accepted species names (The Plant List 2019). They are woody trees and shrubs of disjunct distribution in the wet tropics, particularly South America, tropical Asia, and Australia. The unique of Myrtaceae species is in their bark that smooth and shed annually. Another feature of the family is the presence of oil glands that produce essential oils dominated by monoterpenes and sesquiterpenes. Thus, the family is economically important for industries related to spices and pharmaceuticals (Govaerts et al. 2008). Some species of this family have also been scientifically investigated. One of the Myrtaceae species is Syzygium polyanthum (Wight) Walp. (synonym: Eugenia polyantha Wight), which is a tropical tree native to Southeast Asia countries, including Indonesia, Malaysia, Thailand, Vietnam, and the Philippines (Quattrocchi 2012; Wilson 2011). S. polyanthum known as ‘salam’ has edible flowers and fruits, and its dried leaf is used as an important flavoring condiment in Indonesian cuisine (Dalimartha 2005; Renfrew & Sanderson 2005) and several Southeast Asia countries (Parnell et al. 2007). The aromatic fragrance of the leaves is unique, hence the substitution for its fragrance rather difficult to find even among Syzygium species (Hutton 2003). The ripe fruits are edible although slightly astringent and the timber is used for house building and furniture (Quattrocchi 2012). The stem bark of the plant is used as dying agent for wattle and bamboo handcraft in Indonesia (Dalimartha 2005). Besides the use in culinary, ‘salam’ has long been used as folk medicine in Indonesia and Malaysia to treat diarrhea, hypercholesterol, gastritis, hypertension, diabetes mellitus, scabies, itches, gout, cough, cancer servix, kidney stone, arthritis, swollen, and migrain (Chooi 2008; Dalimartha 2008; Hembing 2004; Kurniawati 2010; Patria 2016). Previous studies reported the occurrence of flavonoids, phenolics, phenylpropanoids, phloroglucinols, monoterpene, and phytosterols, mainly from the leaf of the plant (Carroll 2016; Har et al. 2012; Kato et al. 2013; Lelono & Tachibana 2013a, 2013b; Saifudin et al. 2012).

k and root of the plant were investigated, employing methanol extract and organic fractions. Their antiinflammatory activity was based on inhibitory effects on the production of prostaglandin E2 (PGE2 ) in lipopolysaccharide (LPS)-induced human whole blood and antioxidant activity was evaluated using DPPH and FRAP assays.

Sains Malaysiana 51(5)(2022): 1475-1485 http://doi.org/10.17576/jsm-2022-5105-17