PHYTOCHEMICAL COMPOUNDS AND ANTIOXIDANT CAPACITY OF Paederia foetida

Paederia foetida is locally known as ‘akar sekentut’ or ‘daun sekentut’ because of the foul smell produced when the leaves are touched. It was used traditionally to reduce bloating and used by women after giving birth. This local species is overlooked because it is rarely found and often chopped off. Performing research on this species could help to enhance its medicinal value. Thus, this study attempts to analyse antioxidant capacity of fresh and dried leaves and twigs of P. foetida. The phytochemical constituents were initially screened, and the antioxidant capacity was evaluated by determining Total Phenolic Content (TPC), Total Flavonoid Content (TFC) and IC50 values using Follin-Ciocalteu method, AlCl3 method and DPPH assay, respectively. P. foetida showed the presence of phenolics, glycosides, alkaloids, saponins, tannins and terpenoids. The highest TPC and TFC were observed for methanolic extract of fresh twigs with 0.0536 GAE/g and methanolic extract of fresh leaves with 0.1545 QE/g respectively. The IC50 values ranged from 1.50 – 4.88 for all the ethanolic and methanolic extracts except for ethanolic extract of dried twigs of which the value was 16.88. The results obtained from this study revealed the potential of this local species as a promising natural antioxidant. Keyword: Antioxidant, Paederia foetida Introduction Interest in the exploitation of medicinal plants has always been prevalent as it offers many benefits to humankind. The medical values of these plants commonly come from their antioxidant properties and because of this reason, scholars continue conducting research on uncommon medicinal plants species to study their potential in pharmaceuticals, cosmeceuticals, agrochemicals, and other fields. The supremacy of natural antioxidants is undeniable as they have strong ability to destruct free radicals (Lim et al., 2006). Additionally, the use of synthetic antioxidants such as butylatedhydroxytoluene (BHT) and butylatedhydroxyanisole (BHA) has been heavily censured by many health critics and researchers because they are suspected to be the promoters to carcinogenesis (Islam et al., 2018). Thus, finding newer natural antioxidants is in great demand. Secondary metabolites, such as phenolic compounds which include their derivatives such as flavonoids and carotenoids, are biologically active compounds which accountable for the antioxidant properties of plants and herbs. They function as antioxidants because they are significantly involved in the protection against free radicals due to the presence of phenolic rings and hydroxyl groups (Minatel et al., 2017). Paederia foetida or locally known as ‘akar sekentut’ is one of the overlooked medicinal plants in Malaysia. The leaves of P. foetida contain sulphur compounds including dimethyl disulphide (Uddin et al., 2013). Due to the sulphur compounds, it produces a fetid smell which diminishes when cooked. The local community serve this plant as salad or ‘nasi ulam’ GADING Journal of Science and Technology Vol 4 No (1) (2019) – eISSN: 2637-0018 Published by Universiti Teknologi MARA (UiTM) Cawangan Pahang March 2021 | 47 rather than using it as a traditional remedy (Rosli et al., 2013). Old Malay folks use this plant in treating women during confinement and reducing bloating. In India, young leaves and shoots of P. foetida are used to prepare curry. They believe it is good for women after giving birth, excellent as a treatment for kidney problem (Kumar et al., 2014), diarrhea (Chanda et al., 2015), piles (Devi & Sarkar, 2017), and jaundice (Bhattacharya et al., 2015), as well as important during drought as it has nutritional values (Srianta et al., 2012). In addition to that, Chinese used this plant to make a nutritious soup for the sick (Wong & Tan, 1994) and Indonesians use it to cure bloating (Hossan et al., 2010). A small number of studies on this species in other countries have been done, but study on the potential of P. foetida from local species is scarce. This is due to the plant being regularly chopped off, mainly found in undisturbed areas, or rarely planted in home garden unlike ‘ulam raja’ (Cosmos caudatus) and ‘pegaga’ (Centella asiatica). Previous studies have shown that P. foetida contains bioactive compounds such as amino acids, saponin, tannin, phenolics, flavonoid, terpenoid, glycoside, alkaloid, carbohydrates, iridoid, sitosterol, stigmasterol, volatile oil, protein (Chanda et al., 2014; Mazumder et al., 2018). The biological properties of P. foetida have been tested in a few studies such as gastroprotective for gastric ulcer (Chanda et al., 2015), antidiabetic (Vikas et al. 2009), hepatoprotective (Peng et al., 2015), and antidiarrheal activity (Mazumder et al., 2018). A recent study revealed that the extract from P. foetida twigs had antidiabetic potential (Tan et al., 2019). Majority of these studies mainly used P. foetida dried leaves. Herein, we report the phytochemical compounds and the antioxidant capacity of both fresh and dried local P. foetida leaves and twigs. Materials and Methods Materials The leaves and twigs of Paederia foetida (P. foetida) were collected at Pasir Mas, Kelantan, Malaysia. The fresh samples were rinsed with tap water followed by distilled water and air dried before use. The dried samples were subsequently oven dried at 60°C for 72 hours and then stored in an airtight container for further use. Extraction The fresh and dried leaves and twigs of P. foetida were macerated separately with n-hexane, methanol and ethanol at ambient temperature for 3 days following method as described by Dev & Kumar, (2011) and Handrianto & Surahmaida, (2018). The extracts were then evaporated using rotary evaporator at 40°C. Screening for phytochemical constituents The screening tests were conducted using the methods as described by Rao et al., (2016). All samples were screened for phenols, glycosides, saponins, alkaloids, terpenoids, flavonoids and tannins. Total Phenolic Content The total phenolic content (TPC) was determined using Follin-Ciocalteu method. Firstly, stock solution was prepared by dissolving 0.025 gram of Na2CO3 in ethanol and further diluted to 0.1, 0.2, 0.3, 0.4 and 0.5 mg/mL. 1 mL of extract was transferred into a 10 mL volumetric flask with 5 mL of distilled water and 1 mL of Follin reagent. After 5 minutes, Na2CO3 solution was added followed by distilled water. The absorbances of the standard and samples were measured at 760 nm with UV-1800 spectrophotometer (Shimadzu Japan). The total phenolic content was expressed as mg gallic acid equivalent per gram of the sample GADING Journal of Science and Technology Vol 4 No (1) (2019) – eISSN: 2637-0018 Published by Universiti Teknologi MARA (UiTM) Cawangan Pahang March 2021 | 48 (GAE/g). The measurements were made in triplicate. The total phenolic content was calculated using equation (1):