METHANOL LEAF EXTRACT OF Jatropha tanjorensis Ellis and Saroja POSSESS PHYTOCONSTITUENTS WITH FREE RADICAL SCAVENGING ACTIVITY

The body during normal metabolic function produces free radicals which are highly reactive species. Free radicals could also be introduced into the body from the environment. The oxidation induced by reactive oxygen species can result in DNA mutation, membrane protein damage and cell membrane disintegration. The present study assayed the preliminary phytochemicals, total phenolics and total flavonoids and free radicals scavenging ability of methanol extract of Jatropha tanjorensis leaf. Standard methods for determining phytochemicals, reducing power, nitric oxide scavenging, hydroxyl radical, and lipid peroxidation scavenging activity were employed. The phytochemical screening result revealed the presences of phenols, flavonoids, saponin, alkaloids, tannins, terpernoids and steroids. The total phenolic content of methanol extract of Jatropha tanjorensis leaf measured by Folin-Ciocalteau reagent in terms of gallic acid equivalent was 11.35±0.82mgGAE/g. The flavonoid content of the plant sample calculated as Quercetin equivalent was 15.91±1.60mgQCE/g. GC-MS results revealed relevant pharmacological bioactive compounds. The antioxidative activity of the plant’s extract correlated with total phenolic content. The radical scavenging activity showed a dose dependent increase in the reducing power. The minimum NO inhibitory activity was 8.88±0.63 at 200μg/ml and the maximum activity was 32.70±2.71 at 800μg/ml. The minimum percentage H2O2 radical inhibitory activity was 8.30±0.88 at 200μg/ml and a maximum activity was 22.80±2.28 at 800μg/ml. There was also an increase scavenging effect of lipid peroxide radical in concentration dependent manner. The results of this study indicate that the leaf of Jatropha tanjorensis possess antioxidant properties and could serve as free radical inhibitor.


INTRODUCTION
Some pathological conditions are often due to production of free radicals from metabolic side reactions and exogenous sources (Atanu et al., 2018). The activities of these reactive oxygen species (ROS) and reactive nitrogen species (RNS) results in distortion of normal metabolic activities thereby presenting health challenging conditions (Pavithra and Vadivukkarassi, 2015). Generally, radicals implicative role in disease pathology are attributed to loss of cell membrane stability, consequently leading to interactions with basic molecules of proteins, carbohydrates, nucleic acids and lipids (Rahman et al., 2015). Since several pathological conditions are attributed to oxidative stress, in finding remedy to these pathological conditions, scientists are considering perspective of preventing oxidative stress mediated process which can be achieved via free radicals scavenging and radicals quenching with compounds commonly known as antioxidants (Meles et al., 2019). Plant species serve as a major source of several novel biologically active compounds and some of these bioactive compounds are beneficial and serve as natural antioxidants (Danborno et al., 2019). The adverse effects of the reactive oxygen species produced in living things could be inhibited by natural antioxidants. Humans based on this principle depended on plants and plants products to cure various diseases and maintain healthy living. It is on record that natural products have proved to be of great health impact on humans traditionally and scientifically (Oyewole et al., 2011). The nature remains the right source for health promotion and for the supplementation of safe drugs. Great attention is mandatory to explore many unexplored plants with highly effective antioxidant activity. Phenolics and polyphenols are the most widely researched class of bioactive compound (Asif, 2015). A great number of modern medicines have been derived from plants hence plants are considered as important sources of medicinal agents used to treat different diseases (Njoku and Chidi, 2009). Bioactive compounds such as flavonoids, tannins, phenols, and alkaloids, in medicinal plants, play an important role in drug development (Khan, et al., 2019). In recent years, the use of herbs have received considerable attention as an alternative way to compensate for perceived deficiencies in orthodox pharmacotherapy worldwide (Arika et al., 2015).Plant-based natural medicines are popularly acclaimed to be safe, scientists advocate for proper toxicological studies in other to ensure safety in the use of natural medicines (Asif, 2015). The therapeutic effect of these medicinal plants can justifiably be attributed to the phytochemicals in them. Jatropha tanjorensis is green leafy medicinal plant that has found usage in folk medicine. The plant is a common weed of field crops belonging to the family Euphorbiaceae (Oladele et al., 2020). It is usually grown in rain forest zones of West Africa. Jatropha is understood for its use as purgative/laxative and other medicinal purposes. All parts of the plant including seeds, leaves and bark; fresh or as a decoction, are used in traditional and folk medicine as well as veterinary purposes (Chigozie et al., 2018). In southern part of Nigeria like in Edo state the leaf of the plant is locally consumed as vegetable added to daily meal as well as in treating diabetes mellitus due to its anti-hyperglycemic property (Olayiwola et al., 2004). In other part of Nigeria the FUDMA Journal of Sciences (FJS) ISSN online: 2616-1370ISSN print: 2645-2944Vol. 5 No. 3, September, 2021, pp 286-293 DOI: https://doi.org/10.33003/fjs-2021 plant is consumed as soups and as a tonic with the claim that it increases blood volume. There has been claim that it cures anaemia, diabetes and cardiovascular diseases (Omoregie and Osagie, 2011). Jatropha tanjorensis has received tons of attention due to its potential health benefits, availability and affordability. This study was carried out to determine the phytochemical content and antioxidant activity of the plant leaf.

MATERIALS AND METHOD THE PLANT
The leaves of jatropha tanjorensis were obtained from the premises of Federal Polytechnic Nekede, Owerri and subsequently authenticated by a botanist at the Department of Plants Science, Michael Okpara University of Agriculture Umudike.

Phytochemical Screening
The qualitative phytochemical screening was carried out using the methods of Harborne (1973) and Trease and Evans (1989).

GC-MS Analysis
The analysis of bioactive compounds from the extract was carried out at Springboard, Awka, Anambra State, using Agilent Technologies Gas Chromatography systems 7890A coupled with Mass spectrometry 5975C model equipped with HP-5MS column (30 m in length × 250 μm in diameter × 0.25 μm in thickness of film). Helium gas was used as the carrier gas with flow rate of 1.5mL/min. The initial temperature was set at 70 for 0.5min to 280 °C with increasing rate of 12 °C/min and holding time of about 5min. Furthermore, One microliter was injected into 250°C inlet with a splitless mode. The detection of compounds involved an electron ionization system which involves high energy electrons (70 eV). The relative quantity of the compounds present in the extract of henna was expressed as percentage based on peak area produced in the chromatogram.

DISCUSSION
The phytochemical content of Jatropha tanjorensis revealed the bioactive compounds present (Table 1). The result indicates a high presence of flavonoids and alkaloids in Jatropha tanjorensis leaves. The total phenolic content of the plant leaf extract was calculated using the standard curve gallic acid with regression values of Y = 0.0011x + 0.0559 and R2 = 0.9738. While the total flavonoid content of Jatropha tanjoresis leaves was calculated using the standard curve Quercetin with regression values of Y = 0.0008x + 0.0785 and R2 = 0.9816. The high concentration of flavonoids and alkaloids can be attributed to the reason for therapeutic values of Jatropha tanjorensis in the treatment of diabetes mellitus due to its antihyperglycemic property as proposed by Olayiwola et al., (2004). There has been claim that Jatropha tanjorensis leaves cure anaemia, diabetes and cardiovascular diseases (Omoregie and Osagie, 2011). This claim can be justifiably attributed to the high presence of these flavanoids and alkaloids in Jatropha tanjorensis leaves.
Flavonoids are believed to have various therapeutic values such as antihyperglycemic effect (Muriithi, et al., 2015), inhibition of cell proliferation and free radical scavenging activity (Holst, et al., 2008). The improvement of cardiac function, decrease anginas and lowering of cholesterol levels by medicinal plant is attributed to its flavonoids content (Nyamai, et al., 2016). Alkaloids on its own are known to have antidiabetic and antioxidant activity (Yang, et al., 2001). Alkaloid fractions have shown hypoglycemic potential in mice (Cassidy, et al., 2000). The antihypertensive effects, antimalarial activity and anticancer as well as anti-arrythmic effects of alkaloids have been reported (Dholi, et al., 2015;Chiu-Yin, 2002). Studies have shown that alkaloids have antimicrobial, cytotoxic and trypanocidal activity (Nyamai, et al., 2016).
The result of the present work also indicated the presence of other phytochemicals in Jatropha tanjorensis leaf. These Standard Ascorbic Acid include phenols, saponins, tannins, terpenoids and steroids, this is similar and in agreement with the work of Oyewole and Akingbala (2011) which revealed the presence of these phytochemicals in in Jatropha tanjorensis leaf extract. Phenols have been reported to have high antioxidant properties a great attribute to its therapeutic effect (Joshi, et al., 2001). Terpenoids have antioxidant properties and also interact with most regulatory proteins (Wagner and Elmadfa, 2003). Saponins have been reported to have beneficial therapeutic effects they are known to have hypocholesterolaemic, immunostimulant, hypoglycemic effect and anticarcinogenic properties (Ros, 2000). Clinical studies have shown that phytosterol intake leads to up to 15% reduction of LDL-cholesterol (Katan, et al., 2003;O'Neill, et al., 2005). Vanhanen et al., (1993) had reported that Intake of plant sterols reduces both plant sterol and animal cholesterol concentrations in the serum. The indicator that shows a compound potential antioxidant activity is regarded as the reducing power. This reducing properties are generally related with the presence of reductones, which exhibit antioxidant activity by breaking the chain reactions by donating hydrogen atoms. Some precursors of peroxide could react with reductones, thus preventing formation of the oxidants (Meir et al., 1995). In this study, the extract exhibited considerable good reducing power activity though the acscorbic acid has more pronounced activity. Mammalian cells produce nitric oxide which is a free radical involved in the regulation of various physiological processes.
However, there is a close link between excess production of nitric oxide and several diseases. New research target for treating chronic inflammatory diseases is geared towards the development of substances that could prevent the overproduction of nitric oxide (Shen et al., 2002). The result from this study showed that Jatropha tanjorensis leaf could prevent overproduction of Nitric oxide thereby maintaining the normal physiological state of the human system. Hydroxyl radicals are highly potent oxidants, which can react with biomolecules in living cells and cause severe damage (Gulcin, 2006).In the present study, the hydroxyl radical activity was significantly inhibited by the administration of methanol extract of Jatropha tanjorensis leaf to the reaction mixture.

Conclusion
Due to the increase in human diseases especially metabolic diseases such as diabetes, liver disease, myocardial infarction and hypertension, the role played by highly reactive oxygen species such as free radicals has become increasingly relevant and the study on medicinal plants for natural antioxidants is now imperative. This study indicates that Jatropha tanjorensis leaf possess antioxidant properties and could serve as free radical scavengers and act as essential antioxidants.

Conflict of Interest.
Authors declared no conflict of interest.