Phytochemical Screening, Antioxidant and Antimicrobial Activities of Neem Seed (Azadirachta indica) Extracts

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Phytochemical Screening, Antioxidant and Antimicrobial Activities of Neem Seed (Azadirachta indica) Extracts

A. U., Ezera, J. E., Adoga, S. O, and Wapwera, J. A
Department of Chemistry, Faculty of Natural Sciences, University of Jos, Nigeria
Received: 28 May 2023; Accepted: 27 June 2023; Published: 28 July 2023

Abstract: In this study, the phytochemical, antimicrobial and antioxidant activity of neem seed oils (Azadirachta indica) was analyzed. The extract was extracted by solvent extraction using n-hexane, ethyl acetate, methanol and aqueous solvents. The percentage yields of the extraction were 42.50%, 40.70%, 38.30% and 28.50% for the n-hexane, ethyl acetate, methanol and aqueous solvents respectively. The phytochemical screening of the samples revealed the presence of alkaloids, flavonoids, steroids, anthraquinones, cardiac glycosides and terpenoids in neem seed extract. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration of the neem seed extract was determined on Escherichia coli, Staphylococcus aureus, Aspergillus niger and Candida albicans. The MIC for neem seed extract in methanolic extract on E. coli and S. aureus was the least at 6.25% concentration while the MIC on the fungi (A. niger) was at 50% concentration having a zone of inhibition of 7.67± 0.71mm. There was no growth inhibition in C. albicans. The neem seed extract was shown to possess an antioxidant activity using DPPH radical. There was a significant increase in the scavenging activity of the neem seed extract as the concentration increased from 6.25% to 100%. The blended quantity of the neem seed extract showed the highest scavenging activity of 54.19 ± 0.03%. The study shows the extracts of neem seed possess good bioactive agents, antioxidant and antibacterial activity, and therefore they could be effectively used as a natural source of antioxidants and to be detected against gram-positive bacteria.

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Keywords: Phytochemical screening; Antioxidants; Antimicrobial; DPPH; Terpenoids; Neem seed extracts; Minimum Inhibitory Concentration (MIC); Minimum Bactericidal Concentration (MBC).

I. Introduction

Medicinal plants are important species of plants that according to the traditional medicinal practices and also from modern scientific studies are useful for medicinal purposes to alleviate diseases, make human health more invigorating. These plants are contemplated as rich sources of ingredients that can be used in the synthesis and production of drugs (Oladeji et al., 2019). Plants consist of various kinds of chemical constituents known as phytoconstituents, they serve the plants by contributing some secondary functions like; helps in plant growth, safeguarding the plants by activating defense mechanism, imparting color, odor, and flavor to the plants (Molyneux et al., 2007). Natural products and their derivatives exhibit minimal side effects and improved efficacy than other synthetic counterparts. These plant-derived components like flavonoids, quinine, terpenoid etc conduct certain biological functions that enhance therapeutic activities such as anti-carcinogenic, anti-mutagenic, anti-inflammatory, and antioxidant properties (Batiha et al., 2020).
Neem tree (Azadirachta indica) is a member of the mahogany family (Meliaceae) and endemic to the Indian subcontinent (Liauw et al., 2008). Neem tree proliferates in the tropical and semi-tropic climate countries, including Nigeria where it is known as Dongoyaro, with good environmental adaptability. The parts of the neem plant like leaves, barks, flowers, fruits, seeds, and roots were good sources of native medicine for the household treatment of various human illnesses and industrial products (Tesfaye et al., 2018). The neem seed has the highest concentration of oil compared to other parts of the tree and this oil is used as lubricants, insecticides, and drugs for a variety of diseases like; diabetes, leprosy, and tuberculosis (Tesfaye et al., 2018). Neem seed oil is also used in the manufacturing of a large number of skin products such as body lotions, body soaps, and beauty cares facial packs in combination with other natural ingredients.

While the cake that remains after the oil extraction serves as an active ingredient in the manufacturing of mosquito repellent coils (Liauw et al., 2008). Although neem seed oils are not majorly used for cooking purposes because of their offensive odour and bitter taste, similar to the combined odours of garlic and peanut, however, it is used as a preservative agent to prolong the shelf-life of cowpea grains (Ilesanmi and Gungula, 2011). Thus the increase in the production, characterization, and utilization of this seed in vegetable oils to meet global needs.