Preliminary Phytochemical Profiling and Potential of Ricinus communis Leaf Extracts as Natural Sources of Antioxidant and Antimicrobial Agents
Ibrahim M. Nazifi
Department of Science Laboratory Technology, School of Science, Federal Polytechnics, Kaltungo, Gombe, Nigeria.
Sani M. Isyaka
Department of Chemical Sciences, North-Eastern University, Gombe, Nigeria.
Jibril Saidu
Department of Chemistry, Federal University of Kashere, Gombe, Nigeria.
Shirama M. Yakubu
Department of Chemistry, Federal University of Health Sciences, Azare, Bauchi, Nigeria.
Mohammed H. Shagal
Department of Chemistry, Modibbo Adama University, Yola, Adamawa State, Nigeria.
Abdulnafiu Usman
Department of Chemistry, University of Abuja, Abuja, Nigeria.
Abdullahi M. Abdullahi *
Department of Chemistry, Federal University of Health Sciences, Azare, Bauchi, Nigeria and Department of Chemistry, Modibbo Adama University, Yola, Adamawa State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
The increasing emergence of antimicrobial resistance and oxidative stress related diseases has intensified the search for bioactive compounds from medicinal plants. Ricinus communis L. (Euphorbiaceae) is widely used in traditional medicine for the treatment of various ailments including infections and inflammatory conditions. This study aimed to evaluate the antimicrobial and antioxidant activities of crude extracts obtained from the leaves of R. communis. The powdered leaves were successively extracted with petroleum ether, chloroform, ethyl acetate, and methanol using maceration. Percentage recovery ranged from 1.44% (ethyl acetate) to 2.89% (methanol). Preliminary phytochemical screening revealed the presence of alkaloids, flavonoids, and tannins in all extracts, while saponins, anthraquinones, phenols, and cardiac glycosides varied depending on solvent polarity. Antioxidant activity was evaluated using the DPPH radical scavenging assay at concentrations of 250–1000 µg/mL. The petroleum ether and methanol extracts demonstrated the highest radical scavenging activities of 82.59% and 73.42%, respectively, at 1000 µg/mL, compared with 93.80% for ascorbic acid. Chloroform and ethyl acetate extracts showed moderate activities. Antimicrobial activity assessed by the disc diffusion method revealed that chloroform and methanol extracts exhibited strong inhibitory effects against Staphylococcus aureus and Pseudomonas aeruginosa, while moderate activity was observed against Salmonella typhi and Klebsiella pneumoniae. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values further confirmed the antibacterial potential of the extracts. The findings suggest that R. communis leaves contain bioactive secondary metabolites responsible for significant antioxidant and antimicrobial activities, supporting their traditional medicinal applications and highlighting their potential as sources of novel therapeutic agents. Further studies involving purification, structural characterization, and mechanistic investigations are necessary to identify the specific compounds responsible for the observed activity and to evaluate their potential for therapeutic development.
Keywords: Antioxidant, microbial, castor leaves, maceration, activity, organisms