Phytochemical Screening, Antioxidant and Antimicrobial Activities of red and yellow flowered Mirabilis jalapa

Abstract

The phytochemical content, antioxidant capacity, and antimicrobial efficacy of leaf extracts from two forms of Mirabilis jalapa (M. jalapa) - red and yellow flowered- were investigated. Using the cold maceration method with 70% methanol, the presence of alkaloids, flavonoids, carbohydrate, protein, amino acid, phenol, tannins, saponins, , and steroids was confirmed. Fourier-transform infrared (FT-IR) spectrum analysis detected hydroxyl groups (OH), aromatic and aliphatic C-H bonds, aromatic C=C bonds, carbonyl group (C=O), amines (-C-N), and C-O group in both forms red and yellow leaves of M. jalapa.
The antioxidant activity assessed using the1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method showed higher free radical scavenging activities for the red -flowered leaves compared to the yellow-flowered ones at different concentrations. Four human pathogenic microorganisms; Staphylococcus aureus(S. aureus), Escherichia coli(E. coli), Pseudomonas aeruginosa(P. aeruginosa), and Candida albicans(C. albicans) were evaluated for antimicrobial activity by agar well diffusion method.The red-flowered form exhibited higher activity against the tested pathogens compared to the yellow form, likely due to its higher content of phenols and flavonoids in the methanol extracts. The minimum inhibitory concentration (MIC) was found to be 0.195 mg/ml against S. aureus and 0.049 mg/ml against E. coli and P. aeruginosa; for both forms, it was 0.025 mg/ml against C. albicans.