Pharmacognostic standardization and antimicrobial studies of the leaves and seeds of Delonix regia (Boojer. Hook.) Raf. and Peltrophorum pterocarpum (DC) Backer ex K Heyne

Abstract

Standardization is a key process to evaluating the quality, purity and efficacy of natural drugs. The constant rise in antibiotic resistance of certain causative organisms to popular antibiotics has increased the search for alternatives. This study aims to establish pharmacognostic standards for the leaves and seeds of Delonix regia and Peltrophorum pterocarpum and also to evaluate the antimicrobial potential of their methanolic extracts. The samples were found to contain saponins, alkaloids, flavonoids, and tannins. The microscopic evaluation revealed various epidermal features including the presence of trichomes, venation patterns and stomata cells on the abaxial and adaxial surfaces. The physico-chemical and heavy metal results obtained were within the standard limits. The extracts exhibited both antibacterial and antifungal activities against tested microorganisms showing varying zones of inhibition from 13.7mm - 27.0mm. The Minimum Inhibition Concentration (MIC) of the plant drugs was consistently low ranging from 0.6125 - 10% w/v and this can indicate that the test drugs have high resistance mechanisms to these microorganisms. The Minimum Bactericidal Concentration (MBC) showcase varying antimicrobial strengths against selected microbial strains with D. regia leaf extract showing effectiveness at low MBC value of 1.25% W/V. The results underscore the antimicrobial potential of both species, supporting their use as natural alternatives to conventional antibiotics, especially in the treatment of resistant microbial strains. Their phytochemical profiles are key contributors to their efficacy, providing a strong basis for their pharmacognostic and medicinal evaluation.