Investigation of in vitro antimicrobial activities of silver nanoparticles biosynthesised using Kaempferia galanga

Abstract

Diabetic Foot Ulcer (DFU) is a complication of diabetes mellitus that can be worsened by microbial infections. Although antibiotics are used, antimicrobial resistance can lead to the progression of disease. Therefore, silver nanoparticles (AgNPs) could be useful as a potential novel therapeutic agent due to their antimicrobial activities. Kaempferia galanga (Iguru Piyali), which is used in Ayurvedic medicine, was used to biosynthesise AgNPs. Antimicrobial properties of plant crude extracts, extract-coated AgNPs, and uncoated AgNPs were screened in vitro against standard bacterial strains Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), and the fungal strain Candida albicans (ATCC 10231). Rhizomes of Kaempferia galanga were used to prepare crude extracts and were used to synthesise extractcoated AgNPs. Uncoated AgNPs were synthesised using a vitamin C solution. Antimicrobial activities of crude extracts, extract-coated AgNPs, and uncoated AgNPs were screened using the broth micro dilution method (CLSI, 2025). As positive controls, gentamicin and fluconazole were used. Each formulation’s minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and half-maximal inhibitory concentration (IC50) were evaluated. IC50 was calculated using Prism 10.0 (GraphPad Software Inc., La Jolla, CA). Extracts-coated Ag- NPs of Kaempferia galanga showed higher activity compared to the crude extracts and uncoated AgNPs. It showed considerable activity against all three tested microorganisms. Kaempferia galanga extracts-coated AgNPs exhibited excellent antifungal activity and also the lowest MIC value of 0.078 mg/mL against C. albicans MBC and IC50 values were also obtained for each microorganism. It can be concluded that, Kaempferia galanga extracts-coated AgNPs exhibited in vitro antimicrobial activity against S. aureus, P. aeruginosa, and C. albicans, than plant crude extracts and uncoated AgNPs. Moreover, it has shown higher antifungal activity against C. albicans. Further studies are needed to evaluate the pharmacological and antimicrobial activity of Kaempferia galanga plant crude extracts, and extract-coated AgNPs as a topical antimicrobial agent for DFU.