Comparative analysis of antifungal activity of Rhazya stricta ethanolic extracts and biogenic silver nanoparticles against pathogenic fungi

Abstract

Rhazya stricta, a perennial shrub native to the Middle East and South Asia, has been used in traditional medicine for various therapeutic purposes, including antimicrobial action. The current study aimed to compare the antifungal properties of 96% and 50% ethanolic extracts of R. stricta leaves and their biogenic silver nanoparticles (AgNPs). The phytochemical constituents of both extracts were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). The AgNPs were characterized using FTIR, UV-Vis spectroscopy, DLS, and TEM, confirming bioactive chemicals' effective production and existence. The antifungal efficacy was tested on five pathogenic fungi: Drechslera halodes, Drechslera tetramera, Macrophomina phaseolina, Alternaria alternata, and Curvularia australiensis. The 96% ethanol extract inhibited fungal growth the most, with D. halodes, C. australiensis, and A. alternata all experiencing almost 100% inhibition. AgNPs also showed strong antifungal efficacy, with those generated from 96% ethanol extract outperforming those from 50% ethanol extract. This study highlights the potential of R. stricta extracts and their biogenic AgNPs as environmentally friendly antifungal agents, which supports their use in long-term antimicrobial therapy.

Keywords: Rhazya Stricta; Antifungal activities; Ethanolic extracts; Silver nanoparticles.

Fig. 1

Biosynthesis of silver nanoparticles from ethanolic extracts of R. stricta leaves.

Fig. 2

FTIR Spectrums of ethanolic extracts and biosynthesized AgNPs of R. stricta leaves. (A) 96% ethanol, (B) 50% ethanol.

Fig. 3

UV-vis spectra of AgNPs prepared from ethanolic extracts of R. stricta leaves.

Fig. 4

Percentage intensity of particle size distribution of biosynthesized AgNPs of R. stricta leaves extracts. (A) particle size distribution of AgNPs of 96% ethanol extract, (B) particle size distribution of AgNPs of 50% ethanol extract.

Fig. 5

TEM microphotographs of the biogenic AgNPs of R. stricta extracts. The particle size destitution histogram of AgNPs was assessed by JEOL JEM-2100Plus microscope, and the diameter of the particles was calculated in µM at a magnification of 150,000. (A) TEM images of the AgNPs biosynthesized from 96% ethanol, (upper) and 50% ethanol (lower) extract, (B) size destitution histograms.

Fig. 6

The anti-fungal activities of R. stricta 96% ethanol extract and biogenic AgNPs at various concentrations on mycelial growth diameter (mm) of selected phytopathogenic fungi using the plate food technique.

Fig. 7

The anti-fungal activities of R. stricta 50% ethanol extract and biogenic AgNPs at various concentrations on mycelial growth diameter (mm) of selected phytopathogenic fungi using the plate food technique.

Fig. 8

A bar chart summarizes the anti-fungal activities (%IMG) of all the R. stricta preparations used at the highest concentrations compared to the positive control. ** p < 0.01, *** p < 0.001.