Ganoderma lucidum inspired silver nanoparticles and its biomedical applications with special reference to drug resistant Escherichia coli isolates from CAUTI

Abstract

In the search for alternative therapy for infections and other ailments, metallic nanoparticles, mainly silver nanoparticles (AgNPs) synthesized through bioengineered sources are extensively explored. Fungal bioactive compounds and their nanoparticles were reported with the potential biomedical application. A medicinal mushroom Ganoderma lucidum was reported as a repository of rich medicinal properties. In the current study, silver nanoparticles were synthesized using the extracts of G. lucidum and its antimicrobial activity was tested against drug-resistant Escherichia coli isolated from the catheter used for urinary tract infection (CAUTI). The GC-MS study of G. lucidum extracts showed the presence of ethyl acetoacetate ethylene acetal with the highest area percentage of 72.2% and retention time (RT 5873). Pyridine-3-ol is the second primary compound with a peak height of 6.44% and a retention time of 2.143. The third compound is l,4-Dioxane-2,3-diol, with an area of 8.09% and RT 5450. Butylated Hydroxy Toluene [BHT] is the fourth major compound with an area of 3.32%, and 9-Cedranone constitutes the fifth position in occupying the area percentage [1.88] and height 1.56%. Pyrrole is the sixth primary compound registering an area size of 0.96% and height 2.06%. The AgNPs synthesized using G. lucidum extract were in size range 23 and 58 nm as per SEM analysis and within the range wavelength 0.556-0.796 nm as per UV-Vis spectral study. FTIR Spectroscopy and X-ray diffraction analysis (XRD) were made to characterize the formed nanoparticles. The AgNPs synthesized effectively inhibited the growth of E. coli isolated from catheter-associated urinary tract infection and showed resistance to many drugs. The antioxidant potential of the synthesized nanoparticles assessed using DPPH radical scavenging activity, EC50 (µg/ml), and ARP data showed that the prepared nanoparticles were more potent in free radical scavenging activity than the standard quercetin. The cytotoxicity effect of Ag-NPs on breast cancer cell line- MDA-MB-231 confirmed its anticancer potential. The half-maximal inhibitory concentration (IC₅₀) of Ag-NPs to inhibit 50% of the tumor was 9.2 g/mL. The synthesized GL-AgNPs was exhibited a multifocal biomedical potential.

Keywords: Antibacterial activity; Antioxidant; Breast cancer cell line; Ganoderma lucidum; Urinary tract infection.

Fig. 1

(a) G. lucidium (Basidiomycota Fungi); (b) Ethanolic extract of G. lucidum using Soxhlet apparatus.

Fig. 2

Chromatogram showing the photochemical constituents of G. lucidium extracts: I. Ethyl acetoacetate ethylene acetal; II. Pyridine-3-ol; III. l4-Dioxane-2,3-diol; IV. Butylated Hydroxy Toluene; V. 9-Cedranone & VI. Pyrrole.

Fig. 3

Optical photographs of Ganoderma extract and silver nitrate mixture in different proportions and Color changes indicating formation of AgNPs (1. 1:9 – pale green colour -pre NPs formation; 2. 2:8 – Progressing dark brown; 3. 3:7 – Progressing dark brown; 4. 4:6 – Reddish brown showing AgNPs formation; 5. 5:5 – Reddish brown showing AgNPs formation).

Fig 4

UV–Vis spectrum of synthesized GL-AgNPs.

Fig. 5

FTIR spectrum of synthesized GL-AgNPs.

Fig. 6

XRD spectrum of synthesized GL-AgNPs.

Fig. 7

SEM images of GL-NPs showing their morphology at different resolutions. (a–e): (a & b) SEM of GL-NPs captured at 600× magnification. (c & e) SEM of GL-NPs captured at 16,000× magnification. (d) SEM of GL-NPs captured at 40,000× magnification.

Fig. 8

(a) Collection of urine sample; (b–e) E. coli isolated from urine sample of four different patients; (f) Confirmative analyses of E. coli by microscopic image of Gram staining.

Fig. 9

(a–d) Zone of inhibition in MHA plates with wells filled with 25, 50 and 75 µL of GL-AgNPs: (a) plate inoculated with drug resistant E. coli (E1); (b) plate inoculated with E. coli (E5); (c) plate inoculated with E. coli (E3); (d) plate inoculated with E. coli (E4).

Fig. 10

Antimicrobial activity of GL-AgNPs (effective activity only with concentration of 75 µL) against drug resistant E. coli isolates.

Fig. 11

Cytotoxic effect of different concentrations of GL-AgNPs on MDA-MB-231 cells in the MTT assay.