Abstract
Background. With the recent increase in antibiotic resistance to conventional antibiotics, gold nanoparticles, and medicinal plants, extracts present an interesting alternative. Objectives. This study aimed to synthesize, characterize, and evaluate Pyrenacantha grandiflora Baill extracts and gold nanoparticle conjugates against pathogenic bacteria. Methods. We synthesized gold nanoparticles by chemical and biological methods. The nanoparticles were characterized by the use of UV-visible spectrophotometry, followed by transmission electron microscopy (TEM) and energy-dispersive X-ray analysis (EDX). Gold nanoparticles were conjugated to plant extracts and analyzed with a Fourier-transform infrared spectroscope (FTIR). We determined the antimicrobial activity of the conjugates using well diffusion and the microdilution assays. Results. The UV–visible spectra of gold nanoparticles showed a synthesis peak at 530 nm. FTIR analysis indicated functional biomolecules that were associated with plant extract conjugated gold nanoparticles; the formation of C–H group and carbonyl (C=O) groups, –OH carbonyl, and C≡C groups were also observed. Biologically synthesized nanoparticles were star-shaped when observed by TEM with an average size of 11 nm. Gold nanoparticles synthesized with P. grandiflora water extracts showed the largest zone of inhibition (22 mm). When the gold nanoparticles synthesized by the biological method were conjugated with acetone extracts of P. grandiflora, MIC as low as 0.0063 mg/mL was observed against beta-lactamase producing K. pneumonia. The activity of acetone extracts was improved with chemically synthesized gold nanoparticles particularly when beta-lactamase producing E. coli and MRSA were used as test organisms. A synergistic effect was observed against all tested bacteria, except for MRSA when gold nanoparticles were conjugated with acetone extract. Conclusion. Overall, P. grandiflora tuber extracts conjugated with gold nanoparticles showed a very good antibacterial activity that improved both plant extract and gold nanoparticle’s individual activity.
Highlights
New strategies are being developed to improve existing medicines to combat antibiotic resistance among pathogenic microorganisms, and the use of inorganic nanoparticulate materials in conjugation with naturally occurring compounds in combination is more and more appreciated [1]
We have previously reported on the synthesis and evaluation of antibacterial activities of silver nanoparticles using Pyrenacantha grandiflora that is a medicinal plant used by local traditional healers for the treatment of gastrointestinal diseases [8]
Microorganisms and Growth Media. e microorganisms used in the present study are the same as those used in a previous study by our research group that include Magnetospirillum magnetotacticum MS-1 (DSMZ, Germany). is microorganism was used for the biological synthesis of the gold nanoparticles and was grown in a modified chemically defined growth medium supplemented with Isogro
Summary
New strategies are being developed to improve existing medicines to combat antibiotic resistance among pathogenic microorganisms, and the use of inorganic nanoparticulate materials in conjugation with naturally occurring compounds in combination is more and more appreciated [1]. We used gold and P. grandiflora extracts to synthesis nanoparticles and evaluate their antimicrobial activity. Is study aimed to synthesize, characterize, and evaluate Pyrenacantha grandiflora Baill extracts and gold nanoparticle conjugates against pathogenic bacteria. FTIR analysis indicated functional biomolecules that were associated with plant extract conjugated gold nanoparticles; the formation of C–H group and carbonyl (C O) groups, –OH carbonyl, and C≡C groups were observed. When the gold nanoparticles synthesized by the biological method were conjugated with acetone extracts of P. grandiflora, MIC as low as 0.0063 mg/mL was observed against beta-lactamase producing K. pneumonia. E activity of acetone extracts was improved with chemically synthesized gold nanoparticles when beta-lactamase producing E. coli and MRSA were used as test organisms. P. grandiflora tuber extracts conjugated with gold nanoparticles showed a very good antibacterial activity that improved both plant extract and gold nanoparticle’s individual activity
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