Green synthesis of Rosemary oleoresin mediated silver nanoparticles and its effect on Oral pathogens
Trinaina Somas Kandhan1, Anitha Roy2, Dr. Lakshmi. T3, Dr. S. Rajeshkumar4
1Graduate Student, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences,
Saveetha University, Chennai, Tamil Nadu, India.
1Associate Professor, Department of Pharmacology, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India.
*Corresponding Author E-mail: anitharoy2015@gmail.com
ABSTRACT:
Introduction: Nanoparticles have attracted a lot of attention due to their special properties and potential applications which arise due to their large surface area and surface plasmon resonance (SPR) effect. Silver nanoparticles present a strong bactericidal effect and are known to be powerful antibiotics besides being used in anticancer and antiviral therapies. There is an increase in the resistance of bacteria to antibiotics attributed to the overuse and has become an area of concern which led to renewed interests in investigating the efficacy of silver nanoparticles as a potent alternative. Materials and Methods: 1 milli molar of silver nitrate solution in double distilled water was prepared initially. 1 mL of the Rosemary oleoresin was added with the metal solution and was made up to 100 ml. The colour change was observed visually and photographs were recorded. The solution was kept in magnetic stirrer for nanoparticle synthesis. The synthesised NP’s solution was preliminary characterised by using UV-vis-spectroscopy. Agar well diffusion method was used to determine the antibacterial activity of the rosemary oleoresin mediated silver nanoparticles. Different concentrations of rosemary oleoresin mediated Ag NP’s was tested against Staphylococcus aureus, Streptococcus mutans (gram +), and pseudomonas sp using muller hinton agar plates. Results and Discussion: It has been observed that the antibacterial effect of the prepared silver nanoparticles was almost similar against all the organisms used in the study. The maximum zone of inhibition (ZOI) was found against against Pseudomonas sp and minimum ZOI against Streptococcus mutans. It was also been observed that the antibacterial activity of the Rosemary mediated silver nanoparticles increased with increasing concentration. Conclusion: This study indicates, rosemary oleoresin can be used as an environment friendly and non-hazardous material for the synthesis of silver nanoparticles, thus aiding in the elimination of using hazardous reducing agents. The additional antimicrobial activity of rosemary oleoresin mediated silver nanoparticles increases its efficacy in the field of medicine.
KEYWORDS: Rosemary, Nanoparticles, Agar, UV spectrophotometer, Oleoresin.
INTRODUCTION:
The current increase in the resistance of bacteria to antibiotics attributed to the overuse has become an area of concern and has led to renewed interests in investigating the efficacy of silver nanoparticles as a potent alternative.[1,2] Nanoparticles have been employed in many fields such as catalysis, ceramics, drug delivery, diagnosis and cancer therapy.[3] The antibacterial activity of silver containing materials have been used for many applications including the prevention of bacterial colonization in medical devices such as prosthesis, catheters, dental materials and is also found to have potent cytoprotective activity towards HIV infected cells.[3,4]
Silver nanoparticles have been synthesized by a variety of physical and chemical methods but mostly pertain to the reduction of metallic salts such as silver nitrate, hydrazine and polyethylene glycol or even reduction of non toxic agents such as potassium bi tartarate, ascorbic acid, sodium citrate.[5] However these synthetic process employ chemical and physical reagents that are harmful due to their increased environmental toxicity and biological hazards.[6,7] The harmful repercussions of the synthetic manufacture of silver nanoparticles, there have been many endeavors to develop a low energy consuming and to develop “green” techniques.[8]
In this study, rosemary oleoresin was used for the green synthesis of silver nanoparticles. Rosemary is an efficient antimicrobial against strains of staphylococcal and streptococcal species. Rosemary oleoresin is an oil soluble natural extract of rosemary plant. Rosemary is widely used for its antioxidant and protective effects such as hepatoprotectivity.[9,10] The objective of present study was to use green techniques using as rosemary oleoresin to synthesize silver nanoparticles and evaluate its antimicrobial against oral pathogens.
MATERIALS AND METHODS:
Plant material:
Rosemary oleoresin was obtained from Synthite Industries Ltd, Kerala, India as gratis.
Synthesis of nanoparticles:
1 milli molar of silver nitrate was prepared in double distilled water. 10 ml of rosemary oleoresin was added with the metal solution and was made into 100 ml solution. The colour change was observed visually and photographs were recorded. The solution was kept in magnetic stirrer for rosemary mediated silver nanoparticle synthesis.[11,12]
Characterisation of NP’s:
The synthesised rosemary mediated silver NP’s solution were preliminary confirmed by using UV-Vis-spectroscopy. 3ml of the solution was taken in cuvette and scanned in double beam UV-vis-spectrophotometer from 300 nm to 700 nm wavelength. The results were recorded for graphical analysis.[13,14]
Preparation of nanoparticles powder:
The NP’s solution was centrifuged at 8000 rpm for 10 minutes using lark refrigerated centrifuge. The pellet were collected and washed twice with distilled water. The final purified pellet was collected and dried at 600 C and stored in air tight eppendorff tube.
Antibacterial activity of nanoparticles against oral pathogens:
The agar well diffusion method was used to evaluate the antibacterial activity of silver nanoparticles. Rosemary oleoresin mediated Ag NP’s were tested against Staphylococcus aureus, Streptococcus mutans (gram +), and Psuedomonas sp. The fresh bacterial suspension was dispersed on the surface of Muller Hinton agar plates. A different concentration of nanoparticles (25,50, and 100 μL) was incorporated into the wells and the plates were incubated at 37°C for 24 hours. Amoxycillin was used as positive control. Zone of inhibition was recorded in each plate.[15]
RESULTS AND DISCUSSION:
Visual observation:
It is a well known fact that silver nanoparticles exhibit dark brown colour depending on the intensity and size of nanoparticles. The colour change occurs due to the excitation of the surface plasmon resonance (SPR) of the silver nanoparticles[16,17]. When Rosemary oleoresin was added to the silver nitrate solution, the colour of the solution transformed from a turbid whitish yellow colour to dark brown. This colour change has been shown in figures 1. This colour change was indicative of the formation of silver nanoparticles which was further confirmed by UV – vis spectrophotometry.
Figure 1: Visual observation of silver nanoparticles synthesis using rosemary oleoresin
UV-vis spectroscopy:
Figure 2: Graph showing the absorbance of rosemary oleoresin mediated silver nanoparticle by UV-Visible Spectroscopy
UV-Vis spectroscopy is a renowned technique to confirm the formation and stability of silver nanoparticles present in aqueous solution. The UV – Vis spectra was recorded for the prepared rosemary oleoresin mediated silver nanoparticles (Figure 2). It was observed from the spectra that the AgNP’s surface plasmon resonance peak occurs at 420 nm with high absorbance, which was indicative for silver nanoparticles. This confirms the formation of rosemary oleoresin mediated silver nanoparticles.[18,19,20]
Antibacterial Activity:
The Rosemary oleoresin mediated AgNP’s that were synthesised by green techniques were studied for antimicrobial activity against the pathogens, Staphylococcus aureus, Streptococcus mutans, and Pseudomonas species. The diameter of the zone of inhibition (ZOI) was recorded in millimetre around each well in different concentrations levels of rosemary oleoresin mediated AgNP’s against the bacterial species. The results were tabulated and a graph was plotted (Figure 3,4).
It has been observed that the antibacterial effect of the prepared silver nanoparticles was almost similar against all the organisms used in the study with a maximum zone of inhibition against Pseudomonas species and minimum ZOI against Streptococcus mutans. There was an increase in the zone of inhibition with increased concentration. The zone of inhibition for the prepared AgNP’s against Streptococcus mutans at the concentrations 25, 50 and 100 μL was found to be 10 mm, 11 mm and 13 mm respectively. Similarly for Staphylococcus aureus, the zone of inhibition was found to be 10 mm, 13mm and 15 mm. For Pseudomonas sp., the zone of inhibition values are 15 mm, 19 mm and 21 mm respectively. [19,20]
Figure 3: Antibacterial activity of Rosemary oleoresin mediated silver nanoparticles against Pseudomonas species.
Comparison of Zone of Inhibition at various concentrations:
Figure 4: Zone of Inhibition for oral pathogens at 25,50 and 100 μL
The antimicrobial activity of the synthesised silver nanoparticles was attributed to the silver cations released from them, pertaining to the changes in the membrane structure of microbes, which lead to the increased membrane permeability of the bacteria and finally cell death[20].
CONCLUSIONS:
In the present study concludes the potential new effective green technique for synthesis as well as a stabilising agent for the synthesis of silver nanoparticles using rosemary oleoresin. The synthesised rosemary oleoresin mediated AgNP’s showed high antimicrobial activity against Pseudomonas sp. The antimicrobial activity of rosemary oleoresin mediated silver nanoparticles may be used in the field of medicine for effective management of sensitive microorganisms.
ACKNOWLEDGEMENT:
The authors thank Synthite Industries Limited, Kerala for providing the rosemary oleoresin for this project.
CONFLICT OF INTEREST: Nil
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Received on 12.03.2019 Modified on 30.04.2019
Accepted on 21.05.2019 © RJPT All right reserved
Research J. Pharm. and Tech. 2019; 12(11):5379-5382.
DOI: 10.5958/0974-360X.2019.00933.8