MICROWAVE-ASSISTED SYNTHESIS OF AGNP USING AQUEOUS LEAVES EXTRACT OF VINCA ROSEA AND ITS THERAPEUTIC APPLICATION Original Article SWETA PATEL, AISHAANI MAHESHWARI, AMRISH CHANDRA* Amity Institute of Pharmacy, Amity University, Sector 125, Noida 201313, Uttar Pradesh, India Email: achandra3@amity.edu Received: 20 Aug 2015 Revised and Accepted: 02 Nov 2015 ABSTRACT Objective: Green synthesis of silver nanoparticles was attempted with the help of aqueous Vinca rosea leaf extract. The aim of the study was to combine the therapeutic activity of Vinca rosea and the deep tissue penetration capabilities of the silver nanoparticles. Methods: This study focuses on the green synthesis of silver nanoparticles (AgNPs) using an aqueous extract of Vinca rosea leaves, its characterization, and evaluation of its antibacterial and anticancer activity by diffusion method and MTT assay using human lung carcinoma cell line A549 respectively. The nanoparticles were synthesised by exposing the reaction mixture containing silver nitrate and Vinca leaf aqueous extract to microwave radiation. Results: The characterization of synthesised nanoparticles was carried out by observing the peaks on scanning from 250 to 800 nm using UV spectroscopy, the end point for the complete formation of nanoparticles marked by a colour change to reddish brown. Dynamic Light Scattering (DLS) which evaluated particle size uniformity and Scanning Electron Microscopy (SEM) which determines the particle size revealed that the nanoparticles were spherical in shape and measured an average of 50.75 nm. 170µg/ml of AgNPs of Vinca leaf aqueous extract should potent anti- bacterial activity tested by agar well diffusion method as well as the cytotoxic activity which was evaluated by MTT assay. Conclusion: The synthesised nanoparticles were found to be potentially cytotoxic against A549 cell line and also demonstrated anti-bacterial activity. The activity may be attributed to the fact that silver ions are known to impair macromolecules containing sulphur and phosphorus like protein and DNA owing to their small size and high penetration power. Keywords: Vinca, Anti-cancer, Silver nanoparticles. INTRODUCTION Nanoscience has emerged in the past few years as an interdisciplinary science [1] in the fields of sensing [1, 3], imaging [2], targeted drug delivery [4], gene targeting [5], cancer [6] and even artificial implants [10]. Nanoparticles have seen immense interests among researchers [1] due to their distinctive chemical, physical, optical, electronic, magnetic and catalytic properties quiet disparate from the bulk properties [1, 7, 8]. These unique properties can be attributed to their large specific surface area, small size [4], and the surface to volume ratio [1, 9]. However, many of these properties require that the particles apart from being nano-sized should also be uniform and not forming agglomerates [1]. Metal nanoparticles can be prepared using physical approach [1], microbes [7], chemical approach [1, 11], or microwave assisted green synthesis that is by the use of plant extracts [7, 10, 19]. The physical approach is a tedious process [7, 18] utilising methods like evaporation/condensation, thermal decomposition [11, 12] and laser ablation [1, 11, 13] while chemical approach aims at reducing the metal ions into an environmentally safe small metal clusters or aggregates1 using reducing agents like sodium borohydride [1], hydrazine hydrate [11] or ionising radiation1 increasing the price of the manufacturing apart from biological risks [7, 18]. Apart from these, methods such as electrochemical method [11], microwave irradiation [14] and sonochemical synthesis [15] are also used. Microbial synthesis of nanoparticles requires an aseptic condition19 apart from maintaining and culturing of cells making the process time consuming and complex [7, 16, 17]. Thus, in comparison of the above three techniques, using plant extracts as reducing and capping agents for synthesis of metal nanoparticles is more beneficial [7]. Microwave assistance is used so as to suppress enzymatic activity, increase the speed of reaction and keep the procedure eco-friendly [7, 18]. Silver and gold are the most widely used noble metals to prepare nanoscale particles and has gained tremendous importance in the past two decades. In ancient times, silver was used in various clinical conditions like epilepsy, leg ulcers, ulcer debridement, acne, wart removal and venereal infections [10]. Silver foils were applied to surgical wounds to alleviate healing and inhibit post-operative infections [10]. It has also been known for long that silver compounds have antibacterial effects against both aerobic as well as anaerobic bacteria [19]. It has been proved that silver in its nanoscale form as compared to the ionic form has reduced cellular toxicity but retained the antibacterial efficacy probably due to the formation of free radicals from the surface of silver [19] and a large surface to volume ratio [1, 9, 10] which increases reactivity [11], smaller is the size of silver nuclei higher is its efficacy [1, 10]. The application of nanoscale silver has regained its importance due to increased cases of antibiotic resistance by their overuse [11]. The antibacterial activity of AgNPs can not only be used in medicine to prevent infection but also to prevent bacterial colonization on catheters, prostheses, dental materials, vascular grafts and human skin11 by forming a coating on them [19]. The application of AgNPs can thus be classified into diagnostics and therapeutic uses [10]. Synthesis of nanoparticles using plant extract from plant parts like leaves, corns, tubers, buds and bark; is receiving more attention due to the aforementioned benefits [10,19]. The extracts may include phytochemicals like terpenoids, phenol derivatives, quinones, flavonoids, plant enzymes (reductases, hydrogenases) and their derivatives, dihydric phenols which act as reductants in the presence of metal ions [10]. Plant leaf extract of onion [20], Syzygium cumini [21], basil [22], banana peel [23], Saraca indica [7, 10], and Piper nigrum [24] have already been reported to be used in the form of metal nanoparticles of silver and gold [7, 19]. This refreshing technique is merged with the use of medicinal plants to develop an effective system to deliver their therapeutic properties. The study aimed at incorporating the beneficial effects of both herbal & inorganic metal ion for therapeutic efficacy. Nanoparticles being smaller in size may pose to have reduced adverse effects and also show higher potency compared to the conventional dosage forms. Vinca rosea with its well known traditional properties was a herb of choice to evaluate its antimicrobial properties on bacterial International Journal of Pharmacy and Pharmaceutical Sciences ISSN- 0975-1491 Vol 7, Issue 12, 2015 Innovare Academic Sciences