Biogenic synthesis of Silver Nanoparticles and in vitro determination of antidiabetic activity of Cosmos caudatus (Ulam Raja) leaf extract

Present study focuses on the biogenic synthesis of silver nanoparticles by using Cosmos caudatus (CC) under an environmentally friendly and cost-effective manner. C.caudatus is a well-known vegetable in Kelantan and East Coast region. Silver nanoparticles (AgNPs) are metal particles in nano-sized and had been used extensively due to its capability to enhance various biological activities. This is caused by the smaller size of AgNPs which contribute to the high surface volume ratio. Natural biomolecules in C.caudatus might contribute to the bioreduction, formation and stabilization of AgNPs. Synthesized AgNPs were characterized systematically by using UV-Visible spectroscopy, Fourier Transfer Infra-Red (FTIR), Scanning Electron Microscopy (SEM), Energy Diffraction Spectroscopy (EDX) and X-Ray Diffraction (XRD). The experiment started with the synthesizing of AgNPs from C.caudatus leaf extract. Visual inspection was done to observe the changes of color which caused by the bioreduction of silver ions to AgNPs. The color intensity increased with the increase of incubation time. Based on the UV-Vis spectrum, AgNPs of C.caudatus (CC AgNPs) showed the Plasmon resonance peak at 437 nm. FTIR-ATR of CC AgNPs revealed the functional groups that act as the nature capping agent for the formation of AgNPs. XRD analysis showed that the CC AgNPs are in crystalline structure with face centered cubic (fcc) geometry. Results from SEM analysis showed the shape and size of AgNPs. EDX analysis confirmed the presence of silver element by showed a prominent peak and high concentration (80.76 wt %) of silver. In vitro antidiabetic activity of synthesized AgNPs was being explored in this study by using alpha amylase inhibition assay. Acarbose was used as the standard synthetic drug. Effect of inhibitory was increased with the increase of concentration of CC leaf extract and CC AgNPs. The results showed that the CC leaf extract and CC AgNPs have antidiabetic potential.