In the present study, an attempt has been made for the estimation of total phenol and flavonoid content and their radical scavenging properties using Piper betle (L.) leaves. In that, Cultivars i.e., Nov Bangla (NB), Sirugamani-1 (SGM-1) and Halisar Sanchi (HS) were selected for this study. The total phenolic content was ranged from 95.04 to 127.33 mg/100g equivalent to gallic acid and flavonoids were ranged from 51.72 to 61.08 mg/ 100g equivalent to standards of Catechin.  In vitro antioxidant activity was estimated using 1,1-diphenyl-2-picryl hydrazyl (DPPH), free radical scavenging activity, improved ABTS radical cation decolorization assay and ferric reducing antioxidant power (FRAP) assay. Among all the cultivars, The highest Phenol content (93.79%) was observed  for Sirugamani-1 by DPPH method  and highest Phenol content (96.12% & 6791.86 (µg/g) was obtained  for Halisar Sanchi by ABTS assay and FRAP activity  respectively. The study revealed that the leaves of Piper betle (L.) has higher amount of antioxidant activity and it could be used for any novel drug preparation.

In this study, rapid, simple approach was applied for synthesis of silver nanoparticles by using Psidium guajava aqueous leaf extract. The plant extract acts as both reducing agent and capping agent. The green synthesized silver nanoparticles were characterized by using physic-chemical techniques viz, UV-Visible spectroscopy, Fourier Transform Infrared Spectrophotometer [FTIR], Particle size analyser and Scanning electron microscopy. UV-Visible spectrophotometer showed absorbance peak in the range of 419nm.The compounds responsible for silver ions and the functional groups present in plant extract were identified and investigated by FTIR technique. The characterization data reveals that the particles were in crystalline in nature with an average size of 62nm. The silver nanoparticles (Ag NPs) were rapidly synthesized using aqueous extract of guava leaf with AgNO3 solution within 15min at room temperature, without the involvement of any hazardous chemicals. Keywords: Nano particles, green synthesis, Silver,  Psidium guajava and reducing agents.