One pot green synthesize of gold nanoparticles (AuNPs) were achieved using the leaf extracts of Carica papaya (CP) and Catharanthus roseus (CR) and the combination of these two extracts (CPCRM). The synthesized AuNPs were characterized for their size, morphology, crystallinity and their effects on bacterial and cancer cell lines were investigated. The electron microscopy results showed that AuNPs were mostly spherical, however, triangle and hexagonal shaped morphologies were also observed. The infrared spectroscopy and microscopies studies revealed that alkaloids, flavonoids and proteins were present along with AuNPs which are responsible for their stabilization, non-agglomeration and biologically active characteristics including antibacterial and anticancer activity. Among the AuNPs prepared in this study, CPCRM extract showed enhanced activity due to the synergistic effects of both plant extracts. (C) 2015 Elsevier Ltd. All rights reserved.