This study aims to characterize and determine the antibacterial activities of synthesized Strobilanthescrispus-mediated AgNPs (SC-AgNPs) against Streptococcus mutans, Escherichia coli and Pseudomonas aer-uginosa. S. crispus water extract acts as a reducing and capping agent in the synthesis of AgNPs. Thesynthesized AgNPs were characterized by using UV-Vis spectrophotometer, dynamic light scattering(DLS), field emission scanning electron microscope (FESEM), X-ray diffractometer (XRD) and Fouriertransform infra-red (FTIR). FESEM images showed a rough surface with a spherical shape. The averagesize distribution of 75.25 nm with a polydispersity index (PDI) of 0.373. XRD analysis matched the face-centred cubic structure of silver. FTIR analysis revealed a shifted peak from 1404.99 to 1345.00 cm−1.MIC and MBC values of SC-AgNPs were 1.25 mg/mL and 2.5 mg/mL against E. coli, P. aeruginosa andS. mutans, respectively. Time-kill assay showed that SC-AgNPs significantly reduced bacterial growth ascompared to non-treated bacteria. Morphologies of bacteria treated with SC-AgNPs were shrunk, lysed,irregular and smaller as compared to control. SC-AgNPs significantly disrupted the gene expression ofeae A, gtf B and Pel A (p < 0.05). This study indicated that the synthesized SC-AgNPs were stable withenhanced antibacterial activities.

Purpose: The purpose of this study was to investigate apoptotic activity of silver nanoparticle Clinacanthus nutans (AgNps-CN) towards HSC-4 cell lines (oral squamous cell carcinoma cell lines). Methods: Methods involved were MTT assay (cytotoxic activity), morphological cells analysis, flow cytometry and cell cycle analysis and western blot. Results: MTT assay revealed IC50 concentration was 1.61 mu g/mL, 3T3-L1 cell lines were used to determine whether AgNps-CN is cytotoxic to normal cells. At the highest concentration (3 mu g/mL), no cytotoxic activity has been observed. Flow cytometry assay revealed AgNps-CN caused apoptosis effects towards HSC-4 cell lines with significant changes were observed at G1 phase when compared with untreated cells. Morphological cells analysis revealed that most of the cells exhibit apoptosis characteristics rather than necrosis. Protein study revealed that ratio of Bax/Bcl-2 increased mainly due to down-regulation of Bcl-2 expression. Conclusion: AgNps-CN have shown potential in inhibiting HSC-4 cell lines. IC50 was low compared to few studies involving biosynthesized of silver nanoparticles. Apoptosis effects were shown towards HSC-4 cell lines by the increased in Bax/Bcl-2 protein ratio. Further study such as PCR or in vivo studies are required.