Platinum nanoparticles (Pt NPs) was synthesized via a facile and cost competitive ont-pot green mediated synthesis using cell free cultural filtrate (microgravity simulated grown Penicillium chrysogenum) as a reducing agent. The toxicity effect of synthesized Pt NPs toward myoblast C2C12 carcinoma cells was then investigated. The particle size analyzer (DLS) and transmission electron microscopy (TEM) results demonstrates that both NG-Pt NPs and MG-Pt NPS are spherical in shape with an average diameter of 15 nm and 8.5 nm, respectively. The results from UV-visible (UV-vis) spectroscopy and X-ray diffraction (XRD) analysis show a characteristic strong resonance centered at 265 nm and a single crystalline nature, respectively. The results derived from in vitro cytotoxicity showed a significant concentration-dependent decrement in cell viability when C2C12 cells were exposed to Pt NPs. Such decrement in cell viability is because of increased reactive oxygen species (ROS) generation. Cell apoptosis was proved by acridine orange-ethidium bromide (AO/EtBr) dual staining, annexin V-FITC/PI-staining and immunocytochemistry. Moreover, the protein expression of both (i) apoptosis related proteins such as cas-3 and cas-9, (ii) inflammatory response proteins such as TNF-α, TGF-β and NF-κB were significantly upregulated in MG-Pt NPs treated cells than NG-Pt NPs treated cells. Uptake and intracellular localization of MG-Pt NPs caused by accumulation of autophagosomes in C2C12 cells and bacterial cells, indicate that synthesized MG-Pt NPs enable for the swift cell apoptosis than NG-Pt NPs. Interestingly, At the concentration of 40 and 80 μg/ml MG-Pt NPs showed more potent cytotoxicity toward cancer cells while, under identical concentration, NG-Pt NPs exhibited rather lower cytotoxicity. Overall, our results demonstrated that MG-Pt NPs could be selectively inhibit the growth of cancer cells via ROS-mediated nucleus NF-κB and caspases activation when compared to NG-Pt NPs.