Apigenin mediated gold nanoparticle synthesis and their anti-cancer effect on human epidermoid carcinoma (A431) cells

We report that the flavonoid, apigenin (4',5,7,-trihydroxyflavone) is able to form apigenin linked gold nanoparticles (ap-AuNPs) at RT with apigenin itself acting as the stabilizing agent. The synthesized ap-AuNPs have been characterised by UV-Visible spectroscopy, HR-TEM, DLS, FTIR and TGA analyses. The biocompatible nature of ap-AuNPs is shown by their non-toxicity towards normal epidermoid cells (HaCat). Additionally, they are shown to exhibit anti-cancer activity towards epidermoid squamous carcinoma cells (A431). The uptake of ap-AuNPs into A431 cells is seen by TEM. Apoptosis induced by ap-AuNPs in these cells is observed through EtBr/AO and DAPI staining. Flow cytometric results also reveal the occurrence of early apoptotic cells, late apoptotic cells and the presence of sub-G1 population. DNA prepared from ap-AuNPs treated A-431 cells reveals a ladder like pattern in agarose gel electrophoresis indicating oligonucleosomal cleavage which is a hallmark of apoptosis. The ap-AuNPs also inhibit angiogenesis as shown by Chick chorioallantoic membrane (CAM) assay. Taking the results together, we believe that ap-AuNPs show promise in treatment of skin cancer. The ap-AuNPs also have cytotoxic potential against the human cervical squamous cell carcinoma cell line SiHa.