Green synthesis of metal nanoparticles is reputed to have a robust range of biomedical applications. Silver nanoparticles (AgNPs) bio-fabricated using aqueous leaf extract of Annona muricata were characterized and evaluated for in-vitro antioxidant, lipid peroxidation inhibition, anti-diabetic and antimicrobial activities as well as cytotoxicity in human keratinocyte cells (HaCaT).The extract induced colour change of silver salt solution which absorbed at 420 nm and confirmed the formation of AgNPs. FTIR showed that free amide and hydroxyl groups were responsible for the synthesized nanoparticles. Both XRD and SAED confirmed the crystalline nature of the particles with face centered cubic (FCC) phase. The zeta potential revealed -27.2 mV potential and average distribution size of 35 nm. DLS indicated that the majority of the particles were 86.78 nm size and with a polydispersity index (PDI) of 0.329.AgNPs displayed strong activities against DPPH (IC 50 ¼ 51.80 μg/ml), ABTS (IC 50 ¼ 30.78 μg/ml), α-amylase (IC 50 ¼ 0.90 μg/ml) and α-glucosidase (IC 50 ¼ 3.32 μg/ml). The particles exhibited a dose-dependent inhibition of Fe 2þ -induced lipid peroxidation with effective antimicrobial activity against a battery of bacterial strains and cytotoxicity in HaCaT cell line. These findings revealed the potential biomedical applications of the particles and further work will be required to establish its molecular mechanism of action.

Nanotechnology is widely gaining worldwide application in biology and medicine because of its proven efficacy. Annona muricata contains bioactive phytochemicals with an inherent ability to bio-fabricate metal ions nanoparticles (NPs). Annona muricata aqueous leaf extract and its green bio-fabricated silver nanoparticles were evaluated on red blood cells (RBC) for anti-haemolytic activity and cytogenotoxicity on Allium cepa cells. The effects of A. muricata extract (Am-E) and its biofabricated silver nanoparticles (Am-AgNPs) were observed at 0.7, 7.0 and 70.0 µg/ml on H2O2-induced haemolysis in RBC and cyclophosphamide-induced cytogenotoxicity on A. cepa cells. Results showed significant and concentration dependent anti-haemolytic activity of Am-E relative to Am-AgNPs. Significant (P<0.05) reduction of mitotic index was observed in the groups treated with Am-AgNPs compared with Am-E, which indicates cytotoxic effect of the nanoparticles. The Am-E protected A. cepa meristem root cells from cyclophosphamide-induced mitotic repression better than Am-AgNPs. Different degree of chromosomal abnormalities such as chromosome-bridge, sticky chromosome, and c-mitosis were observed in all the treatment groups with chromosome-bridge and sticky chromosome being prominent. This study revealed stronger anti-haemolytic efficacy of Am-E at higher concentrations compared with Am-AgNPs. Chromosomal abnormalities observed in this study suggest greater chromosomal instability as influenced by the nanoparticles compared with the extract on onion cells. The protective effect of the extract against cyclophosphamide-induced chromosomal aberrations may be an indication of its potential as an anti-genotoxic agent.