Photo-assisted bio-fabrication of silver nanoparticles using Annona muricata leaf extract: exploring the antioxidant, anti-diabetic, antimicrobial, and cytotoxic activities.

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 (IC50 = 51.80 µg/ml), ABTS (IC50 = 30.78 µg/ml), α-amylase (IC50 = 0.90 µg/ml) and α-glucosidase (IC50 = 3.32 µg/ml). The particles exhibited a dose-dependent inhibition of Fe2+-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.

Corrigendum to "Antiproliferative and Apoptosis Induction Potential of the Methanolic Leaf Extract of Holarrhena floribunda (G. Don)".

[This corrects the article DOI: 10.1155/2015/756482.].

Cytotoxic and cell cycle arrest properties of two steroidal alkaloids isolated from Holarrhena floribunda (G. Don) T. Durand & Schinz leaves.

BACKGROUND: The plant Holarrhena floribunda (H. floribunda; G. Don) is indigenous to sub-Saharan Africa and is traditionally used to treat several ailments. The present study was carried out to isolate and characterize bioactive compounds with anti-proliferative activity present in H. floribunda extracts. METHODS: Compounds were isolated from H. floribunda using the bioassay-guided fractionation technique of repeated column chromatography and the step-wise application of the MTT reduction assay to assess antiproliferative bioactivity. The structures of the compounds were identified mainly using NMR. The effects of the isolated compounds on the viability, cell cycle and proliferation of human cancer cell lines (MCF-7, HeLa and HT-29) as well as the non-cancerous human fibroblast cell line (KMST-6) were investigated. RESULTS: Bioassay-guided fractionation yielded two steroidal alkaloids: holamine (1) and funtumine (2). The MTT reduction assay shows that both compounds exhibited selective dose-dependent cytotoxicity against the cancer cell lines studied. The isolated compounds induced cell cycle arrest at the G0/G1 and G2/M phases in the cancer cell lines with significant reduction in DNA synthesis. The results obtained show that the cancer cells (MCF-7, HeLa and HT-29) used in this study were more sensitive to the isolated compounds compared to the noncancerous fibroblast cells (KMST-6). CONCLUSION: The ability of the isolated compounds to cause cell cycle arrest and reduce DNA synthesis raises hopes for their possible development and use as potent anticancer drugs. However, more mechanistic studies need to be done for complete validation of the efficacy of the two compounds.

Antiproliferative and Apoptosis Induction Potential of the Methanolic Leaf Extract of Holarrhena floribunda (G. Don).

Natural plant products with potent growth inhibition and apoptosis induction properties are extensively being investigated for their cancer chemopreventive potential. Holarrhena floribunda (HF) is used in a wide range of traditional medicine practices. The present study investigated the antiproliferative and apoptosis induction potential of methanolic leaf extracts of HF against breast (MCF-7), colorectal (HT-29), and cervical (HeLa) cancer cells relative to normal KMST-6 fibroblasts. The MTT assay in conjunction with the trypan blue dye exclusion and clonogenic assays were used to determine the effects of the extracts on the cells. Caspase activities were assayed with Caspase-Glo 3/7 and Caspase-9 kits. Apoptosis induction was monitored by flow cytometry using the APOPercentage and Annexin V-FITC kits. Reactive oxygen species (ROS) was measured using the fluorogenic molecular probe 5-(and-6)-chloromethyl-2',7'-dichlorofluorescein diacetate acetyl ester and cell cycle arrest was detected with propidium iodide. Dose-response analyses of the extract showed greater sensitivity in cancer cell lines than in fibroblast controls. Induction of apoptosis, ROS, and cell cycle arrest were time- and dose-dependent for the cancer cell lines studied. These findings provide a basis for further studies on the isolation, characterization, and mechanistic evaluation of the bioactive compounds responsible for the antiproliferative activity of the plant extract.

Effect of defatted methanolic extract of Holarrhena floribunda leaves in sodium arsenite-induced clastogenecity in Wistar albino rats.

This study examined the effect of defatted methanolic extract of Holarrhena floribunda leaves on sodium arsenite-induced clastogenecity and toxicity in male wistar rats. Animals were randomly allotted into six groups of five rats each and treated as follows; Group A (sodium arsenite (NaAsO3)), Group B (100 mg/kg extract), Group C (100 mg/kg extract plus NaAsO3), Group D (200 mg/kg extract), Group E (200 mg/kg extract plus NaAsO3) and Group F had distilled water. Sodium arsenite (2.5 mg/kg) was given intraperitoneally once per week. The extract was administered through oral gavage for 28 consecutive days. Clastogenecity was evaluated by studying micronuclei formation in polychromatic erythrocytes cells (PCEs) in the bone marrow. Plasma levels of Gamma Glutamyl Transferase (ãGT), Aspartate Amino Transferase (AST), Alanine Amino Transferase (ALT) were determined. Hepatic Reduced Glutathione (GSH), Superoxide Dismutase (SOD), Catalase (CAT), protein and lipid peroxidation were determined. Liver histopathological evaluation was also carried out.The results obtained show that NaAsO3-induced micronuclei formation in PCEs was reduced at 100 and 200 mg/kg of the extract by 7.7% and 38.5% respectively while elevated plasma ãGT and ALT levels were significantly ameliorated (P<0.001). There was no significant difference in plasma AST levels and hepatic SOD activities in all the treated groups as compared with the control. Sodium arsenite-induced reduction of GSH concentration was elevated by the extract at 100 and 200 mg/kg by 18.5% and 11.9% respectively. The reduction of CAT activity by NaAsO3 was also ameliorated at 200 mg/kg extract by 23.3%. The extract at 100 mg/kg significantly reduced NaAsO3-induced lipid peroxidation by 16.4% (P < 0.05). Histological examinations showed that the extract at 100 mg/kg protected NaAsO3-induced liver damage. This study revealed that the leaf extract has potential to ameliorate clastogenecity and toxicity induced by sodium arsenite in rats.