Asian Pacific Journal of Tropical Biomedicine

54-64

Authors: Aarti Sharma, Pushplata Tripathi, Sarita Kumar

Objective: To formulate silver nanocomposites from Achyranthes aspera leaf extracts and evaluate its larvicidal activity against Aedes aegypti. Methods: The silver nanocomposites were synthesized from Achyranthes aspera leaf extracts. The process was optimized and traced through UV-visible and photon correlation spectroscopy. The larvicidal potential of silver nanocomposites of Achyranthes aspera leaf extracts was assessed against the early fourth instars of Aedes aegypti and three non-target organisms. Furthermore, the most effective and eco-safe nanocomposite was characterized by different biophysical techniques including scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FT-IR). Results: The formulated silver nanocomposites exhibited efficient larvicidal efficacy against Aedes aegypti. Bioassay with silver nanocomposites formulated using different AgNO 3 concentrations (3, 4, and 5 mM) revealed respective LC50 values of 37.570, 6.262 and 1.041 μg/mL; 5.819, 1.412 and 0.489 μg/mL; and 5.519, 1.302 and 0.267 μg/mL after 24, 48 and 72 h. The silver nanocomposites with 4 mM AgNO3 were selected for characterization. SEM and TEM analysis revealed spherical, poly-dispersed structure with varied diameters of 1-25 nm. The XRD analysis established the crystalline and face-centred-cubic structure of silver nanocomposites with the maximum peak at a 2θ value of 37.42°. The EDX pattern showed the presence of Ag, O and C in the nanocomposites in their order of weight%. The FT-IR displayed visibly distinct peaks in different ranges demonstrating the intricacy of silver nanocomposites. In addition, the lethal concentrations of silver nanocomposites of Achyranthes aspera leaf extracts against Aedes aegypti larvae were non-toxic to non-target organisms including Gambusia affinis, Daphnia magna and Moina macrocopa. Conclusions: Silver nanocomposites synthesized with leaf extract of Achyranthes aspera provide a cost-effective and eco-safe alternative to conventional insecticides, and can be utilized as a potent mosquito nano-larvicide.

78-86

Authors: Eun Ok Choi, Hyesook Lee, Cheol Park, Gi-Young Kim, Hee-Jae Cha, Suhkmann Kim, Heui-Soo Kim, You-Jin Jeon, Hye Jin Hwang, Yung Hyun Choi

Objective: To investigate whether ethanol extracts of Hizikia fusiforme could induce apoptosis in human prostate cancer PC3 cells. Methods: Cell viability was evaluated using 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide. Apoptosis and mitochondrial membrane potential (MMP) were measured using flow cytometry in PC3 cells. DNA damage was assessed by nuclear staining and DNA fragmentation assay. Expressions of apoptosis-associated proteins were determined by Western blotting assays. Activities of caspase-3, -8, and -9 were determined by colorimetric assay. Moreover, intracellular reactive oxygen species (ROS) generation was detected using a flow cytometer and fluorescence microscope. Results: Treatment of PC3 cells with ethanol extracts of Hizikia fusiforme inhibited proliferation, which was associated with induction of apoptosis, and accompanied by increased expression of Fas, Fas-ligand (FasL), Bax and tBid, and decreased expression of Bcl-2. In addition, ethanol extracts of Hizikia fusiforme reduced c-Flip expression and activated caspase-8, -9 and -3, resulting in an increase in poly (ADP-ribose) polymerase (PARP)cleavage. However, in the presence of a pan-caspase inhibitor, ethanol extracts of Hizikia fusiforme-mediated growth inhibition and apoptosis were significantly attenuated. Ethanol extracts of Hizikia fusiforme also destroyed the integrity of mitochondria due to the loss of MMP, leading to cytosolic release of cytochrome c. Moreover, the levels of ROS were markedly increased by treatment with ethanol extracts of Hizikia fusiforme, which was significantly suppressed by the ROS scavenger N-acetyl-L-cysteine. Further investigation of whether ethanol extracts of Hizikia fusiforme-induced apoptosis was related to the generation of ROS was conducted and the results showed that N-acetyl-L-cysteine fully blocked ethanol extracts of Hizikia fusiforme-induced apoptotic events including loss of MMP, activation of caspase-3, the cytosolic release of cytochrome c and cytotoxicity. Conclusions: Ethanol extracts of Hizikia fusiforme have chemopreventive potential via induction of ROS-dependent apoptosis. Therefore, ethanol extracts of Hizikia fusiforme may be useful for developing effective and selective natural sources to inhibit cancer cell proliferation.