Baskaralingam Vaseeharan

Plectranthus amboinicus leaf extract mediated synthesis of zinc oxide nanoparticles and its control of methicillin resistant Staphylococcus aureus biofilm and blood sucking mosquito larvae.

In this study, zinc oxide nanoparticles were biologically synthesized using the leaf extract of Plectranthus amboinicus (Pam-ZnO NPs). The synthesized Pam-ZnO NPs were characterized by UV-Vis spectrophotometer, FTIR, TEM and XRD analysis. TEM analysis of Pam-ZnO NPs showed the average size of about 20-50 nm. Pam-ZnO NPs control the growth of methicillin-resistant Staphylococcus aureus biofilms (MRSA ATCC 33591) at the concentration of 8-10 μg/ml. Confocal laser scanning microscope (CLSM) images revealed that Pam-ZnO NPs strongly inhibited the biofilm forming ability of S. aureus. In addition, Pam-ZnO NPs showed 100% mortality of fourth instar mosquito larvae of Anopheles stephensi, Culex quinquefasciatus and Culex tritaeniorhynchus at the concentration of 8 and 10 μg/ml. The histopathological studies of Pam-ZnO NPs treated A. stephensi and C. quinquefasciatus larvae revealed the presence of damaged cells and tissues in the mid-gut. The damaged tissues suffered major changes including rupture and disintegration of epithelial layer and cellular vacuolization. The present study conclude that Pam-ZnO NPs showed effective control of S. aureus biofilms and mosquito larvae by damaging the mid gut cells.

Protective effect of ferulic acid and resveratrol against alloxan-induced diabetes in mice.

The present study was to investigate the effect of ferulic acid and resveratrol on alloxan-induced diabetic mice, through analysis of basic biochemical parameters, enzymic as well as non-enzymic activities, lipid peroxidation and immunohistochemical studies. Alloxan was administered as a single dose (75 mg/kg body weight) to induce diabetes in mice. A dose of ferulic acid (10 mg/kg body weight) and resveratrol (20 mg/kg body weight) were administrated orally, to the alloxan-induced diabetic mice. The levels of basic biochemical markers and lipid peroxidation were significantly (P<0.05) increased in alloxan-induced diabetic mice. The levels of antioxidants were significantly (P<0.05) decreased in liver, kidney and serum. Immunohistochemical studies in alloxan induced mice demonstrated a marked increase in the immunoreactivity of nuclear transcription factor (NF-κB). Treating the diabetic mice with doses of ferulic acid and resveratrol restored the changes in the above parameters analyzed. The present study, showed that ferulic acid and resveratrol exerted antioxidant as well as anti-diabetic effects, consequently alleviate liver, kidney and pancreas damage caused by alloxan-induced diabetes, probably through inhibition of the proinflammatory factor, NF-κB.

Antibacterial activity of silver nanoparticles (AgNps) synthesized by tea leaf extracts against pathogenic Vibrio harveyi and its protective efficacy on juvenile Feneropenaeus indicus

Aims:  To determine the antibacterial potential of silver nanoparticles (AgNps) synthesized by tea leaf extract against Vibrio harveyi and its protective effect on juvenile Feneropenaeus indicus.

Medicinal plant derivatives as immunostimulants: an alternative to chemotherapeutics and antibiotics in aquaculture

Aquaculture makes a significant contribution in the production of protein-rich food for human consumption. Aquaculture practices encounter many challenges, and one of the most devastating problems is disease outbreaks caused by microbial pathogens. To control disease outbreaks, several chemotherapeutics and antibiotics were used indiscriminately, which in turn leads to residual problems in the surrounding environment affecting higher animals and also humans. Immunostimulants are considered as an alternative for antibiotics, which will boost the immune system of the cultured organism, thus effectively countering the assault of pathogens. The use of plant materials as immunostimulant will be an ecofriendly approach for the control of pathogens. The botanicals present in the plants have a key role in enhancing the fish immunity. This review focuses on the importance of plant material as immunostimulant in the control of diseases in aquaculture.

Nanoparticles as effective acaricides against ticks—A review

Ticks serve as vectors of a wide range of infectious agents deleterious to humans and animals. Tick bite prevention is based to a large extent on the use of chemical repellents and acaricides. However, development of resistance in targeted ticks, environmental pollution, and contamination of livestock meat and milk are major concerns. Recently, metal, metal oxide and carbon nanoparticles, particularly those obtained through green fabrication routes, were found to be highly effective against a wide array of arthropod pests and vectors. We summarize current knowledge on the toxicity of nanoparticles against tick vectors of medical and veterinary importance. We also discuss the toxicity of products from botanical- and bacterial-based as well as classic chemical nanosynthesis routes, showing differences in bioactivity against ticks based on the products used for the fabrication of nanoparticles. Further research is needed, to validate the efficacy of nanoparticle-based acaricides in the field and clarify mechanisms of action of nanoparticles against ticks. From a technical point of view, the literature analyzed here showed little standardization of size and weight of tested ticks, a lack of uniform methods to assess toxicity and concerns related to data analysis. Finally, an important challenge for future research is the need for ecotoxicology studies to evaluate potential negative effects on non-target organisms and site contamination arising from nanoparticle-based treatments in close proximity of livestock and farmers.

In Vitro Cytotoxic Effects of Gold Nanoparticles Coated with Functional Acyl Homoserine Lactone Lactonase Protein from Bacillus licheniformis and Their Antibiofilm Activity against Proteus Species

ABSTRACT N-acylated homoserine lactonases are known to inhibit the signaling molecules of the biofilm-forming pathogens. In this study, gold nanoparticles were coated with N-acylated homoserine lactonase proteins (AiiA AuNPs) purified from Bacillus licheniformis. The AiiA AuNPs were characterized by UV-visible spectra, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The synthesized AiiA AuNPs were found to be spherical in shape and 10 to 30 nm in size. Treatment with AiiA protein-coated AuNPs showed maximum reduction in exopolysaccharide production, metabolic activities, and cell surface hydrophobicity and potent antibiofilm activity against multidrug-resistant Proteus species compared to treatment with AiiA protein alone. AiiA AuNPs exhibited potent antibiofilm activity at 2 to 8 μM concentrations without being harmful to the macrophages. We conclude that at a specific dose, AuNPs coated with AiiA can kill bacteria without harming the host cells, thus representing a potential template for the design of novel antibiofilm and antibacterial protein drugs to decrease bacterial colonization and to overcome the problem of drug resistance. In summary, our data suggest that the combined effect of the lactonase and the gold nanoparticles of the AiiA AuNPs has promising antibiofilm activity against biofilm-forming and multidrug-resistant Proteus species.

Antibacterial, antibiofilm and cytotoxic effects of Nigella sativa essential oil coated gold nanoparticles

This study reports the biological synthesis of gold nanoparticles using essential oil of Nigella sativa (NsEO-AuNPs). The synthesized NsEO-AuNPs were characterized by UV-visible spectra, X-ray diffraction (XRD), FTIR and Transmission electron microscopy (TEM). UV-vis spectra of NsEO-AuNPs showed strong absorption peak at 540 nm. The X-ray diffraction analysis revealed crystalline nature of nanoparticle with distinctive facets (111, 200, 220 and 311 planes) of NsEO-AuNPs. The FTIR spectra recorded peaks at 3388, 2842, 1685, 1607, 1391 and 1018 cm(-1). TEM studies showed the spherical shape of nanoparticles and the particle size ranges between 15.6 and 28.4 nm. The antibacterial activity of NsEO-AuNPs was greater against Gram positive Staphylococcus aureus MTCC 9542 (16 mm) than Gram negative Vibrio harveyi MTCC 7771 (5 mm) at the concentration of 10 μg ml(-1). NsEO-AuNPs effectively inhibited the biofilm formation of S. aureus and V. harveyi by decreasing the hydrophobicity index (78% and 46% respectively). The in-vitro anti-lung cancer activity confirmed by MTT assay on the cell line of A549 carcinoma cells showed IC50 values of bulk Au at 87.2 μg ml(-1), N. sativa essential oil at 64.15 μg ml(-1) and NsEO-AuNPs at 28.37 μg ml(-1). The IC50 value showed that NsEO-AuNPs was highly effective in inhibiting the A549 lung cancer cells compared to bulk Au and N. sativa essential oil.

Biosynthesis of silver nanoparticles using a probiotic Bacillus licheniformis Dahb1 and their antibiofilm activity and toxicity effects in Ceriodaphnia cornuta.

In the present study, we synthesized and characterized a probiotic Bacillus licheniformis cell free extract (BLCFE) coated silver nanoparticles (BLCFE-AgNPs). These BLCFE-AgNPs were characterized by UV-visible spectrophotometer, XRD, EDX, FTIR, TEM and AFM. A strong surface plasmon resonance centered at 422 nm in UV-visible spectrum indicates the formation of AgNPs. The XRD spectrum of silver nanoparticles exhibited 2θ values corresponding to the silver nanocrystal. TEM and AFM showed the AgNPs were spherical in shape within the range of 18.69-63.42 nm and the presence of silver was confirmed by EDX analysis. Light and Confocal Laser Scanning Microscope (CLSM) images showed a weak adherence and disintegrated biofilm formation of Vibrio parahaemolyticus Dav1 treated with BLCFE-AgNPs compared to control. This result suggests that BLCFE-AgNps may be used for the control of biofilm forming bacterial populations in the biomedical field. In addition, acute toxicity results concluded that BLCFE-AgNPs were less toxic to the fresh water crustacean Ceriodaphnia cornuta (50 μg/ml) when compared to AgNO3 (22 μg/ml). This study also reports a short term analysis (24 h) of uptake and depuration of BLCFE-AgNPs in C. cornuta.

Laurus nobilis leaf extract mediated green synthesis of ZnO nanoparticles: Characterization and biomedical applications

The present study reports the green synthesis of zinc oxide nanoparticles using the aqueous leaf extract of Laurus nobilis (Ln-ZnO NPs) by co-precipitation method. The synthesized Ln-ZnO NPs were characterized by UV-Vis spectroscopy, FTIR, XRD, TEM, SEM and EDX. Ln-ZnO NPs were crystalline in nature, flower like and have hexagonal wurtzite structure with a mean particle size of 47.27nm. The antibacterial activity of Ln-ZnO NPs was greater against Gram positive (Staphylococcus aureus) bacteria than Gram negative (Pseudomonas aeruginosa) bacteria. The zone of inhibition against S. aureus was 11.4, 12.6 and 14.2mm at 25, 50 and 75μgmL-1. The zone of inhibition against P. aeruginosa was 9.8, 10.2 and 11.3mm at 25, 50 and 75μgmL-1. The light and confocal laser scanning microscopic images evidenced that Ln-ZnO NPs effectively inhibited the biofilm growth of S. aureus and P. aeruginosa at 75μgmL-1. The cytotoxicity studies revealed that Ln-ZnO NPs showed no effect on normal murine RAW264.7 macrophage cells. On the other hand, Ln-ZnO NPs were effective in inhibiting the viability of human A549 lung cancer cells at higher concentrations of 80μgmL-1. The morphological changes in the Ln-ZnO NPs treated A549 lung cancer cells were observed under phase contrast microscope.

Exploitation of chemical, herbal and nanoformulated acaricides to control the cattle tick, Rhipicephalus ( Boophilus ) microplus – A review

The tick Rhipicephalus (Boophilus) microplus is a key vector of bacterial and protozoan diseases causing heavy economic losses directly and indirectly in animal husbandry. In the past decades, the control of ticks faced some major issues, such as the rapid development of resistance in targeted vectors and non-target effects on human health and the environment, due to the employ of synthetic acaricides and repellents. Eco-friendly pesticides for treating and controlling animal parasites such as ticks were mainly from medicinal plants and thus they form the richest entity for manufacturing resources for drugs. Even though there are efforts made to discover reliable plant-based acaricides to control ectoparasites in animal husbandry, the effective control of R. (B.) microplus ticks still represent a major challenge in current veterinary entomology. Recently, a wide number of promising attempts have been conducted to use herbal preparations and green-fabricated nanoparticles for the control of R. (B.) microplus. The aim of this review is to critically summarize and discuss the use of herbal preparations used in ethno-veterinary as well as green-fabricated nanoparticles as novel acaricides for the control of the cattle tick R. (B.) microplus.