Targeting the oxidative stress response has recently emerged as a promising strategy for the development of therapeutic drugs for a broad spectrum of diseases. Supporting this strategy, we have reported that chitosan nanoparticles synthesized with a controlled size had selective cytotoxicity in leukemia cells through the mechanism related to reactive oxygen species (ROS) generation. Herein, we found that the cellular uptake of chitosan nanoparticles was enhanced in a time dependent manner and inhibited the cellular proliferation of leukemia cells in a dose dependent manner with elevation of the reactive oxygen species (ROS) showing a stronger effect on apoptosis, associated with the upregulation of caspase activity and the depletion of reduced glutathione. Propidium iodide and calcein staining demonstrated the central role of the chitosan nanoparticles in triggering elevated ROS, inducing cell death and intracellular oxidative activity. The enhanced free radical scavenging activity of the chitosan nanoparticles further iterates its antioxidant activity. In vitro quantitative phase imaging studies at the single cell level further demonstrated the inhibition of cellular proliferation with significant changes in cellular behavior and this supported our hypothesis. Hemocompatibility tests demonstrated that chitosan nanoparticles could be used safely for in vivo applications. Our findings suggest that chitosan nanoparticles may be a promising redox active candidate for therapeutic applications.

Synthetic auxins such as 1-naphthalene acetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) have been extensively used in plant tissue cultures and as herbicides because they are chemically more stable and potent than most endogenous auxins. A tool for rapid in planta detection of these compounds will enhance our knowledge about hormone distribution and signaling and facilitate more efficient usage of synthetic auxins in agriculture. In this work, we show the development of real-time and nondestructive in planta NAA and 2,4-D nanosensors based on the concept of corona phase molecular recognition (CoPhMoRe), to replace the current state-of-the-art sensing methods that are destructive and laborious. By designing a library of cationic polymers wrapped around single-walled carbon nanotubes with general affinity for chemical moieties displayed on auxins and its derivatives, we developed selective sensors for these synthetic auxins, with a particularly large quenching response to NAA (46%) and a turn-on response to 2,4-D (51%). The NAA and 2,4-D nanosensors are demonstrated in planta across several plant species including spinach, Arabidopsis thaliana (A. thaliana), Brassica rapa subsp. chinensis (pak choi), and Oryza sativa (rice) grown in various media, including soil, hydroponic, and plant tissue culture media. After 5 h of 2,4-D supplementation to the hydroponic medium, 2,4-D is seen to accumulate in susceptible dicotyledon pak choi leaves, while no uptake is observed in tolerant monocotyledon rice leaves. As such, the 2,4-D nanosensor had demonstrated its capability for rapid testing of herbicide susceptibility and could help elucidate the mechanisms of 2,4-D transport and the basis for herbicide resistance in crops. The success of the CoPhMoRe technique for measuring these challenging plant hormones holds tremendous potential to advance the plant biology study.

One of the pathological hallmarks of Alzheimer’s disease (AD) is the abnormal aggregation of amyloid beta (Aβ) peptides. Therefore the detection of Aβ peptides and imaging of amyloid plaques are considered as promising diagnostic methods for AD. Here we report a bifunctional nanoprobe prepared by conjugating gold nanoparticles (AuNPs) with Rose Bengal (RB) dye. RB is chosen due to its unique Raman fingerprints and affinity with Aβ peptides. After the conjugation, Raman signals of RB were significantly enhanced due to the surface-enhanced Raman scattering (SERS) effect. Upon binding with Aβ42 peptides, a spectrum change was detected, and the magnitude of the spectrum changes can be correlated with the concentration of target peptides. The peptide/probe interaction also induced a remarkable enhancement in the probes’ fluorescence emission. This fluorescence enhancement was further utilized to image amyloid plaques in the brain slices from transgenic mice. In this study, the RB-AuNPs were used for both SERS-based detection of Aβ42 peptides and fluorescence-based imaging of amyloid plaques. Compared to monofunctional probes, the multifunctional probe is capable to provide more comprehensive pathophysiological information, and therefore, the implementation of such multifunctional amyloid probes is expected to help the investigation of amyloid aggregation and the early diagnosis of AD.

Sweet basil (Ocimum basilicum) plants produce its characteristic phenylpropene-rich essential oil in specialized structures known as peltate glandular trichomes (PGTs). Eugenol and chavicol are the major phenylpropenes produced by sweet basil varieties whose synthetic pathways are not fully elucidated. Eugenol is derived from coniferyl acetate by a reaction catalysed by eugenol synthase. An acyltransferase is proposed to convert coniferyl alcohol to coniferyl acetate which is the first committed step towards eugenol synthesis. Here, we perform a comparative next-generation transcriptome sequencing of different tissues of sweet basil, namely PGT, leaf, leaf stripped of PGTs (leaf–PGT), and roots, to identify differentially expressed transcripts specific to PGT. From these data, we identified a PGT-enriched BAHD acyltransferase gene ObCAAT1 and functionally characterized it. In vitro coupled reaction of ObCAAT1 with eugenol synthase in the presence of coniferyl alcohol resulted in eugenol production. Analysis of ObCAAT1-RNAi transgenic lines showed decreased levels of eugenol and accumulation of coniferyl alcohol and its derivatives. Coniferyl alcohol acts as a common substrate for phenylpropene and lignin biosynthesis. No differences were found in total lignin content of PGTs and leaves of transgenic lines, indicating that phenylpropene biosynthesis is not coupled to lignification in sweet basil.

Glaucoma, one of the leading causes of blindness, is an eye disease caused by irregularities in the ocular aqueous outflow system causing an elevated intraocular pressure. High resolution imaging of the aqueous outflow system comprising trabecular meshwork is immensely valuable to vision analysts and clinicians in comprehending the disease state for the efficacious analysis and treatment of glaucoma. Currently available ocular imaging devices are unable to deliver high resolution images for the visualization of the trabecular meshwork. A method to obtain high resolution (sub‐micrometer) images of the trabecular meshwork using Bessel‐Gauss beam scanned light sheet fluorescence microscopy is presented and the optical sectioning capability of this technique to obtain three‐dimensional volumetric images of the trabecular meshwork of an intact eye without any physical dissection is demonstrated. Figure: Three‐dimensional visualization of trabecular meshwork of porcine eye.

Gold (Au) nanoparticles display enhanced near-infrared (NIR) photothermal effects upon the formation of clusters. We studied the photothermal properties of Au nanosphere clusters on the single-particle level using photothermal heterodyne imaging (PTHI) microscopy to understand the enhancement mechanisms. NIR photothermal responses of Au nanoparticle clusters were found to significantly increase from monomers to trimers. The averaged PTHI signal intensity of Au nanosphere dimers and trimers is ∼10 and ∼25 times that of monomers. The NIR photothermal effect of clustered nanospheres strongly correlates with their longitudinal plasmon mode. Clustered Au nanospheres were demonstrated to exhibit dual-capability NIR photothermal imaging and therapy of human prostate cancer cells with high efficiency and selectivity. This strategy can be potentially utilized for simultaneous cancer imaging and therapy with 3D selectivity.

Spearmint produces and stores large amounts of monoterpenes, mainly limonene and carvone, in glandular trichomes and is the major natural source of these compounds. Towards producing heterologous monoterpenes in spearmint, we first reduced the flux into the native limonene pathway by knocking down the expression of limonene synthase (MsLS) by RNAi method. The MsLS RNAi lines exhibited a huge reduction in the synthesis of limonene and carvone. Detailed GC-MS and LC-MS analysis revealed that MsLS RNAi plants also showed an increase in sesquiterpene, phytosterols, fatty acids, flavonoids, and phenolic metabolites, suggesting an interaction between the MEP, MVA shikimate and fatty acid pathways in spearmint. Three different heterologous monoterpene synthases namely, linalool synthase and myrcene synthase from Picea abies and geraniol synthase from Cananga odorata were cloned and introduced independently into the MsLS RNAi mutant background. The expression of these heterologous terpene synthases resulted mainly in production of monoterpene derivatives. Of all the introduced monoterpenes geraniol showed the maximum number of derivatives. Our results provide new insights into MEP pathway interactions and regulation and reveals the existence of mechanisms for complex metabolism of monoterpenes in spearmint.

Citation: Sreelatha S., Jayachitra A., Targeting biofilm inhibition using Quercetin -Interaction with bacterial cell membrane and ROS mediated biofilm control. Functional Foods in Health and Disease 2018; 8(6): 292-306 ABSTRACT Background: Quercetin is an active nutraceutical ingredient widely distributed in foods, vegetables, fruits, and more. Quercetin is a versatile functional food with extensive protective effects against many infectious and degenerative diseases due to their antioxidant activities. Apsergillus niger is a filamentous fungus and the most abundant mold found in the environment. This fungus has been the source of several bioactive compounds and industrial enzymes through biotransformation. Aim:In this report we emphasized the potential of Aspergillus species for the selective conversion of rutin to quercetin, which involved stereoselective and regiospecific reactions with enhanced production and minimization of the formation of toxic wastes. This fungal microbe was able to transform the complex structure of rutin to quercetin with remarkable catalytic activity for the reaction with high product yield. The quercetin produced demonstrated the ability to inhibit biofilm formation and eradicate established biofilm involving the production of reactive oxygen species (ROS) indicative of membrane activity. These results suggest quercetin may have implications in biofilm control targeting reactive oxygen species as a novel therapeutic strategy. Methods: Quercetin was synthesized by microbial biotransformation recruiting Aspergillus niger.The synthesis of quercetin was compared with the chemical process. Furthermore, the quercetin produced by the biotransformation process was characterized by high performance thin layer liquid chromatography. The quercetin produced was assessed for biological activities. The antimicrobial activity, hemolytic activity, inhibition of biofilm by crystal violet staining, and cell viability by confocal laser scanning microscope was assessed. The membrane interaction effect and oxidant scavenging effect by DPPH, Intracellular ROS release, and lipid peroxidation was measured. Results:Quercetin produced by microbial transformation demonstrated antimicrobial activity against S. aureus by effectively inhibiting the growth and dispersion of preformed biofilms. Quercetin demonstrated a significant free radical scavenging activity and significant inhibition of lipid peroxidation. Significant release of reactive oxygen species was observed in bacterial cells.