Bifunctional cysteine gold nanoclusters for ß-amyloid fibril inhibition and fluorescence imaging: a distinctive approach to manage Alzheimer's disease.

Alzheimer's disease (AD) is a progressive complex neurodegenerative disorder affecting millions of individuals worldwide. Currently, there is no effective treatment for AD. AD is characterized by the deposition of amyloid plaques/fibrils. One major strategy for managing this disease is by slowing the progression of AD using different drugs which could potentially limit free-radical formation, oxidative stress and lipid peroxidation and promote the survival of neurons exposed to ß-amyloid. Inhibition of amyloid fibrillization and clearance of amyloid plaques/fibrils are essential for the prevention and treatment of AD. The thiophilic interaction between the side chain of an aromatic residue in a polypeptide and a sulphur atom of the compound can effectively inhibit amyloid fibril formation. In this work, we have synthesized cysteine-capped gold nanoclusters (Cy-AuNCs) which exhibit inherent red emission and can disintegrate amyloid fibrils through the aforementioned thiophilic interactions. Herein, we also used molecular docking to study the thiophilic interactions between the sulphur atom of Cy-AuNCs and the aromatic rings of the protein. Finally, the gold cluster was functionalized with a brain targeting molecule, Levodopa (AuCs-LD), to specifically target the brain and to facilitate passage through the blood brain barrier (BBB). Both Cy-AuNCs and AuCs-LD showed good biocompatibility and the inherent fluorescence properties of nanoclusters enabled real time imaging. The efficacy of the nanoclusters to disintegrate amyloid fibrils and their ability to cross the BBB were demonstrated both in vitro and in vivo in the BBB model and the AD animal model respectively. Our results imply that nanoparticle-based artificial molecular chaperones may offer a promising therapeutic approach for AD.

Simultaneous detection of different probe molecules using silver nanowires as SERS substrates.

Metallic silver nanowires with high yield were synthesized using a modified seed mediated approach at room temperature. Ribbon-like nanostructures were obtained when the concentration of NaOH was lower and further increase of NaOH transformed it into long nanowires. These nanowires possess high aspect ratio, with length and diameter ~6.5 µm and 17 nm respectively. The surface enhanced Raman scattering activity of these nanowires was tested with three different probe molecules viz., crystal violet, malachite green and nile blue chloride using visible (514.4 nm) and near-infrared (784.8 nm) excitation lines. The minimum detection limits for crystal violet and nile blue chloride molecules were found to be down to 10-7 M with good linear responses, as evidenced by values of correlation coefficients, indicating their potential for a variety of applications such as sensing. Principal component analysis was performed with the surface enhanced Raman spectra in order to discriminate the dye molecules and their mixture, simultaneously. The first two principal components, which provided 69.80 and 27.93% of the total data variance, could be conveniently represented as a two dimensional PCA score plot. The score plot showed clear clustering of probe molecules and their mixture. The relative contribution of wavenumbers to each of the two principal components was identified by plotting the PCA loading matrix. These results further promote possibilities of quantification of multiplexed SERS detection and analysis.

Influence of processing parameters on the quality of soycurd (tofu).

Tofu, a non-fermented soybean curd is a nutritious and digestible product with a high quality protein. Tofu making procedure includes soaking of beans, grinding, filtering, boiling, coagulating and moulding. The flavour, quality and the texture of tofu produced is significantly influenced by its processing parameters. Studies were carried out on the processing parameters like solid content of milk, thermal treatment of soybeans with sodium bicarbonate, stirring time after adding coagulant and moulding of tofu on the texture and quality of tofu. Our studies showed that the texture of the final product depended on the solid content of milk before coagulation. Pretreatment of soybeans with sodium bicarbonate, for 10 min and milk obtained with low solid content of 7° Brix resulted in regular, smooth textured tofu with less beany flavour. Duration of stirring during coagulation and moulding parameters had a significant effect on the yield of tofu. Stirring the milk after adding the coagulant for 5 s before settling and pressing the tofu with a load of 1,000 g initially for 15 min followed by 500 g for another 15 min, yielded (22.6 g/100 ml of milk) soft textured firm tofu.

Accelerated fermentation of 'idli' batter using soy residue okara.

The aim of this work was to reduce the natural fermentation period of 'idli' from the conventional 14 h to 10 h by adding underutilized okara for the preparation of 'idli'. Black gram was partially substituted with soy residue okara in the ratio of (1:1). After 14 h of natural fermentation, the pH and total acidity of control 'idli' batter was 4.51 and 0.64% and that of okara fortified 'idli' batter was 4.53 and 0.43%, respectively. The amount of CO2 released by the control and okara fortified batter was 19.7% and 33.6% respectively. The viable count of yeast and mold, lactics and mesophilic bacteria in control & okara batter increased with time reaching 9.00 & 10.34, 8.66 & 7.69, and 8.65 & 9.47 log10 cfu/g, respectively at the end of 10 h of natural fermentation. Okara fortified 'idli' was soft and spongy compared to control 'idli' .

Isoflavone phytoestrogens in soymilk fermented with ß-glucosidase producing probiotic lactic acid bacteria.

Isoflavones significantly contribute to human health and disease prevention, and exist as glucosides and aglycones. The ß-glucosidase enzyme that hydrolyzes glucosides to aglycones is very sensitive to molecular structure, and thus the profile of the isoflavones can affect their rate of hydrolysis. Soymilk was fermented with Lactobacillus acidophilus B4496 (La), Lactobacillus bulgaricus CFR2028 (Lb), Lactobacillus casei B1922 (Lc), Lactobacillus plantarum B4495 (Lp) and Lactobacillus fermentum B4655 (Lf) for 48 h at 37°C. ß-Glucosidase activity was determined using p-nitrophenyl ß-D-glucopyranoside as a substrate and the hydrolysis was carried out in soymilk. During fermentation, maximum growth was seen at 24 h with Lb, Lc, Lp and Lf and at 48 h with La. Polyphenol content ranged from 12.98 to 17.90 at 24 h and from 12.44 to 15.24 mg/100 ml at 48 h of fermentation. All the lactic acid bacteria produced ß-glucosidase enzyme, which hydrolyzed isoflavone glucosides to aglycones at a significant level (P < 0.05) in the fermented soymilk.

Bioconversion of isoflavone glycosides to aglycones, mineral bioavailability and vitamin B complex in fermented soymilk by probiotic bacteria and yeast.

AIM: To study the role of ß-glucosidase producing probiotic bacteria and yeast in the biotransformation of isoflavone glycosides to aglycones, mineral bioavailability and vitamin B complex in fermented soymilk. METHODS AND RESULTS: Five isolates of probiotic lactic acid bacteria (LAB), Lactobacillus acidophilus B4496, Lactobacillus bulgaricus CFR2028, Lactobacillus casei B1922, Lactobacillus plantarum B4495 and Lactobacillus fermentum B4655 with yeast Saccharomyces boulardii were used to ferment soymilk to obtain the bioactive isoflavones, genistein and daidzein. High-performance liquid chromatography was used to analyse the concentration of isoflavones. Bioactive aglycones genistein and daidzein after 24 and 48 h of fermentation ranged from 97.49 to 98.49% and 62.71 to 92.31% respectively with different combinations of LAB with yeast. Increase in bioavailability of minerals and vitamin B complex were also observed in fermented soymilk. CONCLUSIONS: LAB in combination with yeast S. boulardii has great potential for the enrichment of bioactive isoflavones, enhancing the viability of LAB strains, decreasing the antinutrient phytic acid and increasing the mineral bioavailability in soymilk fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: Fermentation of soymilk with probiotic organisms improves the bioavailability of isoflavones, assists in digestion of protein, provides more soluble calcium, enhances intestinal health and supports immune system. Increased isoflavone aglycone content in fermented soymilk improves the biological functionality of soymilk.

Influence of natural coagulants on isoflavones and antioxidant activity of tofu.

Tofu (instead of preparing using synthetic coagulant) was prepared using coagulants of plant origin (Citrus limonum, Garcinia indica, Tamarindus indica, Phyllanthus acidus and Passiflora edulis). Total crude protein and fat contents were highest in tofu prepared using G. indica and T. indica (72.5% dbw) compared to synthetic coagulant. Tofu prepared with natural coagulants had signifi cantly higher antioxidant activity compared to synthetic coagulant. Bioconversion of isoflavone glucosides (daidzin and genistin) into their corresponding bioactive aglycones (daidzein and genistein) was observed in tofu. The difference between glucosides and aglycones contents in soy milk was significant but there was not much difference in tofu coagulated with synthetic and natural coagulants.

Biomolecules and nutritional quality of soymilk fermented with probiotic yeast and bacteria.

Soymilk was fermented with five isolates of probiotic lactic acid bacteria and in combination with probiotic yeast Saccharomyces boulardii. Nutritional profile like fat, protein, ash, pH, acidity, polyphenol, and protein hydrolysis were analyzed. Polyphenol content decreased from 265.88 to 119 microg/ml with different cultures. Protein hydrolysis ranged from 2.46 to 2.83 mmol l(-1) with different cultures. The antioxidant activity was assessed using different methods like 1, 1-diphenyl-2-picrylhydrazyl free radical-scavenging assay, inhibition of ascorbate autoxidation, and measurement of reducing activity. The activities varied with the starters used but, nevertheless, were significantly higher than those found in unfermented soymilk. Bioconversion of the isoflavone glucosides (daidzin + genistin) into their corresponding bioactive aglycones (daidzein + genistein) was observed during soymilk fermentation. Total glucosides in soyamilk were 26.35 mg/100 ml. In contrast, aglycones genistein and daidzein were quantitatively lesser accounting 2.91 mg/100 ml (genistein 1.17 mg/100 ml and daidzein 1.19 mg/100 ml). Soymilk fermented with probiotic cultures resulted in the reduction of glycosides ranging from 0.40 mg to 1.36 mg/100 ml and increase in aglycones ranging from 6.32 mg to 13.66 mg/100 ml.