Crystal to Hydrogel Transformation in S-Benzyl-L-Cysteine-Containing Cyclic Dipeptides - Nanostructure Elucidation and Applications.

Cyclic dipeptides (CDPs) are crucial building blocks for a range of functional nanomaterials due to their simple chemical structure and high molecular stability. In this investigation, we synthesized a set of S-benzyl-L-cysteine-based CDPs (designated as P1-P6) and thoroughly examined their self-assembly behavior in a methanol-water solvent to elucidate the relationship between their structure and gelation properties. The hydrophobicity of the amino acids within the CDPs was gradually increased. The present study employed a comprehensive array of analytical techniques, including NMR, FT-IR, AFM, thioflavin-T, congo-red CD, X-ray crystallography, and biophysical calculations like Hirshfield Surface analysis and DFT analysis. These methods revealed that in addition to hydrogen bonding, the hydrophobic nature of the amino acid side chain significantly influences the propensity of CDPs to form hydrogels. Each CDP yielded distinct nanofibrillar networks rich in ß-sheet structures, showcasing unique morphological features. Moreover, we explored the practical application of these CDP-based hydrogels in water purification by utilizing them to remove harmful organic dyes from contaminated water. This application underscores the potential of CDPs in addressing environmental challenges, offering a promising avenue for the future development of these materials in water treatment technologies.

S-Benzyl cysteine based cyclic dipeptide super hydrogelator: Enhancing efficacy of an anticancer drug via sustainable release.

Peptide-based low molecular weight supramolecular hydrogels hold promising aspects in various fields of application especially in biomaterial and biomedical sciences such as drug delivery, wound healing, tissue engineering, cell proliferation, and so on due to their extreme biocompatibility. Unlike linear peptides, cyclic peptides have more structural rigidity and tolerance to enzymatic degradation and high environmental stability which make them even better candidates for the above-said applications. Herein, a new small cyclic dipeptide (CDP) cyclo-(Leu-S-Bzl-Cys) (P1) consisting of L-leucine and S-benzyl protected L-cysteine was reported which formed a hydrogel at physiological conditions (at 37°C and pH = 7.46). The hydrogel formed from the cyclic dipeptide P1 showed very good tolerance towards environmental parameters such as pH and temperature and was seen to be stable for more than a year without any deformation. The hydrogel was thermoreversible and stable in the pH range 6-12. Mechanical strength of P1 hydrogel was measured by rheology experiments. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM) images revealed that, in aqueous solvents, P1 self-assembled into a highly cross-linked nanofibrillar network which immobilized water molecules inside the cages and formed the hydrogel. The self-assembled cyclic dipeptide acquired the antiparallel ß-sheet secondary structure, which was evident from CD and Fourier transform infrared (FT-IR) studies. The ß-sheet arrangement and formation of amyloid fibrils were further established by ThT binding assay. Furthermore, P1 was able to form a hydrogel in the presence of the anticancer drug 5-fluorouracil (5FU), and sustainable release of the drug from the hydrogel was measured in vitro. The hydrogelator P1 showed almost no cytotoxicity towards the human colorectal cancer cell line HCT116 up to a considerably high concentration and showed potential application in sustainable drug delivery. The co-assembly of 5FU and P1 hydrogel exhibited much better anticancer activity towards the HCT116 cancer cell line than 5FU alone and decreased the IC50 dose of 5FU to a much lower value.

Complete mitochondrial genome sequencing of Oxycarenus laetus (Hemiptera: Lygaeidae) from two geographically distinct regions of India.

Oxycarenus laetus is a seed-sap sucking pest affecting a variety of crops, including cotton plants. Rising incidence and pesticide resistance by O. laetus have been reported from India and neighbouring countries. In this study, O. laetus samples were collected from Bhatinda and Coimbatore (India). Pure mtDNA was isolated and sequenced using Illumina MiSeq. Both the samples were found to be identical species (99.9%), and the complete genome was circular (15,672 bp), consisting of 13 PCGs, 2 rRNA, 23 tRNA genes, and a 962 bp control region. The mitogenome is 74.1% AT-rich, 0.11 AT, and - 0.19 GC skewed. All the genes had ATN as the start codon except cox1 (TTG), and an additional trnT was predicted. Nearly all tRNAs folded into the clover-leaf structure, except trnS1 and trnV. The intergenic space between trnH and nad4, considered as a synapomorphy of Lygaeoidea, was displaced. Two 5 bp motifs AATGA and ACCTA, two tandem repeats, and a few microsatellite sequences, were also found. The phylogenetic tree was constructed using 36 mitogenomes from 7 super-families of Hemiptera by employing rigorous bootstrapping and ML. Ours is the first study to sequence the complete mitogenome of O. laetus or any Oxycarenus species. The findings from this study would further help in the evolutionary studies of Lygaeidae.

Synthesis of N-Fused Triazole-Piperazine-Quinazolinones via One-Pot Tandem Click Reaction and Cross-Dehydrogenative Coupling.

Herein, a one-pot protocol to synthesize tetracyclic triazole-piperazine-quinazolinone-fused N-heterocyclic scaffolds is reported. In this strategy, a tandem approach of two highly efficient synthetic reactions, click and cross-dehydrogentive coupling reactions, with high atom economy were employed to obtain the target N-fused scaffolds. Being highly functional group tolerable, this method has broad substrate scope. Interestingly, some of these derivatives showed strong white solid-state fluorescence.

Detection of Lysosome by a Fluorescent Heterocycle: Development of Fused Pyrido-Imidazo-Indole Framework via Cu-Catalyzed Tandem N-Arylation.

Fluorescent active small molecules for organelle-specific bioimaging are in great demand. We synthesized 20 different pyrido-imidazo-indole fused heterocycles (6-5-5-6 ring) via copper catalyzed tandem N-arylation reaction in moderate to good yields. Due to decent fluorescent property, lysosome-directing moieties were attached on two of these heterocycles. Delightfully, those molecules tracked lysosome with bright blue fluorescence and colocalized with a known lysosome marker (Lysotracker Red) in human/murine cells. Therefore, it may be considered as a rapid (10 min) lysosome staining probe.