Bharat Bhusan Subudhi

Inhibition of Chikungunya Virus Replication by 1-[(2-Methylbenzimidazol-1-yl) Methyl]-2-Oxo-Indolin-3-ylidene] Amino] Thiourea(MBZM-N-IBT)

Chikungunya virus (CHIKV) infection is one of the most challenging human Arboviral infections with global significance and without any specific antiviral. In this investigation, 1-[(2-methylbenzimidazol-1-yl) methyl]-2-oxo-indolin-3-ylidene] amino] thiourea (MBZM-N-IBT) was synthesised as a molecular hybrid of 2-methyl benzimidazole and isatin-β-thiosemicarbazone and its anti-CHIKV property was evaluated. The release of infectious virus particles was calculated by plaque assay, expression profile of viral RNA was estimated by RT-PCR and viral protein profiles were assessed by Western blot and FACS analyses. The safety index of MBZM-N-IBT was found to be >21. The CHIKV infectious viral particle formation was abrogated around 76.02% by MBZM-N-IBT during infection in mammalian system and the viral RNA synthesis was reduced by 65.53% and 23.71% for nsP2 and E1 respectively. Surprisingly, the viral protein levels were reduced by 97% for both nsP2 and E2. In the time-of-addition experiment it abrogated viral infection at early as well as late phase of viral life cycle, which indicates about multiple mechanisms for its anti-CHIKV action. In silico analysis justified development of MBZM-N-IBT with good affinities for potential target proteins of CHIKV and related virus. With predictions of good drug-likeness property, it shows potential of a drug candidate which needs further experimental validation.

Development and characterization of lysine-methotrexate conjugate for enhanced brain delivery

Abstract Background information: Methotrexate (MTX), an anticancer drug of choice, has poor permeability across blood-brain barrier (BBB) making it unsuitable for brain tumor application. Its brain availability and scope of application was improved by preparation of reversible conjugate with lysine by capitalizing the endogenous transport system of lysine at BBB. Methods: To enhance its delivery to brain, MTX was reversibly conjugated with l-Lysine by an amide linkage. It was characterized by advanced spectroscopy techniques including IR, NMR and MS. Furthermore, conjugate was assessed for stability, toxicity and drug release ability. In vivo distribution studies were done by radioscintigraphy study using 99mTc radioisotope. Results: The structure of prodrug was confirmed by 1H-NMR, 13C-NMR and Mass. The m/e (mass to charge ratio) fragment was found at [M + H] 711.32 in Mass spectra. Stability and metabolic studies suggested that conjugate was stable at physiological pH (in Phosphate buffer pH 7.4 t1/2 is 70.25 ± 2.17 h and in plasma t1/2 is 193.57 ± 2.03 min) and circulated adequately to release MTX slowly in brain. In vivo biodistribution study showed that prodrug significantly increased the level of MTX in brain when compared with pharmacokinetic parameter of parent drug. Conclusion: The brain permeability of MTX was enhanced significantly by this conjugate.

Development of reversible glutamine conjugate of methotrexate for enhanced brain delivery

Poor permeability of methotrexate across blood brain barrier limits its scope for application against brain cancer. Glutamine is transported to brain actively by multiple amino acid transporters and protects against complications of chemotherapy. To use glutamine as a carrier, a reversible conjugate of methotrexate was developed with structural features of glutamine. This was stable and released methotrexate effectively. The brain uptake was enhanced significantly

Current Strategies for Inhibition of Chikungunya Infection

Increasing incidences of Chikungunya virus (CHIKV) infection and co-infections with Dengue/Zika virus have highlighted the urgency for CHIKV management. Failure in developing effective vaccines or specific antivirals has fuelled further research. This review discusses updated strategies of CHIKV inhibition and provides possible future directions. In addition, it analyzes advances in CHIKV lifecycle, drug-target development, and potential hits obtained by in silico and experimental methods. Molecules identified with anti-CHIKV properties using traditional/rational drug design and their potential to succeed in subsequent stages of drug development have also been discussed. Possibilities of repurposing existing drugs based on their in vitro findings have also been elucidated. Probable modes of interference of these compounds at various stages of infection, including entry and replication, have been highlighted. The use of host factors as targets to identify antivirals against CHIKV has been addressed. While most of the earlier antivirals were effective in the early phases of the CHIKV life cycle, this review is also focused on drug candidates that are effective at multiple stages of its life cycle. Since most of these antivirals require validation in preclinical and clinical models, the challenges regarding this have been discussed and will provide critical information for further research.

Development of amino acid conjugated sulfonamides as potent antiulcer agent

A series of 2-{[(4-methylphenyl) sulfonyl] amino}-3-sulfanylpropanoic acid (1a) and its analogs 1b–j have been synthesized. These compounds were screened for their in vivo efficacy in pyloric ligation model. Compounds 1a and 1b with higher antiulcer potential were further screened in other gastric models to explore the mode of antiulcer action. To further understand the mode of action, in vitro inhibition of H+/K+ ATPase activity in gastric microsome isolated from rat stomach was studied. This was rationalized by in silico experiments.

Effect of semicrystalline polymers on self-emulsifying solid dispersions of nateglinide: In vitro and in vivo evaluation

Abstract This study was undertaken to improve solubility and bioavailability of nateglinide by preparation of stable self-emulsifying solid dispersions (SESDs). The influence of semicrystalline polymers (poloxamer 407, gelucire 50/13) and method of preparation on dissolution behavior, in vivo performance and stability of nateglinide SESDs were investigated. After optimization, SESDs were prepared at 1:5 weight ratio of nateglinide and polymer individually. All the SESDs were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction and scanning electron microscopy. Aqueous solubility of nateglinide was enhanced by 91.82-fold. The SESDs (poloxamer 407-based solid dispersions) achieved rapid and complete drug release (∼100% within 45 min) at pH 2. The improved dissolution appeared to be well correlated with the enhanced bioavailability of nateglinide in rabbits. After oral administration of SESDs (poloxamer 407-based solid dispersions), Cmax and AUC of nateglinide were increased by ∼2.92 and 1.77-folds, respectively, signifying the effectiveness of solid dispersions to improve the bioavailability of nateglinide. Stability during storage was established to show prevention of recrystallization. In conclusion, SESDs with poloxamer 407 in solvent method appeared to be an economic and promising technique to improve the dissolution, bioavailability, and stability of nateglinide.

Chikungunya virus nsP1 interacts directly with nsP2 and modulates its ATPase activity

Chikungunya virus (CHIKV) is a mosquito-borne virus, which has created an alarming threat in the world due to unavailability of vaccine and antiviral compounds. The CHIKV nsP2 contains ATPase, RTPase, helicase and protease activities, whereas, nsP1 is a viral capping enzyme. In alphaviruses, the four non-structural proteins form the replication complex in the cytoplasm and this study characterizes the interaction between CHIKV nsP1 and nsP2. It was observed that, both the proteins co-localize in the cytoplasm and interact in the CHIKV infected cells by confocal microscopy and immunoprecipitation assay. Further, it was demonstrated through mutational analysis that, the amino acids 1-95 of nsP2 and 170-288 of nsP1 are responsible for their direct interaction. Additionally, it was noticed that, the ATPase activity of nsP2 is enhanced in the presence of nsP1, indicating the functional significance of this interaction. In silico analysis showed close (≤1.7 Å) polar interaction (hydrogen bond) between Glu4, Arg7, 96, 225 of nsP2 with Lys256, 206, Val367 and Phe312 of nsP1 respectively. Hence, this investigation provides molecular characterization of CHIKV nsP1-nsP2 interaction which might be a useful target for rational designing of antiviral drugs.

Conjugation to Ascorbic Acid Enhances Brain Availability of Losartan Carboxylic Acid and Protects Against Parkinsonism in Rats

Identification of renin-angiotensin system in the interplay of hypertension and neurodegeneration has paved the way for the repurposing of antihypertensive drugs against Parkinsonism. Losartan carboxylic acid (LCA), the potent AT1 blocker metabolite of losartan, suffers from poor bioavailability and brain access. Since ascorbate transporters have earlier shown enough flexibility as carriers, we have conjugated losartan carboxylic acid to ascorbic acid with the aim of achieving higher oral/brain availability. Ester of LCA and ascorbic acid (FED) was developed keeping in view the substrate specificity of ascorbate transporters. Oral/brain bioavailability was assessed using in vivo pharmacokinetic model. Effect on central nervous system (CNS) and protection against Parkinsonism was evaluated using in vivo models. FED enhanced bioavailability of LCA. The higher brain availability of LCA enabled CNS protection as evident from the increase in locomotor activity, improved motor coordination, and protection against drug-induced catatonia. In conclusion, FED offers an approach to repurpose LCA against Parkinsonism. This can encourage further investigation to simultaneously address hypertension and neurodegeneration.

Brain Delivery of Chemotherapeutics in Brain Cancer.

Treatment of brain tumour is a major challenge. This is mainly because of the limited bioavailability of chemotherapeutics in the brain. The major hurdle for brain availability of anticancer agents is the blood brain barrier (BBB). BBB is supposed to protect the brain and maintain homeostasis. It allows vital nutrient for normal brain function and effluxes out foreign toxic substance. Advance in knowledge of bidirectional movement across BBB has allowed development of strategies to enhance brain availability of chemotherapeutics for management of brain tumour. In this review we have focussed on various approaches adopted for enhancing delivery of anticancer agents. We have given a critical analysis of the approaches for further research.