Synthesis, characterization and pharmacological evaluation of certain enzymatically cleavable NSAIDs amide prodrugs

Switchable synthesis of 3-aminoindolines and 2'-aminoarylacetic acids using Grignard reagents and 3-azido-2-hydroxyindolines

The switchable synthesis of 3-aminoindolines and 2'-aminoaryl acetic acids from the same substrates, 3-azido-2-hydroxyindolines, was developed through denitrogenative electrophilic amination of Grignard reagents. The key to success is the serendipitous discovery that the reaction conditions, including solvents and reaction temperature, can affect the chemoselectivity. It is noteworthy that isotope-labeling experiments revealed the occurrence of the aziridine intermediate in the production of 2'-aminoaryl acetic acids.

Role of ASM/Cer/TXNIP signaling module in the NLRP3 inflammasome activation

BACKGROUND

This study aimed to explore the effects of ceramide (Cer) on NLRP3 inflammasome activation and their underlying mechanisms.

METHODS

Lipopolysaccharide (LPS)/adenosine triphosphate (ATP)-induced NLRP3 inflammasome activation in J774A.1 cells and THP-1 macrophages was used as an in vitro model of inflammation. Western blotting and real-time PCR (RT-PCR) were used to detect the protein and mRNA levels, respectively. IL-1β and IL-18 levels were measured by ELISA. ASM assay kit and immunofluorescence were used to detect ASM activity and Cer content.

RESULTS

Imipramine, a well-known inhibitor of ASM, significantly inhibited LPS/ATP-induced activity of ASM and the consequent accumulation of Cer. Additionally, imipramine suppressed the LPS/ATP-induced expression of thioredoxin interacting protein (TXNIP), NLRP3, caspase-1, IL-1β, and IL-18 at the protein and mRNA level. Interestingly verapamil, a TXNIP inhibitor, suppressed LPS/ATP-induced activation of TXNIP/NLRP3 inflammasome but did not affect LPS/ATP-induced ASM activation and Cer formation. TXNIP siRNA and verapamil inhibited C2-Cer-induced upregulation of TXNIP and activation of the NLRP3 inflammasome. In addition, the pretreatment of cells with sulfo-N-succinimidyl oleate (SSO), an irreversible inhibitor of the scavenger receptor CD36, blocked Cer-induced upregulation of nuclear factor-κB (NF-κB) activity, TXNIP expression, and NLRP3 inflammasome activation. Inhibition of NF-κB activation by SN50 prevented Cer-induced upregulation of TXNIP and activation of the NLRP3 inflammasome but did not affect CD36 expression.

CONCLUSION

This study demonstrated that the ASM/Cer/TXNIP signaling pathway is involved in NLRP3 inflammasome activation. The results documented that the CD36-dependent NF-κB-TXNIP signaling pathway plays an essential role in the Cer-induced activation of NLRP3 inflammasomes in macrophages.

In silico guided designing of 4-(1H-benzo[d]imidazol-2-yl)phenol-based mutual-prodrugs of NSAIDs: synthesis and biological evaluation

The free COOH group of conventional NSAIDs is a structural feature for non-selective cyclooxygenase (COX) inhibition and the molecular cause of their gastrointestinal (GI) toxicity. In this context, an in house database of synthesizable ester prodrugs of some well-known NSAIDs was developed by combining their -COOH group with -OH of a newly identified antioxidant 4-(1H-benzo[d]imidazol-2-yl)phenol (BZ). The antioxidant potential of BZ was unveiled through in silico PASS prediction and in vitro/in vivo evaluation. The in house database of NSAIDs-BZ prodrugs was first subjected to screening with our previously reported pharmacophore models of hCES1 (AAHRR.430) and hCES2 (AHHR.21) for determining hydrolytic susceptibility. Biotransformation behaviour of screened prodrugs was then assessed by using QM/MM and sterimol parameterization, followed by ADMET calculations to predict the drug likeness. On the basis of in silico results, five prodrugs were duly synthesized and the best three were subject to the in vivo evaluation for their anti-inflammatory, analgesic, antioxidant activities, and ulcerogenic index. Among these prodrugs, BN₂ and BN₅ displayed better anti-inflammatory and analgesics potential in comparison to their parent drugs. All the prodrugs were found to be gastro sparing in the rat model and significantly improved the levels of oxidative stress biomarkers in both blood plasma as well as gastric homogenate.

Fail-safe nano-formulation of prodrug of sulfapyridine: Preparation and evaluation for treatment of rheumatoid arthritis

Aim of the present study was to give a second life to the long-abandoned drug, sulfapyridine (SP) for its anti-arthritic potential by design of nano-vesicular delivery system. For this, intra-articular delivery of its liposomal formulation was tried. As the prepared formulation exhibited rapid drug leakage, an arthritis responsive prodrug of SP showing lability towards synovial enzymes was synthesized to exploit the over-expression of arthritis specific enzymes. Prodrug (SP-PD) exhibited better retention in liposomes as compared to the drug, preventing its escape from synovium. Hydrolysis of SP-PD in human plasma and synovial fluid indicated its high susceptibility to enzymes. The liposomes of SP-PD exhibited larger mean size, less PDI and higher zeta potential as compared to those for SP liposomes. In arthritic rats, prodrug liposomes were found to reverse the symptoms of inflammation, including the levels of biochemical markers. Liposomes of bio-responsive prodrug, therefore, offer a revolutionary approach in the treatment of rheumatoid arthritis.

In silico design, synthesis, characterization and pharmacological evaluation of captopril conjugates in the treatment of renal fibrosis

Application of glutamic acid and taurine conjugates of captopril for kidney targeting.

Synthesis, Anti-Inflammatory Activity, and In Silico Study of Novel Diclofenac and Isatin Conjugates

The design, synthesis, and development of novel non-steroidal anti-inflammatory drugs (NSAIDs) with better activity and lower side effects are respectable area of research. Novel Diclofenac Schiff's bases (M1, M2, M4, M7, and M8) were designed and synthesized, and their respective chemical structures were deduced using various spectral tools (IR, ¹H NMR, ¹³C NMR, and MS). The compounds were synthesized via Schiff's condensation reaction and their anti-inflammatory activity was investigated applying the Carrageenan-induced paw edema model against Diclofenac as positive control. Percentage inhibition of edema indicated that all compounds were exhibiting a comparable anti-inflammatory activity as Diclofenac. Moreover, the anti-inflammatory activity was supported via virtual screening using molecular docking study. Interestingly compound M2 showed the highest in vivo activity (61.32% inhibition) when compared to standard Diclofenac (51.36% inhibition) as well as the best binding energy score (-10.765) and the virtual screening docking score (-12.142).

A Stability-Indicating RP-HPLC-UV Method for Determination and Chemical Hydrolysis Study of a Novel Naproxen Prodrug

A new naproxen amide prodrug was synthesized and spectrally characterized and a simple, precise, and accurate stability-indicating RP-HPLC method was developed and validated for determination and chemical hydrolysis study of the prodrug. Forced degradation studies were conducted as per the International Conference on Harmonization (ICH) guidelines to establish the stability-indicating power of the method. Separations were performed on a C18 column (150 × 4.6 mm i.d., 5 μm p.s.). The mobile phase consisted of acetonitrile and phosphate buffer pH 4.0 in the ratio 60 : 40. The flow rate and injection volume were 1.0 mL/min and 15 μL, respectively. The peaks were monitored at 272 nm. The average retention time is 5.136 min. The linearity of the method was investigated in the range of 10–50 μg/mL and r2 was found to be larger than 0.9987. The LOD and LOQ were found to be 1.853 and 5.615 μg/mL, respectively. Results indicated that the degradants are well resolved and separated from the prodrug. Hydrolysis kinetics studies were carried out in buffer solutions (pH 1.2, 5.5 and 7.4) to establish the fate of the prodrug. The half-lives in the respective buffers were 23.5, 262, and 334 hours indicating sufficient stability to attain the goal of oral delivery.