Isolation and characterization of a novel flavanone glycoside from an endemic plant Haplanthodes neilgherryensis.

The chemical characterization study of an endemic plant, Haplanthodes neilgherryensisis (Wight) R.B. Majumdar from Western Ghats of India, resulted in to the isolation of a new flavanone glycoside, 5-hydroxy-7-methoxy-8-O-ß-D-glucopyranosyl-2S-flavanone (1), along with 3 known flavonoids, 7-O-methyl dihydrowogonin (2), 7-O-methyl wogonin (3), andrographidine C (4). The structure of 1 was elucidated by using 1 D and 2 D NMR and HRMS experimental data, while for the known compounds, 1H NMR and mass spectrometry data were compared with the reported literature. Compound 1 was tested in vitro to check the improvement in uptake of glucose by the L6 rat skeletal muscle tissues and the observed EC50 value was 5.8 µM, while rosiglitazone showed EC50 of 2.7 µM.

Gastric-sparing nitric oxide-releasable 'true' prodrugs of aspirin and naproxen.

Nitric oxide-releasing non-steroidal anti-inflammatory drugs (NO-NSAIDs) are gaining attention as potentially gastric-sparing NSAIDs. Herein, we report a novel class of '1-(nitrooxy)ethyl ester' group-containing NSAIDS as efficient NO releasing 'true' prodrugs of aspirin and naproxen. While an aspirin prodrug exhibited comparable oral bioavailability and antiplatelet activity (i.e., TXB2 inhibition) to those of aspirin, a naproxen prodrug exhibited better bioavailability than naproxen. These promising NO-NSAIDs protected experimental rats from gastric damage. We therefore believe that these promising NO-NSAIDs could represent a new class of potentially 'Safe NSAIDs' for the treatment of arthritic pain, inflammation and cardiovascular disorders in the case of NO-aspirin.

Mutual prodrugs containing bio-cleavable and drug releasable disulfide linkers.

We report herein the design and synthesis of several representative examples of novel mutual prodrugs containing nine distinct types of self-immolative drug-releasable disulfide linkers with urethane, ester, carbonate, or imide linkages between the linker and any two amine/amide/urea (primary or secondary) or carboxyl or hydroxyl (including phenolic)-containing drugs. We also report drug release profiles of a few representative mutual prodrugs in biological fluids such as simulated gastric fluid and human plasma. We also propose plausible mechanisms of drug release from these mutual prodrugs. We have also conducted a few mechanistic studies based on suggested sulfhydryl-assisted cleavage of mutual prodrugs and characterized a few important metabolites to give support to the proposed mechanism of drug release from the reported mutual prodrugs.

Antifungal activity of hydrochloride salts of tylophorinidine and tylophorinine.

The antimicrobial efficacy of two phenanthroindolizidine alkaloids, tylophorinidine hydrochloride (TdnH) and tylophorinine hydrochloride (TnnH), isolated from the plant Tylophora indica (local name, Antamul) was evaluated. These were screened for in vitro antifungal and antibacterial activities. Both compounds exhibited potent antifungal activity displaying minimum inhibitory concentrations (MIC) in the range of 2-4 microg/mL for TdnH and 0.6-2.5 microg/mL for TnnH against Candida species.

NO-NSAIDs. Part 3: nitric oxide-releasing prodrugs of non-steroidal anti-inflammatory drugs.

In continuation of our efforts to discover novel nitric oxide-releasing non-steroidal anti-inflammatory drugs (NO-NSAIDs) as potentially "Safe NSAIDs," we report herein the design, synthesis and evaluation of 21 new NO-NSAIDs of commonly used NSAIDs such as aspirin, diclofenac, naproxen, flurbiprofen, ketoprofen, sulindac, ibuprofen and indomethacin. These prodrugs have NO-releasing disulfide linker attached to a parent NSAID via linkages such as an ester (compounds 9-16), a double ester (compounds 17-24), an imide (compounds 25-30) or an amide (compounds 31-33). Among these NO-NSAIDs, the ester-containing NO-aspirin (9), NO-diclofenac (10), NO-naproxen (11), and the imide-containing NO-aspirin (25), NO-flurbiprofen (27) and NO-ketoprofen (28) have shown promising oral absorption, anti-inflammatory activity and NO-releasing property, and also protected rats from NSAID-induced gastric damage. NO-aspirin compound 25, on further co-evaluation with aspirin at equimolar doses, exhibited comparable dose-dependent pharmacokinetics, inhibition of gastric mucosal prostaglandin E(2) (PGE(2)) synthesis and analgesic properties to those of aspirin, but retained its gastric-sparing properties even after doubling its oral dose. These promising NO-NSAIDs could therefore represent a new class of potentially "Safe NSAIDs" for the treatment of arthritic pain and inflammation.

Oral bioavailability, efficacy and gastric tolerability of P2026, a novel nitric oxide-releasing diclofenac in rat.

The present study was designed to evaluate, P2026 [(2-((2-(nitrooxy)ethyl)disulfanyl)ethyl 2-(2-(2,6-dichlorophenylamino)phenyl)acetate)], a novel NO (nitric oxide) donor prodrug of diclofenac for its ability to release NO and diclofenac, and whether P2026 provides advantage of improved activity/gastric tolerability over diclofenac. Oral bioavailability of P2026 was estimated from plasma concentration of diclofenac and nitrate/nitrite (NOx). Anti-inflammatory activity was evaluated in three different models of inflammation: acute (carrageenan-induced paw oedema), chronic (adjuvant-induced arthritis), and systemic (lipopolysaccharide-induced endotoxic shock). Gastric tolerability was evaluated from compound's propensity to cause gastric ulcers. P2026 exhibited dose-dependent diclofenac and NOx release. Similar to diclofenac, P2026 showed potent anti-inflammatory activity in acute and chronic model, whereas it improved activity in systemic model. Both diclofenac and P2026 inhibited gastric prostaglandin, but only diclofenac produced dose-dependent haemorrhagic ulcers. Thus, the results suggest that coupling of NO and diclofenac contribute to improved gastric tolerability while retaining the anti-inflammatory properties of diclofenac.