Abubakar Wani

Discovery of a marine-derived bis-indole alkaloid fascaplysin, as a new class of potent P-glycoprotein inducer and establishment of its structure-activity relationship.

The screening of IIIM natural products repository for P-gp modulatory activity in P-gp over-expressing human adenocarcinoma LS-180 cells led to the identification of 7 natural products viz. withaferin, podophyllotoxin, 3-demethylcolchicine, agnuside, reserpine, seseberecine and fascaplysin as P-gp inducers. Fascaplysin (6a), a marine-derived bis-indole alkaloid, was the most potent among all of them, showing induction of P-gp with EC50 value of 25 nM. P-gp induction is one of the recently targeted strategy to increase amyloid-β clearance from Alzheimer brains. Thus, we pursued a medicinal chemistry of fascaplysin to establish its structure-activity relationship for P-gp induction activity. Four series of analogs viz. substituted quaternary fascaplysin analogs, D-ring opened quaternary analogs, D-ring opened non-quaternary analogs, and β-carbolinium analogs were synthesized and screened for P-gp induction activity. Among the total of 48 analogs screened, only quaternary nitrogen containing analogs 6a-g and 10a, 10h-l displayed promising P-gp induction activity; whereas non-planar non-quaternary analogs 9a-m, 13a-n, 15a-h were devoid of this activity. The P-gp induction activity of best compounds was then confirmed by western-blot analysis, which indicated that fascaplysin (6a) along with 4,5-difluoro analog of fascaplysin 6f and D-ring opened analog 10j displayed 4-8 fold increase in P-gp expression in LS-180 cells at 1 μM. Additionally, compounds 6a and 6f also showed inhibition of acetylcholinestease (AChE), an enzyme responsible for neuronal loss in Alzheimers disease. Thus, fascaplysin and its analogs showing promising P-gp induction along with AChE inhibition at 1 μM, with good safety window (LS-180: IC50 > 10 μM, hGF: 4 μM), clearly indicates their promise for development as an anti-Alzheimer agent.

Meridianin derivatives as potent Dyrk1A inhibitors and neuroprotective agents.

Meridianins are a group of marine-derived indole alkaloids which are reported to possess kinase inhibitory activities. In the present Letter, we report synthesis of N1-substituted and C-ring modified meridianin derivatives and their evaluation as Dyrk1A inhibitors and neuroprotective agents. Among the library of 52 compounds screened, morpholinoyl linked derivative 26b and 2-nitro-4-trifluoromethyl phenyl sulfonyl derivative 29v displayed potent inhibition of Dyrk1A with IC50 values of 0.5 and 0.53 μM, respectively. The derivative 26b also inhibited Dyrk2 and Dyrk3 with IC50 values of 1.4 and 2.2 μM, respectively showing 2.2 and 4.4 fold selectivity for Dyrk1A with respect to Dyrk2 and Dyrk3. The compound 26b was not cytotoxic to human neuroblastoma SH-SY5Y cells (IC50>100 μM) and it displayed significant neuroprotection against glutamate-induced neurotoxicity in these cells at 10 μM. Molecular modelling studies of compound 26b led to identification of key interactions in the binding site of Dyrk1A and the possible reasons for observed Dyrk1A selectivity over Dyrk2.

Osthol and curcumin as inhibitors of human Pgp and multidrug efflux pumps of Staphylococcus aureus: reversing the resistance against frontline antibacterial drugs

The in-house IIIM natural product repository of 302 small molecules was screened for their ability to inhibit P-glycoprotein (Pgp) in Pgp-overexpressing human adenocarcinoma LS-180 cells. The screening has identified 13 natural products displaying significant Pgp-inhibition activity, which include praeruptorin B, curcumin, imperatorin, osthol, 5,7-diacetoxy-8-(3-methyl-2-butenyl)-coumarin, 5,7-dihydroxy-8-(3-methyl-2-butenyl) coumarin, pongamol, phellopterin, tangeretin, 3-(2-methyl but-3-en-2-yl) xanthyletin, 7-demethyl osthol, allorottlerin and tetrahydroangeolide. These natural products were then screened for their effects on bacterial efflux pump inhibition activity against NorA (Staphylococcus aureus), MdeA (S. aureus Mupr-1), TetK (S. aureus SA-K2192), and MsrA (S. aureus SA-K2191) efflux pumps. Curcumin and osthol showed significant inhibition of the S. aureus NorA efflux pump with 8- and 4-fold reductions in the MIC of ciprofloxacin at 25 μM. The molecular docking studies of curcumin and osthol with the human Pgp and S. aureus NorA efflux pump identified plausible binding modes and binding sites for these natural products.

Design, synthesis and P-gp induction activity of aryl phosphonate esters: identification of tetraethyl-2-phenylethene-1,1-diyldiphosphonate as an orally bioavailable P-gp inducer

The clearance of amyloid-beta is mediated by the P-glycoprotein (P-gp) transporter pump located at the blood brain barrier. Therefore, the induction of P-gp has been considered as a potential therapeutic strategy for the treatment of Alzheimers disease. The expression of P-gp is regulated through a nuclear receptor, pregnane X receptor (PXR). Thus, herein we investigated the potential of a known PXR activator, diphosphonate ester SR12813 (6a), for P-gp induction activity and further studied its structure–activity relationship. The diphosphonate ester SR12813 along with three series of analogs, viz. aryl alkylidene, aryl alkynyl, and aryl α-amino phosphonate esters, were synthesized and screened for P-gp induction activity in P-gp overexpressing adenocarcinoma LS180 cells using rhodamine 123 efflux assay. The parent compound SR12813 along with several new analogs displayed P-gp induction activity at 5 μM. Western blot analysis indicated that tetraethyl-2-phenylethene-1,1-diyldiphosphonate (6c) and tetraethyl-2-(anthracene-10-yl)ethene-1,1-diyldiphosphonate (6s) showed 7–8-fold increase in P-gp expression in LS180 cells. The diphosphonate ester 6c displayed excellent aqueous solubility, no cytochrome P450 inhibition liability and no efflux pump substrate liability. Furthermore, it exhibits an excellent oral pharmacokinetic profile in BALB/c mice with AUC0–∞ of 2067 ng h mL−1 and 37.6% oral bioavailability. The results presented here clearly indicate the potential of this scaffold to increase the clearance of brain Aβ across the BBB and thus its promise for development as a potential anti-Alzheimer agent.

Soluble Aβ1-42 suppresses TNF-α and activates NLRP3 inflammasome in THP-1 macrophages

HighlightsSoluble amyloid beta (sA&bgr;1‐42) plays a dual role in the process of inflammation.sA&bgr;1‐42 activates NLRP3 inflammasome on the one hand and suppresses the secretion of TNF‐&agr; on the other hand.sA&bgr;1‐42 may have protective role in the brain against inflammatory damage. Abstract Deposition of amyloid‐&bgr; in Alzheimer’s disease is accompanied by chronic inflammation, which involves raised levels of pro‐inflammatory cytokines TNF‐&agr;, IL‐6 and IL‐1&bgr;. However, the role of A&bgr;1‐42 in the inflammatory process, before it gets deposited into aggregates has not been investigated thoroughly. Through this study, we are illustrating the dual role of soluble A&bgr;1‐42 (sA&bgr;1‐42) in activating the NLRP3 inflammasome and simultaneously inhibiting TNF‐&agr; secretion. Our data suggested that the treatment of chronically induced THP‐1 macrophages and N9 microglial cells with sA&bgr;1‐42 can suppress the major inflammatory cytokine TNF‐&agr; without affecting the level of IL‐6. However, the activation of NLRP3 inflammasome was well evidenced by secretion of IL‐1&bgr;, increased expression of NLRP3 and caspase‐1, implicating sA&bgr;1‐42 in enhancing and suppressing one or other type of inflammation. Further investigation revealed that sA&bgr;1‐42 was able to severely abrogate the expression of NF‐&kgr;B, p50 and restricting the translocation of NF‐&kgr;B, p65 to nucleus by inhibiting phosphorylation of I&kgr;B‐&agr; in THP‐1 macrophages. These data indicate that the sA&bgr;1‐42 may play a dual role during inflammatory process, wherein, it may be involved in protecting the cells from inflammatory damage due to TNF‐&agr;. This ability of sA&bgr;1‐42 might be playing some role in protecting the brain cells during the process of aging and Alzheimer’s disease, where, chronic inflammatory environment plays a vital role.

Murrayanine Attenuates Lipopolysaccharide-induced Inflammation and Protects Mice from Sepsis-Associated Organ Failure

Murrayanine (MK) is the main compound isolated from Murraya koenigii, an aromatic plant belonging to the Rutaceae family, also known as curry leaf tree. Murrayanine was reported to possess potential antioxidant, antimycobacterial and antifungal effects. However, its effect in sepsis remains unclear. This study was designed to investigate the anti‐inflammatory effect of MK using both in vitro and in vivo assay. Results of this study indicated that MK decreased NO, TNF‐α and IL‐6 production in both lipopolysaccharide (LPS)‐stimulated RAW 264.7 cells and murine peritoneal macrophages. Moreover, iNOS and COX‐2 protein expression as well as their downstream product, PGE2, was also decreased effectively in RAW 264.7 cells. Furthermore, MK decreased the phosphorylation of IKB and repressed NF‐kB activity in LPS‐activated RAW 264.7 cells. Additionally, we evaluated MK efficacy in vivo using LPS‐induced sepsis, a systemic inflammation model in mice. Administration of MK inhibits pro‐inflammatory cytokines (TNF‐α and IL‐6) secretion; decreases AST, ALT, BUN and CRE level in mouse sera; mitigates lung, liver and kidney injuries; and also increases LPS‐challenged mice survival rate. Collectively, our results suggest that MK exerts potential as a new anti‐inflammatory and immunosuppressive drug in sepsis treatment.

The amino analogue of β-boswellic acid efficiently attenuates the release of pro-inflammatory mediators than its parent compound through the suppression of NF-κB/IκBα signalling axis

Graphical abstract Figure. No Caption available. HighlightsComparative study of &bgr;‐boswellic acid and its analogue, BA‐25 for anti‐inflammatory potential.BA‐25 strongly inhibits the expression iNOS, COX‐2 in LPS‐evoked RAW 264.7 cells.Also suppresses the expression of TNF&agr;, IL‐1&bgr;, IL‐6, PGE2 & LTB4 efficiently.Checks inflammatory mediators via ROS‐dependent activation of NF‐&kgr;B/I&kgr;B&agr; axis.BA‐25 also shows modulatory potential in paw oedema modelled BALB/c mice. &NA; Natural product derivatives have proven to be cutting edge window for drug discovery and development. BA‐25 (3‐&agr;‐o‐acetoxy‐4&bgr;‐amino‐11‐oxo‐24‐norurs‐12‐ene) an amino analogue of &bgr;‐boswellic acid exhibited inhibition of TNF‐&agr; and IL‐6 in THP‐1 cells as demonstrated previously, however, the effect on principal inflammatory mediators such as cyclooxygenase‐2 (COX‐2), inducible nitric oxide synthase (iNOS) and the pathways that mediate this function remains unknown. This study was designed to examine the comparative anti‐inflammatory activity of BA‐25 with its parent compound, &bgr; boswellic acid both in vitro and in vivo. The effect of BA and BA‐25 on suppression of NO, PGE2, LTB4, COX‐2 in LPS‐stimulated RAW 264.7 cells was determined by ELISA, RT‐PCR and ROS by flow cytometry. Phosphorylation of NF‐kBp65, IKB degradation was determined by western blotting and also the nuclear localization of NF‐kBp65 was assessed by immunofluorescence. Furthermore, this study was extended on Carrageenan induced paw oedema modelled BALB/c mice. A novel derivative BA‐25, reported first time notably decreased the LPS (1 &mgr;g/mL) induced upregulation in the transcription of TNF‐&agr;, IL‐6, iNOS and COX‐2. Also the protein expression of iNOS and COX‐2 as well as their downstream products NO and PGE2 respectively, were also decreased efficiently at a concentration of 10 &mgr;M than BA. Moreover, LPS upregulated NF‐kB p65 expression and I&kgr;B degradation was significantly decreased after BA‐25 treatment. In addition, the treatment of BA‐25 also restored the paw oedema and decreased the magnitude of histopathological alterations. Our data together suggested that BA‐25 might be regarded as prospective therapeutic anti‐inflammatory alternative and demands further investigation in pharmacological studies.