Anamika Sharma

Role of melatonin in regulating matrix metalloproteinase‐9 via tissue inhibitors of metalloproteinase‐1 during protection against endometriosis

Abstract:  Endometriosis is a gynecological disease of women and plausibly regulated by matrix metalloproteinases (MMPs). However, mechanisms of alterations in MMPs during endometriosis remain unclear. Human endometriotic tissues possessing varying degrees of severity were examined for expression of MMPs and tissue inhibitors of metalloproteinase (TIMP)‐1. In addition, endometriosis was generated in mice and endometriotic tissues were tested for MMP‐9 activity. Results show significant upregulation of secreted and synthesized proMMP‐9 activity with duration and severity of endometriosis. Along with upregulation of activity, the expression of proMMP‐9 was found increased while TIMP‐1 expression followed an inverse trend. The effect of melatonin, a major secretory product of the pineal gland, on endometriosis was examined in preventive and therapeutic models in mice. The results show that melatonin arrested lipid peroxidation and protein oxidation and downregulated proMMP‐9 activity and expression in a time and dose‐dependent manner while protecting and regressing peritoneal endometriosis. Moreover, the attenuated activity and expression of proMMP‐9 were associated with subsequent elevation in the expression of TIMP‐1. Our study reveals for the first time the role of melatonin in arresting peritoneal endometriosis in mice and a novel marker, expression ratio of proMMP‐9 versus TIMP‐1, was identified for assessing severity and progression of endometriosis.

Matrix metalloproteinase‐9 activity and expression is reduced by melatonin during prevention of ethanol‐induced gastric ulcer in mice

Abstract:  Matrix metalloproteinases (MMPs) play an important role in degradation of gastric extracellular matrix proteins. However, no reports are available on the relationship between the activity of MMPs and gastric ulceration induced by alcohol. Our objective was to investigate the effect of melatonin (N‐acetyl‐5‐methoxytryptamine) on the regulation of MMP‐9 and MMP‐2 activities during prevention of ethanol‐induced gastric ulcer. Biochemical and zymographic methods were used to analyze MMP‐9 and ‐2 activities in gastric tissues of Balb/c mice following induction of gastric ulcer by ethanol. Our studies reveal that melatonin arrested cell injury, protein carbonyl formation, and lipid peroxidation in mice during gastroprotection. Melatonin dose‐dependently reduced proMMP‐9 activity that was induced (∼ 25‐fold) during ethanol‐induced gastric ulceration. Severity of gastric ulcers were correlated proportionately with increased dose of ethanol and elevated activity of proMMP‐9 and ‐2. The reduced activities of MMP‐9 and ‐2 were associated with reduced expression of TNF‐α and increased expression of tissue inhibitors of metalloproteinases (TIMP‐1 and TIMP‐2). We conclude that melatonins ability to prevent ethanol‐induced gastric ulceration in mice is related to a reduction in proMMP‐9 activity and expression.

Melatonin promotes angiogenesis during protection and healing of indomethacin-induced gastric ulcer: role of matrix metaloproteinase-2.

Abstract:  Matrix metalloproteinase (MMP)‐2 is considered as a crucial regulator of angiogenesis, a process of new blood vessel formation. We reported previously that melatonin (N‐acetyl‐5‐methoxy tryptamine), an antioxidant and anti‐inflammatory agent, prevents indomethacin‐induced gastric ulcers. Herein, we investigated the effect of melatonin on MMP‐2‐mediated angiogenesis during gastroprotection. Angiogenic properties of melatonin were tested in both rat corneal micropocket assay and in mouse model of indomethacin‐induced gastric lesions. Melatonin augmented angiogenesis that was associated with amelioration of MMP‐2 expression and activity and, upregulation of vascular endothelial growth factor (VEGF) in rat cornea. Melatonin prevented gastric lesions by promoting angiogenesis via upregulation of VEGF followed by over‐expression of MMP‐2. Similarly, healing of gastric lesions was associated with early expression of VEGF followed by MMP‐2. In addition, upregulation of MMP‐2 was parallel to MMP‐14 and inverse to tissue inhibitor of metalloprotease (TIMP)‐2 expression during gastroprotection. Our data demonstrated that melatonin exerts angiogenesis through MMP‐2 and VEGF over‐expression during protection and healing of gastric ulcers. This study highlights for the first time a phase‐associated regulation of MMP‐2 activity in gastric mucosa and an angiogenic action of melatonin to rescue indomethacin‐induced gastropathy.

Curcumin Heals Indomethacin-Induced Gastric Ulceration by Stimulation of Angiogenesis and Restitution of Collagen Fibers via VEGF and MMP-2 Mediated Signaling

AIM We examined the molecular mechanism of curcumin in a preventive and therapeutic model of indomethacin-induced gastric ulceration with regard to angiogenic processes. RESULTS Disrupted blood vessels, reduced collagen matrices, and significant (60%) injury to mucosal cells were observed during ulceration. In addition, ulcerated tissues exhibited decreased matrix metalloproteinase (MMP)-2 and vascular endothelial growth factor (VEGF) expression in blood vessels. Interestingly, curcumin blocked ulceration by induction of collagenization and angiogenesis in gastric tissues via upregulation of MMP-2, membrane type (MT) 1-MMP, VEGF, and transforming growth factor (TGF)-β at protein and messenger ribonucleic acid (mRNA) levels. To examine the angiogenic properties of curcumin, we employed a chorioallantoic membrane model and Matrigel assay. During healing, curcumin promoted collagenization and angiogenesis as well as enhanced MMP-2 activity via positive MT1-MMP regulation and negative tissue inhibitor of metalloproteinase-2 regulation. INNOVATION Our study demonstrates that curcumin-mediated healing is associated with increased MMP-2, TGF-β, and VEGF expression and that it plays a pivotal role as an angiogenic modulator by stimulating vascular sprout formation and collagen fiber restoration in ulcerated tissues. CONCLUSION We conclude that curcumin remodels gastric tissues by restoring the collagen architecture and accelerating angiogenesis.

Upregulation of collagenase-1 and -3 in indomethacin-induced gastric ulcer in diabetic rats: role of melatonin.

Abstract:  Collagenases are key proteases involved in inflammation and injury. We addressed whether collagenases have an association with the susceptibility of gastric injury under diabetes as well as the effect of melatonin on collagenases in ulcerated gastric tissues. Diabetes was induced in rats by a single dose of streptozotocin (STZ) followed by gastric ulceration using indomethacin, and melatonin’s action was studied by its application prior to indomethacin exposure. Ulcer indices and damage were elevated significantly in gastric tissues of diabetic compared with nondiabetic rats. Melatonin reversed the effect of indomethacin during protection of gastric ulcers in diabetic rats. Matrix metalloproteinase (MMP)‐13 (i.e., collagenase‐3) was upregulated in diabetic gastric mucosa and enhanced further upon ulceration while melatonin ameliorated their activity. In addition, gastric tissues showed enhanced expression of both MMP‐1 (i.e., collagenases‐1) and ‐13 significantly in diabetic rats compared with nondiabetic animals and more so during ulceration while tissue inhibitors of metalloproteinase‐1 (TIMP‐1) showed an opposite trend. MMP‐2 activities exhibited a ∼50% downregulation during gastric ulceration which were rescued by melatonin. Moreover, increased expression of both MMP‐1 and ‐13 was mediated by activator protein‐1 activation via extracellular signal‐regulated kinase 1/2 which were parallel to upregulation of tumor necrosis factor‐α, interleukin‐1β, and heat shock protein‐70 during ulceration. Melatonin arrested collagenase expression by downregulation of these signaling molecules thereby halting the progression of the disease. We conclude that diabetic gastric tissues are susceptible to ulceration and associated with MMP‐1 and ‐13 upregulation in indomethacin‐induced injury. Additionally, melatonin protects the gastric damage under diabetes via regulation of both MMP‐1 and ‐13.

Synthesis and Antimicrobial Evaluation of Some Novel Trisubstituted s-Triazine Derivatives Based on Isatinimino, Sulphonamido, and Azacarbazole

A study directed towards exploring the temperature-dependent reactivity of the chlorine atoms of 2,4,6-trichloro-s-triazine (TCT) in the nucleophilic displacement reaction, allowed a facile replacement of its chlorine atoms in succession with (i) N-amino methyl substituted isatin-3-hydrazones, (ii) N1-substituted-4-amino benzene sulphonamides, and (iii) 8-amino-4-oxo-N-benzyl-azacarbazole to produce the corresponding 2,4,6-trisubstituted-s-triazine, namely; 2-(N-amino methyl substituted isatin-3-hydrazinyl)-4-(N1-substituted-4′-amino benzenesulfonamidyl)-6-(8′-amino-4′-oxo-N-benzylazacarbazolyl)-1,3,5-triazine derivatives in acceptable yields. The compounds prepared were further evaluated for their antibacterial activity against E. coli and B. subtilis and antifungal activities against A. niger and A. flavus, and some of them showed promising activity profile.

Synthesis, Characterization, and Tautomerism of 1,3-Dimethyl Pyrimidine-2,4,6-Trione s-Triazinyl Hydrazine/Hydrazone Derivatives

1,3,5-Triazines and pyrimidine-2,4,6-triones belong to that class of compounds which are well known in literature for possessing wide range of biological activities. Here, we report a new family of compounds that encompasses these two structures. The union of both heterocycles was carried out through a hydrazone moiety incorporated into an acetyl group at the position 5 of 1,3-dimethyl pyrimidine derivative. The synthetic strategy adopted allowed the preparation of the target compounds with excellent yields and good purities. The synthesized compounds were well characterized by NMR (1H and 13C), HRMS, and elemental analysis. Furthermore, the tautomerism of enhydrazine versus hydrazone has also been studied.

Understanding Tetrahydropyranyl as a Protecting Group in Peptide Chemistry

Abstract Tetrahydropyranyl (Thp) is recognized as a useful protecting group for alcohols in organic synthesis. It has several advantages, including low cost, ease of introduction, general stability to most non‐acidic reagents, it confers good solubility, and the ease with which it can be removed if the functional group it protects requires manipulation. However, little attention has been paid to Thp in peptide chemistry. Provided here is a concise analysis of the Thp protection of various amino acid functionalities (OH, SH, NH and COOH) and its application to peptide synthesis. Thp is a useful moiety for the side‐chain protection of serine, threonine and cysteine and is suitable for the Fmoc/tBu solid‐phase peptide synthesis strategy. The immobilized version of 3,4‐dihydro‐2H‐pyran, the so‐called Ellman resin, is also discussed as a useful solid support for anchoring the side chains of serine, threonine and tryptophan residues.

Exploring the Orthogonal Chemoselectivity of 2,4,6-Trichloro-1,3,5-triazine (TCT) as a Trifunctional Linker with Different Nucleophiles: Rules of the Game

The study involves exploring the three orthogonal sites for aromatic nucleophilic substitution in cyanuric chloride (TCT). The preferential order of incorporation of different nucleophiles (such as alcohol, thiol, and amine) was addressed both experimentally and theoretically. The preferential order for incorporating nucleophiles in TCT was found to be alcohol > thiol > amine.

Chemical Composition, Cytotoxic and Antibacterial Activities of Essential Oils of Cultivated Clones of Juniperus communis and Wild Juniperus Species

Needles of seven cultivated clones (C1 – C7) of Juniperus communis at lower altitude and three wild Juniperus species (J. communis, J. recurva and J. indica) at higher altitudes were investigated comparatively for their essential oils (EOs) yields, chemical composition, cytotoxic and antibacterial activities. The EOs yields varied from 0.26 to 0.56% (v/w) among samples. Sixty‐one volatile components were identified by gas chromatography‐mass spectrometry (GC/MS) and quantified using gas chromatography GC (FID) representing 82.5 – 95.7% of the total oil. Monoterpene hydrocarbons (49.1 – 82.8%) dominated in all samples (α‐pinene, limonene and sabinene as major components). Principal component analysis (PCA) of GC data revealed that wild and cultivated Juniperus species are highly distinct due to variation in chemical composition. J. communis (wild species) displayed cytotoxicity against SiHa (human cervical cancer), A549 (human lung carcinoma) and A431 (human skin carcinoma) cells (66.4 ± 2.2%, 74.4 ± 1.4% and 57.4 ± 4.0%), respectively, at 200 μg/ml. EOs exhibited better antibacterial activity against Gram‐positive bacteria than against Gram‐negative bacteria with the highest zone of inhibition against Staphylococcus aureus MTCC 96 (19.2 ± 0.7) by clone‐7. As per the conclusion of the findings, EOs of clone‐2, clone‐5 and clone‐7 can be suggested to the growers of lower altitude, as there is more possibility of uses of these EOs in food and medicinal preparations.