Synthesis and Structural Characterization of Novel Dimers of Dipyridothiazine as Promising Antiproliferative Agents

Many new isomeric dipyridothiazine dimers have been presented as molecules with anticancer potential. These compounds were obtained in efficient syntheses of 1,6-, 1,8-, 2,7- and 3,6-diazaphenothiazines with selected alkylaromatic linkers. The structures of these compounds has been proven with two-dimensional spectroscopic techniques (COSY, NOESY, HSQC and HMBC) and high-resolution mass spectrometry (HRMS). In silico analyses of probable molecular targets were performed using the Way2Drug server. All new dimers were tested for anticancer activity against breast cancer line MCF7 and colon cancer line SW480. Cytotoxicity was assessed on normal L6 muscle cells. The tested dimers had high anticancer potential expressed as IC50 and the selectivity index SI. The most active derivative, 4c, showed an IC50 activity of less than 1 µM and an SI selectivity index higher than 100. Moreover, the compounds were characterized by low toxicity towards normal cells, simultaneously indicating a high cytostatic potential.

In Vitro Antioxidant and Fibroblast Migration Activities of Fractions Eluded from Dichloromethane Leaf Extract of Marantodes pumilum

(1) The complexity of diabetes and diabetic wound healing remains a therapeutic challenge because proper and systematic wound care and management are essential to prevent chronic microbial infection and mechanical damage to the skin. Marantodes pumilum, locally known as 'Kacip Fatimah', is an herb that has been previously reported to possess anti-inflammatory, analgesic, antinociceptive and antipyretic properties. The current study aims to assess the antioxidant and fibroblast cell migration activities of the fractions eluded from the dichloromethane extract of M. pumilum leaves. (2) The total antioxidant capacity of M. pumilum was assessed using the total proanthocyanidins and phosphomolybdenum assays, while DPPH, nitric oxide, hydrogen peroxide and superoxide free radical scavenging assays were tested to determine the antioxidant potential of M. pumilum. An in vitro scratch wound assay was performed to measure the fibroblast cell migration rate using normal and insulin-resistant human dermal fibroblast cells. (3) All M. pumilum fractions exhibited good antioxidant and fibroblast cell migration activity, among which fractions A and E displayed the greatest effect. (4) M. pumilum's fibroblast migration activity could be attributed to its strong antioxidant properties along with its previously reported properties.

Palmatine Inhibits Up-Regulation of GRP78 and CALR Protein in an STZ-Induced Diabetic Rat Model

BACKGROUND

Diabetes Mellitus (DM) is characterized by hyperglycemia (high blood glucose levels) which is due to the destruction of insulin-producing β-cells in the islets of Langerhans in the pancreas. It is associated with oxidative and endoplasmic reticulum stress. The plant alkaloid Palmatine has been previously reported to possess antidiabetic and antioxidant properties as well as other protective properties against kidney and liver tissue damage.

OBJECTIVE

Here, we investigated the ability of Palmatine to reduce the up-regulation of chaperone proteins Glucose Regulatory Protein 78 (GRP78), and Calreticulin (CALR) protein in a Streptozotocin (STZ)-induced diabetic rat model.

METHODS

Streptozotocin (STZ) induced diabetes in Sprague Dawley rats treated with 2mg/kg of Palmatine for 12 weeks after the elevation of plasma glucose levels above 11mmol/L post-STZ administration. Proteins were extracted from the pancreas after treatment and Two-Dimensional gel electrophoresis (2-DE), PDQuest 2-D analysis software genomic solutions and mass spectrometer were used to analyze differentially expressed protein. Mass Spectrometry (MS/MS), Multidimensional Protein Identification Technology (MudPIT) was used for protein identification.

RESULTS

There was an up-regulation of the expression of chaperone proteins CALR and GRP78 and down-regulation of the expression of antioxidant and protection proteins peroxidoxin 4 (Prdx4), protein disulfide isomerase (PDIA2/3), Glutathione-S-Transferase (GSTs), and Serum Albumin (ALB) in non-diabetic rats. Palmatine treatment down-regulated the expression of chaperone proteins CALR and GRP78 and up-regulated the expression of Prdx4, PDIA2/3, GST, and ALB.

CONCLUSION

Palmatine may have activated antioxidant proteins, which protected the cells against reactive oxygen species and endoplasmic stress. The result is in consonance with our previous report on Palmatine.

Design, synthesis, and biological evaluation of 1,8-naphthyridine glucosamine conjugates as antimicrobial agents

In the quest for discovering potent antimicrobial agents with lower toxicity, we envisioned the design and synthesis of nalidixic acid-D-(+)-glucosamine conjugates. The novel compounds were synthesized and evaluated for their in vitro antimicrobial activity against Gram positive bacteria, Gram negative bacteria and fungi. Cytotoxicity using MTT assay over L6 skeletal myoblast cell line, ATCC CRL-1458 was carried out. In vitro antimicrobial assay revealed that 1-ethyl-7-methyl-4-oxo-N-(1,3,4,6-tetra-O-acetyl-2-deoxy-D-glucopyranose-2-yl)-[1,8]-naphthyridine-3-carboxamide (5) and 1-ethyl-7-methyl-4-oxo-N-(2-deoxy-D-glucopyranose-2-yl)-[1,8]-naphthyridine-3-carboxamide(6) possess growth inhibitory activity against resistant Escherichia coli NCTC, 11954 (MIC 0.1589 mM) and Methicillin resistant Staphylococcus aureus ATCC, 33591 (MIC 0.1589 mM). Compound (5) was more active against Listeria monocytogenes ATCC 19115 (MIC 0.1113 mM) in comparison with the reference nalidixic acid (MIC 1.0765 mM). Interestingly, compound (6) had potential antifungal activity against Candida albicans ATCC 10231 (MIC <0.0099 mM). Remarkably, the tested compounds had low cytotoxic effect. This study indicated that glucosamine moiety inclusion into the chemical structure of the marketed nalidixic acid enhances antimicrobial activity and safety.

The properties of red seaweed (Kappaphycus alvarezii) and its effect on mammary carcinogenesis

The edible red seaweed (Kappaphycus alvarezii) is one of the algae species which was found to be rich in nutrients and nutraceutical. Hence, K. alvarezii may have the ability to suppress cancer through its antiproliferative properties. The aim of this study was to investigate the potential compounds of K. alvarezii, cytotoxicity properties of K. alvarezii extract on breast cancer cell line (MCF-7), investigated toxicity effect of high dosage K. alvarezii extract in rats and determined the effect of K. alvarezii on 7, 12-dimethylbenz[a]anthracene (DMBA) mammary carcinogenesis in rats. The method of LCMS/MS and MTT assay were used. For animal study, sub-chronic toxicity method was used, the rats were supplemented with 2000mg/kg body weight daily of K. alvarezii crude extracts by oral gavage. For the anticancer effect of K. alvarezii crude extracts, this study consisted of three groups of the experimental, untreated and normal group of rats. The experimental and untreated groups of rats were induced with mammary tumour with DMBA. The experimental group of rats was given with K. alvarezii crude extracts orally. The results were being used to compare with the untreated group of rats and normal group of rats. All the rats were fed with standard diet and water ad libitum. Mortality, behavior changes and tumour sizes were observed specifically. The differences between the three groups of rats were evaluated by using the ANOVA test. By using LCMS/MS method, six unknown compounds were analysed. K. alvarezii crude extract reduced the cell viability of MCF-7 from 84.91% to 0.81% and the IC₅₀ value is 4.1±0.69mg/mL. For sub-chronic and heavy metal toxicity studies, no significant difference was found in haematological and biochemical values of the control group and experimental group. The growth rate of tumours in the untreated group of rats was found significantly higher than the experimental group of rats. Besides that, the white blood cells level in untreated group was found significantly higher than the experimental group and the normal group. In conclusion, K. alvarezii extract might able to slow down the growth rate of the tumour cells, therefore, identification of an active compound of inhibition growth rate of the tumour cells can be positively carried out in the future.