Synthesis of psoralen derivatives and their blocking effect of hKv1.5 channel

Phytochemical and Pharmacological Aspects of Psoralen - A Bioactive Furanocoumarin from Psoralea corylifolia Linn

Since long ago, medicinal plants have played a vital role in drug discovery. Being blessed and rich in chemovars with diverse scaffolds, they have unique characteristics of evolving based on the need. The World Health Organization also mentions that medicinal plants remain at the center for meeting primary healthcare needs as the population relies on them. The plant-derived natural products have remained an attractive choice for drug development owing to their specific biological functions relevant to human health and also the high degree of potency and specificity they offer. In this context, one such esteemed phytoconstituent with inexplicable biological potential is psoralen, a furanocoumarin. Psoralen was the first constituent isolated from the plant Psoralea corylifolia, commonly known as Bauchi. Despite being a life-saver for psoriasis, vitiligo, and leukoderma, it also showed immense anticancer, anti-inflammatory, and anti-osteoporotic potential. This review brings attention to the possible application of psoralen as an attractive target for rational drug design and medicinal chemistry. It discusses the various methods for the total synthesis of psoralen, its extraction, the pharmacological spectrum of psoralen, and the derivatization done on psoralen.

Psoralen Derivatives: Recent Advances of Synthetic Strategy and Pharmacological Properties

Psoralen or furocoumarin is a linear three ring heterocyclic compound. Psoralens are planar, tricyclic compounds, consisting of a furan ring fused to a coumarin moiety. Psoralen has been known for a wide spectrum of biological activities, spanning from cytotoxic, photosensitizing, insecticidal, antibacterial to antifungal effect. Thus, several structural changes were introduced to explore the role of specific positions with respect to the biological activity. Convenient approaches utilized for the synthesis of psoralen skeleton can be categorized into two parts: (i) the preparation of the tricyclic ring system from resorcinol, (ii) the exocyclic modification of the intact ring system. Furthermore, although psoralens have been used in diverse ways, we mainly focus in this work on their clinical utility for the treatment of psioraisis, vitiligo and skin-related disorder.

Challenges Faced with Small Molecular Modulators of Potassium Current Channel Isoform Kv1.5

The voltage-gated potassium channel Kv1.5, which mediates the cardiac ultra-rapid delayed-rectifier (IKur) current in human cells, has a crucial role in atrial fibrillation. Therefore, the design of selective Kv1.5 modulators is essential for the treatment of pathophysiological conditions involving Kv1.5 activity. This review summarizes the progress of molecular structures and the functionality of different types of Kv1.5 modulators, with a focus on clinical cardiovascular drugs and a number of active natural products, through a summarization of 96 compounds currently widely used. Furthermore, we also discuss the contributions of Kv1.5 and the regulation of the structure-activity relationship (SAR) of synthetic Kv1.5 inhibitors in human pathophysiology. SAR analysis is regarded as a useful strategy in structural elucidation, as it relates to the characteristics that improve compounds targeting Kv1.5. Herein, we present previous studies regarding the structural, pharmacological, and SAR information of the Kv1.5 modulator, through which we can assist in identifying and designing potent and specific Kv1.5 inhibitors in the treatment of diseases involving Kv1.5 activity.

Synthesis, X-ray Analysis, Biological Evaluation and Molecular Docking Study of New Thiazoline Derivatives

A series of new thiazoline derivatives were synthesized. Structure analyses were accomplished employing ¹H-NMR, ¹³C-NMR, X-ray and MS techniques. The in vitro antitumor activities were assessed against human hepatocellular carcinoma (HepG-2) and colorectal carcinoma (HCT-116) cell lines. The results revealed that the thiazolines 5b and 2c exhibited significant activity against the two cell lines. The in vitro antimicrobial screening showed that the thiazolines 2c, 5b and 5d showed promising inhibition activity against Salmonella sp. Additionally, the inhibition activity of thiazolines 2e and 5b against Escherichia coli was comparable to that of the reference compound gentamycin.

Synthesis, α-Amylase Inhibitory Activity and Molecular Docking Studies of 2,4-Thiazolidinedione Derivatives

Introduction:

2,4-Thiazolidinedione and its derivatives exhibit a variety of pharmacological activities including antidiabetic, antiviral, antifungal, anti-inflammatory, anti-cancer and aldose reductase inhibitory activities. Keeping in mind the pharmacological potential of 2,4-Thiazolidinedione derivatives as antidiabetic agents, seven arylidene derivatives of 2,4-thiazolidinedione1(a-g)and four corresponding acetic acid derivatives 2(a-d)have been synthesized by a three-step procedure.

Methods:

All the synthesized compounds were characterized by elemental analysis, FTIR,1HNMR, and13CNMR and further screened for their α-amylase inhibitory potential.

Results:

All the compounds1(a-g)and2(a-d)showed varying degree of α-amylase inhibition, especially compound1c(IC50= 6.59μg/ml),1d(IC50=2.03μg/ml) and1g(IC50= 3.14μg/ml) displayed significantly potent α-amylase inhibition as compared to the standard acarbose (IC50= 8.26μg/ml). None of the acetic acid derivatives of 5-arylidene-2,4-thiazolidinedione showed prominent inhibitory activity. Docking results indicated that the best binding conformation was found inside the active site cleft of enzyme responsible for hydrolysis of carbohydrates.

Conclusion:

Therefore, it can be concluded that 2,4-thiazolidinedione derivatives can be used as effective lead molecules for the development of α-amylase inhibitors for the management of diabetes.

Effect of thiazolidinedione phenylacetate derivatives on wound-healing activity

The aim of this work was to evaluate the synthesis and structure-activity relationship of 4-((2,4-dioxothiazolidin-5-ylidene)methyl)phenyl 2-phenylacetate derivatives as potential wound-healing agents. The IC₅₀ values of the lead compounds ranged from 0.01 to 0.05 µM. These compounds also increased the levels of extracellular prostaglandin E₂ (PGE₂) in A549 cells. Among the synthesized compounds, compounds 66, 67, 69, and 86 increased PGE₂ levels 3- to 4-fold of those achieved with the negative control. Introduction of a halogen at the intermediate phenyl ring, compounds 66, 67, 69, and 86 resulted in higher IC₅₀ values, which indicated lower cytotoxicity than that observed upon the introduction of other substituents at the same position. In particular, cells exposed to compound 69 showed significantly improved wound healing, and the wound closure rate achieved was approximately 3.2-fold higher than that of the control. Therefore, compound 69 can be used for tissue regeneration and treatment of diverse diseases caused by PGE₂ deficiency. Overall, our findings suggested that compound 69 might be a novel candidate for skin wound therapy.

A novel psoralen derivative-MPFC enhances melanogenesis via activation of p38 MAPK and PKA signaling pathways in B16 cells

As an active compound, psoralen is present in various Chinese herbal medicines and has exhibited significant activity in skin disease treatment. Its derivative 8-methoxypsoralan (8-MOP) is the most commonly used drug to induce repigmentation of vitiligo. In our previous screening assays, 4-methyl-6-phenyl-2H-furo[3,2-g]chromen-2-one (MPFC), a psoralen derivative, was identified as more effective tyrosinase and melanin activator than the positive control 8-MOP in consideration of low doses, as well as low toxicity. The overall purpose of this study was to characterize the melanogenic effect and mechanisms of MPFC in B16 cells. The melanin biosynthesis effects of MPFC were determined by examination of cellular melanin contents, tyrosinase activity assay, cyclic adenosinemonophosphate (cAMP) assay, and western blotting of MPFC-stimulated B16 mouse melanoma cells. Our results showed that MPFC enhanced both melanin synthesis and tyrosinase activity in a concentration-dependent manner as well as significantly activated the expression of melanogenic proteins such as tyrosinase, tyrosinase-related protein-1 and tyrosinase-related protein-2. Western blot analysis showed that MPFC increased the phosphorylation of p38 mitogen-activated protein kinase and cAMP response element-binding protein (CREB) as well as the expression of microphthalmia-associated transcription factor (MITF). Moreover, MPFC stimulated intracellular cAMP levels and induced tyrosinase activity and melanin synthesis were attenuated by H89, a protein kinase A inhibitor. These results indicated that MPFC-mediated activation of the p38 MAPK and the protein kinase A (PKA) pathway may shed light on a novel approach for an effective therapy for vitiligo.

Synthesis and Studies of Potential Antifungal and Antibacterial Agents New Aryl Thiazolyl Mercury (II) Derivatives Compounds

Combination of mercaptothiazoles and mercury phenyl chloride synthesized some new compounds of thiazoles. Firstly some mercaptothiazoles with different sorts have been synthesized, and then synthesized compounds were reacted with different mercury phenyl chloride structures. At last, each of these synthesized compounds was purified. Consequently, these structures were recrystallized using oil ether. Forming product through chromatogram (TLC) and combination ofRfwith other compound'sRfof were identified, and their purity percent was recognized. The1H-NMR and other methods like FT-IR and mass spectroscopy have determined all of compounds. Obtained results of synthesized compounds showed that reactions were carried out with suitable speed and high yield.

Downregulation of Kv1.5 K channels by the AMP-activated protein kinase

BACKGROUND

The voltage gated K(+) channel Kv1.5 participates in the repolarization of a wide variety of cell types. Kv1.5 is downregulated during hypoxia, which is known to stimulate the energy-sensing AMP-activated serine/threonine protein kinase (AMPK). AMPK is a powerful regulator of nutrient transport and metabolism. Moreover, AMPK is known to downregulate several ion channels, an effect at least in part due to stimulation of the ubiquitin ligase Nedd4- 2. The present study explored whether AMPK regulates Kv1.5.

METHODS

cRNA encoding Kv1.5 was injected into Xenopus oocytes with and without additional injection of wild-type AMPK (α1 β 1γ1), of constitutively active (γR70Q)AMPK (α1 β 1γ1(R70Q)), of inactive mutant (αK45R)AMPK (α1(K45R)β1γ1), or of Nedd4-2. Kv1.5 activity was determined by two-electrode voltage-clamp. Moreover, Kv1.5 protein abundance in the cell membrane was determined by chemiluminescence and immunostaining with subsequent confocal microscopy.

RESULTS

Coexpression of wild-type AMPK(WT) and constitutively active AMPK(γR70Q), but not of inactive AMPK(αK45R) significantly reduced Kv1.5-mediated currents. Coexpression of constitutively active AMPKγR70Q further reduced Kv1.5 K(+) channel protein abundance in the cell membrane. Co-expression of Nedd4-2 similarly downregulated Kv1.5-mediated currents.

CONCLUSION

AMPK is a potent regulator of Kv1.5. AMPK inhibits Kv1.5 presumably in part by activation of Nedd4- 2 with subsequent clearance of channel protein from the cell membrane.

Activation of voltage gated K⁺ channel Kv1.5 by β-catenin

Voltage-gated Kv1.5 channels are expressed in a wide variety of tissues including cardiac myocytes, smooth muscle and tumor cells. Kv1.5 channel activity is modified by N-cadherin, which in turn binds the multifunctional oncogenic protein β-catenin. The present experiments explored the effect of β-catenin on Kv1.5 channel activity. To this end, Kv1.5 was expressed in Xenopus oocytes with or without β-catenin and the voltage-gated Kv current determined by dual electrode voltage clamp. As a result, expression of β-catenin significantly increased the voltage-gated Kv current at positive potentials. The stimulating effect of β-catenin on Kv1.5 was not dependent on the stimulation of transcription since it was observed even in the presence of the transcription inhibitor actinomycin D. Specific antibody binding to surface Kv1.5 in Xenopus oocytes revealed that β-catenin enhances the membrane abundance of Kv1.5. Further experiments with brefeldin A showed that β-catenin fosters the insertion of Kv1.5 into rather than delaying the retrieval from the plasma membrane. According to electrophysiological recordings with mutant β-catenin, the effect on Kv1.5 requires the same protein domains that are required for association of β-catenin with cadherin. The experiments disclose a completely novel function of β-catenin, i.e. the regulation of Kv1.5 channel activity.

Synthesis of new pyrazolyl-2, 4-thiazolidinediones as antibacterial and antifungal agents

BACKGROUND

Thiazolidine-2, 4-diones (TZDs) have become a pharmacologically important class of heterocyclic compounds since their introduction in the form of glitazones into the clinical use for the treatment of type 2 diabetes. TZDs lower the plasma glucose levels by acting as ligands for gamma peroxisome proliferators-activated receptors. In addition, this class of heterocyclic compounds possesses various other biological activities such as antihyperglycemic, antimicrobial, anti-inflammatory, anticonvulsant, insecticidal, etc. TZDs are also known for lowering the blood pressure thereby reducing the chances of heart failure and micro-albuminuria in the patients with type 2 diabetes.

RESULTS

We have described herein the synthesis of three series of compounds, namely, ethyl 2-((Z)-5-((3-aryl-1-phenyl-1H-pyrazol-4-yl)methylene)-2, 4-dioxothiazolidin-3-yl)acetates (4), methyl 2-((Z)-5-((3-aryl-1-phenyl-1H-pyrazol-4-yl)methylene)-2, 4-dioxothiazolidin-3-yl)acetates (5), and 2-((Z)-5-((3-aryl-1-phenyl-1H-pyrazol-4-yl)methylene)-2, 4-dioxothiazolidin-3-yl)acetic acids (6). The compounds 4 and 5 were synthesized by Knoevenagel condensation between 3-aryl-1-phenyl-1H-pyrazole-4-carbaldehydes (1) and ethyl/methyl 2-(2, 4-dioxothiazolidin-3-yl)acetates (3, 2) in alcohol using piperidine as a catalyst. The resultant compounds 4 and 5 having ester functionality were subjected to acidic hydrolysis to obtain 6. All the new compounds were tested for their in vitro antibacterial and antifungal activity.

CONCLUSIONS

Knoevenagel condensation approach has offered an easy access to new compounds 4-6. Antimicrobial evaluation of the compounds has shown that some of the compounds are associated with remarkable antifungal activity. In case of antibacterial activity, these were found to be effective against Gram-positive bacteria. However, none of the compounds were found to be effective against Gram-negative bacteria.

Effect of psoralen on the cloned Kv3.1 currents

The psoralen, a furocoumarin derivative, on the cloned neuronal rat Kv3.1 channels stably expressed in Chinese hamster ovary cells was investigated using the whole-cell patch-clamp technique. Psoralen reduced Kv3.1 whole-cell currents in a reversible concentration-dependent manner, with an IC50 value and a Hill coefficient of 2.3 +/- 0.03 microM and 0.9 +/- 0.08, respectively. Psoralen accelerated the decay rate of inactivation of Kv3.1 currents without modifying the kinetics of current activation. The psoralen-induced inhibition of Kv3.1 channels was voltage-dependent, with a steep increase over the voltage range of channel opening. However, the inhibition exhibited voltage independence over the voltage range in which channels are fully activated. Psoralen slowed the deactivation time course, resulting in a tail crossover phenomenon when the tail currents, recorded in the presence and absence of psoralen, were superimposed. Inhibition of Kv3.1 by psoralen was use-dependent at a frequency of 1 Hz. The present results suggest that psoralen acts on Kv3.1 currents as an open-channel blocker.

Modulation of human Kv1.5 channel kinetics by N-cadherin

Kv1.5 is expressed in multiple tissues including heart, brain, macrophages, as well as vascular, airway, and intestinal smooth muscle cells. Kv1.5 currents contribute to cardiac repolarization. In cardiac myocytes Kv1.5 colocalizes with N-cadherin. As Kv1.5 expression increases following establishment of cell-cell contacts and N-cadherin influences the activity of other ion channels, we explored whether N-cadherin participates in the regulation of Kv1.5 activity. To this end, we expressed Kv1.5 in Xenopus oocytes with or without additional expression of N-cadherin. Coexpression of N-cadherin was followed by a approximately 2- to 3-fold increase of Kv1.5 induced current. The effect of N-cadherin was not paralleled by significant alterations of Kv1.5 channel abundance within the oocyte cell membrane but resulted primarily from accelerated recovery from inactivation. In conclusion, N-cadherin modifies Kv1.5 channel activity and is thus a novel candidate signaling molecule participating in the regulation of a variety of functions including cardiac action potential and vascular tone.