Virapong Prachayasittikul

Synthesis, biological evaluation and molecular docking of novel chalcone-coumarin hybrids as anticancer and antimalarial agents.

A new series of chalcone-coumarin derivatives (9-19) linked by the 1,2,3-triazole ring were synthesized through the azide/alkyne dipolar cycloaddition. Hybrid molecules were evaluated for their cytotoxic activity against four cancer cell lines (e.g., HuCCA-1, HepG2, A549 and MOLT-3) and antimalarial activity toward Plasmodium falciparum. Most of the synthesized hybrids, except for analogs 10 and 16, displayed cytotoxicity against MOLT-3xa0cell line without affecting normal cells. Analogs (10, 11, 16 and 18) exhibited higher inhibitory efficacy than the control drug, etoposide, in HepG2 cells. Significantly, the high cytotoxic potency of the hybrid 11 was shown to be non-toxic to normal cells. Interestingly, the chalcone-coumarin 18 was the most potent antimalarial compound affording IC50 value of 1.60xa0μM. Molecular docking suggested that the cytotoxicity of reported hybrids could be possibly due to their dual inhibition of α- and β-tubulins at GTP and colchicine binding sites, respectively. Furthermore, falcipain-2 was identified to be a plausible target site of the hybrids given their antimalarial potency.

Cytochrome P450 enzyme mediated herbal drug interactions (Part 1)

It is well recognized that herbal supplements or herbal medicines are now commonly used. As many patients taking prescription medications are concomitantly using herbal supplements, there is considerable risk for adverse herbal drug interactions. Such interactions can enhance the risk for an individual patient, especially with regard to drugs with a narrow therapeutic index such as warfarin, cyclosporine A and digoxin. Herbal drug interactions can alter pharmacokinetic or/and pharmacodynamic properties of administered drugs. The most common pharmacokinetic interactions usually involve either the inhibition or induction of the metabolism of drugs catalyzed by the important enzymes, cytochrome P450 (CYP). The aim of the present article is to provide an updated review of clinically relevant metabolic CYP-mediated drug interactions between selected herbal supplements and prescription drugs. The commonly used herbal supplements selected include Echinacea, Ginkgo biloba, garlic, St. Johns wort, goldenseal, and milk thistle. To date, several significant herbal drug interactions have their origins in the alteration of CYP enzyme activity by various phytochemicals. Numerous herbal drug interactions have been reported. Although the significance of many interactions is uncertain but several interactions, especially those with St. John’s wort, may have critical clinical consequences. St. John’s wort is a source of hyperforin, an active ingredient that has a strong affinity for the pregnane xenobiotic receptor (PXR). As a PXR ligand, hyperforin promotes expression of CYP3A4 enzymes in the small intestine and liver. This in turn causes induction of CYP3A4 and can reduce the oral bioavailability of many drugs making them less effective. The available evidence indicates that, at commonly recommended doses, other selected herbs including Echinacea, Ginkgo biloba, garlic, goldenseal and milk thistle do not act as potent or moderate inhibitors or inducers of CYP enzymes. A good knowledge of the mechanisms of herbal drug interactions is necessary for assessing and minimizing clinical risks. These processes help prediction of interactions between herbal supplements and prescription drugs. Healthcare professionals should remain vigilant for potential interactions between herbal supplements/medicines and prescription drugs, especially for drugs with a narrow therapeutic index are used.

Food safety in Thailand 2: Pesticide residues found in Chinese kale (Brassica oleracea), a commonly consumed vegetable in Asian countries.

There is increasing public concern over human health risks associated with extensive use of pesticides in agriculture. Regulation of pesticide maximum residue limits (MRLs) in food commodities is established in many developed countries. For Thailand, this regulation exists in law but is not fully enforced. Therefore, pesticide residues in vegetables and fruits have not been well monitored. This study investigated the pesticide residues in Chinese kale, a commonly eaten vegetable among Asians. The Chinese kale samples (N = 117) were purchased from markets in Nakhon Pathom Province, Thailand, and analyzed for the content of 28 pesticides. Analysis was performed by the multiresidual extraction followed by GC-MS/MS. Of pesticides investigated, 12 pesticides were detected in 85% of the Chinese kale samples. Although carbaryl, deltamethrin, diazinon, fenvalerate and malathion were found in some samples, their levels were lower than their MRLs. However, in 34 samples tested, either carbofuran, chlorpyrifos, chlorothalonil, cypermethrin, dimethoate, metalaxyl or profenofos was detected exceeding their MRLs. This represents a 29% rate of pesticide detection above the MRL; a rate much higher than in developed countries. Washing vegetables under running water significantly reduced (p < 0.05) profenofos residues by 55%. The running water method did not significantly decrease cypermethrin residues in the samples but washing with vinegar did. Our research suggests that routine monitoring of pesticide residues is necessary to reduce the public health risks associated with eating contaminated vegetables. Washing vegetables before consumption is advisable as this helps to reduce the level of pesticide residues in our daily intake.

Synthesis and molecular docking of 1,2,3-triazole-based sulfonamides as aromatase inhibitors.

A series of 1,4-disubstituted-1,2,3-triazoles (13-35) containing sulfonamide moiety were synthesized and evaluated for their aromatase inhibitory effects. Most triazoles with open-chain sulfonamide showed significant aromatase inhibitory activity (IC50=1.3-9.4μM). Interestingly, the meta analog of triazole-benzene-sulfonamide (34) bearing 6,7-dimethoxy substituents on the isoquinoline ring displayed the most potent aromatase inhibitory activity (IC50=0.2μM) without affecting normal cell. Molecular docking of these triazoles against aromatase revealed that the compounds could snugly occupy the active site of the enzyme through hydrophobic, π-π stacking, and hydrogen bonding interactions. The potent compound 34 was able to form hydrogen bonds with Met374 and Ser478 which were suggested to be the essential residues for the promising inhibition. The study provides compound 34 as a potential lead molecule of anti-aromatase agent for further development.

Design, synthesis and molecular docking studies of novel N-benzenesulfonyl-1,2,3,4-tetrahydroisoquinoline-based triazoles with potential anticancer activity

A novel series of N-benzenesulfonyl-1,2,3,4-tetrahydroisoquinolines (14-33) containing triazole moiety were designed and synthesized through rational cycloadditions using the modified Pictet-Spengler reaction and the Click chemistry. Antiproliferative activity against four cancer cell lines (e.g., HuCCA-1, HepG2, A549 and MOLT-3) revealed that many substituted triazole analogs of benzoates (20, 29) and benzaldehydes (30, 32) exhibited anticancer activity against all of the tested cancer cell lines in which the ester analog 20 was shown to be the most potent compound against HuCCA-1 (IC50xa0=xa00.63xa0μM) and A549 (IC50xa0=xa00.57xa0μM) cell lines. Triazoles bearing phenyl (15, 24), tolyl (26, 27), acetophenone (19), benzoate (20, 29), benzaldehyde (21, 30) and naphthalenyl (25) substituents showed stronger anticancer activity against HepG2 cells than that of the etoposide. Interestingly, the p-tolyl analog (27) displayed the most potent inhibitory activity (IC50xa0=xa00.56xa0μM) against HepG2 cells without affecting normal cells. Of the investigated tetrahydroisoquinoline-triazoles, the promising compounds 20 and 27 were selected for molecular docking against AKR1C3, which was identified to be a plausible target site.

Novel 1,4-naphthoquinone-based sulfonamides: Synthesis, QSAR, anticancer and antimalarial studies

A novel series of 1,4-naphthoquinones (33-44) tethered by open and closed chain sulfonamide moieties were designed, synthesized and evaluated for their cytotoxic and antimalarial activities. All quinone-sulfonamide derivatives displayed a broad spectrum of cytotoxic activities against all of the tested cancer cell lines including HuCCA-1, HepG2, A549 and MOLT-3. Most quinones (33-36 and 38-43) exerted higher anticancer activity against HepG2 cell than that of the etoposide. The open chain analogs 36 and 42 were shown to be the most potent compounds. Notably, the restricted sulfonamide analog 38 with 6,7-dimethoxy groups exhibited the most potent antimalarial activity (IC₅₀ = 2.8 μM). Quantitative structure-activity relationships (QSAR) study was performed to reveal important chemical features governing the biological activities. Five constructed QSAR models provided acceptable predictive performance (Rcv 0.5647-0.9317 and RMSEcv 0.1231-0.2825). Four additional sets of structurally modified compounds were generated in silico (34a-34d, 36a-36k, 40a-40d and 42a-42k) in which their activities were predicted using the constructed QSAR models. A comprehensive discussion of the structure-activity relationships was made and a set of promising compounds (i.e., 33, 36, 38, 42, 36d, 36f, 42e, 42g and 42f) was suggested for further development as anticancer and antimalarial agents.

Maximizing computational tools for successful drug discovery.

Drug discovery is an iterative cycle of identifying promising hits followed by lead optimization via bioisosteric replacements. In the search for compounds affording good bioactivity, equal importance should also be placed on achieving those with favorable pharmacokinetic properties. Thus, the balance and realization of both key properties is an intricate problem that requires great caution. In this editorial, the authors explore the available computational tools in the context of the extant of big data that has borne out via advents of the Omics revolution. As such, the selection of appropriate computational tools for analyzing the vast number of chemical libraries, target proteins and interactomes is the first step toward maximizing the chance for success. However, in order to realize this, it is also necessary to have a solid foundation on the big concepts of drug discovery as well as knowing which tools are available in order to give drug discovery scientists the best opportunity.

Synthesis, anticancer activity and QSAR study of 1,4-naphthoquinone derivatives

A series of 2-substituted amino-3-chloro-1,4-naphthoquinone derivatives (3-12) were synthesized as anticancer agents and tested against four cancer cell lines including HepG2, HuCCA-1, A549 and MOLT-3. The most potent cytotoxic activity against the HepG2, HuCCA-1 and A549 cell lines was found to be m-acetylphenylamino-1,4-naphthoquinone (8) affording IC50 values of 4.758, 2.364 and 12.279 μM, respectively. On the other hand, p-acetylphenylamino-1,4-naphthoquinone (9) exhibited the most potent cytotoxic activity against the MOLT-3 cell line with an IC50 of 2.118 μM. Quantitative structure-activity relationship (QSAR) investigations provided good predictive performance as observed from cross-validated R of 0.9177-0.9753 and RMSE of 0.0614-0.1881. The effects of substituents at the 2-amino position on the naphthoquinone core structure and its corresponding influence on the cytotoxic activity were investigated by virtually constructing additional 1,4-naphthoquinone compounds (13-36) for which cytotoxic activities were predicted using equations obtained from the previously constructed QSAR models. Interpretation of informative descriptors from QSAR models revealed pertinent knowledge on physicochemical properties governing the cytotoxic activities of tested cancer cell lines. It is anticipated that the QSAR models developed herein could provide guidelines for further development of novel and potent anticancer agents.

Synthesis and cytotoxicity of novel 4-(4-(substituted)-1H-1,2,3-triazol-1-yl)-N-phenethylbenzenesulfonamides

AbstractA new series of 4-(4-(substituted)-1H-1,2,3-triazol-1-yl)-N-phenethylbenzenesulfonamide derivatives 5 were synthesized through the Click approach and evaluated for their cytotoxic activity against four cancer cell lines (HuCCA-1, HepG2, A549, and MOLT-3). Most of the synthesized triazoles 5 displayed cytotoxicity against MOLT-3 cell line, except for analogs 5a–c and 5e. Significantly, 4-phenyltriazoles (5a and 5n), 4-(naphthalen-2-yloxy)methyltriazole 5d, as well as 4-((2-oxo-2H-chromen-7-yl)oxy)methyltriazole 5l showed higher cytotoxic activity against HepG2 cells than the reference drug, etoposide. Interestingly, the 4-phenyltriazole 5a was the most potent and promising compound with IC50 value of 9.07xa0μM against HepG2 cell line. The analog 5a also exerted the highest cytotoxic activity against HuCCA-1 cells. This finding provides the novel lead molecules for further development.n

Predictive QSAR modeling of aldose reductase inhibitors using Monte Carlo feature selection

This study explores the chemical space and quantitative structure-activity relationship (QSAR) of a set of 60 sulfonylpyridazinones with aldose reductase inhibitory activity. The physicochemical properties of the investigated compounds were described by a total of 3230 descriptors comprising of 6 quantum chemical descriptors and 3224 molecular descriptors. A subset of 5 descriptors was selected from the aforementioned pool by means of Monte Carlo (MC) feature selection coupled to multiple linear regression (MLR). Predictive QSAR models were then constructed by MLR, support vector machine and artificial neural network, which afforded good predictive performance as deduced from internal and external validation. The investigated models are capable of accounting for the origins of aldose reductase inhibitory activity and could be utilized in predicting this property in screening for novel and robust compounds.