Molecular modeling parameters predict antioxidant efficacy of 3-indolyl compounds

 Many dietary constituents, such as indole-3-carbinol, are chemoprotective in toxicity and carcinogenicity bioassays. Indole-3-carbinol and related congeners appear to protect partly via radical and electrophile scavenging. To develop better chemoprotective indoles with lower intrinsic toxicity, we performed molecular graphic and quantum-mechanical analyses of model indolyl compounds to ascertain the determinant molecular features for antioxidant activity. We examined eight structurally related 3-indolyl compounds for relationships between antioxidation potential (using in vitro lipid peroxidation assays) and electronic, polar, and steric parameters, including bond dissociation energies, bond lengths, dipole moments, electronic charge densities, and molecular size parameters. Electronic features of the 3-methylene carbon and 1-nitrogen were not predictive of antioxidative potency due to extensive charge delocalization of the cation radical following electron abstraction from the nitrogen. Antioxidant efficacy of 3-indolyl compounds was most strongly predicted by molecular size parameters and by the energy of electron abstraction as calculated from the difference in heat of formation between the parent compound and its cation radical. A highly predictive multiple linear regression correlation model (r ²=0.97) was obtained using the parameters of heat of formation, molecular weight, log P, and diplole moment. Received: 21 November 1995/Accepted: 19 March 1996     

Synthesis and pharmacological evaluation of some (pyridyl)cyclopropylmethyl amines and their methiodides as nicotinic receptor ligands

A series of 3- and (4-pyridyl)cyclopropylmethyl amines and their quaternary ammonium derivatives have been synthesized; they can be considered as rigid analogues of nicotine. The compounds have been tested on rat cerebral cortex to measure the affinity for the central nicotinic receptor. Only the methiodides show affinity in the micromolar range. The results obtained can provide useful information on the topography of the nicotinic receptor-binding site.     

Bioactive phenols in algae: The application of pressurized-liquid and solid-phase extraction techniques

A new extraction technique based on the off-line combination of pressurized-liquid with solid-phase extraction (PLE–SPE) is described. The method was used for the extraction of bioactive phenolic acids (protocatechuic, p-hydroxybenzoic, 2,3-dihydroxybenzoic, chlorogenic, vanillic, caffeic, p-coumaric, salicylic acid), cinnamic acid and hydroxybenzaldehydes (p-hydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde, vanillin) from in vitro culture of two freshwater algae (Anabaena doliolum and Spongiochloris spongiosa) and from food products of marine macroalgae Porphyra tenera (nori) and Undaria pinnatifida (wakame). For the identification and quantification of the compounds the molecular ions [M−H]⁻ and specific fragments were analyzed by quadrupole mass spectrometry analyzer connected on-line with a reversed-phase HPLC system. Our analysis showed that the freshwater algae and marine algal products contained submicrogram or microgram level of above-mentioned phenols per gram of lyophilized sample. In addition, the total phenol content (Folin–Ciocalteu assay) and antioxidant activity (TEAC assay, Trolox equivalent antioxidant capacity assay) of the PLE–SPE extracts were determined and discussed.     

Preliminary screening the antioxidant potential of in vitro-propagated Amsonia orientalis: An example to sustainable use of rare medicinal plants in pharmaceutical studies

Amsonia orientalis (European Bluestar) is a critically endangered plant species with medicinal and ornamental properties. The rare availability of the species in nature limits its potential to be used for various purposes. However, plant tissue culture is an effective method for the cultivation of such vulnerable species without damaging their natural populations, which are very limited in nature for scientific purposes. By taking advantage of plant tissue culture, this study aimed to measure the phenolic substance and flavonoid contents in leaf extracts of in vitro-propagated Amsonia orientalis, and to investigate their antioxidant potentials through phosphomolybdate and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. The crude extracts prepared in water, aqueous ethanol, methanol, and acetone were tested. The highest phenolic substance content was found in the ethanolic extracts, while statistically the same flavonoid contents were found in the ethanolic, methanolic, and acetone extracts. Although the water extract had lesser flavonoid content, it exhibited a notable antioxidant property. The ethanolic leaf extract gave the highest antioxidant and DPPH radical scavenging activity, especially when used at 1 mg mL^?1 concentration. Also, the TLC fingerprint profile validated the presence of valuable phytoconstituents in the leaves of the plant. This study indicated that ultrasound-assisted extraction of minimal amounts of dried leaf samples from in vitro-propagated plants might be adequate for the pre-screening of the antioxidant capacity of rare plant species.     

Interaction of benzopyranone derivatives and related compounds with human concentrative nucleoside transporters 1, 2 and 3 heterologously expressed in porcine PK15 nucleoside transporter deficient cells. Structure-activity relationships and determinants of transporter affinity and selectivity

Unlike the major equilibrative nucleoside transporters, there is a dearth of potent specific inhibitors of concentrative nucleoside transporters (CNTs). We investigated the interaction of benzopyranone derivatives and related compounds with human (h) CNTs in newly established PK15NTD transfectant cells stably expressing hCNT1 or hCNT2, and previously established PK15NTD/hCNT3 cells. Flavones exhibited the highest inhibitory activity against hCNT2 and hCNT3, whereas the most potent selective inhibitor of hCNT1 was a coumarin derivative. hCNT3 was the only transporter that exhibited moderate sensitivity to the chalcones tested. The most active compound was 6-hydroxy-7-methoxyflavone, which was hCNT3-specific with an IC₅₀ of 0.57 ± 0.20 μM, and over 40-fold more potent than the standard CNT inhibitor, phloridzin (IC₅₀ of 25 ± 3.5 μM). The SAR (Structure-Activity Relationship) shows that high potency against all three hCNTs is conferred by the presence of hydroxyl substituents at both the 7- and 8-positions of flavones and isoflavones. CoMFA (Comparative Molecular Field Analysis) and CoMSIA (Comparative Molecular Similarity Indices Analysis) 3D-QSAR (three-Dimensional Quantitative Structure-Activity Relationship) modeling indicated that electrostatic and hydrophobic properties were the most influential for interactions between the flavonoids and hCNT1, while electrostatic, hydrophobic and hydrogen bond donor properties were predominate for interactions with hCNT2 and hCNT3. The 3D-QSAR results also suggested possible commonalities in hydrogen bonding interactions of flavonoids and nucleosides, suggesting similarities between the hCNT-binding sites of the two classes of compounds. We report the most potent and selective non-nucleoside CNT inhibitors to date; which may serve as research tools and/or leads for further inhibitor development.     

小檗碱及其类似物体外缺糖缺氧条件下对PC12细胞生存及其对COX-2抑制作用的比较

本文对小檗碱及其5个类似物对体外缺糖缺氧再灌注PC12细胞的保护作用及其对COX-2的抑制作用进行了实验观察,并就它们的构效关系进行了分析。造模方法为缺糖缺氧4小时复灌24小时。以MTT法检测小檗碱及其类似物对细胞的保护作用。以实时定量PCR和Western blot方法检测COX-2的mRNA和蛋白的表达。结果表明,小檗碱及其类似物均能够对抗缺糖缺氧再灌所引起的细胞损伤、抑制COX-2的表达。小檗碱和小檗红碱作用最强,其最大有效剂量为0.31μg/mL,其最小有效剂量分别为0.02和0.04μg/mL。巴马汀作用较弱。R2和R3位的亚甲二氧基是小檗碱及其类似物的活性基团。而且R2,R3,R9和R10位的亚甲二氧基影响小檗碱及其类似物对COX-2的亲和力。R9位的羟基取代不影响其活性。     

Discovery of new antifungal leads via pharmacophore modeling and QSAR analysis of fungal N-myristoyl transferase inhibitors followed by in silico screening

N-Myristoyl transferase is an essential enzyme for fungal growth and survival. The continuous interest in the development of new antifungal agents prompted recent interest in developing new potent inhibitors of fungal N-myristoyl transferase. In this context, we combined pharmacophore and QSAR modeling to explore the structural requirements for potent N-myristoyl transferase inhibitors employing 55 known N-myristoyl transferase ligands. Four binding pharmacophore models emerged in the optimal QSAR equations (R(2)(44) = 0.81-0.83, F-statistic = 47.89-58.83, r(2)(L00)= 0.77-0.80, against 11 external test inhibitors = 0.61-0.71). The successful pharmacophores were complemented with exclusion spheres to optimize their receiver operating characteristic curve profiles. The QSAR equations and their associated pharmacophore models were validated by the identification and experimental evaluation of new promising antifungal leads retrieved from the NCI database and our in-house-built database of established drugs and agrochemicals.     

Synthesis and in vitro antioxidant activity of some new fused pyridine analogs

A new series of pyrano[3,2-c]pyridines, pyrazolo[4,3-c]pyridines, and pyrido[4,3-d]pyrimidines were synthesized and screened for their in vitro antioxidant activity. Compounds 13, 14, 15, 23, 29, 30, and 31 exhibited the most active oxygen free-radical scavenger activity with percentage inhibitions of 99.4, 99.6, 99.8, 97.3, 99.0, 99.3, and 99.5%; respectively, which is comparable to the curcumin potency. Most of the tested compounds proved to be safe towards peripheral multinuclear neutrophils (PMNs). The detailed synthesis and antioxidant activity data are reported.     

Secondary plant substances in various extracts of the leaves,fruits, stem and bark of Caraipa densifolia Mart.

Thirty secondary plant substances were detected in various extracts of the leaves, fruits, stem and bark of Caraipadensifolia Mart. Phenolic compounds were preliminarily identified and quantitated by HPLC–ESI-MS and the structures of the compounds, purified by semi-preparative HPLC, were further characterized by nano-ESI-MS–MS. The presence of gallic acid, 3,4-dihydroxybenzoic acid, neochlorogenic acid, chlorogenic acid, methyl gallate, p-coumaric acid quinate, epicatechin, procaynidin dimer B₂, procyanidin trimer C₁, syringic acid, 1,2,3,6-tetragallate glucoside, 1,3,4,6-tetragallate glucoside, corilagin, ellagic acid, methyl ellagic acid rhamnoside, quercetin-3-O-rhamnoside, two apigenin-C-glycosides (vitexin and isovitexin) and two luteolin-C-glycosides (orientin and isoorientin) are reported in this species for the first time. In addition, the previously reported following terpenoids, lupeol, lupenone, betulinic acid, betulin, friedelin and a previously non-characterized terpenoid in this species, friedelinol were identified and quantitated by GC–MS. A previously identified sterol was β-sitosterol along with stigmasterol in this species for the first time. The vitamins α-tocopherol and γ-tocopherol were also identified in extracts of the leaves of Caraipa species for the first time. The data shows that the botanical parts of C. densifolia Mart. has a much richer spectrum of secondary plant substances than previously reported.     

Stability of vitamins C and E in topical microemulsions for combined antioxidant therapy

An interesting strategy for protecting skin from excessive exposure to free radicals is to support the skin endogenous antioxidant system. As the balance between different skin antioxidants is very important, a combined therapy using at least two antioxidants is desirable. In the present work, o/w, w/o, and gel-like microemulsions (ME), all composed of the same ingredients, were selected as carrier systems for dermal delivery of vitamins C and E. Gel-like ME was found to offer the best protection for both vitamins, although other ME also significantly increased their stability compared with that solution. In the presence of vitamin C no decrease in vitamin E content occurred. To obtain ME appropriate for dermal use, their viscosity was increased by adding thickening agents. On the basis of visual examination of viscosity and physical stability of thickened systems, several thickeners were selected. The addition of thickener significantly increased the viscosity of ME and changed the behavior of systems from ideal Newtonian to thixotropic. Finally, the stability of both vitamins was examined as a function of thickening agent and of the location of vitamins in the ME. The addition of thickeners changed the stability of at least one vitamin, but the systems generally still protected vitamins better than solutions. It is likely that the changes in internal organization of ME resulting from the addition of thickener, confirmed by thermal analysis and changes in solubility of oxygen in the outer phase, were the most important factors that influenced the stability of vitamins in thickened systems.     

Protein binding of glycopeptide antibiotics with diverse physical-chemical properties in mouse,rat, and human serum

In previous studies of the pharmacokinetics and urinary excretion of nine glycopeptides with diverse isoelectric points (pI),as pIdecreases, the total systemic and renal clearance, urinary recovery, and volume of distribution decrease, whereas the half-life increases. With glycopeptides of similar pI,clearance decreases and half-life increases with increasing lipophilicity. The present study examines the serum protein binding of these glycopeptide antibiotics in mouse, rat, and human serum and calculates the previously reported pharmacokinetic parameters for these drugs based on unbound concentration. Increased negative charge and lipophilicity increase serum protein binding (90-fold, f_u 83% to 0.96%), which decreases the renal clearance and total systemic clearance (90-fold, 16.4 to 0.18 ml/min/kg) of these drugs. Increased serum protein binding also decreases the volume of distribution of these compounds, but this change is relatively small (sixfold, 755 to 131 ml/kg) compared with the change in total systemic clearance causing an increase in elimination half-life (25-fold, 20 to 492 min). The results demonstrate that the large differences in the total systemic clearance and half-life of these glycopeptide antibiotics are primarily due to dramatic differences in serum protein binding and notto differences in the intrinsic elimination processes (enzymes or transport proteins). It appears that the same physical-chemical properties that govern the protein binding and pharmacokinetics of small organic molecules govern the disposition of these high-molecular weight glycopeptide antibiotics.     

Differential effect of antioxidant treatment on plasma and tissue paraoxonase activity in hyperleptinemic rats

Recent studies suggest that adipose tissue hormone, leptin, is involved in atherogenesis, especially in obese subjects. Previously, we have demonstrated that experimentally induced hyperleptinemia decreases plasma paraoxonase 1 (PON1) activity. The aim of this study was to investigate whether treatment with synthetic antioxidant, Tempol, modulates the effect of leptin on plasma and tissue PON1 in the rat. Leptin was administered at a dose of 0.25 mgkg-1 s.c. twice daily for 7 days and Tempol was added to the drinking water at a concentration of 2 mM. Leptin reduced plasma PON1 activity toward paraoxon, phenyl acetate and gamma-decanolactone to 71.1, 72.3 and 57.1% of control, respectively. In addition, leptin decreased PON1 activity toward paraoxon in aorta, renal cortex and medulla to 78.6, 49.2 and 48.0% of control, respectively, but had no effect on PON1 in heart, lung and liver. PON1 activity toward phenyl acetate was lower following leptin treatment only in aorta. Leptin increased plasma concentration and urinary excretion of isoprostanes as well as malonyldialdehyde + 4-hydroxyalkenals level in aorta, renal cortex and renal medulla. Coadministration of Tempol prevented leptin-induced oxidative stress and normalized PON1 activity in aorta and kidney. However, Tempol had no effect on plasma PON1 in leptin-treated rats. These data indicate that hyperleptinemia decreases tissue PON1 activity through oxidative stress-dependent mechanism. In contrast, leptin-induced downregulation of plasma PON1 is not mediated by oxidative stress.     

Structure-activity relationships and in silico models of P-glycoprotein (ABCB1) inhibitors

Abstract

1. The efflux pump p-glycoprotein (P-gp/ABCB1) has received enormous attention in drug (xenobiotic) disposition due to its role in modulation of the drug availability and in protection of sensitive organs.

2. P-gp mediated efflux is one of main mechanisms for multidrug resistance in cancer cells. A main approach to reverse the resistance and restore the drug efficacy is to use specific inhibitors of P-gp that suppress the efflux activity.

3. This review summarizes the binding capabilities of known chemical inhibitors based on the analyses of structure–activity relationships, and computational modeling of the inhibitors as well as the binding site of P-gp protein.

4. The molecular models will facilitate the design of lead inhibitors as drug candidates. Also, it helps scientists in early drug discovery phase to synthesize chemical series with better understanding of their P-gp binding liabilities.     

糖电解质类注射液生产过程中的抗氧化应用及分析

目的提高糖电解质类注射液质量。方法采用通过控制外部条件,如使用惰性气体置换、使用抗氧化剂等,降低氧对注射液的影响的方法。结果在使用惰性气体置换的情况下,氧化产物5-羟甲基糠醛浓度明显降低;在使用抗氧化剂后,制剂中没有氧化产物5-羟甲基糠醛产生。结论通过控制良好的外部条件,有效提高了抗氧化效率,提高糖电解质类注射液质量。     

硫色满酮并氮杂环衍生物体外抗真菌活性及构效关系研究

对硫色满酮并氮杂环衍生物进行体外抗真菌实验,筛选具有抗真菌活性的化合物并探讨其构效关系。方法：利用微量稀释法,以氟康唑和两性霉素B为阳性对照药,测定硫色满酮类并氮杂环衍生物对白色念珠菌、新生隐球菌、断发毛癣茵、红色毛癣菌、申克孢子丝菌（菌丝相）、石膏样小孢子菌、卡氏枝孢霉、黑曲霉、絮状毛癣菌的体外抑菌活性。结果：Bb,Da,Db,I,K对絮状表皮癣菌抑制作用显著,尤其Db的MIC低于两性霉素B;K对石膏样小孢子丝菌的MIC与两性霉素B相当。二甲氨基和甲氧基取代后,抗真菌比其他取代基化合物抗真菌活性高。结论：硫色满酮并氮杂环衍生物对常见致病真菌有一定的体外抑菌活性,值得深入研究。     

Free radicals and antioxidant status in rat liver after dietary exposure of environmental mercury

Potential health effect of dietary exposure to environmental mercury was examined in this study. Dietary exposure significantly increased content of reduced glutathione (GSH) and activity of glutathione peroxidase (GSH-Px) in rat liver at 7 or 20 days (P < 0.05; P < 0.01), but parameters droped to normal levels after 90 days of exposure. The early increases of the two antioxidants were partly associated with the co-accumulated selenium. However, activity of superoxide dismutase (SOD) was observed significantly decreased after 30 and 90 days of exposure (P < 0.05, P < 0.05). Changes of antioxidants were paralleled by the induction and aggravation of free radicals in rat liver at 30 and 90 days (P < 0.01, P < 0.01), increased nitric oxide (NO) content at 90 days (P < 0.01). The excess availability of free radicals and the decreased levels of antioxidants resulted in a significant increase of malonyldialdehyde (MDA) after 90 days of exposure, indicating the aggravation of hepatic oxidative status. A number of biomarkers were required to monitor and minimize the health risk for the local population.     

Inhibitory action of adenosine and adenosine analogs on neurotransmission in the olfactory cortex slice of guinea pig - structure-activity relationships

The postsynaptic potential (PSP) was recorded from thin slices of the olfactory cortex of the guinea pig. Application of adenosine and adenine nucleotides such as 5'-ATP, 5'-ADP and 5'-AMP in the incubation medium, depressed the amplitude of the PSP without altering the presynaptic fiber potential. The other purine and pyrimidine derivatives had no inhibitory effect. The inhibitory action of adenosine and adenine nucleotides on the PSP were manifest at concentrations of 5 microM-1 mM. Adenosine, 5'-ATP, 5'-ADP and 5'-AMP were equipotent in evoking depression of PSPs. Inhibition occurred within 10-20 sec after administration of the agents and the depressant effect disappeared rapidly after the removal of the compounds from the medium. Theophylline reversed and prevented the inhibition produced by adenosine and adenine nucleotides. To test the structure-activity relationships of these compounds, adenosine analogs and adenine nucleotide derivatives were applied to the medium. The 6-aminopurine riboside (adenosine radical) was found to be essential for inhibitory action on the PSP. Among adenosine analogs, the presence of at least one hydrogen atom in the amino group at the 6-position of the purine, and the OH group at the 2'-position of the ribose was essential for inhibitory activity.     

利福霉素类抗生素及其构效关系研究进展

本文综述了抗结核病利福霉素类抗生素的不同结构修饰方法、构效关系(SAR)及其典型衍生物。同时,本文阐述了这些衍生物体内外抗结核分枝杆菌(MTB)活性,甚至包括一些候选药物的临床试验结果。其中重点讲述了利福平、利福布汀和利福拉齐的结构修饰衍生物,而目前利福布汀和利福拉齐的衍生物是近年利福霉素类抗结核药物研究的热点,发现了一些有较好开发前景的新候选物,如RFA-2和RFA-2,且利福平衍生物rifalong和利福霉素类杂合物也值得关注。     

Design,Synthesis, anticancer evaluation and in silico studies of 2,4,6-trimethoxychalcone derivatives

Chalcone, a common chemical scaffold of many naturally occurring compounds, has been widely used as an effective template for drug discovery due to its broad biological activities. In this study, a series of chalcone derivatives were designed and synthesized based on the hybridization of 1-(2,4,6-trimethoxyphenyl)butan-1-one with chalcone. Interestingly, most of the target compounds exhibited inhibitory effect of tumor cells in vitro. Especially, (E)-3-(5-bromopyridin-2-yl)-1-(2,4,6-trimethoxyphenyl)prop-2-en-1-one (B3) revealed over 10-fold potency than 5-fluorocrail against the Hela and MCF-7 cells with IC₅₀ values of 3.204 and 3.849 μM respectively. Moreover, B3 displayed low toxicity on normal cells. Further experiments indicated that B3 effectively inhibited the proliferation and migration of tumor cells, and promoted their apoptosis. The calculation and prediction of ADME showed that the target compounds may have good pharmacokinetic properties and oral bioavailability. Reverse molecular docking suggested that the possible target of B3 is CDK1. Taken together, these results suggested that B3 appears to be a promising candidate that merits further attention in the development of anticancer drugs.