Captopril and 6-mercaptopurine: Whose SH possesses higher antioxidant ability?

Synthesis and Isolation of Phenol- and Thiol-Derived Epicatechin Adducts Prepared from Avocado Peel Procyanidins Using Centrifugal Partition Chromatography and the Evaluation of Their Antimicrobial and Antioxidant Activity

Polyphenols from agro-food waste represent a valuable source of bioactive molecules that can be recovered to be used for their functional properties. Another option is to use them as starting material to generate molecules with new and better properties through semi-synthesis. A proanthocyanidin-rich (PACs) extract from avocado peels was used to prepare several semi-synthetic derivatives of epicatechin by acid cleavage in the presence of phenol and thiol nucleophiles. The adducts formed by this reaction were successfully purified using one-step centrifugal partition chromatography (CPC) and identified by chromatographic and spectroscopic methods. The nine derivatives showed a concentration-dependent free radical scavenging activity in the DPPH assay. All compounds were also tested against a panel of pathogenic bacterial strains formed by Listeria monocytogenes (ATCC 7644 and 19115), Staphylococcus aureus (ATCC 9144), Escherichia coli (ATCC 11775 and 25922), and Salmonella enterica (ATCC 13076). In addition, adducts were tested against two no-pathogenic strains, Limosilactobacillus fermentum UCO-979C and Lacticaseibacillus rhamnosus UCO-25A. Overall, thiol-derived adducts displayed antimicrobial properties and, in some specific cases, inhibited biofilm formation, particularly in Listeria monocytogenes (ATCC 7644). Interestingly, phenolic adducts were inactive against all the strains and could not inhibit its biofilm formation. Moreover, depending on the structure, in specific cases, biofilm formation was strongly promoted. These findings contribute to demonstrating that CPC is a powerful tool to isolate new semi-synthetic molecules using avocado peels as starting material for PACc extraction. These compounds represent new lead molecules with antioxidant and antimicrobial activity.

Is it still worth renewing nucleoside anticancer drugs nowadays?

Nucleoside has situated the convergence point in the discovery of novel drugs for decades, and a large number of nucleoside derivatives have been constructed for screening novel pharmacological properties at various experimental platforms. Notably, nearly 20 nucleosides are approved to be used in the clinic treatment of various cancers. Nevertheless, the blossom of synthetic nucleoside analogs in comparison with the scarcity of nucleoside anticancer drugs leads to a question: Is it still worth insisting on the screening of novel anticancer drugs from nucleoside derivatives? Hence, this review attempts to emphasize the importance of nucleoside analogs in the discovery of novel anticancer drugs. Firstly, we introduce the metabolic procedures of nucleoside anticancer drug (such as 5-fluorouracil) and summarize the designing of novel nucleoside anticancer candidates based on clinically used nucleoside anticancer drugs (such as gemcitabine). Furthermore, we collect anticancer properties of some recently synthesized nucleoside analogs, aiming at emphasizing the availability of nucleoside analogs in the discovery of anticancer drugs. Finally, a variety of synthetic strategies including the linkage of sugar moiety with nucleobase scaffold, modifications on the sugar moiety, and variations on the nucleobase structure are collected to exhibit the abundant protocols in the achievement of nucleoside analogs. Taken the above discussions collectively, nucleoside still advantages for the finding of novel anticancer drugs because of the clearly metabolic procedures, successfully clinic applications, and abundantly synthetic routines.

7,8-dihydroxyflavone displayed antioxidant effect through activating HO-1 expression and inhibiting caspase-3/PARP activation in RAW264.7 cells

Flavonoids, which contain a benzo-γ-pyrone (C6-C3-C6) skeleton, have been reported to exhibit effective antioxidant ability. This study aimed to compare the antioxidant activities of 7,8-dihydroxyflavone (7,8-DHF) and 7-hydroxyflavone (7-HF) in H2 O2 , lipopolysaccharide (LPS), or tert-butyl hydroperoxide (t-BHP)-induced RAW264.7 cells, respectively. The antioxidant capacities of 7,8-DHF and 7-HF were firstly evaluated by 2,2-azinobis-3-ethyl-benzothiazoline-6-sulphonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. Then, reactive oxygen species (ROS), super oxide dismutase (SOD), and malondialdehyde (MDA) productions in H2 O2 , LPS, or t-BHP-induced RAW264.7 cells were tested and compared, respectively. Finally, the antioxidant mechanisms of 7-HF and 7,8-DHF were initially investigated by western blot. Our results showed that 7,8-DHF possessed stronger free-radical scavenging capacity than 7-HF. Both 7,8-DHF and 7-HF suppressed MDA production and ROS accumulation, improved the activity of SOD in H2 O2 , LPS, or t-BHP-induced RAW264.7 cells, respectively. And 7,8-DHF exerted a better antioxidant effect than 7-HF, especially in t-BHP-induced oxidative stress. Mechanically, 7,8-DHF prevented the activation of poly ADP-ribosepolymerase and caspase-3, meanwhile markedly upregulated the expression of HO-1 protein in t-BHP-induced oxidative stress. These results suggested that 7,8-DHF might serve as a potential pharmaceutical drug against oxidative stress injury.

Experimental and Molecular Modeling Studies on the Complexation of Chromium(III) with the Angiotensin-Converting Enzyme Inhibitor Captopril

Captopril (CPT) is an inhibitor of angiotensin I converting enzyme, used as a medication for the treatment of people with high blood pressure, renal insufficiency, and cardiovascular diseases. It inhibits the angiogenesis process, vasoconstriction, and tumor metastasis. Some metal-captopril complexes exhibit antimicrobial activities. In the current work, the formation of the Cr^III-CPT complex was studied spectrophotometrically and potentiometrically in aqueous solution. Kinetics of Cr^III-CPT complex formation was spectrophotometrically studied over the pH range 3.20-4.20, at an ionic strength of 0.3 M at 30-50 °C. Cr^III-CPT complex formation was potentiometrically studied at 25 °C, where ligand protonation constants and complexes' overall stability constants were calculated. UV-vis absorption spectra were executed to confirm the complex formation. Density functional theory and molecular dynamics simulation were performed to search the geometries of the Cr^III-CPT complex. Atoms in molecules and interaction region indicator calculations are used to investigate intermolecular interactions for the formation of Cr^III-CPT complex. The antimicrobial activity of the CPT ligand and Cr^III-CPT complex on the prevention and control of environmental pathogenic bacteria, as tested on both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative bacteria Escherichia coli (E. coli) via agar disc diffusion method, assess the ability to use as an antimicrobial agent. CPT had shown good antimicrobial activity against both types of bacteria, which had increased slightly the zone of inhibition in Cr-CPT that indicates the increased efficacy due to Cr(III) antimicrobial activity via its oxidative damage to the bacterial cell wall. No previous study tested the CPT antimicrobial activity against Gram-positive ones such as S. aureus.

Multicomponent Reactions for Integrating Multiple Functional Groups into an Antioxidant

A large number of convincing evidences has revealed the correlation of the pathogeny of diseases with the oxidative damages of DNA, protein, biomembrane, and other biological species, while supplementation of antioxidants is demonstrated to be a promising way to avoid, at least, rectify the unbalance redox status in vivo. Although many endeavors have focused on synthesis of antioxidants, a main hurdle still hinders the wide usages of synthetic antioxidants because of low bioavailability and potential cytotoxicity. The search for antioxidants with multiple functional groups being recognized by different receptors becomes a much sought by researchers, and multicomponent reactions (MCRs) provide with powerful tools for the construction of multifunctional antioxidants. Presented herein is a personal account on the application of MCRs for the synthesis of multifunctional antioxidants, while radical-induced oxidation of DNA acts as the experimental system for evaluating antioxidative effect. Concretely, the Biginelli three-component reaction (3CR) affords such a dihydropyrimidine scaffold that the tautomerization between C=S and C-SH leads to antioxidative effect. The Povarov 3CR is able to integrate multiple antioxidative groups, i. e., ferrocenyl and -N(CH₃ )₂ , into a quinoline scaffold, while the Groebke 3CR provides with imidazo[1,2-a]pyridine skeleton for inhibiting DNA oxidation. Additionally, the Knoevenagel-related MCRs also become efficient strategies for achieving radical-scavengers. On the other hand, the Ugi 4CR and Passerini 3CR result in the dipeptide and α-acyloxycarboxamide, respectively, with the benefit for the integration of antioxidative features by aliphatic chains. Therefore, MCRs have emerged as efficient tools for integrating multiple antioxidative features into one molecule in order to meet with complicated requirements from various biological surroundings.

Efficiency comparison of apigenin-7-O-glucoside and trolox in antioxidative stress and anti-inflammatory properties

OBJECTIVES

Chamomile has long been used as a medicinal plant due to its antioxidative and anti-inflammatory activity. Apigenin-7-O-glucoside (AG) is one of the major ethanol extract components from chamomile; however, the underlying mechanism remains unclear.

METHODS

In this study, the antioxidant potential and the anti-inflammatory activities of AG were analysed and compared with those of trolox. We demonstrate the protective effects of AG on free radical-induced oxidative damage of DNA, proteins and erythrocytes. Flow cytometry assay was used to detect ROS production. Additionally, the expression of anti-oxidation-related and inflammation-related factors was detected by ELISA and Western blotting, respectively.

KEY FINDINGS

AG and trolox showed different efficiency as antioxidant in different experimental systems. AG had similar effect as trolox to inhibit H₂ O₂ -induced ROS production in RAW264.7 cells, while exerted stronger inhibition against free radical-induced oxidative damage on erythrocytes than trolox. Interestingly, compared with trolox, AG also had stronger inhibitory effect on LPS-induced NF-κB/NLRP3/caspase-1 signalling in RAW246.7 cells.

CONCLUSIONS

These results suggest the potential of AG as a pharmaceutical drug for anti-oxidation and anti-inflammation, and the combined usage of AG and trolox might promote its efficacy. Our findings will provide new insights into the development of new drugs with antioxidative and anti-inflammatory functions.

Bridging free radical chemistry with drug discovery: A promising way for finding novel drugs efficiently

Many diseases have been regarded to correlate with the in vivo oxidative damages, which are caused by overproduced free radicals from metabolic process or reactive oxygen species (ROS). This background motivates chemists to explore free radical reactions and to design a number of antioxidants, but whether free radical chemistry can be applied to accelerate the efficacy of the drug discovery is still underrepresented. Herein, in light of recent findings as well as kinetics on free radical reaction, the discipline of free radical chemistry is introduced to be a novel tool for finding potential drugs from antioxidant libraries accumulated during the study on free radical chemistry. These antioxidants provide with such abundant types of structural skeleton that might be employed to inhibit oxidations in different biological microenvironments. Although the in vitro characterization on the antioxidative property exerts a potential role of an antioxidant as a prodrug, the in vivo investigation on the property for quenching free radicals will make a final decision for the antioxidant whether it is worthy to be further explored pharmacologically. Therefore, it is reasonable to expect that bridging free radical chemistry with the pharmacological research will provide with a succinct way for finding novel drugs efficiently.

Chemiluminometric determination of captopril in a multi-pumping flow system

In this work, a simple, versatile and fully automated analytical methodology for the chemiluminometric determination of captopril - an angiotensin II-converting-enzyme (ACE) inhibitor - in pharmaceutical formulations, is proposed. The developed methodology was based on the enhancement by captopril of the chemiluminescence emission of tris(2,2'-bipyridyl)ruthenium(II). In sulphuric acid medium tris(2,2'-bipyridyl)ruthenium(II) was oxidized by cerium(IV) and converted into a reactive oxidant specie [Ru(bpy)(3)](3+), which was subsequently reduced with captopril in order to yield a significant enhancement of the original chemiluminescence emission that was directly related to captopril concentration. The analytical process was implemented by resorting to an automated multi-pumping flow system (MPFS) that enabled the establishment of multiple reaction interfaces, which, in combination with the created pulsed flowing stream assured a fast and reproducible sample/reagent mixing and reaction development essential to guarantee the generation and subsequent measurement of the short-lived species involved in the chemiluminescent process. The developed system employed three solenoid micro-pumps as the only flow manifold active components. These assured the insertion, propelling and commuting of all solutions. The automatic actuation of the solenoid micro-pumps provided an easily programmed, operated and controlled analytical flow system, exhibiting high versatility, efficiency and compactness at a low cost. Under the optimized experimental conditions, the proposed method allowed the determination of captopril for concentrations between 2×10(-3) and 1.5×10(-1)mmolL(-1) (r=0.9996, n=6) and a sampling frequency of about 58 determinations per hour, producing 620μL of waste per determination. The results obtained for pharmaceutical formulations were statistically comparable to those provided by the reference procedure with a relative deviation between -2.32 and 1.39%. The possible mechanism of the chemiluminescence reaction was also discussed in this work.

Therapeutic effect of captopril, pentoxifylline, and cordyceps sinensis in pre-hepatic portal hypertensive rats

BACKGROUND/AIM

Portal hypertension is an important and potentially fatal complication of liver disease whereby cellular and fibrotic alterations manifest to increase portal venous pressure. The aim of this study is to investigate the effect of captopril, pentoxifylline (PTX), and cordyceps sinensis in pre-hepatic portal hypertensive rats.

SETTINGS AND DESIGN

Wistar male rats were divided at random into 3 main groups: the first group: control rats. The second group: sham-operated rats and the third group: prehepatic portal hypertensive rats (PHPHT) induced by regulated pre-hepatic portal vein ligation. After 14 days, Group 3 was subdivided into 5 subgroups. Subgroup (1): portal vein-ligated (PVL) was killed at once; Subgroup (2): received distilled water for 30 days (untreated PVL group); subgroups 3-5 were treated with captopril (60 mg/kg, orally); PTX (100 mg/kg, orally); and C. sinensis (200 mg/kg, orally), respectively, as a single daily dose for 30 days.

PATIENTS AND METHODS

Portal pressure, nitric oxide (NO), antioxidant enzymes, Liver enzymes, and creatinine levels were measured to evaluate the status of the liver state.

RESULTS

Portal vein ligation produced significant increments in liver enzymes, NO, creatinine and portal pressure concomitant with significant decrements in glutathione content and superoxide dismutase activity. Treatment with captopril, PTX, and C. sinensis resulted in a significant reduction in liver enzymes, NO, creatinine and portal pressure and observable increase in antioxidant enzymes.

CONCLUSIONS

captopril, PTX, and C. sinensis have promising effect in controlling PHPHT and reducing hyperdynamic circulatory state through reduction of portal pressure and NO level.

Properties of synthetic homoisoflavonoids to reduce oxidants and to protect linoleic acid and dna against oxidation

3-(2'-, 3'-, and 4'-Hydroxybenzylidene)-7-methoxychroman-4-one (o-, m-, and p-HBMC) was synthesized for the clarification of the influence of the hydroxyl group at the B ring on the antioxidant activity of homoisoflavonoid. The three homoisoflavonoids used herein can reduce peroxynitrite. p-HBMC exhibited high activity to reduce singlet oxygen. Furthermore, o-, m-, and p-HBMC can scavenge the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS(*+)) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and galvinoxyl radicals. The rates of o-HBMC trapping of DPPH and galvinoxyl radicals were higher than those of m- and p-HBMC, whereas m-HBMC can trap ABTS(*+) rapidly. o-HBMC was found to possess high activity in the beta-carotene-linoleic acid bleaching test and to protect methyl linoleate against 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH)-induced oxidation efficiently. Finally, o-HBMC served as a prooxidant in Cu(2+)/glutathione (GSH)- and hydroxyl radical-mediated oxidations of DNA. m- and p-HBMC protected DNA against hydroxyl radical-mediated oxidation of DNA effectively, and o- and p-HBMC behaved as antioxidants to protect DNA against AAPH-induced oxidation. Thus, the hydroxyl group attaching to the ortho- and para-positions in the B ring was of importance for the homoisoflavonoid's enhancement of antioxidant activity.