Protective effect of Caffeic Acid Phenethyl Ester (CAPE) against oxidative stress

Antiradical properties of curcumin, caffeic acid phenethyl ester, and chicoric acid: a DFT study

The antiradical properties and possible mechanisms of action of the tautomers of curcumin, caffeic acid phenethyl ester (CAPE), and chicoric acid (CA) have been studied within density functional theory (DFT). We calculated global chemical reactivity descriptors from conceptual DFT, pK_a, bioavailability, and toxicity to evaluate the antiradical properties and characterize these species. Our final level of theory is the M06-2X functional with the 6-31 + G* basis set; we selected this level after performing a benchmark calibration and validation among different levels. Solvent effects were modeled via the continuum solvation model based on density (SMD). We used water and pentyl ethanoate as solvents to simulate the physiological conditions. The free radical scavenger capacity was analyzed for three possible oxidative stress mechanisms: single electron transfer (SET), hydrogen atom transfer (HAT), and xanthine oxidase (XO) inhibition. The results indicate that neutral curcumin, CA, and CAPE behave as antireductants. The most favorable mechanism turns out to be HAT, where CA and CAPE stand out. In conclusion, our DFT study strongly indicates that neutral curcumin, CAPE, and CA would very likely perform well as antiradical drugs with recommended therapeutic use, supported by their non-toxic nature.

Enzymes, In Vivo Biocatalysis, and Metabolic Engineering for Enabling a Circular Economy and Sustainability

Since the industrial revolution, the rapid growth and development of global industries have depended largely upon the utilization of coal-derived chemicals, and more recently, the utilization of petroleum-based chemicals. These developments have followed a linear economy model (produce, consume, and dispose). As the world is facing a serious threat from the climate change crisis, a more sustainable solution for manufacturing, i.e., circular economy in which waste from the same or different industries can be used as feedstocks or resources for production offers an attractive industrial/business model. In nature, biological systems, i.e., microorganisms routinely use their enzymes and metabolic pathways to convert organic and inorganic wastes to synthesize biochemicals and energy required for their growth. Therefore, an understanding of how selected enzymes convert biobased feedstocks into special (bio)chemicals serves as an important basis from which to build on for applications in biocatalysis, metabolic engineering, and synthetic biology to enable biobased processes that are greener and cleaner for the environment. This review article highlights the current state of knowledge regarding the enzymatic reactions used in converting biobased wastes (lignocellulosic biomass, sugar, phenolic acid, triglyceride, fatty acid, and glycerol) and greenhouse gases (CO₂ and CH₄) into value-added products and discusses the current progress made in their metabolic engineering. The commercial aspects and life cycle assessment of products from enzymatic and metabolic engineering are also discussed. Continued development in the field of metabolic engineering would offer diversified solutions which are sustainable and renewable for manufacturing valuable chemicals.

Potential of natural products as radioprotectors and radiosensitizers: opportunities and challenges

Natural products can be used as natural radiosensitizers and radioprotectors, showing promising effects in cancer treatments in combination with radiotherapy, while reducing ionizing radiation (IR) damage to normal cells/tissues. The different effects of natural products on irradiated normal and tumor cells/tissues have attracted more and more researchers' interest. Nonetheless, the clinical applications of natural products in radiotherapy are few, which may be related to their low bioavailability in the human body. Here, we displayed the radiation protection and radiation sensitization of major natural products, highlighted the related molecular mechanisms of these bioactive substances combined with radiotherapy to treat cancer, and critically reviewed their deficiency and improved measures. Lastly, several clinical trials were presented to verify the clinical application of natural products as radiosensitizers and radioprotectors. Further clinical evaluation is still needed. This review provides a reference for the utilization of natural products as radiosensitizers and radioprotectors.

Antihyperglycemic activity of crude extract and isolation of phenolic compounds with antioxidant activity from Moringa oleifera Lam. leaves grown in Southern Brazil

The antihyperglicemic activity of crude extract from Moringa oleifera leaves and isolation of phenolic compounds with antioxidant activity using bioguided assay were employed by the first time in leaves cultivated in Brazil. The hydroalcoholic extract (HE) was produced by using ethanol:water (80:20 v/v) and purified by solid-liquid procedure using solvents in ascending order of polarity. The ethyl acetate fraction (Fr-EtOAc) presented high antioxidant potential and it was purified using chromatographic techniques rendering isolated compounds that were identified from the spectral data. The HE extract (500 mg kg^-1) was adimistrated in diabetic rats induced by streptozotocin and chemical markers and lipid peroxidation in liver and kidney were evaluated. The Fr-EtOAc showed high antioxidant potential by FRAP reduction method (1678 µmol Fe²⁺ g^-1), DPPH and ABTS scavenging methods (526.7 and 671.5 µmol TEAC g^-1 respectively) and ORAC assay (3560.6 µmol TEAC g^-1). Therefore, the Fr-EtOAc was purified and yielded three bioactive subfractions (S-12, S-13 abd S-15) that were rechromatoghaphed in HPLC-SemiPrep. After that, two main bioactive glycosylated flavonoids (isoquercitrin and astragalin) and phenolic acid (3-O-caffeoylquinic acid) were obtained. Additionally, the HE extract provided protection against oxidative damage in liver and kidney of diabetic rats ameliorating endogenous antioxidant defenses by increase catalase (CAT), glutathione S-transferase (GST) and non-protein thiol groups (NPSH) levels as well as decreased the lipid peroxidation in these tissues. Our results indicate that three phenolic compounds with high antioxidant activity were isolated and, the chemical composition of HE crude extract, rich in flavonoids glycosylated could be intimately related to antihyperglycemic action. So, it is possible to suggest that these compounds may be used as chemical biomarkers for this plant in Brazil, ensuring quality and supporting the use of aerial parts in tradicional medicine.

Seasonality Modulates the Cellular Antioxidant Activity and Antiproliferative Effect of Sonoran Desert Propolis

The main chemical composition and pharmacological potential of propolis from arid and semi-arid regions of the Sonoran Desert have been previously reported. Caborca propolis (CP), from an arid zone of the Sonoran Desert, has shown a polyphenolic profile that suggests a mixed plant origin, presenting poplar-type markers, as well as a 6-methoxylated flavonoid, xanthomicrol, characteristic of Asteraceae plants. In addition, CP has shown significant antioxidant properties and antiproliferative activity on cancer cells. In this study, we analyzed the influence of collection time on the chemical constitution, antiproliferative activity and protective capacity of CP against reactive oxygen species (ROS), by using HPLC–UV–diode array detection (DAD) analysis, 3-(4,5-dimethylthiazol-2-yl)-2,5-Dimethyltetrazoliumbromide (MTT) and 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assays, as well as cellular antioxidant activity (CAA) assay on murine B-cell lymphoma M12.C3.F6 cells. HPLC–UV–DAD analyses of seasonally collected CP (one-year period) revealed quantitative differences among the most abundant CP constituents: pinocembrin, galangin, chrysin and pinobanksin-3-O-acetate. Though all seasonal samples of CP induced an antiproliferative effect in M12.C3.F6 cells, CP from autumn showed the highest inhibitory activity (IC₅₀: 5.9 ± 0.6 µg/mL). The DPPH assay pointed out that CP collected in autumn presented the highest antioxidant potential (IC₅₀: 58.8 ± 6.7 µg/mL), followed by winter (65.7 ± 12.2 µg/mL) and spring (67.0 ± 7.5 µg/mL); meanwhile, the summer sample showed a lesser antioxidant capacity (IC₅₀: 98.7 ± 2.5 µg/mL). The CAA assay demonstrated that CP induced a significant protective effect against ROS production elicited by H₂O₂ in M12.C3.F6 cells. Pretreatment of M12.C3.F6 cells with CP from spring and autumn (25 and 50 µg/mL for 1 h) showed the highest reduction in intracellular ROS induced by H₂O₂ (1 and 5 mM). These results indicate that the antiproliferative effect and cellular antioxidant activity of CP are modulated by quantitative fluctuations in its polyphenolic profile due to its collection time.

Bioinspired tailoring of fluorogenic thiol responsive antioxidant precursors to protect cells against H2O2-induced DNA damage

Natural antioxidants, like phenolic acids, possess a unique chemical space that can protect cellular components from oxidative stress. However, their polar carboxylic acid chemotype reduces full intracellular antioxidant potential due to limited diffusion through biological membranes. Here, we have designed and developed a new generation of hydrophobic turn-on fluorescent antioxidant precursors that upon penetration of the cell membrane, reveal a more polar and more potent antioxidant core and simultaneously become fluorescent allowing their intracellular tracking. Their activation is stimulated by polarity alteration by sensing intracellular signals and specifically biothiols. In our design, the carboxylic group of phenolic acids that originally restricts cell entrance is derivatized and conjugated through Copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC) to a coumarin derivative that its fluorescence properties are quenched with a biothiol activatable element. This more hydrophobic precursor readily penetrates cell membrane and once inside the cell the antioxidant core is revealed upon sensing glutathione, its fluorescence is restored in a turn-on manner and the generation of a more polar character traps the molecule inside the cell. This turn-on fluorescent antioxidant precursor that can be applied to phenolic acids, was developed for rosmarinic acid and the conjugate was named as RCG. The selectivity and responsiveness of RCG towards the most abundant biothiols was monitored through a variety of biophysical techniques including UV-Vis, fluorescence and NMR spectroscopy. The electrochemical behavior and free radical scavenging capacity of the precursor RCG and the active compound (RC) was evaluated and compared with the parent compound (rosmarinic acid) through cyclic voltammetry and EPR spectroscopy, respectively. The stability of the newly synthesized bioactive conjugate RC was found significantly higher than the parent rosmarinic acid when exposed to oxygen. Cell uptake experiments were conducted and revealed the internalization of RCG. The degree of intracellular DNA protection offered by RCG and its active drug (RC) on exposure to H₂O₂ was also evaluated in Jurkat cells.

Caffeic Acid Phenethyl Ester Effects: In Silico Study of its Osteoimmunological Mechanisms

Background:

Biological system complexity impedes the drug target identification by biological experiments. Thus drugs, rather than acting on target site only, can interact with the entire biological system. Study of this phenomenon, known as network pharmacology, provides grounds for biological target identification of new drugs or acts as a foundation for the discovery of new targets of present drugs. No publication is available on the interaction network of CAPE.

Aim:

This study was aimed at the investigation of the candidate targets and possible interactions of caffeic acid phenethyl ester (CAPE) involved in its osteoimmunological effects.

Methods:

This study encompasses the investigation of candidate targets and possible interactions of CAPE by analyzing through PASS Prediction and constructing a biological network of CAPE.

Results:

In response to input (CAPE), PASS Prediction generated a network of 1723 targets. While selecting the probability to be active (Pa) value greater than 0.7 brought forth only 27 targets for CAPE. Most of these targets predicted the therapeutic role of CAPE as an osteoimmunological agent. Apart from this, this network pharmacology also identified 10 potential anti-cancer targets for CAPE, out of which 7 targets have been used efficiently in developing potent osteoimmunological drugs.

Conclusion:

This study provides scientific prediction of the mechanisms involved in osteoimmunological effects of CAPE, presenting its promising use in the development of a natural therapeutic agent for the pharmaceutical industry. CAPE targets identified by web-based online databases and network pharmacology need additional in silico assessment such as docking and MD simulation studies and experimental verification to authenticate these results.

CAPE-pNO2 ameliorated diabetic nephropathy through regulating the Akt/NF-κB/ iNOS pathway in STZ-induced diabetic mice

Diabetic nephropathy (DN) is one of the most severe complications of diabetes mellitus. This study aimed to determine the effects and potential mechanism of caffeic acid para-nitro phenethyl ester (CAPE-pNO₂), a derivative of caffeic acid phenethyl ester (CAPE), on DN; In vivo, intraperitoneal injections of streptozotocin (STZ) were used to induce diabetes in mice; then, the mice were intraperitoneally injected daily with CAPE or CAPE-pNO₂ for 8 weeks. The mice were sacrificed, and blood samples and kidney tissues were collected to measure biological indexes. The results showed that CAPE and CAPE-pNO₂ could lower serum creatinine, blood urea nitrogen, 24-h albumin excretion, malondialdehyde and myeloperoxidase levels and increase superoxide dismutase activity in diabetic mice. According to HE, PAS and Masson staining, these two compounds ameliorated structural changes and fibrosis in the kidneys. In addition, the immunohistochemical and western blot results showed that CAPE and CAPE-pNO₂ inhibited inflammation through the Akt/NF-κB pathway and prevented renal fibrosis through the TGF-β/Smad pathway. In vitro, CAPE and CAPE-pNO₂ inhibited glomerular mesangial cell (GMC) proliferation, arrested cell cycle progression and suppressed ROS generation. These compounds also inhibited ECM accumulation via regulating the TGF-β1, which was a similar effect to that of the NF-κB inhibitor PDTC. More importantly, CAPE and CAPE-pNO₂ could up-regulate nitric oxide synthase expression in STZ-induced diabetic mice and HG-induced GMCs. CAPE-pNO₂ had stronger effects than CAPE both in vivo and in vitro. These data suggest that CAPE-pNO₂ ameliorated DN by suppressing oxidative stress, inflammation, and fibrosis via the Akt/NF-κB/ iNOS pathway.