Caffeic Acid Phenethyl Ester (CAPE): Biosynthesis, Derivatives and Formulations with Neuroprotective Activities

Neurodegenerative disorders are characterized by a progressive process of degeneration and neuronal death, where oxidative stress and neuroinflammation are key factors that contribute to the progression of these diseases. Therefore, two major pathways involved in these pathologies have been proposed as relevant therapeutic targets: The nuclear transcription factor erythroid 2 (Nrf2), which responds to oxidative stress with cytoprotecting activity; and the nuclear factor NF-κB pathway, which is highly related to the neuroinflammatory process by promoting cytokine expression. Caffeic acid phenethyl ester (CAPE) is a phenylpropanoid naturally found in propolis that shows important biological activities, including neuroprotective activity by modulating the Nrf2 and NF-κB pathways, promoting antioxidant enzyme expression and inhibition of proinflammatory cytokine expression. Its simple chemical structure has inspired the synthesis of many derivatives, with aliphatic and/or aromatic moieties, some of which have improved the biological properties. Moreover, new drug delivery systems increase the bioavailability of these compounds in vivo, allowing its transcytosis through the blood-brain barrier, thus protecting brain cells from the increased inflammatory status associated to neurodegenerative and psychiatric disorders. This review summarizes the biosynthesis and chemical synthesis of CAPE derivatives, their miscellaneous activities, and relevant studies (from 2010 to 2023), addressing their neuroprotective activity in vitro and in vivo.

Propolis: An update on its chemistry and pharmacological applications

Propolis, a resinous substance produced by honeybees from various plant sources, has been used for thousands of years in traditional medicine for several purposes all over the world. The precise composition of propolis varies according to plant source, seasons harvesting, geography, type of bee flora, climate changes, and honeybee species at the site of collection. This apiary product has broad clinical applications such as antioxidant, anti-inflammatory, antimicrobial, anticancer, analgesic, antidepressant, and anxiolytic as well asimmunomodulatory effects. It is also well known from traditional uses in treating purulent disorders, improving the wound healing, and alleviating many of the related discomforts. Even if its use was already widespread since ancient times, after the First and Second World War, it has grown even more as well as the studies to identify its chemical and pharmacological features, allowing to discriminate the qualities of propolis in terms of the chemical profile and relative biological activity based on the geographic place of origin. Recently, several in vitro and in vivo studies have been carried out and new insights into the pharmaceutical prospects of this bee product in the management of different disorders, have been highlighted. Specifically, the available literature confirms the efficacy of propolis and its bioactive compounds in the reduction of cancer progression, inhibition of bacterial and viral infections as well as mitigation of parasitic-related symptoms, paving the way to the use of propolis as an alternative approach to improve the human health. However, a more conscious use of propolis in terms of standardized extracts as well as new clinical studies are needed to substantiate these health claims.

Bioinductive and anti-inflammatory properties of Propolis and Biodentine on SHED

Objectives

This study aimed to evaluate and compare the cell viability, differentiation potential and anti-inflammatory potential of propolis and Biodentine™ on stem cells isolated from human exfoliated deciduous teeth (SHED).

Materials and methods

SHED were segregated and cultured from the dental pulp of children after therapeutic extraction. Microculture Tetrazolium Assay (MTT) assay was carried out for assessing cell proliferation potential of propolis and Biodentine at different concentrations. As per the results from cell proliferation assay, cell differentiation potential of SHED was evaluated at concentration of 12.5 μg/ml using Alizarin Red staining. The anti-inflammatory potential of test materials was evaluated using gelatin zymography by detecting MMP-2 and MMP-9.

Results

The maximum cell proliferation percentage of SHED treated with propolis and Biodentine was observed at a concentration of 12.5 μg/ml, on day 7, 14 and 21 with Biodentine having maximum cell proliferation potential followed by propolis. SHED treated with Biodentine showed maximum cell differentiation on day 7 (107.16), 14 (106.29) and 21 (107.72). However, anti-inflammatory activity against MMP-2 was 95 % with propolis and 85 % with Biodentine and whereas, against MMP-9 it was 65 % for propolis and 47 % for Biodentine.

Conclusion

Propolis shows comparable cell viability, cell proliferation and differentiation potential on SHED when compared to Biodentine. It also exhibits better invitro anti-inflammatory activity on SHED compared to Biodentine. Further studies are warranted to validate the application of propolis as an effective and economical alternative biocompatible agent to Biodentine for vital pulp therapies.

Experimental Evidence for Therapeutic Potentials of Propolis

Propolis is produced by honeybees from materials collected from plants they visit. It is a resinous material having mixtures of wax and bee enzymes. Propolis is also known as bee glue and used by bees as a building material in their hives, for blocking holes and cracks, repairing the combs and strengthening their thin borders. It has been extensively used since ancient times for different purposes in traditional human healthcare practices. The quality and composition of propolis depend on its geographic location, climatic zone and local flora. The New Zealand and Brazilian green propolis are the two main kinds that have been extensively studied in recent years. Their bioactive components have been found to possess a variety of therapeutic potentials. It was found that Brazilian green propolis improves the cognitive functions of mild cognitive impairments in patients living at high altitude and protects them from neurodegenerative damage through its antioxidant properties. It possesses artepillin C (ARC) as the key component, also known to possess anticancer potential. The New Zealand propolis contains caffeic acid phenethyl ester (CAPE) as the main bioactive with multiple therapeutic potentials. Our lab performed in vitro and in vivo assays on the extracts prepared from New Zealand and Brazilian propolis and their active ingredients. We provided experimental evidence that these extracts possess anticancer, antistress and hypoxia-modulating activities. Furthermore, their conjugation with γCD proved to be more effective. In the present review, we portray the experimental evidence showing that propolis has the potential to be a candidate drug for different ailments and improve the quality of life.

Antioxidant effect of caffeic acid phenethyl ester in experimentally induced periodontitis

OBJECTIVES

The aim of the present study was to evaluate the antioxidant effect of systemically administered caffeic acid phenethyl ester (CAPE) in periodontitis.

MATERIALS AND METHODS

Forty rats were randomly divided into four groups: control, lipopolysaccharide-induced experimental periodontitis (LPS), CAPE 5: LPS+5 μmol/kg/day CAPE, and CAPE 10: LPS+10 μmol/kg/day CAPE. Following lipopolysaccharide-induced experimental periodontitis, CAPE was administered intraperitoneally for 28 days. Gingival and serumal total antioxidant status (TAS) and total oxidant status (TOS) were analyzed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Gingival tissue TAS was significantly higher with CAPE application compared with the LPS group and was highest in the CAPE 10 group (p<0.05). Gingival tissue TOS was highest in the LPS group, and both of the CAPE dosages decreased the gingival tissue TOS, with the highest decrease in the CAPE 10 group (p<0.05). The differences were not significant for serumal TAS or TOS levels (p>0.05).

CONCLUSIONS

The effect of CAPE on increased TAS and decreased TOS levels in inflamed gingival tissue indicates the antioxidant therapeutic potential of CAPE in periodontitis.

CLINICAL RELEVANCE

Within the limitations of this study, CAPE may be suggested as an effective host modulator agent for reducing oxidative stress in gingival tissue and might be considered as an adjunctive therapy in periodontitis.

Defensive impact of propolis against CCl4 actuated rats' testicular damage

Objective:

The paper’s primary goal is to report the devastating impact of carbon tetrachloride (CCl₄) on rat testicular tissue and the possible protecting function of propolis against CCl₄ based on its free radical scavenging and inflammatory relief properties.

Materials and Methods:

A total of 24 adult male albino rats had been classified into four groups (six rats/group). Rats of group 1 served as control, whereas groups 2–4 received propolis (200 mg/kg/day), CCl₄ (3 ml/kg/day), and propolis/CCl₄, respectively. After 4 weeks, the collected sera were applied for the estimation of lipid profile and sex hormones. Also, histopathological picture, malondialdehyde, and tumor necrosis factor alpha (TNFα) gene profile was measured in collected testicular tissues.

Results:

The present information revealed a noteworthy change (p < 0.05) in lipid profile, decrease in testicular weight, testosterone, antioxidants values along with a prominent increase (p < 0.05) in estradiol, lipid peroxidation values, and expression of TNFα in rats administrated with CCl₄ compared to control. Moreover, the histopathological profile showed the degeneration of the epithelium. Interestingly, propolis attenuated the destructive effect of CCl₄ on rat testes.

Conclusion:

The examined dose of propolis reduced oxidation, and inflammatory reactions resulted from CCl₄ exposure and proved that it might have a helpful part in free radicals interceded diseases.

Cardiovascular Effects of Caffeic Acid and Its Derivatives: A Comprehensive Review

Caffeic acid (CA) and its phenethyl ester (CAPE) are naturally occurring hydroxycinnamic acids with an interesting array of biological activities; e.g., antioxidant, anti-inflammatory, antimicrobial and cytostatic. More recently, several synthetic analogs have also shown similar properties, and some with the advantage of added stability. The actions of these compounds on the cardiovascular system have not been thoroughly explored despite presenting an interesting potential. Indeed the mechanisms underlying the vascular effects of these compounds particularly need clarifying. The aim of this paper is to provide a comprehensive and up-to-date review on current knowledge about CA and its derivatives in the cardiovascular system. Caffeic acid, CAPE and the synthetic caffeic acid phenethyl amide (CAPA) exhibit vasorelaxant activity by acting on the endothelial and vascular smooth muscle cells. Vasorelaxant mechanisms include the increased endothelial NO secretion, modulation of calcium and potassium channels, and modulation of adrenergic receptors. Together with a negative chronotropic effect, vasorelaxant activity contributes to lower blood pressure, as several preclinical studies show. Their antioxidant, anti-inflammatory and anti-angiogenic properties contribute to an important anti-atherosclerotic effect, and protect tissues against ischemia/reperfusion injuries and the cellular dysfunction caused by different physico-chemical agents. There is an obvious shortage of in vivo studies to further explore these compounds' potential in vascular physiology. Nevertheless, their favorable pharmacokinetic profile and overall lack of toxicity make these compounds suitable for clinical studies.

Genome-Protecting Compounds as Potential Geroprotectors

Throughout life, organisms are exposed to various exogenous and endogenous factors that cause DNA damages and somatic mutations provoking genomic instability. At a young age, compensatory mechanisms of genome protection are activated to prevent phenotypic and functional changes. However, the increasing stress and age-related deterioration in the functioning of these mechanisms result in damage accumulation, overcoming the functional threshold. This leads to aging and the development of age-related diseases. There are several ways to counteract these changes: 1) prevention of DNA damage through stimulation of antioxidant and detoxification systems, as well as transition metal chelation; 2) regulation of DNA methylation, chromatin structure, non-coding RNA activity and prevention of nuclear architecture alterations; 3) improving DNA damage response and repair; 4) selective removal of damaged non-functional and senescent cells. In the article, we have reviewed data about the effects of various trace elements, vitamins, polyphenols, terpenes, and other phytochemicals, as well as a number of synthetic pharmacological substances in these ways. Most of the compounds demonstrate the geroprotective potential and increase the lifespan in model organisms. However, their genome-protecting effects are non-selective and often are conditioned by hormesis. Consequently, the development of selective drugs targeting genome protection is an advanced direction.

Bioavailability and In Vivo Antioxidant Activity of a Standardized Polyphenol Mixture Extracted from Brown Propolis

Several lines of evidence demonstrate the antioxidant, anti-inflammatory and antimicrobial activities of propolis, mostly ascribed to its polyphenol content. However, little is known regarding the bioavailability of propolis in acute and prolonged settings of oral administration. In this study, we first determined the content of the main polyphenols in a brown propolis extract obtained using a patented extraction method (Multi Dinamic Extraction—M.E.D.) by RP-HPLC-UV-PDA-MSn analysis, followed by the bioavailability of galangin and chrysin, the most abundant polyphenols in the mixture (7.8% and 7.5% respectively), following acute (single bolus of 500 mg/kg containing about 3.65 mg of the polyphenol mixture) and prolonged (100, 250 and 500 mg/kg body for 30 days) oral administration in 30 male 8 weeks old C57BL/6 wild-type mice. In the acute setting, blood was taken at 30 s and 5, 10, 15, 20, 25, 30, 45, 60 and 120 min following the oral bolus. In the prolonged setting, blood samples were obtained after 10, 20 or 30 days of administration. At the end of treatment, expression of antioxidant enzymes (superoxyde dismutase, SOD-1; catalase, CAT; glutathione peroxidase, GSS) was evaluated in liver tissue. Following both acute and prolonged administration, neither galangin nor chrysin were detectable in the plasma of mice, whereas the glucuronide metabolite of galangine was detectable 5 min after acute administration. At the end of the prolonged treatment SOD-1 was found to have increased significantly, unlike CAT and GSS. Overall, these data suggest that oral administration of whole brown propolis extract is followed by rapid absorption and metabolization of galangin followed by adaptations of the antioxidant first line defense system.

Phytochemical screening and in vitro antibacterial, antifungal, antioxidant and antitumor activities of the red propolis Alagoas

The study aimed to evaluate the antimicrobial activity, antioxidant, toxicity and phytochemical screening of the Red Propolis Alagoas. Antimicrobial activity was evaluated by disk diffusion method. Determination of antioxidant activity was performed using the DPPH assay (1.1-diphenyl-2-picrylhydrazyl), FTC (ferric thiocyanate) and determination of phenolic compounds by Follin method. Toxicity was performed by the method of Artemia salina and cytotoxicity by MTT method. The phytochemical screening for the detection of allelochemicals was performed. The ethanol extract of propolis of Alagoas showed significant results for antimicrobial activity, and inhibitory activity for Staphylococcus aureus and Candida krusei. The antioxidant activity of the FTC method was 80% to 108.3% hydrogen peroxide kidnapping, the DPPH method showed an EC50 3.97 mg/mL, the content of total phenolic compounds was determined by calibration curve gallic acid, resulting from 0.0005 mg/100 g of gallic acid equivalent. The extract was non-toxic by A. salina method. The propolis extract showed high activity with a higher percentage than 75% inhibition of tumor cells OVCAR-8, SF-295 and HCT116. Chemical constituents were observed as flavonones, xanthones, flavonols, and Chalcones Auronas, Catechins and leucoanthocyanidins. It is concluded that the extract can be tested is considered a potential source of bioactive metabolites.

Development of a novel biomaterial with an important osteoinductive capacity for hard tissue engineering

In this study we designed a composite biomaterial based on a high viscosity soft propolis extract (70% propolis) and shell clam, with antiseptic and osteoinductive qualities, that can be used in dentistry, orthopedics and other areas where hard tissue regeneration is needed. We assessed it in interaction with stabilized human cells isolated from dental papilla of wisdom teeth (D1MSCs). We performed detailed characterization of the obtained material by Scanning Electronic Microscopy (SEM), X-Ray Diffraction (XRD), Energy Dispersive X-Ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR) techniques. SEM investigation revealed the roughness and porosity of the shell, which acted like a scaffold, as it allowed cells to penetrate the pores, proliferate on the surface, spread and grow in the depressions provided by the substrate. in vitro cell viability, proliferation and differentiation assays showed that the newly obtain biomaterial presented low toxicity on D1MSCs and determined the development of numerous osteogenic nodules that were in a higher number even than in the specific induction medium. Our results demonstrated that the shell-propolis based biomaterial promoted and sustained human stem cells attachment, proliferation and differentiation, presenting an important osteoinductive effect essential for mineralized tissue reparation process.

Potential role of propolis in wound healing: Biological properties and therapeutic activities

Propolis is a resinous mixture that honey bees collect from the tree buds, sap flows, or other botanical sources. The chemical composition of propolis varies and depends on the geographical area, time of collection, seasonality, illumination, altitude, and food availability during propolis exploitation. The goal of this review is to discuss important concepts including mechanisms of action and therapeutic activities of propolis. The PubMed, ScienceDirect, and Cochrane Library databases were searched for the literature published from January the 1st 2000 to October the 1st 2017. Sixteen animals and three clinical studies were included. A quantitative and qualitative review was performed on the clinical trials and the animal studies were comprehensively overviewed. In this study, the clinical trials have been combined and the results were provided as meta-analysis. Propolis is a non-toxic natural product; however some cases of allergy and contact dermatitis to this compound have been described mainly among beekeepers. An important factor in impaired wound healing is biofilm formation; propolis as an anti-microbial agent can reduce biofilm generation and result in accelerated healing processes. Most of the in vivo studies on various wound models suggested the beneficial roles of propolis on experimental wound healing and this has also been approved in the clinical trial studies. However, there is a lack of information concerning, dose, side effects and clinical effectiveness of propolis on wounds. As the effectiveness of propolis between different products is variable, more characterizations should be done and future investigations comparing different propolis based products and characterization of their specific roles on different models of wounds are highly appreciated.

Chemical analyses and in vitro and in vivo toxicity of fruit methanol extract of Sechium edule var. nigrum spinosum

CONTEXT

Sechium edule (Jacq.) Sw. (Cucurbitaceae) is used in ethnomedicine, but the diversity of the varietal groups of this species has not often been considered. This is important because we previously reported that different variety of species exhibit different activities across different tumor cell lines.

OBJECTIVE

This study investigates the chemical composition and biological activities of extracts obtained from S. edule var. nigrum spinosum.

MATERIALS AND METHODS

The leukemia P388 cell line and mononuclear bone marrow cells (MNCBMs) were treated with the extract at a concentration ranging from 40 to 2370 μg/mL for cytotoxicity and viability assays. CD-1 mice were treated with 8-5000 mg/kg extract and monitored every hour for the first 24 h and subsequently for seven days for signs of toxicity (LD₅₀). In addition, the chromatographic profile of the extract was determined by HPLC.

RESULTS

The extract inhibits the proliferation of both P388 cells and MNCBMs, with IC₅₀ values of 927 and 1911 μg/mL, respectively, but reduced the viability and induced the apoptosis of only leukemia cells. The LD₅₀ was higher than 5000 mg/kg, and this concentration did not alter the blood chemistry or cell count but doubled the mitotic index in the bone marrow. The HPLC showed the presence of cucurbitacins, phloridzin, naringenin, phloretin, apigenin, and gallic, chlorogenic, vanillic, p-hydroxybenzoic, caffeic, and p-coumaric acids.

DISCUSSION AND CONCLUSION

Sechium edule var. nigrum spinosum contains bioactive compounds that explain the antiproliferative and nutraceutical activities, and its lack of physiological side effects constitutes an added value to a widely consumed vegetable.

Effect of Green and Brown Propolis Extracts on the Expression Levels of microRNAs, mRNAs and Proteins, Related to Oxidative Stress and Inflammation

A large body of evidence highlights that propolis exerts many biological functions that can be ascribed to its antioxidant and anti-inflammatory components, including different polyphenol classes. Nevertheless, the molecular mechanisms are yet unknown. The aim of this study is to investigate the mechanisms at the basis of propolis anti-inflammatory and antioxidant activities. The effects of two brown and green propolis extracts-chemically characterized by RP-HPLC-PDA-ESI-MSn-on the expression levels of miRNAs associated with inflammatory responses (miR-19a-3p and miR-203a-3p) and oxidative stress (miR-27a-3p and miR-17-3p), were determined in human keratinocyte HaCat cell lines, treated with non-cytotoxic concentrations. The results showed that brown propolis, whose major polyphenolic components are flavonoids, induced changes in the expression levels of all miRNAs, and was more active than green propolis (whose main polyphenolic components are hydroxycinnamic acid derivatives) which caused changes only in the expression levels of miR-19a-3p and miR-27a-3p. In addition, only brown propolis was able to modify (1) the expression levels of mRNAs, the target of the reported miRNAs, which code for Tumor Necrosis Factor-α (TNF-α), Nuclear Factor, Erythroid 2 Like 2 (NFE2L2) and Glutathione Peroxidase 2 (GPX2), and (2) the protein levels of TNF-α and NFE2L2. In conclusion, brown and green propolis, which showed different metabolite profiles, exert their biological functions through different mechanisms of action.

Caffeic acid phenethyl ester protects against glucocorticoid-induced osteoporosis in vivo: Impact on oxidative stress and RANKL/OPG signals

Glucocorticoid-induced osteoporosis (GIO) is one of the most common causes of secondary osteoporosis. Given that glucocorticoids are considered as a main component of the treatment protocols for a variety of inflammation and immune-mediated diseases besides its use as adjuvant to several chemotherapeutic agents, it is crucial to find ways to overcome this critical adverse effect. Caffeic acid phenethyl ester (CAPE), which is a natural compound derived from honeybee propolis displayed promising antiosteoporotic effects against mechanical bone injury in various studies. The current work aimed at investigating the potential protective effect of CAPE against GIO in vivo with emphasis on the modulation of oxidative status and receptor activator of NF-kB ligand (RANKL)/osteoprotegrin (OPG) signaling. The results showed that CAPE opposed dexamethasone (DEX)-mediated alterations in bone histology and tartarate-resistant acid phosphatase (TRAP) activity. In addition, CAPE restored oxidative balance, Runt-related transcription factor 2 (RunX2) expression and reduced caspase-3 activity in femur tissues. Co-administration of CAPE with DEX normalized RANKL/OPG ratio and Akt activation indicating a reduction in DEX-osteoclastogenesis. In conclusion, concurrent treatment of CAPE with DEX exhibited promising effects in the protection against DEX-induced osteoporosis through opposing osteoclastogenesis and protecting osteoblasts. The potent antioxidant activity of CAPE is, at least in part, involved in its anti-apoptotic effects and modulation of RunX2 and RANKL/OPG signals. The use of CAPE-enriched propolis formulas is strongly recommended for patients on chronic glucocorticoid therapy to help in the attenuation of GIO.

Caffeic Acid Phenethyl Ester: A Review of Its Antioxidant Activity, Protective Effects against Ischemia-reperfusion Injury and Drug Adverse Reactions

Propolis, a honey bee product, has been used in folk medicine for centuries for the treatment of abscesses, canker sores and for wound healing. Caffeic acid phenethyl ester (CAPE) is one of the most extensively investigated active components of propolis which possess many biological activities, including antibacterial, antiviral, antioxidant, anti-inflammatory, and anti-cancer effects. CAPE is a polyphenolic compound characterized by potent antioxidant and cytoprotective activities and protective effects against ischemia-reperfusion (I/R)-induced injury in multiple tissues such as brain, retina, heart, skeletal muscles, testis, ovaries, intestine, colon, and liver. Furthermore, several studies indicated the protective effects of CAPE against chemotherapy-induced adverse drug reactions (ADRs) including several antibiotics (streptomycin, vancomycin, isoniazid, ethambutol) and chemotherapeutic agents (mitomycin, doxorubicin, cisplatin, methotrexate). Due to the broad spectrum of pharmacological activities of CAPE, this review makes a special focus on the recently published data about CAPE antioxidant activity as well as its protective effects against I/R-induced injury and many adverse drug reactions.

Inhibition of Cytochrome P450 by Propolis in Human Liver Microsomes

Although propolis is one of the most popular functional foods for human health, there have been no comprehensive studies of herb-drug interactions through cytochrome P450 (CYP) inhibition. The purpose of this study was to determine the inhibitory effects of propolis on the activities of CYP1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1 and 3A4 using pooled human liver microsomes (HLMs). Propolis inhibited CYP1A2, CYP2E1 and CYP2C19 with an IC₅₀ value of 6.9, 16.8, and 43.1 μg/mL, respectively, whereas CYP2A6, 2B6, 2C9, 2D6, and 3A4 were unaffected. Based on half-maximal inhibitory concentration shifts between microsomes incubated with and without nicotinamide adenine dinucleotide phosphate, propolis-induced CYP1A2, CYP2C19, and CYP2E1 inhibition was metabolism-independent. To evaluate the interaction potential between propolis and therapeutic drugs, the effects of propolis on metabolism of duloxetine, a serotonin-norepinephrine reuptake inhibitor, were determined in HLMs. CYP1A2 and CYP2D6 are involved in hydroxylation of duloxetine to 4-hydroxy duloxetine, the major metabolite, which was decreased following propolis addition in HLMs. These results raise the possibility of interactions between propolis and therapeutic drugs metabolized by CYP1A2.

Brazilian red propolis: phytochemical screening, antioxidant activity and effect against cancer cells

BACKGROUND

The implementation of new public healthcare models that stimulate the use of natural products from traditional medicine, as a so-called integrated medicine, refers to an approach that use best of both conventional medicine and traditional medicine. Propolis is a widely used natural product by different ancient cultures and known to exhibit biological activities beneficial for health. The large number of studies conducted with propolis had shown that its chemical composition differs as a function of the climate, plant diversity and bee species and plays an important role on its therapeutic properties. The aim of this study was to analyse the phytochemical profile of the ethanolic extract of red propolis (EEP) and its fractionation, antioxidant action of EEP and its fractions hexane, cloroform and ethyl acetate and cytotoxic activity of EEP on human tumour cell lines SF-295 (glioblastoma), OVCAR-8 (ovary) and HCT-116 (colon).

METHODS

EEP was obtained by maceration with absolute ethanol, then it was concentrated in rotaevaporator up to complete evaporation of the solvent. The crude extract was fractionated with hexane, ethyl acetate, chloroform and methanol and they were subjected to phytochemical screening and total phenolic compounds. Antioxidant activity of EEP and fractions was done by means of the 2,2-diphenyl-1-picryhydrazyl (DPPH) method. Biomarkers of red propolis were identified by LC-Orbitrap-FTMS. To assess cytotoxic activity of the extract, cells were exposed to EEP over 72 h. Cell viability was assessed by means of MTT assay. The percentage of cell growth inhibition (IC50) was analysed by means of non-linear regression, and the absorbance values of the various investigated concentrations were subjected to one-factor analysis of variance (ANOVA) followed by Tukey's or Tamhane's tests (α = 0.05).

RESULTS

The results obtained using phytochemical screening and LC-Orbitrap-FTMS indicated the presence of phlobaphene tannins, catechins, chalcones, aurones, flavonones, flavonols, xanthones, pentacyclic triterpenoids and guttiferones in Brazilian red propolis. EEP and its hexane, chloroform and ethyl acetate fractions obtained by liquid-liquid partitioning exhibited satisfactory antioxidant percentages. EEP (IC50 < 34.27 μg/mL) exhibited high levels of cytotoxicity on all human tumour cell lines tested when compared to negative control.

CONCLUSIONS

C-Orbitrap-FTMS was useful to establish the chemical profile of the red propolis. Brazilian red propolis has antioxidant properties and decreases substantially the percentage of cell survival of human tumour cells; thus, it has potential to serve as an anticancer drug.

Caffeic acid phenethyl ester inhibits 3-MC-induced CYP1A1 expression through induction of hypoxia-inducible factor-1α

Caffeic acid phenethyl ester (CAPE), a natural component of propolis, is reported to have anticarcinogenic properties, although its precise chemopreventive mechanism remains unclear. In this study, we examined the effects of CAPE on 3-methylcholanthrene (3-MC)-induced CYP1A1 expression and activities. CAPE reduced the formation of the benzo[a]pyrene-DNA adduct. Moreover, CAPE inhibited 3-MC-induced CYP1A1 activity, mRNA expression, protein level, and promoter activity. CAPE treatment also decreased 3-MC-inducible xenobiotic-response element (XRE)-linked luciferase, aryl hydrocarbons receptor (AhR) transactivation and nuclear localization. CAPE induced hypoxia inducible factor-1α (HIF-1α) protein level and HIF-1α responsible element (HRE) transcriptional activity. CAPE-mediated HIF-1α reduced 3-MC-inducible CYP1A1 protein expression. Taken together, CAPE decreases 3-MC-mediated CYP1A1 expression, and this inhibitory response is associated with inhibition of AhR and HIF-1α induction.

Possible molecular targets for therapeutic applications of caffeic acid phenethyl ester in inflammation and cancer

Of the various derivatives of caffeic acid, caffeic acid phenethyl ester (CAPE) is a hydrophobic, bioactive polyphenolic ester obtained from propolis extract. The objective in writing this review article was to summarize all published studies on therapeutics of CAPE in inflammation and cancer to extract direction for future research. The possible molecular targets for the action of CAPE, include various transcription factors such as nuclear factor-κB, tissue necrosis factor-α, interleukin-6, cyclooxygenase-2, Nrf2, inducible nitric oxide synthase, nuclear factor of activated T cells, hypoxia-inducible factor-1α, and signal transducers and activators of transcription. Based on the valuable data on its therapeutics in inflammation and cancer, clinical studies of CAPE should also be conducted to explore its toxicities, if any.

Protective Effect of Total Phenolic Compounds from Inula helenium on Hydrogen Peroxide-induced Oxidative Stress in SH-SY5Y Cells

Inula helenium has been reported to contain a large amount of phenolic compounds, which have shown promise in scavenging free radicals and prevention of neurodegenerative diseases. This study is to investigate the neuroprotective effects of total phenolic compounds from I. helenium on hydrogen peroxide-induced oxidative damage in human SH-SY5Y cells. Antioxidant capacity of total phenolic compounds was determined by radical scavenging activity, the level of intracellular reactive oxygen species and superoxide dismutase activity. The cytotoxicity of total phenolic compounds was determined using a cell counting kit-8 assay. The effect of total phenolic compounds on cell apoptosis due to hydrogen peroxide-induced oxidative damage was detected by Hoechst 33258 and Annexin-V/PI staining using fluorescence microscope and flow cytometry, respectively. Mitochondrial function was evaluated using the mitochondrial membrane potential and mitochondrial ATP synthesis by JC-1 dye and high performance liquid chromatography, respectively. It was shown that hydrogen peroxide significantly induced the loss of cell viability, increment of apoptosis, formation of reactive oxygen species, reduction of superoxide dismutase activity, decrease in mitochondrial membrane potential and a decrease in adenosine triphosphate production. On the other hand, total phenolic compounds dose-dependently reversed these effects. This study suggests that total phenolic compounds exert neuroprotective effects against hydrogen peroxide-induced oxidative damage via blocking reactive oxygen species production and improving mitochondrial function. The potential of total phenolic compounds and its neuroprotective mechanisms in attenuating hydrogen peroxide-induced oxidative stress-related cytotoxicity is worth further exploration.

Caffeic acid phenethyl ester and therapeutic potentials

Caffeic acid phenethyl ester (CAPE) is a bioactive compound of propolis extract. The literature search elaborates that CAPE possesses antimicrobial, antioxidant, anti-inflammatory, and cytotoxic properties. The principal objective of this review article is to sum up and critically assess the existing data about therapeutic effects of CAPE in different disorders. The findings elaborate that CAPE is a versatile therapeutically active polyphenol and an effective adjuvant of chemotherapy for enhancing therapeutic efficacy and diminishing chemotherapy-induced toxicities.

Effects of propolis on lingual mucosa response of hamsters submitted to experimental carcinogenesis

OBJECTIVE

To assess the tissue reaction of the lingual mucosa in hamsters submitted to daily, alternating, topical applications of 9,10-dimethyl-1,2-benzanthracene (DMBA) and a commercial brand of an ethanol propolis extract (EPE).

METHODS

A total of 60 hamsters were divided into three groups with two experimental periods (13 and 20 weeks). The lateral edge of the tongue was submitted to daily, alternating, topical applications of 0.5% DMBA and 30% EPE (EPE group, n=20), 0.5% of DMBA and aqueous propolis extract (APE group, n=20) and 0.5% of DMBA and saline solution (DMBA group, n=20). The occurrence of clinical and histological alterations was analyzed, along with the measurement of the area and volume of the clinical alterations, the determination of structural and cytological alterations of the squamous epithelial tissue with atypias and the measurement of the histological area of squamous cell carcinomas.

RESULTS

There were no significant differences among groups regarding any of the variables analyzed in the two evaluation periods. At week 13, a single squamous cell carcinoma occurred in the EPE group. At week 20, the greatest occurrence of squamous cell carcinoma was also in the EPE group.

CONCLUSION

The mechanism of EPE (30% alcohol content) affecting the onset of tissue reaction and the promotion of carcinogenesis has not been clarified yet.

Enhanced antioxidant effect of caffeic acid phenethyl ester and Trolox in combination against radiation induced-oxidative stress

Combinations of antioxidants are believed to be more effective than single antioxidant because when antioxidants are combined they support each other synergistically to create a magnified effect. Discovering the enhancer effects or synergies between bioactive components is valuable for resisting oxidative stress and improving health benefits. The aim of this study was to investigate a possible cooperation of natural antioxidant caffeic acid phenethyl ester (CAPE) with synthetic antioxidant Trolox in the model systems of chemical generation of free radicals, lipid peroxidation of microsomes and radiation-induced oxidative injury in L929 cells. Based on the intermolecular interaction between CAPE and Trolox, the present study shows a synergistic effect of CAPE and Trolox in combination on elimination of three different free radicals and inhibition of lipid peroxidation initiated by three different systems. CAPE and Trolox added simultaneously to the L929 cells exerted an enhanced preventive effect on the oxidative injury induced by radiation through decreasing ROS generation, protecting plasma membrane and increasing the ratios of reduced glutathione/oxidized glutathione and the expression of key antioxidant enzymes mediated by nuclear factor erythroid 2 p45-related factor 2 (Nrf2). Our results showed for the first time that administration of CAPE and Trolox in combination may exert synergistic antioxidant effects, and further indicate that CAPE and Trolox combination functions mainly through scavenging ROS directly, inhibiting lipid peroxidation and promoting redox cycle of GSH mediated by Nrf2-regulated glutathione peroxidase and glutathione reductase expression.

The protective effects of caffeic acid phenethyl ester in isoniazid and ethambutol-induced ocular toxicity of rats

PURPOSE

This study intended to examine the effect of caffeic acid phenethyl ester (CAPE) on isoniazid (INH) and/or ethambutol (ETM)-induced retina and optic nerve toxicity in a rat model.

METHODS

This study included eight groups, each containing 10 rats. The groups were Control, INH, ETM, CAPE, INH+CAPE, ETM+CAPE, INH+ETM and INH+ETM+CAPE. Rats were given orally 50 mg/kg/d of INH and 50 mg/kg/d of ETM in tap water for 30 d. 10 μmol/kg of CAPE were intraperitoneally injected for 30 d. The first dose of CAPE was given 24 h before the INH and ETM treatment and continued until sacrifice. Control group was given only tap water for 30 d. Rats were anaesthetized and sacrificed on the 30th day of experiment. Superoxide dismutase (SOD) activities, malondialdehyde (MDA), total anti-oxidant status (TAS), total oxidant status (TOS) were measured on the dissected and excised retina and optic nerve samples. Fellow eyes were used for histopathologic evaluation and the retinal ganglion cell (RGC) count. In addition, CAPE, INH and ETM interaction with SOD isoforms were calculated in silico.

RESULTS

The SOD activity and TAS levels were found significantly higher in CAPE-treated groups compared to INH and/or ETM-treated groups (p < 0.0001). But the MDA, and TOS levels were significantly lower in CAPE-treated groups (p < 0.0001). The mean RGC count is significantly decreased in INH, ETM and INH+ETM groups compared with INH+CAPE, ETM+CAPE and INH+ETM+CAPE groups, respectively (p values 0.001, 0.042, and 0.001 respectively). Besides, in silico calculations showed that binding affinity of CAPE to SOD isotypes was higher than that of INH and ETM.

CONCLUSION

This study demonstrates that CAPE treatment may decrease the oxidative stress in the retina and optic nerve of INH- and ETM-treated rats and may prevent RGC loss. As an underlying mechanism, CAPE and SOD interaction seems crucial for alleviation of ocular oxidative stress and RGCs toxicity.

Probiotic metabolites as epigenetic targets in the prevention of colon cancer

Dietary interventions for preventing colon cancer have recently attracted increased attention from researchers and clinicians. The probiotics have emerged as potential therapeutic agents but are also regarded as healthy dietary supplements for nutrition and health applications. The probiotic metabolome may interfere with various cellular and molecular processes, including the onset and progression of colon cancer. Probiotic metabolites may lead to the modulation of diverse cellular signal transduction and metabolic pathways. The gut microbial metabolites (organic acids, bacteriocins, peptides, etc.) have been noted to interact with multiple key targets in various metabolic pathways that regulate cellular proliferation, differentiation, apoptosis, inflammation, angiogenesis, and metastasis. Progress in this field suggests that epigenetic alterations will be widely used in the near future to manage colon cancer. The present review provides insights into the molecular basis of the therapeutic applications and the chemopreventive activities of certain probiotic metabolites, with emphasis on the interaction between these metabolites and the molecular signaling cascades that are considered to be epigenetic targets in preventing colon cancer.

Is propolis safe as an alternative medicine?

Propolis is a resinous substance produced by honeybees as defense against intruders. It has relevant therapeutic properties that have been used since ancient times. Nowadays, propolis is of increasing importance as a therapeutic, alone or included in many medicines and homeopathic products or in cosmetics. Propolis is produced worldwide and honeybees use the flora surrounding their beehives for its production. Therefore its chemical composition may change according to the flora. The phenolic and volatile fractions of propolis have been revised in the present study, as well as some of the biological properties attributed to this natural product. An alert is given about the need to standardize this product, with quality control. This has already been initiated by some authors, mainly in the propolis from the poplar-type. Only this product can constitute a good complementary and alternative medicine under internationally acceptable quality control.

Lipophilic caffeic acid derivatives protect cells against H2O2-Induced DNA damage by chelating intracellular labile iron

Naturally occurring cinnamic acid derivatives are ubiquitously distributed in the plant kingdom, and it has been proposed that their consumption contributes to the maintenance of human health. However, the molecular mechanisms underlying their health keeping effects remain unknown. In the present investigation, we evaluated the capacity of several cinnamic acid derivatives (trans-cinnamic, p-coumaric, caffeic and ferulic acids, as well as caffeic acid-methyl and -propyl esters) to protect cells from oxidative stress-induced DNA damage. It was observed that effective protection was based on the ability of each compound to (i) reach the intracellular space and (ii) chelate intracellular "labile" iron. These results support the notion that numerous lipophilic iron chelating compounds, present abundantly in plant-derived diet components, may protect cells in conditions of oxidative stress and in this way be important contributors toward maintenance of human health.

The potential usage of caffeic acid phenethyl ester (CAPE) against chemotherapy-induced and radiotherapy-induced toxicity

Protection of the patients against the side effects of chemotherapy and radiotherapy regimens has attracted increasing interest of clinicians and practitioners. Caffeic acid phenethyl ester (CAPE), which is extracted from the propolis of honeybee hives as an active component, specifically inhibits nuclear factor κB at micromolar concentrations and show ability to stop 5-lipoxygenase-catalysed oxygenation of linoleic acid and arachidonic acid. CAPE has antiinflammatory, antiproliferative, antioxidant, cytostatic, antiviral, antibacterial, antifungal and antineoplastic properties. The purpose of this review is to summarize in vivo and in vitro usage of CAPE to prevent the chemotherapy-induced and radiotherapy-induced damages and side effects in experimental animals and to develop a new approach for the potential usage of CAPE in clinical trial as a protective agent during chemotherapy and radiotherapy regimens.

Caffeic acid phenethyl ester (CAPE) prevents methotrexate-induced hepatorenal oxidative injury in rats

OBJECTIVES

This study aimed to investigate the antioxidant and anti-inflammatory effects of caffeic acid phenethyl ester (CAPE) on the methotrexate (MTX)-induced hepatorenal oxidative damage in rats.

METHODS

Following a single dose of methotrexate (20 mg/kg), either vehicle (MTX group) or CAPE (10 µmol/kg, MTX + CAPE group) was administered for five days. In other rats, vehicle (control group) or CAPE was injected for five days, following a single dose of saline injection. After decapitation of the rats, trunk blood was obtained, and the liver and kidney tissues were removed for histological examination and for the measurement of malondialdehyde (MDA) and glutathione (GSH) levels and myeloperoxidase (MPO) and sodium potassium-adenosine triphosphatase (Na(+)/K(+) -ATPase) activity. TNF-α and IL-1β levels were measured in the blood.

KEY FINDINGS

Methotrexate administration increased the tissue MDA levels, MPO activity and decreased GSH levels and Na(+)/K(+) -ATPase activity, while these alterations were reversed in the CAPE-treated MTX group. Elevated TNF-α and IL-1β levels were also reduced with CAPE treatment.

CONCLUSIONS

The results of this study revealed that CAPE, through its anti-inflammatory and antioxidant actions, alleviates methotrexate-induced oxidative damage, which suggests that CAPE may be of therapeutic benefit when used with methotrexate.

Cytotoxic constituents of propolis inducing anticancer effects: a review

Objectives

Propolis is a honeybee product used extensively in traditional medicine for its antioxidant, anti-inflammatory, immunomodulatory and anticancer effects. Propolis exhibits a broad spectrum of biological activities because it is a complex mixture of natural substances. In this review, the antitumour effects of propolis extracts and its constituents (e.g. flavonoids, terpenes and caffeic acid phenethyl ester) are discussed.

Key findings

The effect of propolis on experimental carcinogenesis is discussed, as well as its possible mechanisms of action against tumours, involving apoptosis, cell cycle arrest and interference on metabolic pathways. Propolis seems to be efficient against different tumour cells both in vitro and in vivo, which suggests its potential in the development of new anticancer drugs.

Summary

Propolis extracts may be important economically and would allow a relatively inexpensive cancer treatment. Preclinical investigations are needed to further elucidate the benefits of propolis and its antitumour properties.

The bioactive compounds alpha-chaconine and gallic acid in potato extracts decrease survival and induce apoptosis in LNCaP and PC3 prostate cancer cells

We recently reported that colored potato extracts and an anthocyanin rich fraction suppressed lymph-node carcinoma of the prostate (LNCaP) and prostate cancer-3 (PC-3) prostate cancer cell proliferation and induced apoptosis via caspase-dependent and caspase-independent pathways. Chlorogenic acid, caffeic acid, gallic acid, catechin, malvidin, and glycoalkaloids (alpha-chaconine and solanine) have now been identified as the major bioactive components of potato, and their effects on LNCaP and PC-3 cell proliferation and apoptosis have been investigated. alpha-chaconine (5 microg/ml) and gallic acid (15 microg/ml) exhibited potent antiproliferative properties and increased cyclin-dependent kinase inhibitor p27 levels in both cell lines. Both alpha-chaconine and gallic acid induced poly [adenosine diphosphate (ADP)] ribose polymerase cleavage and caspase-dependent apoptosis in LNCaP cells; however, caspase-independent apoptosis through nuclear translocation of endonuclease G was observed in both LNCaP and PC-3 cells. alpha-chaconine and gallic acid activated c-Jun N-terminal protein kinase (JNK), and this response played a major role in induction of caspase-dependent apoptosis in LNCaP cells; whereas modulation of JNK and mitogen-activated protein kinase did not affect alpha-chaconine- and gallic acid-induced caspase-independent apoptosis. These results suggest that apoptosis induced by whole potato extracts in prostate cancer cell lines may be in part due to alpha-chaconine and gallic acid.

Synthesis of a series of caffeic acid phenethyl amide (CAPA) fluorinated derivatives: comparison of cytoprotective effects to caffeic acid phenethyl ester (CAPE)

A series of catechol ring-fluorinated derivatives of caffeic acid phenethyl amide (CAPA) were synthesized and screened for cytoprotective activity against H2O2 induced oxidative stress in human umbilical vein endothelial cells (HUVEC). CAPA and three fluorinated analogs were found to be significantly cytoprotective when compared to control, with no significant difference in cytoprotection between caffeic acid phenethyl ester (CAPE) and CAPA.

Antioxidant hydroquinones substituted by beta-1,6-linked oligosaccharides in wheat germ

Seven new compounds that demonstrate antioxidant properties, 4-hydroxy-3-methoxyphenyl beta-d-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (1), 4-hydroxyphenyl beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (2), 4-hydroxy-3-methoxyphenyl beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl-(1-->6)beta-D-glucopyranoside (3), 4-hydroxy-3-methoxyphenyl beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (4), 4-hydroxy-3,5-dimethoxyphenyl beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (5), 4-hydroxy-3,5-dimethoxyphenyl beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (6), and 4-hydroxy-2-methoxyphenyl beta-d-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (7), were isolated from wheat germ. The structures were determined by spectroscopic and chemical methods. Compound 1 was the most abundant, approximately 2 mg isolated from each gram of wheat germ. The antioxidant activity of compounds 1-7 was determined by the Trolox equivalent antioxidant capacity assay, and 2 and 7 showed higher values than the other compounds. Compounds 1 and 3-6 reacted with the radical cation reagent within a few seconds, whereas 2 and 7 required several minutes for complete reaction. Compound 1 was shown to protect plasmid DNA from oxidative stress damage caused by hydrogen peroxide; this effect was concentration-dependent.