Safety assessment of a newly synthesized copolymer for micellar delivery of hydrophobic caffeic acid phenethyl ester.

Caffeic acid phenethyl ester (CAPE), a major pharmacologically active component of poplar type propolis, is known for its proapoptotic, anti-inflammatory, antioxidant, antiviral, and enzyme inhibiting activities. The aim of this study was to perform an in vitro and in vivo safety assessment of a micellar system based on a newly synthesized copolymer, consisting of polyglycidol and poly(allyl glycidyl ether) (C12-PAGE-PG) as a drug delivery platform for CAPE. The in vitro studies on HepG2 and L929 cells by MTT and LDH assays after treatment with the empty and CAPE-loaded micelles showed no cytotoxic effects of the empty micelles and retained cytotoxic activity of CAPE loaded in the micelles. No hemolysis or stimulation of mouse lymphocytes or macrophages was observed in vitro. In vivo hematological, biochemical, and histological assays on rats, treated with the empty (2580 and 5160 µg/kg) or CAPE-loaded (375 and 750 µg CAPE/kg) micelles did not reveal pathological changes of any of the parameters assayed after 14-days' treatment. In conclusion, initial toxicological data characterize C12-PAGE-PG as a non-toxic and promising copolymer for development of micellar drug delivery systems, particularly for a hydrophobic active substance as CAPE.

Hydroxytyrosol enhances cisplatin-induced ototoxicity: Possible relation to the alteration in the activity of JNK and AIF pathways.

Hydroxytyrosol (HT), a polyphenol widely contained as an ester in olive fruits and olive leaves, exhibits a broad spectrum of effectiveness. The present study was designed to investigate the effect of HT alone as well as in the combination with cisplatin on the House Ear Institute-Organ of Corti 1 cells (HEI-OC1) and C57BL/6 cochlear hair cells in vitro. The cell viability was measured by cell counting kit-8 (CCK8) assay. The levels of reactive oxygen species were evaluated by Dichloro-dihydro-fluorescein diacetate (DCFH-DA) staining. The expression of phosphorylated Jun N-terminal kinase (p-JNK) and cleaved-caspase 3 was assessed by Western blotting. The apoptosis was detected by terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) staining. The distribution of apoptosis inducing factor (AIF) was determined by immunofluorescent staining. HT alleviated the levels of reactive oxygen species in both untreated state and after cisplatin stimulus. However, HT at concentration of 100 µM decreased the cell viability of HEI-OC1 from 100 ± 17.38% in control group to 50.17 ± 1.89% and increased the expression of p-JNK and c-caspase 3 from 0.62 ± 0.10, 0.20 ± 0.050 in the control group to 1.24 ± 0.18, 0.85 ± 0.18 in the group treated with 30 µM cisplatin, as well as to 1.64 ± 0.14, 1.44 ± 0.12 in the group with 30 µM cisplatin +100 µM HT, respectively. Meanwhile, HT triggered AIF transferring to nuclei and, also, led to cochlear HCs arranging disorderly and missing. Moreover, HT elevated the expression of p-JNK and c-caspase 3 from 1.00 ± 0.27, 1.00 ± 0.26 in the control group to 2.23 ± 0.24, 22.87 ± 3.80 in the group with 30 µM cisplatin, and to 2.75 ± 0.23, 31.56 ± 3.86 in the group with 30 µM cisplatin+100 µM HT correspondingly. Taken together, data from this work reveal that HT itself possesses toxic effect on HCs mainly thorough AIF-dependent apoptosis, while, it aggravates the ototoxicity-caused by cisplatin via both JNK and AIF pathways related apoptosis. Findings from this work offer clear evidence that that HT might not be recommended to utilize for preventing cisplatin-induced ototoxicity.

Caffeic acid phenethyl ester, a coffee polyphenol, inhibits DNA methylation in vitro and in vivo.

DNA methylation represents an important epigenetic regulation of the genome. Earlier studies have suggested that dietary phenolic compounds including those contained in coffee, tea and soy products may modulate the level of DNA methylation. In this study, we first characterize the effect of caffeic acid phenethyl ester (CAPE) and other dietary phenolic compounds on DNA methylation in vitro. The IC50 values of CAPE, daidzein, isorhamnetin and genistein are 7.6, 6.9, 6.2, and 4.3 µM, respectively, in an in-vitro enzymatic assay system. Computational analysis indicates that CAPE, daidzein, isorhamnetin and genistein can bind inside the DNA substrate-binding site in human DNMT1 with a favorable binding energy. In an animal study, we find that maternal CAPE treatment shifts the coat color distribution of the 21-day-old Avy/a offspring towards the yellow phenotype, indicating that CAPE inhibits the methylation of the agouti gene promoter sequence in vivo. The results from this study may shed light on the potential epigenetic effect in the offspring resulting from maternal intake of certain coffee phenolics during pregnancy.

Acute/Subacute and Sub-Chronic Oral Toxicity of a Hidroxytyrosol-Rich Virgin Olive Oil Extract.

The objective of this study was to determine the acute (one single dose), subacute (14 days), and sub-chronic (90 days) toxicity of an aqueous virgin olive oil (VOO) extract rich in hydroxytyrosol in rats. For acute/subacute toxicity, rats were divided into three groups. The control group received distilled water (n = 9), another experimental group received a single dose of 300 mg/kg (n = 3), and a third group received one dose of 2000 mg/kg (n = 4) during 14 days. The sub-chronic study included 60rats distributed in three groups (n = 20: 10 males and 10 females) receiving daily different three doses of the VOO extract in the drinking water during 90 days: (1) 100 mg/kg, (2) 300 mg/kg, and (3) 1000 mg/kg. In parallel, a fourth additional group (n = 20: 10 males and 10 females) did not receive any extract (control group). Clinical signs, body weight, functional observations of sensory and motor reactivity, hematological and biochemical analyses, and macroscopic and microscopic histopathology were evaluated. No adverse effects were observed after the administration of the different doses of the hydroxytyrosol-rich VOO extract, which suggests that the enrichment of VOO in its phenolic compound is safe, and can be used as functional foods for the treatment of chronic degenerative diseases.

Caffeic acid phenethyl ester (CAPE)-derivatives act as selective inhibitors of acetylcholinesterase.

Unexpected inhibitory effects against eeAChE could be found for a newly synthesized class of caffeic acid phenethyl ester (CAPE) derivatives. Thus, phenethyl-(E)-3-(3,5-dimethoxy-4-phenethoxyphenyl)-acrylate (Ki = 1.97 ±â€¯0.38 µM, Ki´â€¯= 2.44 ±â€¯0.07 µM) and 4-(2-(((E)-3-(3,4-bis(benzyloxy)phenyl)acryloyl)oxy)ethyl)-1,2-phenylene (2E,2'E)-bis(3-(3,4-bis(benzyloxy)phenyl)acrylate) (Ki = 0.72 ±â€¯0.31 µM, Ki´â€¯= 1.80 ±â€¯0.21 µM) showed very good inhibition of eeAChE, while being non cytotoxic for malignant human cancer cells and non-malignant mouse fibroblasts. Also, they are weak inhibitors for BChE (from equine serum).

Modulation of LPS-induced nitric oxide production in intestinal cells by hydroxytyrosol and tyrosol metabolites: Insight into the mechanism of action.

At intestinal level, after acute or chronic exposure to iNOS-derived NO, a toxic mechanism of action leads to inflammation and degenerative diseases. The aim of this study was to investigate the effect of glucuronide and sulfate metabolites of the extra virgin olive oil phenols tyrosol (Tyr) and hydroxytyrosol (HT), in comparison with their parent compounds, on the release of NO following exposure to a pro-inflammatory stimulus, the bacterial lipopolysaccharide (LPS). Human colon adenocarcinoma cells (Caco-2), differentiated as normal enterocytes, were treated with pathological concentrations of LPS, in order to stimulate iNOS pathway, which involves NF-ĸB activation through IĸBα phosphorylation and subsequent degradation induced by Akt or MAPKs. All the tested metabolites inhibited NO release induced by LPS, acting as inhibitors of iNOS expression, with an efficacy comparable to that of the parent compounds. HT and Tyr metabolites were effective in the inhibition of IĸBα degradation. No one of the compounds was able to inhibit Akt activation, whereas they modulated p38 and ERK1/2 MAPK. Obtained data show that HT and Tyr metabolites are able to prevent a pathological NO overproduction at intestinal level, where they concentrate, thus significantly contributing to the protective activity exerted by their parent compounds against inflammation.

Anti-inflammatory effects of olive-derived hydroxytyrosol on lipopolysaccharide-induced inflammation in RAW264.7 cells.

The control of inflammation, which arises from complex biological responses to harmful stimuli, is an important determinant of both clinical outcomes and patient comfort. However, the side effects of many current therapies such as non-steroidal anti-inflammatory drugs mean that new safe treatments are required. We previously reported that 12.5 µg/ml hydroxytyrosol (HT) suppressed gene expression of the inducible nitric oxide (NO) synthase (iNOS) isoform and NO production, in mouse peritoneal macrophages treated with lipopolysaccharide (LPS), where nuclear factor-κB (NF-κB) gene expression was not altered. The present study evaluated the anti-inflammatory effects of various concentrations of HT in LPS-induced RAW264.7 mouse macrophages. HT suppressed NF-κB signaling and downregulated LPS-mediated expression of iNOS, cyclooxygenase-2, tumor necrosis factor alpha, and interleukin-1ß at 12.5 µg/ml, resulting in reduced production of NO and prostaglandin E2. At lower concentrations, HT seemed to act via another signaling pathway to regulate the inflammatory response. In contrast, HT did not suppress LPS-induced expression of phosphorylated p44/42 mitogen-activated protein kinase. This study showed that HT had anti-inflammatory effects on LPS-stimulated RAW264.7 cells. HT is already available as a nutritional supplement and no toxic effects have been reported. Hence, HT represents a potential novel anti-inflammatory agent.

Quantitative Structure-Cytotoxicity Relationship of Cinnamic Acid Phenetyl Esters.

BACKGROUND/AIM: Many phenolic acid phenethyl esters possess diverse biological effects including antioxidant, cytoprotective, anti-inflammation and anti-tumor activities. However, most previous antitumor studies have not considered the cytotoxicity against normal cells. Ten cinnamic acid phenetyl esters were subjected to quantitative structure-activity relationship (QSAR) analysis, based on their cytotoxicity and tumor-specificity, in order to find their new biological activities. MATERIALS AND METHODS: Cytotoxicity against four human oral squamous cell carcinoma cell lines and three oral normal mesenchymal cells was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Tumor specificity (TS) was evaluated by the ratio of the mean 50% cytotoxic concentration (CC50) against normal oral cells to that against human oral squamous cell carcinoma cell lines. Potency-selectivity expression (PSE) value was calculated by dividing the TS value by CC50 against tumor cells. Apoptosis markers were detected by western blot analysis. Physicochemical, structural and quantum-chemical parameters were calculated based on the conformations optimized by force-field minimization. RESULTS: Western blot analysis demonstrated that [9] stimulated the cleavage of caspase-3, suggesting the induction of apoptosis. QSAR analysis demonstrated that TS values were correlated with shape, size and ionization potential. CONCLUSION: Chemical modification of the lead compound may be a potential choice for designing a new type of anticancer drugs.

Expanding Upon Styrene Biosynthesis to Engineer a Novel Route to 2-Phenylethanol.

2-Phenylethanol (2PE) is a key molecule used in the fragrance and food industries, as well as a potential biofuel. In contrast to its extraction from plant biomass and/or more common chemical synthesis, microbial 2PE production has been demonstrated via both native and heterologous expression of the yeast Ehrlich pathway. Here, a novel alternative to this established pathway is systematically engineered in Escherichia coli and evaluated as a more robust and efficient route. This novel pathway is constructed via the modular extension of a previously engineered styrene biosynthesis pathway, proceeding from endogenous l-phenylalanine in five steps and involving four heterologous enzymes. This "styrene-derived" pathway boasts nearly a 10-fold greater thermodynamic driving force than the Ehrlich pathway, and enables reduced accumulation of acetate byproduct. When directly compared using a host strain engineered for l-phenylalanine over-production, preservation of phosphoenolpyruvate, and reduced formation of byproduct 2-phenylacetic acid, final 2PE titers via the styrene-derived and Ehrlich pathways reached 1817 and 1164 mg L-1 , respectively, at yields of 60.6 and 38.8 mg g-1 . Following optimization of induction timing and initial glucose loading, 2PE titers by the styrene-derived pathway approached 2 g L-1 - nearly a two-fold twofold increase over prior reports for 2PE production by E. coli employing the Ehrlich pathway.

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 (CAPE) revisited: Covalent modulation of XPO1/CRM1 activities and implication for its mechanism of action.

Caffeic acid phenethyl ester (CAPE) is the bioactive constituent of propolis from honeybee hives and is well known for its anti-inflammatory, anticarcinogenic, antioxidant, and immunomodulatory properties. Herein, we revisited the cellular mechanism underlying the diverse biological effects of CAPE. We demonstrated that XPO1/CRM1, a major nuclear export receptor, is a cellular target of CAPE. Through nuclear export functional assay, we observed a clear shift of XPO1 cargo proteins from a cytoplasmic localization to nucleus when treated with CAPE. In particular, we showed that CAPE could specifically target the non-catalytic and conserved Cys528 of XPO1 through the means of mass spectrometric analysis. In addition, we demonstrated that the mutation of Cys528 residue in XPO1 could rescue the nuclear export defects caused by CAPE. Furthermore, we performed position-restraint molecular dynamics simulation to show that the Michael acceptor moiety of CAPE is the warhead to enable covalent binding with Cys528 residue of XPO1. The covalent modulation of nuclear export by CAPE may explain its diverse biological effects. Our findings may have general implications for further investigation of CAPE and its structural analogs.

Tyrosol and hydroxytyrosol derivatives as antitrypanosomal and antileishmanial agents.

Trypanosomiasis and leishmaniasis keep being a real challenge for health and development of African countries. Existing treatments have considerable side effects and increase resistance of the parasites. We have measured antitrypanosomal and antileishmanial activity of natural phenols, tyrosol (TYR) and hydroxytyrosol (HT) and several of their esters and metabolites. We found significant IC50 values against Trypanosoma brucei for HT decanoate ester and HT dodecanoate ester (0.6 and 0.36 µM, respectively). This represents a large increase in activity with respect to HT (79 and 132 fold, respectively). Moreover, both compounds displayed a high selectivity index against MRC-5, a non-tumoral human cell line (118 and 106, respectively). Then, we synthesized a focused library of compounds to explore structure-activity. We found the ether and thiourea analogs of HT decanoate ester and HT dodecanoate ester also showed IC50 values against T. brucei in the low micromolar range. In conclusion, the di-ortho phenolic ring and medium size alkyl chain are essential for activity whereas the nature of the chemical bond among them seems less important.

Investigations into the genotoxic potential of olive extracts.

The phenolic anti-oxidant 3-hydroxytyrosol (HT) is a major constituent of olives and olive oil. Published data showed it was negative in the Ames test at concentrations up to 5 µL per plate, but did induce chromosomal aberrations in human lymphocytes. HIDROX, an olive extract containing approximately 2.4% HT, was reported as both positive and equivocal in an Ames test in different papers from the same laboratory. Negative results for micronucleus induction in vivo in both an acute study and as part of a 90-day rat toxicity study were also reported for HIDROX. Given the widespread use and consumption of olives, olive oil and olive extracts, it was important to obtain more data. Here we confirm that pure HT, and an olive extract containing 15% HT, both induced micronuclei in cultured cells in vitro, but show that these responses were either due to high levels of cytotoxicity or to reaction of HT with culture medium components to produce hydrogen peroxide. Another extract (H40) containing 40% HT also induced micronuclei in vitro, probably via the same mechanism. However, both extracts were negative in robust Ames tests. The 15% HT formulated extract did not induce micronuclei in rat bone marrow after 4 weeks of dosing up to 561 mg HT/kg/day. H40 produced increased rat bone marrow micronucleus frequencies at 250 and 500 mg HT/kg/day in a 90-day toxicity study, but the results were questionable for various reasons. However, when two different batches of this extract were tested in acute micronucleus studies at doses up to 2000 mg HT/kg, giving plasma exposures that exceeded those in the 90-day study, negative results were obtained. Based on weight of evidence it is concluded that the olive extracts tested are not genotoxic at high doses in vivo, and any genotoxic risks for human consumers are negligible.

Dose-dependent metabolic disposition of hydroxytyrosol and formation of mercapturates in rats.

Hydroxytyrosol (HT), one of the major polyphenols present in olive oil, is known to possess a high antioxidant capacity. The aim of the present study was to investigate dose dependent (0, 1, 10 and 100 mg/kg) alterations in the metabolism of HT in rats since it has been reported that metabolites may contribute to biological effects. Special attention was paid to the activation of the semiquinone-quinone oxidative cycle and the formation of adducts with potential deleterious effects. Thus, we developed a novel analytical methodology to monitor the in vivo formation of the HT mercapturate, N-acetyl-5-S-cysteinyl-hydroxytyrosol in urine samples. Biomarkers of hepatic and renal toxicity were evaluated within the dose range tested. Following HT administration, dose-dependent effects were observed for the recovery of all the metabolites studied. At the lowest dose of 1 mg/kg, the glucuronidation pathway was the most relevant (25-30%), with lower recoveries for sulfation (14%), while at the highest dose of 100 mg/kg, sulfation was the most prevalent (75%). In addition, we report for the first time the formation of the mercapturate conjugate of HT in a dose-dependent manner. The biochemical data did not reveal significant toxic effects of HT at any of the doses studied. An increase in the GSH/GSSG ratio at the highest dose was observed indicating that the products of HT autoxidation are counteracted by glutathione, resulting in their detoxification. These results indicate that the metabolic disposition of HT is highly dependent on the dose ingested.

Hydroxytyrosol is not genotoxic in vitro.

Hydroxytyrosol (HT) is an olive-derived phenol endowed with several biological activities, some of which demonstrated in humans. Indeed, the European Food Safety Authority (EFSA) allows the health claim that HT (≥5mg/d) "protects LDL particles from oxidative damage". In terms of safety, HT has been investigated as the predominant part of raw olive mill waste water extracts that have been granted the Generally Recognized as Safe (GRAS) status. Also, a long-term toxicological study of HT proposed a NOAEL of 500mg/kg/d. As several HT-containing supplements and functional foods are entering the market, we sought to investigate the genotoxic and mutagenic potential of HT, using well-established in vitro models, i.e. the chromosomal aberration assay and the Ames test (by using the Salmonella typhimurium TA 100, TA98, TA1535, and TA1537 strains and Escherichia coli WP2(pKM101)), with and without S9-induced metabolic activation). Even though we cannot rule out that prolonged exposure to HT and its metabolites might have untoward effects, the results of this study indicate that HT is non-genotoxic and non-mutagenic at concentrations that far exceed those attainable after intake.

Selective cytotoxic activity of new lipophilic hydroxytyrosol alkyl ether derivatives.

Recent data suggest that hydroxytyrosol, a phenolic compound of virgin olive oils, has anticancer activity. This communication reports the synthesis of decyl and hexadecyl hydroxytyrosyl ethers, as well as the cytotoxic activity of hydroxytyrosol and a series of seven hydroxytyrosol alkyl ether derivatives against A549 lung cancer cells and MRC5 non-malignant lung fibroblasts. Hydroxytyrosyl dodecyl ether (HTDE) showed the highest selective cytotoxicity, and possible mechanisms of action were investigated; results suggest that HTDE can moderately inhibit glycolysis, induce oxidative stress, and cause DNA damage in A549 cells. The combination of HTDE with the anticancer drug 5-fluorouracil induced a synergistic cytotoxicity in A549 cancer cells but not in non-malignant MRC5 cells. HTDE also displayed selective cytotoxicity against MCF7 breast cancer cells versus MCF10 normal breast epithelial cells in the 1-30 µM range. These results suggest that the cytotoxicity of HTDE is more potent and selective than that of parent compound hydroxytyrosol.

In vitro and in vivo safety evaluation of Acer tegmentosum.

ETHNOPHARMACOLOGICAL RELEVANCE: Acer tegmentosum, which contains salidroside and tyrosol, has been used for the treatment of hepatic disorders in eastern Asia. However, little is known about its safety. AIM OF THE STUDY: To determine the safety of Acer tegmentosum, we evaluated its acute oral toxicity and genotoxicity profiles. MATERIALS AND METHODS: Salidroside and tyrosol present in Acer tegmentosum were quantified using high-performance liquid chromatography. Acute oral toxicity testing of Acer tegmentosum was performed in rats. Genotoxicity of Acer tegmentosum was assessed by bacterial reverse mutation, chromosomal aberration, and bone marrow micronucleus tests. All the tests were conducted in accordance with the good laboratory practices. RESULTS: The amounts of salidroside and tyrosol in Acer tegmentosum were found to be 85.01±1.21mg/g and 3.12±0.04mg/g, respectively. In the bacterial reverse mutation test, Acer tegmentosum increased the number of revertant Salmonella typhimurium TA98 colonies, regardless of metabolic activation by S9 mixture. In contrast, Acer tegmentosum application did not significantly increase the number of chromosomal aberrations in Chinese hamster ovary (CHO)-K1 cells and micronucleated polychromatic erythrocytes in mice. In the acute oral toxicity test, the median lethal dose (LD50) of Acer tegmentosum was found to be >2000mg/kg in rats. CONCLUSION: Take together, Acer tegmentosum exhibits mutagenicity, which was evident from the bacterial reverse mutation test. Further studies are needed to identify the components responsible for such an effect and the underlying mechanisms.

Oral and dermal developmental toxicity studies of phenylethyl alcohol in rats.

Phenylethyl alcohol (PEA) was tested for developmental toxicity. Pregnant rats were fed 0, 83, 266, or 799 mg/kg/d PEA on gestation days (GDs) 6 to 15; only minimal, nonsignificant effects were observed. In dermal studies, PEA (neat) was applied to the skin on GDs 6 to 15 at dosages of 0, 140, 430, or 1400 mg/kg/d and at 0, 70, 140, 280, 430, or 700 mg/kg/d in a corroborative study. Observations included maternal and embryo-fetal toxicity/abnormalities at 1400 mg/kg/d, increased incidences of rudimentary cervical ribs at ≥430 mg/kg/d, and reduced fetal body weights at ≥140 mg/kg/d. Dermal maternal and developmental no-observed-adverse-effect levels are 70 mg/kg/d, based on dermal irritation and reductions (nonsignificant) in fetal body weights. Human exposure from fragrances is 0.02 mg/kg/d, resulting in a margin of safety >2600, when marked differences in dermal absorption between rats and humans are considered. Under normal fragrance use conditions, PEA is not a developmental toxicity hazard for humans.

Toxicological evaluation of pure hydroxytyrosol.

Of all the phenolic constituents of olives and extra virgin olive oil, hydroxytyrosol is currently being actively exploited as a potential supplement or preservative to be employed in the nutraceutical, cosmeceutical, and food industry. In terms of safety profile, hydroxytyrosol has only been investigated as the predominant part of raw olive mill waste water extracts, due to the previous unavailability of appropriate quantities of the pure compound. We report the toxicological evaluation of hydroxytyrosol and, based on the results, propose a No Observed Adverse Effects Level (NOAEL) of 500mg/kg/d.

Ethanolic extract of propolis, chrysin, CAPE inhibit human astroglia cells.

PURPOSE: The aim of the present study was to examine the effect of freeze dried ethanolic extract of propolis (EEP), chrysin and caffeic acid phenethyl ester (CAPE) dependently on their concentrations on the viability and morphology of human astroglia cells line (SVGp12). MATERIAL AND METHODS: Using gas chromatography - mass spectroscopy (GC-MS) we have established the composition of lyophilisate of EEP collected in Podlasie region (Poland). After 24 h, 48 h and 72 h of exposition to EEP or its ingredients we evaluated the survivability of human astroglia cells (SVGp12) using MTT test. Morphological analysis of human astroglia cells was defined by transmission electron microscope. RESULTS: About 70 ingredients of EEP were evaluated by GC-MS. We obtained the strong decline of viability of astroglia cells SVGp12 approximately to 16% after EEP; 33% after chrysin and 25% after CAPE application. Condensed form of mitochondria observed in transmission electron microscope may indicate activation of intrinsic pathway of apoptosis induced by EEP, chrysin and CAPE in SVGp12 cell line. CONCLUSION: This study showed that EEP, chrysin and CAPE reduced viability of human astroglia cells probably due to apoptosis process.