DNA damage induced by caffeic acid phenyl ester in the presence of Cu(II) ions: Potential mechanism of its anticancer properties

Phytochemical composition, cytotoxicity, antioxidant and antimicrobial responses of Lavandula dentata L. grown under different levels of heavy metals stress condition

In order to know if the heavy metals stress condition is boon or bane for the plants growth, Lavandula dentata species was planted in pots under different levels of heavy metals stress condition and the phytochemical composition, cytotoxicity, antioxidant and antimicrobial responses of their leaf ethanolic extracts toward this stress condition were investigated compared to the control samples. Our findings showed significant differences in heavy metals bioaccumulation, photosynthetic pigments and total phenolic/flavonoids contents among L. dentata leafs ethanolic extracts, grown under different levels of heavy metals stress condition. The L. dentata leafs extracts, grown under Zn and Cu stress condition, showed the highest antioxidant and antimicrobial activities than those grown under Cd and Pb stress condition. Comparatively, the L. dentata leafs extracts, grown under Zn stress condition, showed higher antioxidant activity, and those, grown under Cu stress condition, showed higher antimicrobial activity. The highest cytotoxicity was showed by L. dentata leaf extracts, grown under Cd and Pb stress condition, which lead to conclude that these extracts could be served as a novel scaffold in search for new drugs against cancer. In conclusion, the highlighted variability reflects the high impact of heavy metals stress condition on phytochemical composition and consequently on the biological activities of medicinal plants. Such impact led to conclude that we should select medicinal plants extracts to be investigated carefully depending on this stress condition, in order to isolate the bioactive components or to have the best quality of extracts in terms of biological activities.

Possible Side Effects of Polyphenols and Their Interactions with Medicines

Polyphenols are an important component of plant-derived food with a wide spectrum of beneficial effects on human health. For many years, they have aroused great interest, especially due to their antioxidant properties, which are used in the prevention and treatment of many diseases. Unfortunately, as with any chemical substance, depending on the conditions, dose, and interactions with the environment, it is possible for polyphenols to also exert harmful effects. This review presents a comprehensive current state of the knowledge on the negative impact of polyphenols on human health, describing the possible side effects of polyphenol intake, especially in the form of supplements. The review begins with a brief overview of the physiological role of polyphenols and their potential use in disease prevention, followed by the harmful effects of polyphenols which are exerted in particular situations. The individual chapters discuss the consequences of polyphenols’ ability to block iron uptake, which in some subpopulations can be harmful, as well as the possible inhibition of digestive enzymes, inhibition of intestinal microbiota, interactions of polyphenolic compounds with drugs, and impact on hormonal balance. Finally, the prooxidative activity of polyphenols as well as their mutagenic, carcinogenic, and genotoxic effects are presented. According to the authors, there is a need to raise public awareness about the possible side effects of polyphenols supplementation, especially in the case of vulnerable subpopulations.

Caffeic acid phenethyl ester induces radiosensitization via inhibition of DNA damage repair in androgen-independent prostate cancer cells

In the present study, we evaluated the radiomodulatory potential of caffeic acid phenethyl ester (CAPE), an active component of traditional herbal medicine propolis. CAPE has been identified as a potent anticancer agent in multiple cancer types and is reported to have the dual role of radioprotection and radiosensitization. However, the radiomodulatory potential of CAPE in prostate cancer (PCa), which eventually becomes radioresistant is not known. Therefore, we studied the effect of co-treatment of CAPE and gamma radiation on androgen-independent DU145 and PC3 cells. The combination treatment sensitized PCa cells to radiation in a dose-dependent manner. The radiosensitizing effect of CAPE was observed in both cell lines. CAPE enhanced the level of ionizing radiation (IR)-induced gamma H2AX foci and cell death by apoptosis. The combination treatment also decreased the migration potential of PCa cells. This was confirmed by increased expression of E-cadherin and decrease in vimentin expression. CAPE sensitized PCa cells to radiation in vitro and induced apoptosis, augmented phosphorylation of Akt/mTOR, and hampered cell migration. At the mechanistic level, co-treatment of CAPE and IR inhibited cell growth by decreasing RAD50 and RAD51 proteins involved in DNA repair. This resulted in enhanced DNA damage and cell death. CAPE might represent a promising new adjuvant for the treatment of hormone-refractory radioresistant PCa.

Evaluation of the In Vitro Cytotoxic Activity of Caffeic Acid Derivatives and Liposomal Formulation against Pancreatic Cancer Cell Lines

Pancreatic cancer belongs to the most aggressive group of cancers, with very poor prognosis. Therefore, there is an important need to find more potent drugs that could deliver an improved therapeutic approach. In the current study we searched for selective and effective caffeic acid derivatives. For this purpose, we analyzed twelve compounds and evaluated their in vitro cytotoxic activity against two human pancreatic cancer cell lines, along with a control, normal fibroblast cell line, by the classic MTT assay. Six out of twelve tested caffeic acid derivatives showed a desirable effect. To improve the therapeutic efficacy of such active compounds, we developed a formulation where caffeic acid derivative (7) was encapsulated into liposomes composed of soybean phosphatidylcholine and DSPE-PEG₂₀₀₀. Subsequently, we analyzed the properties of this formulation in terms of basic physical parameters (such as size, zeta potential, stability at 4 °C and morphology), hemolytic and cytotoxic activity and cellular uptake. Overall, the liposomal formulation was found to be stable, non-hemolytic and had activity against pancreatic cancer cells (IC₅₀ 19.44 µM and 24.3 µM, towards AsPC1 and BxPC3 cells, respectively) with less toxicity against normal fibroblasts. This could represent a promising alternative to currently available treatment options.

Mechanism of synergistic DNA damage induced by caffeic acid phenethyl ester (CAPE) and Cu(II): Competitive binding between CAPE and DNA with Cu(II)/Cu(I)

Caffeic acid phenethyl ester (CAPE) is an active polyphenol of propolis from honeybee hives, and exhibits antioxidant and interesting pharmacological activities. However, in this study, we found that in the presence of Cu(II), CAPE exhibited pro-oxidative rather than antioxidant effect: synergistic DNA damage was induced by the combination of CAPE and Cu(II) together as measured by strand breakage in plasmid DNA and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation, which is dependent on the molar ratio of CAPE:Cu(II). Production of Cu(I) and H₂O₂ from the redox reaction between CAPE and Cu(II), and subsequent OH formation was found to be responsible for the synergistic DNA damage. DNA sequencing investigations provided more direct evidence that CAPE/Cu(II) caused preferential cleavage at guanine, thymine and cytosine residues. Interestingly, we found there are competitive binding between CAPE and DNA with Cu(II)/Cu(I), which changed the redox activity of Cu(II)/Cu(I), via complementary applications of different analytical methods. The observed DNA damage was mainly attributed to the formation of DNA-Cu(II)/Cu(I) complexes, which is still redox active and initiated the redox reaction near the binding site between copper and DNA. Based on these data, we proposed that the synergistic DNA damage induced by CAPE/Cu(II) might be due to the competitive binding between CAPE and DNA with Cu, and site-specific production of OH near the binding site of copper with DNA. Our findings may have broad biological implications for future research on the pro-oxidative effects of phenolic compounds in the presence of transition metals.

Synthesis and Structure Analysis of 4-Benzyl-1-[(2E)-3-(3-Bromo-4-Hydroxy-5-Methoxyphenyl)Prop-2-Enoyl]Piperazine Hydrochloride

4-Benzyl-1-[(2 E)-3-(3-bromo-4-hydroxy-5-methoxyphenyl)prop-2-enoyl]piperazine hydrochloride was prepared from 3-(3-bromo-4-acetyloxy-5-methoxyphenyl)-2-propenoic acid and benzylpiperazine. Its piperazine ring exhibits a chair conformation.

Antioxidant and pro-oxidant challenge of tannic acid in mussel hemocytes exposed to cadmium

The present study investigates the antioxidant and pro-oxidant behavior of tannic acid (TA) in hemocytes of mussel Mytilus galloprovincialis, in the presence or the absence of cadmium (Cd). TA at concentrations up to 20 μM, primarily found to be no toxic (in terms of cell viability, superoxide anions, nitric oxide and lipid peroxidation products currently estimated), significantly diminished the cytotoxic and oxidative effects induced by the metal (50 and/or 100 μM) in all cases. On the other hand, higher concentrations of TA (40 and 60 μM) were toxic, thus enhancing Cd-mediated cytotoxic and oxidative effects. The present study showed TA beneficiary properties in hemocytes of mussels, at least at low concentrations, while TA at concentrations higher than 20 μM could serve as an excellent oxidized substrate, thus enhancing toxic effects either alone or with the presence of micromolar concentrations of non transition metals, such as Cd.

Formation of biopolymers owing to the oxidation of esculetine by Cu(II) ions in a Ca-polygalacturonate network

Pectic acids participate in the transport of heavy metal ions in the root apoplasm by establishing interactions that can lead to their partial or total immobilization. The ions accumulated can be mobilized by phenolic compounds and organic acids of the root exudates. In this context, we tested, in aqueous phase, the ability of malic acid and esculetine (ESC) to mobilize the Cu(II) ions accumulated in a Ca-polygalacturonate matrix (Ca-PGA) used as a model of the root apoplasm. The results show that at pH 5.0 and 6.0 malic acid mobilizes about 22% and 34% of the Cu(II) accumulated, respectively, whereas ESC about 12% and 25%. ESC was found to cause the reduction of Cu(II) to Cu(I) with formation of ESC oxidation products. The study of the Cu(II)-ESC binary system evidenced that one molecule of ESC reduces one Cu(II) ion with formation of semiquinonic radicals that couple to form two dimers. The Cu(II) reduction by ESC was found faster in the presence of malic acid.

Natural polyphenols may ameliorate damage induced by copper overload

The effect of the simultaneous exposure to transition metals and natural antioxidants frequently present in food is a question that needs further investigation. We aimed to explore the possible use of the natural polyphenols caffeic acid (CA), resveratrol (RES) and curcumin (CUR) to prevent damages induced by copper-overload on cellular molecules in HepG2 and A-549 human cells in culture. Exposure to 100μM/24h copper (Cu) caused extensive pro-oxidative damage evidenced by increased TBARS, protein carbonyls and nitrite productions in both cell types. Damage was aggravated by simultaneous incubation with 100μM of CA or RES, and it was also reflected in a decrease on cellular viability explored by trypan blue dye exclusion test and LDH leakage. Co-incubation with CUR produced opposite effects demonstrating a protective action which restored the level of biomarkers and cellular viability almost to control values. Thus, while CA and RES might aggravate the oxidative/nitrative damage of Cu, CUR should be considered as a putative protective agent. These results could stimulate further research on the possible use of natural polyphenols as neutralizing substances against the transition metal over-exposure in specific populations such as professional agrochemical sprayers and women using Cu-intrauterine devices.

Effect of interaction between phenolic compounds and copper ion on antioxidant and pro-oxidant activities

Phenolic compounds are widely used in food and cosmetics to prevent undesirable oxidation. On the other hand, phenolic compounds are also strong reducing agents and under in vitro conditions and in the presence of copper ion, they can act as pro-oxidants. In this study, we conducted electron spin resonance (ESR) measurements for the increase in reactive oxygen species (ROS) in relation to their structure and interaction with transition metals. Moreover, the antioxidant activity was assessed with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, and the pro-oxidant effect of phenolic compounds on DNA damage was assessed by measuring 8-hydroxy-2'-deoxyguanosine (8-OHdG), which is effectively formed during oxidative damage. In conclusion, ortho-dihydroxyl groups that can chelate with Cu(2+) induce the greatest pro-oxidant activity. Moreover, the interaction between phenolic compounds and copper induced to H(2)O(2). The obtained results indicated that ROS participated in oxidative DNA damage induced by phenolic compounds in the presence of Cu(2+).

Inhibitory effect of caffeic acid on cancer cell proliferation by oxidative mechanism in human HT-1080 fibrosarcoma cell line

Caffeic acid (3,4-dihydroxy cinnamic acid) (CA) is naturally found in fruits, vegetables, olive oil, and coffee. This study was undertaken to evaluate the anticancer effect of caffeic acid on HT-1080 human fibrosarcoma cell line. The antiproliferative effect of caffeic acid was determined by MTT assay, and the oxidative stress was determined by lipid peroxidation, changes in the enzymatic, and non-enzymatic antioxidant status. To understand the mode of antiproliferative effect of CA, the authors observed intracellular ROS levels by DCFH-DA method, mitochondrial membrane potential alterations by Rh-123 staining, oxidative DNA damage by comet assay, and apoptotic morphological changes by AO/EtBr-staining method. The results show that caffeic acid enhances lipid peroxidative markers such as TBARS, CD, and LHP in HT-1080 cell line. Caffeic acid enhances the ROS levels, which is evidenced by the increased DCF fluorescence. Further, caffeic acid treatment altered the mitochondrial membrane potential in HT-1080 cells. Similarly, the authors observed increased oxidative DNA damage (% Tail DNA, % Tail length, Tail moment, and olive tail moment), and apoptotic morphological changes in caffeic acid-treated groups. These data suggest that caffeic acid exhibits potent anticancer effect in HT-1080 cell line, and that it may be used as an anticancer agent.

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.

Knipholone anthrone from Kniphofia foliosa induces a rapid onset of necrotic cell death in cancer cells

The present study examines the comparative cytotoxicity of knipholone (KP) and knipholone anthrone (KA) in leukaemic and melonocyte cancer cell lines. It was found that KA induces a rapid onset of cytotoxicity with IC(50) values ranging from 0.5 to 3.3 μM. In comparison to KA, KP was 70-480-times less toxic to cancer cells. Morphological and biochemical studies revealed that the cytotoxicity of KA was coupled with a quick loss of membrane integrity leading to necrotic cell death. The study identified KA as a new class of natural potential anticancer agent with a wide range of toxicological and pharmacological implications.

3,4-dihydroxybenzaldehyde purified from the barley seeds (Hordeum vulgare) inhibits oxidative DNA damage and apoptosis via its antioxidant activity

Barley is a major crop worldwide. It has been reported that barley seeds have an effect on scavenging ROS. However, little has been known about the functional role of the barley on the inhibition of DNA damage and apoptosis by ROS. In this study, we purified 3,4-dihydroxybenzaldehyde from the barley with silica gel column chromatography and HPLC and then identified it by GC/MS. And we firstly investigated the inhibitory effects of 3,4-dihydroxybenzaldehyde purified from the barley on oxidative DNA damage and apoptosis induced by H(2)O(2), the major mediator of oxidative stress and a potent mutagen. In antioxidant activity assay such as DPPH radical and hydroxyl radical scavenging assay, Fe(2+) chelating assay, and intracellular ROS scavenging assay by DCF-DA, 3,4-dihydroxybenzaldehyde was found to scavenge DPPH radical, hydroxyl radical and intracellular ROS. Also it chelated Fe(2+). In in vitro oxidative DNA damage assay and the expression level of phospho-H2A.X, it inhibited oxidative DNA damage and its treatment decreased the expression level of phospho-H2A.X. And in oxidative cell death and apoptosis assay via MTT assay and Hoechst 33342 staining, respectively, the treatment of 3,4-dihydroxybenzaldehyde attenuated H(2)O(2)-induced cell death and apoptosis. These results suggest that the barley may exert the inhibitory effect on H(2)O(2)-induced tumor development by blocking H(2)O(2)-induced oxidative DNA damage, cell death and apoptosis.