The ameliorative effect of Primula vulgaris on cisplatin-induced nephrotoxicity in rats and quantification of its phenolic components using LC-ESI-MS/MS.

Cisplatin (CDDP) is an important chemotherapeutic agent, accumulation of which in kidney tissue causes nephrotoxicity and renal failure. The aim of this study was to evaluate, for the first time in the literature, the protective effect of dimethyl sulfoxide (DMSO) extract of Primula vulgaris leaf (PVE) against CDDP-induced nephrotoxicity in rats. The PVE content was characterized using liquid chromatography-mass spectrometry. Nephrotoxicity was induced with a single dose of CDDP (7.5 mg/kg). Thirty female Wistar-Albino rats were divided into five groups (control, DMSO, CDDP (7.5 mg/kg), CDDP + PVE (25 mg/kg), and CDDP + PVE (50 mg/kg)). Biochemical and histopathological analyses were then performed. Rutin, gallic acid, p-coumaric acid and protocatechuic acid were identified as major components of PVE. Total antioxidant status and glutathione (GSH) values increased significantly in the serum samples from the treatment group compared to the CDDP group, while blood urea nitrogen, creatinine, oxidative stress index, malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), total oxidant status, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) values decreased significantly. GSH levels increased significantly in the treatment group compared to the CDDP group, while TNF-α, caspase-3, 8-OHdG, MDA levels and damage scores decreased significantly. In conclusion, PVE exhibited strong protective effects through its anti-apoptotic, antioxidant, and anti-inflammatory activities against nephrotoxicity and oxidative damage caused by CDDP in rats.

An Investigation of the Antiproliferative Effect of Rhododendron luteum Extract on Cervical Cancer (HeLa) Cells via Nrf2 Signaling Pathway.

The aim of the present study was to investigate the role of Rhododendron luteum extract (RLE) in the induction of Nrf2­related oxidative stress and endoplasmic reticulum (ER) stress in human cervical cancer (HeLa) cells. The antiproliferative effect of RLE on HeLa and fibroblast cells was determined using the MTT assay. The effects of RLE on the cell cycle, apoptosis, and production of reactive oxygen species (ROS) in HeLa cells were evaluated using fluorescent probes. The mRNA expression levels of Nrf2 [and its targets glutamate-cysteine ligase catalytic subunit (GCLC), and glucose-6-phosphate dehydrogenase (G6PD)], and C/EBP homologous protein (CHOP, an ER stress marker were determined using reverse transcription­quantitative polymerase chain reaction (RT-PCR). The results demonstrated that RLE exhibited a selective cytotoxic effect (2.9-fold) on HeLa cells compared to fibroblast cells. RLE arrested the cell cycle at the S phase, and induced apoptosis, ER stress, and ROS formation. In addition, RLE significantly suppressed the expression levels of Nrf2, GCLC and G6PD (0.65, 0.69, and 0.54-fold, respectively) and increased the expression of CHOP (4.48-fold) in HeLa cells at 72 h of treatment (p < 0.05). These results show that the antiproliferative effect of RLE occurs through the Nrf2 and ER stress pathways, and the results should now be supported by further in vivo studies.

The effect of homocysteine on the expression of CD36, PPARγ, and C/EBPα in adipose tissue of normal and obese mice.

The purpose of this study was to investigate the effect of homocysteine (Hcy) on CD36, PPARγ, and C/EBPα gene and protein expression in adipose tissue obtained from normal and high-calorie diet obesity models. CD36, PPARγ, and C/EBPα gene expression and protein levels in adipose tissue specimens were determined using the RT-PCR and ELISA methods, respectively. Significantly increased CD36 gene expression was observed in adipose tissue from obese mice, while Hcy significantly reduced CD36 gene expression in adipose tissue from normal and obese mice. PPARγ and C/EBPα gene expression levels decreased significantly in all groups compared to the normal group. In addition, levels of both PPARγ and C/EBPα gene expression were lower with Hcy supplementation compared to their own controls. In conclusion, Hcy's reduction of CD36 gene expression in adipose tissue may be one probable factor in hyperhomocysteinemia representing an independent risk factor for cardiovascular diseases.

Rosa canina Extract has Antiproliferative and Proapoptotic Effects on Human Lung and Prostate Cancer Cells.

Although several studies have investigated the cytotoxic effects of different Rosa species, there has been only limited research into the cytotoxic effect of Rosa canina. The purpose of this research was to evaluate the antioxidant properties, phenolic characterization, and cytotoxic effects of R. canina on human lung (A549) and prostate (PC-3) cancer cells and the possible mechanisms involved. The antioxidant properties and phenolic characterization of the extract were determined using spectrophotometric methods and RP-HPLC, respectively. The cytotoxic activity of the extract was determined using the MTT assay. The mechanism involved in the extract's cytotoxic effect was then evaluated in terms of apoptosis, the cell cycle, mitochondrial membrane potential (MMP), and caspase activity using fluorometric and luminometric methods. The TPC value of the extract was 58.97 ± 2.22 mg gallic acid equivalents per gram sample, and ascorbic acid and p-coumaric acid were detected as major phenolics in the extract. R. canina extract exhibited a selective cytotoxic effect on A549 and PC-3 cells compared to normal fibroblast cells. The extract induced cell cycle arrest at the G1 phase and apoptosis via reduced MMP and increased caspase activity in these cells. Phytomedical applications of R. canina may represent promising approaches in the treatment of cancer.

Effect of Turkish Propolis on miRNA Expression, Cell Cycle, and Apoptosis in Human Breast Cancer (MCF-7) Cells.

Enriched in flavonoid compounds, phenol acids, and terpene derivatives, propolis has been shown to regulate apoptosis signaling pathways and alter the expression of microRNAs (miRNAs). In the present study, it has been aimed to examine the effects of Turkish propolis on miRNA levels of breast cancer (MCF-7) cells, and its relationship with cell proliferation and apoptosis. Cytotoxic activity of ethanolic propolis extract (EEP) was evaluated using MTT assay. Mechanisms involved in the cytotoxic action of Turkish propolis in MCF-7 cells were investigated with regard to apoptosis and cell cycle using flow cytometry and western blot. Mitochondrial membrane potential (MMP) were evaluated by spectrofluorometric method. miRNA levels were detected by qRT-PCR method. EEP exhibited selective toxicity against MCF-7 cells compared to normal fibroblast cells. EEP increased the cell cycle arrest at the G1 phase. EEP elevated the apoptotic cell death through increasing pro-apoptotic protein levels (p21, Bax, p53, p53-Ser46, and p53-Ser15), decreasing MMP and altering the expression levels of specific tumor suppressors (miR-34, miR-15a, and miR-16-5p) and oncogenic (miR-21) miRNAs. These data support that Turkish propolis may be evaluated as a potential natural agent for new anticancer drugs in future.

Dimethyl Sulfoxide Extract of Dianthus carmelitarum Induces S Phase Arrest and Apoptosis in Human Colon Cancer Cells.

Although several studies have investigated the cytotoxic effects of different Dianthus species, there has been only limited research into the cytotoxic effect of Dianthus carmelitarum. The purpose of this research was to evaluate the phenolic characterization and the cytotoxic effect of D. carmelitarum on human colon cancer (WiDr) cells and the possible mechanisms involved. Total polyphenolic contents (TPC) and phenolic characterization of the extract were evaluated using the Folin-Cioceltau method and reversed-phase high performance liquid chromatography (RP-HPLC), respectively. The cytotoxic activity of the extract was determined using the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay. The mechanism involved in the extract's cytotoxic effect was then evaluated in terms of apoptosis and the cell cycle using flow cytometry, while mitochondrial membrane potential (MMP) was investigated using the fluorometric method. The TPC value of the extract was 784.8 ± 40.3 mg gallic acid equivalent per 100 g sample, and sinapic acid and benzoic acid were detected as major phenolics in the extract. D. carmelitarum extract exhibited a selective cytotoxic effect (3.6-fold) on WiDr cells compared to normal colon cells. The extract induced cell cycle arrest at the S phase and apoptosis via reduced MMP in WiDr cells. Phytomedical and nutraceutical applications of D. carmelitarum may represent promising approaches in the treatment of cancer.

Primula vulgaris extract induces cell cycle arrest and apoptosis in human cervix cancer cells.

Primula vulgaris belongs to the genus Primula, members of which are frequently used in folk medicine. Various studies have investigated the cytotoxic effect of different Primula species, but there have been limited studies on the cytotoxic effect of P. vulgaris. The aim of this study was to investigate the cytotoxic effects, and possible mechanisms involved, of P. vulgaris flower extract on human cervical cancer (HeLa) cells. The cytotoxic effect of the extract on HeLa cells was revealed using the MTT assay. Mechanisms involved in the extract's cytotoxic effect were then investigated in terms of apoptosis, mitochondrial membrane potential, and the cell cycle, using fluorometric methods. P. vulgaris flower extract exhibited selective cytotoxic effects against HeLa cells by arresting their cell cycle at the S phase, and inducing the number of apoptotic cells compared to normal fibroblast cells by reducing mitochondrial membrane potential in a concentration-dependent manner. This is the first study to reveal the antiproliferative effect of P. vulgaris flower extract. Further studies are now needed to identify the cytotoxic molecules in the extract and their mechanisms.

Cytotoxic effect of Rosa canina extract on human colon cancer cells through repression of telomerase expression.

Rosa canina is a member of the genus Rosa that has long been used for medical objectives. Several studies have reported cytotoxic effects of different Rosa species, but there has been only limited investigation of the cytotoxic effect of R. canina. The purpose of the current study was to examine the potential effect of R. canina extract on cell viability, the cell cycle, apoptosis, and the expression of telomerase in human colon cancer (WiDr) cells. The cytotoxic effect of the extract was determined using MTT assay. The mechanism involved in the cytotoxic effect of the extract was then evaluated in terms of apoptosis and the cell cycle using flow cytometry. Mitochondrial membrane potential (MMP) was investigated using the fluorometric method, and expression levels of telomerase were studied using RT-PCR. R. canina extract exhibited a selective cytotoxic effect on WiDr cells compared with normal colon cells. The extract induced cell cycle arrest at the S phase and apoptosis via reduced MMP in WiDr cells. R. canina extract significantly repressed telomerase expressions at treatment times of 48 and 72 h in WiDr cells. Our results suggest that R. canina may have considerable potential for development as a novel natural product-based anticancer agent.

Cytotoxic effect of Rosa canina extract on human colon cancer cells through repression of telomerase expression / 药物分析学报

Rosa canina is a member of the genus Rosa that has long been used for medical objectives. Several studies have reported cytotoxic effects of different Rosa species, but there has been only limited investigation of the cytotoxic effect of R. canina. The purpose of the current study was to examine the potential effect of R. canina extract on cell viability, the cell cycle, apoptosis, and the expression of telomerase in human colon cancer (WiDr) cells. The cytotoxic effect of the extract was determined using MTT assay. The mechanism involved in the cytotoxic effect of the extract was then evaluated in terms of apoptosis and the cell cycle using flow cytometry. Mitochondrial membrane potential (MMP) was investigated using the fluorometric method, and expression levels of telomerase were studied using RT-PCR. R. canina extract exhibited a selective cytotoxic effect on WiDr cells compared with normal colon cells. The extract induced cell cycle arrest at the S phase and apoptosis via reduced MMP in WiDr cells. R. canina extract significantly repressed telomerase expressions at treatment times of 48 and 72 h in WiDr cells. Our results suggest that R. canina may have considerable potential for development as a novel natural product-based anticancer agent.

Primula vulgaris extract induces cell cycle arrest and apoptosis in human cervix cancer cells / 药物分析学报

Primula vulgaris belongs to the genus Primula, members of which are frequently used in folk medicine. Various studies have investigated the cytotoxic effect of different Primula species, but there have been limited studies on the cytotoxic effect of P. vulgaris. The aim of this study was to investigate the cytotoxic effects, and possible mechanisms involved, of P. vulgaris flower extract on human cervical cancer (HeLa) cells. The cytotoxic effect of the extract on HeLa cells was revealed using the MTT assay. Mechanisms involved in the extract's cytotoxic effect were then investigated in terms of apoptosis, mitochondrial membrane potential, and the cell cycle, using fluorometric methods. P. vulgaris flower extract exhibited selective cytotoxic effects against HeLa cells by arresting their cell cycle at the S phase, and inducing the number of apoptotic cells compared to normal fibroblast cells by reducing mitochondrial membrane potential in a concentration-dependent manner. This is the first study to reveal the antiproliferative effect of P. vulgaris flower extract. Further studies are now needed to identify the cytotoxic molecules in the extract and their mechanisms.

Detection of autoantibodies against carbonic anhydrase I and II in the plasma of patients with gastric cancer.

Cancer is the second leading cause of death and gastric cancer is the fourth most common cancer type worldwide. Investigation of autoantibodies in cancer patients has been a popular research area in recent years. The aim of the current study was to investigate carbonic anhydrase I and II (CA I and II) autoantibodies in the plasma of subjects with gastric cancer based on the information and considerations of autoimmune relation of gastric cancer. Anti-CA I and II antibody levels were investigated by ELISA in plasma samples of fifty two patients with gastric cancer and thirty five healthy peers. Anti-CA I and II antibody titers of the gastric cancer group were significantly higher compared with the control group (p = 0.004, p = 0.0001, respectively). Plasma anti-CA I levels of the metastatic group were lower than the non-metastatic group and this difference was found statistically significant (p < 0.05), but there was no statistical difference between plasma anti-CA II levels of the groups. CA I and II autoantibody titers in patients with gastric cancer were found higher compared to healthy subjects and the results suggest that these autoantibodies may be involved in the pathogenesis of gastric cancer.

Antiproliferative and apoptotic effect of Morus nigra extract on human prostate cancer cells.

Background: Morus nigra L. belongs to the family Moraceae and is frequently used in traditional medicine. Numerous studies have investigated the antiproliferative effects of various extracts of different Morus species, but studies involving the in vitro cytotoxic effect of M. nigra extract are very limited. The purpose of this study was to evaluate the phenolic composition and antioxidant activity of dimethyl sulfoxide extract of M. nigra (DEM) and to investigate, for the first time, the probable cytotoxic effect in human prostate adenocarcinoma (PC-3) cells together with the mechanism involved. Methods: Total polyphenolic contents (TPC), ferric reducing antioxidant power (FRAP) and phenolic compounds of DEM were evaluated using spectrophotometric procedures and HPLC. The cytotoxic effect of DEM on PC-3 cells was revealed using the MTT assay. Mechanisms involved in the cytotoxic effect of DEM on PC-3 cells were then investigated in terms of apoptosis, mitochondrial membrane potential and cell cycle using flow cytometry, while caspase activity was investigated using luminometric analysis. Results: TPC and FRAP values were 20.7 ± 0.3 mg gallic acid equivalents and 48.8 ± 1.6 mg trolox equivalents per g sample, respectively. Ascorbic acid and chlorogenic acid were the major phenolic compounds detected at HPLC analysis. DEM arrested the cell cycle of PC-3 cells at the G1 phase, induced apoptosis via increased caspase activity and reduced mitochondrial membrane potential. Conclusions: Our results indicate that M. nigra may be a novel candidate for the development of new natural product based therapeutic agents against prostate cancer.

Carbonic anhydrase I and II autoantibodies in Behçet's disease.

BACKGROUND: Behçet's disease is a vasculitis, seen more frequently around the Mediterranean and the Far East, and evinces with oral and genital ulcerations, skin lesions and uveitis. Carbonic anhydrase (CA) is a metalloenzyme which is widely distributed in the living world, and it is essential for the regulation of acid-base balance. Anti-CA antibodies have been reported in many disorders, such as systemic lupus erythematosus, Sjögren's syndrome, rheumatoid arthritis, endometriosis, idiopathic chronic pancreatitis, type 1 diabetes and Graves' disease. The goal of this study was to investigate CA I and II autoantibodies in Behçet's disease (BD). METHODS: 35 patients with BD and 29 healthy controls were included in the study and CA I and II autoantibody levels were investigated by ELISA. RESULTS: The CA I and II autoantibody levels of BD group were significantly higher than the healthy group (p=0.013, p inf 0.0001, respectively). A cut-off value of 0.250 ABSU for anti-CA I was associated with 34 % sensitivity and 100 % specificity and a cut-off value of 0.171 ABSU for anti-CA II was associated with 54 % sensitivity and 100 % specificity for predicting BD. CONCLUSION: The CA I and II autoantibody levels in patients with BD were found higher compared to control group and the results suggest that CA I and II autoantibodies may be involved in the pathogenesis of BD.

Morus Rubra Extract Induces Cell Cycle Arrest and Apoptosis in Human Colon Cancer Cells Through Endoplasmic Reticulum Stress and Telomerase.

Many studies have reported cytotoxic effects of different Morus species, but there have been only limited studies on the cytotoxic effect of Morus rubra. The aims of this study were to evaluate the cytotoxic effect of dimethyl sulfoxide extract of M. rubra and to investigate, for the first time, its probable cytotoxic activity in human colon cancer (WiDr) cells, together with the mechanism involved. The cytotoxic activity of extract was determined using MTT assay. The mechanism involved in the cytotoxic effect of extract was then evaluated in terms of apoptosis, and the cell cycle using flow cytometry, mitochondrial membrane potential (MMP) was investigated using the fluorometric method, and expression levels of telomerase and C/EBP homologous protein (CHOP) were investigated using reverse-transcription PCR (RT-PCR). M. rubra extract exhibited moderate selective cytotoxicity on colon cancer cells compared with fibroblast cells. Extract induced cell cycle arrest at the G1 phase and apoptosis via reduced MMP in WiDr cells. Additionally, M. rubra extract significantly repressed telomerase and induced CHOP expressions in WiDr cells. Our results demonstrate that targeting telomerase and endoplasmic reticulum stress represents a promising strategy in colon cancer therapy, and M. rubra may have considerable potential for development as a novel natural product-based anticancer agent.

Selective cytotoxic effect of Rhododendron luteum extract on human colon and liver cancer cells.

PURPOSE: The genus Rhododendron is distributed entirely in the world with the exception of South and Central America and Africa, growing in a large diversity of climatic conditions. This genus is a rich source of phenolic compounds, especially flavonoids, essential oils, chromones, terpenoids, and steroids. It has many biological properties such as antioxidant, anti-inflammatory, antiviral, antibacterial, anticancer, antidiabetic, immunomodulatory, cardioprotective and hepatoprotective among others due to their polyphenolic constituents. The objective of the current study was to evaluate the antioxidant properties and cytotoxic activity of dimethyl sulfoxide extract of flowers of Rhododendron luteum (DEFR) for the first time. METHODS: The total polyphenolic contents (TPC), total flavonoid contents (TFC) and ferric reducing antioxidant power (FRAP) of the extract were evaluated using spectrophotometric procedures. The cytotoxic activity of the extract on three cancers (human breast, colon and liver carcinoma) and human foreskin fibroblast cells was determined using the MTT assay. RESULTS: TPC and FRAP values were found 54.2±0.38 mg gallic acid equivalents and 164.2±1.77 mg trolox equivalents per to g sample, respectively. R.luteum extract exhibited selective cytotoxicity against colon and liver cancer cells compared to normal fibroblast cells, while this selective cytotoxicity was not observed in breast cancer cells. CONCLUSION: Our results demonstrate that the Rhododendron luteum may be a great source of antioxidant and antitumor natural agents due to their capability of decreasing cancer cells proliferation.

Evaluation of the radioprotective effect of Turkish propolis on foreskin fibroblast cells.

AIM OF STUDY: Propolis is a resinous bee product, rich of polyphenolic compounds and flavonoids. It is known that in different geographic zones its chemical composition varies due to the different plant sources. Many biological properties including antimicrobial, antioxidative, anti-inflammatory, antitumoral, antigenotoxic, antimutagenic, cytostatic activities have been ascribed to propolis. These biological effects are predominantly attributed to its content of polyphenols. In this study, we aimed to evaluate the radioprotective effect of ethanolic extract of Turkish propolis. (EETP) against γ-ray-induced DNA damage on fibroblast cells using comet assay for the first time. MATERIALS AND METHODS: Fibroblast cells were pretreated 15 and 30 min with concentrations of 100, 200 and 300 µg/mL EETP then they were exposed to 3 Gy γ-rays. Amifostine (synthetic aminothiol compound) was used as a positive control. RESULTS: The results showed a significant decrease in γ-ray-induced DNA damage on cells treated with EETP and amifostine when compared to only irradiated cells. (P < 001). CONCLUSION: It was concluded that EETP prevent γ-ray-induced DNA damage in fibroblast cells and might have radioprotective activity.

Positive correlation between insulin resistance and iron overload-induced oxidative stress in patients with fanconi anemia (FA)- and non-FA-related bone marrow failure: The results of a multicenter study.

This study investigated the relationship between DNA, protein, and lipid oxidations and insulin resistance in patients with Fanconi anemia (FA)- and non-FA-related bone marrow failure. Sixteen patients with FA, 7 non-FA-related aplastic anemia, and 10 controls were included in the study. Fasting blood glucose, simultaneous insulin, hepcidin, ferritin, 8-hydroxy deoxyguanosine (8-OHdG), protein carbonyls, malondialdehyde (MDA), and homeostatic model assessment-insulin resistance (HOMA-IR) were investigated in the patients and controls. Diepoxybutane test-positive (DEB+) patients were diagnosed with FA, whereas DEB-patients were diagnosed as non-FA. 8-OHdG levels in both FA and non-FA patients were significantly higher than those in the controls (P = .001 and P = .005, respectively). Serum ferritin levels were also higher in FA and non-FA patients than in the controls (P = .0001 and P = .005, respectively). Insulin resistance (IR) was significantly higher in FA patients than in non-FA patients and controls (P = .005 and P = .015, respectively). Significant differences were observed between 8-OHdG, ferritin, and MDA levels in patients with or without IR (P = .009, P = .001, and P = .013, respectively). Moderate and strong relations of 44% and 85% were determined between IR and ferritin levels in patients with FA or non-FA (P = .08 and P = .014, respectively). FA and non-FA patients exhibited a tendency to IR. IR was related to ferritin levels, and ferritin levels were also correlated with oxidative stress. These findings suggest that the increased rate of IR in patients with FA and non-FA may derive from increased oxidative stress, which may in turn be due to elevated serum ferritin levels.

Antiproliferative and proapoptotic activity of Turkish propolis on human lung cancer cell line.

Cancer is a heterogeneous disease, two of whose characteristic features are uncontrollable cell proliferation and insufficient apoptosis. Various studies have investigated the antiproliferative effects of propolis, a natural bee product, from different countries, and its cytotoxic effects have been attributed to its polyphenol contents. The purpose of this study was to show the cytotoxic effects, and possible mechanisms involved, of ethanolic extract of Turkish propolis (EEP) on the human lung cancer (A549) cell line. Cytotoxic activity of EEP on A549 cells was revealed using the MTT assay. Mechanisms involved in the cytotoxic action of EEP on A549 cells were then investigated in terms of apoptosis, mitochondrial membrane potential and cell cycle using flow cytometry, endoplasmic reticulum stress using RT-PCR, and caspase activity using luminometric analysis. EEP exhibited selective toxicity against A549 cells compared to normal fibroblast cells. We determined that EEP arrested the cell cycle of A549 cells at the G1 phase, induced endoplasmic reticulum stress, caspase activity, and apoptosis and reduced mitochondrial membrane potential. These results indicate that Turkish propolis is capable of reducing cancer cell proliferation and may have a promising role to play in the development of new anticancer drugs in the future.

Systemic oxidant/antioxidant balance in human abdominal aortic aneurysm.

The aim of this study was to evaluate the oxidant-antioxidant balance in patients with abdominal aortic aneurysms (AAA). Forty-two consecutive patients with AAA and 46 control subjects were included. Total oxidant status (TOS) and total antioxidant status (TAS) levels were measured and the oxidative stress index (OSI) value determined. Serum TOS and OSI values in patients with AAA were higher than those in the controls (p < 0.001, p < 0.001, respectively). There was a positive correlation between abdominal aortic diameters, serum TOS levels (r = 0.592, p < 0.001) and OSI values (r = 0.598, p < 0.001). A cut-off value of 17.68 µmol H2O2equivalent/L for TOS was associated with 86% sensitivity and 83% specificity and a cut-off value of 1.77 for OSI was associated with 86% sensitivity and 81% specificity for predicting AAA. Systemic oxidative imbalance develops in patients with AAA, particularly as a result of an increase in TOS.

Effects of Turkish propolis on expression of hOGG-1 and NEIL-1.

BACKGROUND/AIM: Propolis is a bee product with antioxidative, antimutagenic, and other beneficial properties, and it is used as a natural drug. It is rich in polyphenolic compounds. Its composition varies depending on the particular geographical region. Oxidative stress is caused by an imbalanced free radical production and antioxidant system. The effects of flavonoids on the expression of DNA repair enzymes have been examined previously; however, no study has investigated the effects of propolis. This study investigated the effects of ethanolic extracts of Turkish propolis (EEP) on the expression of DNA repair enzymes. MATERIALS AND METHODS: The effects of EEP and tertiary-butyl-hydroperoxide (t-BHP) on cell viability were determined using MTT DNA damage was determined using comet assay. mRNA expression of target enzymes was detected using RT-PCR. RESULTS: According to the cytotoxicity analysis, after a recovery time of 4 h, appropriate damage agent t-BHP and optimum EEP concentrations were 300 µM and 200 µg/mL, respectively. 8-Oxoguanine-glycosylase (hOGG-1) and endonuclease-VIII-like-1 (NEIL-1) expressions increased in the positive control group (t-BHP alone) and the study group (t-BHP+EEP). Maximum increase in NEIL-I expression was at hour 12 in the positive control group and at hour 8 in the study group. CONCLUSION: EEP can be considered as a potential source of functional food and pharmaceutical agents.