Spectrophotometric analysis of flavonoid-DNA interactions and DNA damaging/protecting and cytotoxic potential of flavonoids in human peripheral blood lymphocytes

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This study investigated the mechanisms of hydroquinone toxicity and assessed the relationships between its cytotoxic, genotoxic, and cytogenetic effects tested at 8, 140, and 280 µg mL -1 in human peripheral blood lymphocytes exposed for 24 h. The outcomes of the treatments were evaluated using the apoptosis/necrosis assay, the alkaline comet assay, and the cytokinesis-block micronucleus (CBMN) cytome assay. The tested hydroquinone concentrations produced relatively weak cytotoxicity in resting lymphocytes, which mostly died via apoptosis. Hydroquinone's marked genotoxic effects were detected using the alkaline comet assay. Significantly decreased values of all comet parameters compared to controls indicated specific mechanisms of hydroquinone-DNA interactions. Our results suggest that the two higher hydroquinone concentrations possibly led to cross-linking and adduct formation. Increased levels of DNA breakage measured following exposure to the lowest concentration suggested mechanisms related to oxidative stress and inhibition of topoisomerase II. At 8 µg mL -1 , hydroquinone did not significantly affect MN formation. At 140 and 280 µg mL -1 , it completely blocked lymphocyte division. The two latter concentrations also led to erythrocyte stabilization and prevented their lysis. At least two facts contribute to this study's relevance: (I) this is the first study that quantifies the degree of reduction in total comet area measured in lymphocyte DNA after hydroquinone treatment, (II) it is also the first one on a lymphocyte model that adopted the "cytome" protocol in an MN assay and found that lymphocytes exposure even to low hydroquinone concentration resulted in a significant increase of nuclear bud frequency. Considering the limitations of the lymphocyte model, which does not possess intrinsic metabolic activation, in order to unequivocally prove the obtained results further studies using other appropriate cell lines are advised.

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confidence: 99%

In vitro assessment of the cytotoxic, DNA damaging, and cytogenetic effects of hydroquinone in human peripheral blood lymphocytes

Jurica

Karačonji

Benković

et al. 2017

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“…Rusak et al (19) have shown that the Q/La complex intercalates even better to dsDNA and RNA and is more stable than Q alone. Strong intercalation and the arrest of cell division is probably the mechanism of cytotoxic activity of the Q/La complex.…”

Section: Discussionmentioning

confidence: 99%

“…The consequences of intercalative and prooxidative effects are shown in Table 1; the highest complex concentration caused signifi cant DNA breakage, while Q and La did not. It is important to mention that it takes a long incubation time for the dose-dependent effect of quercetin on DNA to show (19), but long incubation seriously compromises Q's stability (11). In contrast, the time needed for the Q/La complex to cause signifi cant biological damage was short (3 hours) at concentrations which are relatively low.…”

Section: Discussionmentioning

confidence: 99%

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Cytotoxic and Genotoxic Effects of the Quercetin/Lanthanum Complex on Human Cervical Carcinoma Cells In Vitro

Durgo

Halec

Šola

et al. 2011

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Quercetin is the main fl avonoid in diet with a potential in the treatment of cancer, cardiovascular, and neurodegenerative diseases. Due to its specifi c planar chemical structure, quercetin readily forms chelates with metal ions. Complexes of bioactive compounds and metal ions such as lanthanum often show strong cytotoxic and antitumour properties. The aim of this study was to compare the genotoxic effects of the quercetin/lanthanum complex on human cervical carcinoma cells with compare it to the effects of free ligands, quercetin, and lanthanum alone. The quercetin/lanthanum complex showed considerable cytotoxicity in the concentration range of (100 to 1000) mmol mL -1 and exposure time of three hours. The complex also induced a dose-dependent pro-oxidative effects and the formation of single-strand and double-strand DNA breaks. Although we obtained promising results on the cell level, future experiments should answer whether the quercetin/lanthanum complex is cancer-specific and stable enough in physiological conditions to make a potential new antitumour drug. Arh Hig Rada Toksikol 2011;62:221-227 Evidence abounds about antitumour activity of small-molecule compounds, including metal complexes with fl avonoids, which directly interact with DNA (1). Recently, much attention has also been paid to how cancer cell growth and apoptosis are affected by rare earth metals and compounds such as lanthanum and cerium salts (2, 3). KEY WORDS: chelates, DNA damage, fl avonoid/metal complexes, oxidative damage Durgo K et al. QUERCETIN/LANTHANUM COMPLEX EFFECTS ON HUMAN CERVICAL CARCINOMA CELLSLanthanum salts can arrest the cell cycle in the G1/S phase in leukemic cell lines (2) and inhibit telomerase activity in the lymphoblastoid tumour cell line (3). Both induce apoptotic events. Contrary to this effect observed in tumour cells, no effect could be determined in normal bone marrow haematopoietic cells (2). Lanthanum complexed with bioactive compounds from plants has shown even stronger cytotoxic effect than when administered alone (4), suggesting that electron transfer and oxidative stress are responsible for the cytotoxic effect. Kostova et al. (5) found that lanthanum complexes with biscoumarins caused apoptotic cell death of several leukaemia and lymphoma cell lines, causing DNA fragmentation and morphological changes. The authors believe that this cytotoxic effect depends on the metal-ligand structure. Wang et al. (1) analysed a lanthanum-naringenin Schiff-base complex and found that the ligands were coordinated to the lanthanum ion through deprotonated hydroxyl groups. This complex bound directly to calf-thymus DNA, probably through intercalation, while the same concentrations caused a strong cytotoxic effect on human leukaemia and lung adenocarcinoma cells. Intercalation is the main cytotoxic mechanism of numerous antitumour agents such as cisplatin, but their use is limited by drug resistance. Determination and synthesis of new agents

“…We prepared three replicate slides per sample of treated cells as described in detail by Rusak et al (21). The slides were immersed in freshly prepared ice-cold alkaline lysis solution (2.5 mol L -1 NaCl, 100 mmol L -1 Na 2 EDTA, 10 mmol L -1 Tris-HCl, 1 % Nasarcosinate, pH 10) with 1 % Triton X-100 and 10 % dimethyl sulfoxide (Kemika, Zagreb, Croatia) for one hour.…”

Section: Alkaline Comet Assaymentioning

confidence: 99%

Genotoxic Effects of Green Tea Extract on Human Laryngeal Carcinoma Cells In Vitro

Durgo

Kostić

Gradiški

et al. 2011

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Green tea (Camellia sinensis) contains several bioactive compounds which protect the cell and prevent tumour development. Phytochemicals in green tea extract (mostly fl avonoids) scavenge free radicals, but also induce pro-oxidative reactions in the cell. In this study, we evaluated the potential cytotoxic and prooxidative effects of green tea extract and its two main fl avonoid constituents epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) on human laryngeal carcinoma cell line (HEp2) and its crossresistant cell line CK2. The aim was to see if the extract and its two fl avonoids could increase the sensitivity of the cisplatin-resistant cell line CK2 in comparison to the parental cell line. The results show that EGCG and green tea extract increased the DNA damage in the CK2 cell line during short exposure. The cytotoxicity of EGCG and ECG increased with the time of incubation. Green tea extract induced lipid peroxidation in the CK2 cell line. The pro-oxidant effect of green tea was determined at concentrations higher than those found in traditionally prepared green tea infusions.