Protective activity of Cynara scolymus L. leaf extract against chemically induced complex genomic alterations in CHO cells

Guidance for the use and interpretation of assays for monitoring anti-genotoxicity

Since DNA damage can occur spontaneously or be produced by the environmental genotoxins in living cells, it is important to investigate compounds that can reverse or protect DNA damage. An appropriate methodology is essential for the responsive identification of protection offered against DNA damage. This review includes information on the current state of knowledge on prokaryotic cell-based assays (SOS chromotest, umu test, vitotox assay) and cytogenetic techniques (micronucleus assay, chromosome aberration test and sister chromatid exchange assay) with an emphasis on the possibility to explore genoprotective compounds. Throughout the last decade, studies have extrapolated the scientific methodologies utilized for genotoxicity to assess genoprotective compounds. Therefore, shortcomings of genotoxicity studies are also mirrored in antigenotoxicity studies. While regulatory authorities around the world (OECD, US-EPA and ICH) continue to update diverse genotoxic assay strategies, there are still no clear guidelines/approaches for efficient experimental design to screen genoprotective compounds. As a consequence, non-synergetic and inconsistent implementation of the test method by the researchers to execute such simulations has been adopted, which inevitably results in unreliable findings. The review has made the first attempt to collect various facets of experimentally verified approaches for evaluating genoprotective compounds, as well as to acknowledge potential significance and constraints, and further focus on the assessment of end points which are required to validate such action. Henceforth, the review makes an incredible commitment by permitting readers to equate several components of their test arrangement with the provided simplified information, allowing the selection of convenient technique for the predefined compound from a central repository.

Antigenotoxic, antiproliferative and antimetastatic properties of a combination of native medicinal plants from Argentina

ETHNOPHARMACOLOGICAL RELEVANCE

Jarilla is the common name of an appreciated group of native plants from the semi-arid region in Argentina (Larrea cuneifolia Cav., Larrea divaricata Cav. and Zuccagnia punctata Cav.) that have been historically consumed to heal respiratory, musculoskeletal and skin ailments, as well as recommended for weakness/tiredness, hypertension, diabetes and cancer treatment. It was previously reported that some biological properties could be improved when these plants are used jointly. Infusions of a defined mixture, composed by three Jarilla species, L. cuneifolia: L. divaricata: Z. punctata (0.5:0.25:0.25) (HM2) showed synergistic and additive effect on antioxidant activity even after passing through the gastro-duodenal tract.

AIM OF THE STUDY

The main purpose of this work was to evaluate antigenotoxic, antitumor, and anti-metastatic properties of the Jarilla species that grow in the Northwest of Argentina and a herbal combination of them.

MATERIAL AND METHODS

Infusions of Jarilla mixture (HM2), and of each single plant species were prepared. Phenolic profiles of infusions were analyzed by HPLC-ESI-MS/MS and two relevant chemical markers were quantified. The antigenotoxic activity was evaluated by using the Ames test and the Cytokinesis-Block Micronucleus (CBMN) assay against direct mutagens. Evaluations of both cytotoxicity and antiproliferative effects were conducted on tumor and non-tumor cell lines. Both in vivo tumoral growth and metastasis inhibition were evaluated by using a carcinoma model on Balb/c mice.

RESULTS

HM2 mix could suppress genetic and chromosome mutations induced by 4-nitro-o-phenylendiamine (4-NPD) and doxorubicin. Herbal mixture and single plant infusions showed cytotoxic effect against mammary, uterus, and brain tumoral cells without a selective action vs normal human cell line. HM2 mix was able to reduce mammary tumor mass on the Balb/c mice model and showed a significant reduction in the number of metastatic nodules in the lungs.

CONCLUSIONS

Our results suggest that the combinations of three Jarilla species from northwest Argentina would be a promising alternative to treat or slow down the development of chronic diseases, such as cancer.

In vitro genotoxic and antigenotoxic effects of cynarin

ETHNOPHARMACOLOGICAL RELEVANCE

Cynarin is an artichoke phytochemical that possesses a variety of pharmacological features including free-radical scavenging and antioxidant activity. The origin of artichoke species appears to be Mediterranean region. Two of these species, globe artichoke (Cynara cardunculus var. scolymus L.) and cardoon (Cynara cardunculus var. altilis DC), are widely cultivated and consumed. This vegetable, as the basis of the mediterranean diet, has been used as herbal medicine for its therapeutic effects since ancient times. Therefore, this study was performed to determine genotoxic and antigenotoxic effects of cynarin against MMC (mitomycin C) and H₂O₂ (hydrogen peroxide) induced genomic instability using chromosome aberrations (CAs), sister chromatid exchanges (SCEs), micronucleus (MN), and comet assays in human lymphocytes.

MATERIALS AND METHODS

Lymphocytes obtained from two healthy volunteers (1 male and 1 female) were exposed to different concentrations of cynarin (12-194 μM) alone and the combination of cynarin and MMC (0.60 μM) or cynarin and H₂O₂ (100 μM, only for comet assay).

RESULTS

Cynarin alone did not induce significant genotoxic effect in the CA, SCE (except 194 μM), MN, and comet assays. The combination of some concentrations of cynarin and MMC decreased the frequency of CAs, SCEs and MN induced by MMC. Furthermore, the combination of cynarin and H₂O₂ reduced all comet parameters at all the concentrations compared to H₂O₂ alone. While the highest concentrations of cynarin significantly decreased mitotic index (MI), the combination of cynarin and MMC increased the reduction of MI induced by MMC alone.

CONCLUSION

All the results obtained in this study demonstrated that cynarin exhibited antigenotoxic effects rather than genotoxic effects. It is believed that cynarin can act as a potential chemo-preventive against genotoxic agents.

Cytotoxic, antioxidative, genotoxic and antigenotoxic effects of Horchata, beverage of South Ecuador

BACKGROUND

"Horchata" is an herbal mixture infusion consumed in Southern Ecuador; 66% of its plants are anti-inflammatory medicinal plant, and 51% are analgesics. Anti-inflammatory substances can prevent carcinogenesis mediated by cytotoxic effects and can prevent DNA damage. The aim of this study was to evaluate the cytotoxicity and apoptotic/antigenotoxic effects of horchata as well as its mechanism.

METHODS

Nine different varieties of horchata were prepared in the traditional way and then freeze-dried. Phytochemical screening tested for the presence of secondary metabolites using standard procedures and antioxidant activities. The cytotoxic activity was evaluated on cerebral astrocytoma (D-384), prostate cancer (PC-3), breast cancer (MCF-7), colon cancer (RKO), lung cancer (A-549), immortalized Chinese hamster ovary cells (CHO-K1), and human peripheral blood lymphocytes via a MTS assay. The pro-apoptotic effects were evaluated with Anexin V/Propidium Iodide and western blot of Bax, Bcl-2, TP53, and TP73. Induction and reduction of ROS were assessed by fluorimetry. Genotoxic and antigenotoxic effects were evaluated with a comet assay and micronuclei on binucleated cells.

RESULTS

Five of nine horchatas had cytotoxic effects against D-384 while not affecting normal cells. These horchatas induce cell death by apoptosis modulated by p53/p73. In CHO-K1 cells, the horchatas decrease the damage induced by hydrogen peroxide and Mitomycin C measured in the comet and micronucleus assay respectively.

CONCLUSIONS

The IC50 range of effective horchatas in D-384 was 41 to 122 μg·mL-1. This effect may be related to its use in traditional medicine (brain tonic). On the other hand, immortalized Chinese hamster ovary cells (CHO-K1) and lymphocytes did not show a cytotoxic effect. The most potent horchata induced apoptosis via a p53/p73-mediated mechanism. The horchatas present antigenotoxic properties, which may be related to the antioxidant capacity. Future studies on horchata components are necessary to understand the interactions and beneficial properties.

Artichoke (Cynara cardunculus L. var. scolymus) waste as a natural source of carbonyl trapping and antiglycative agents

The role of polyphenolic compounds extractable from artichoke solid wastes in the formation of advanced glycation end products (AGEs) was studied. Outer bracts and stems were extracted using different water-ethanol mixtures and HPLC-DAD analyses indicated aqueous and hydro-alcoholic 20:80 stem extracts as the richest in polyphenols. The samples were characterized in their phenolic composition (using mass spectrometry) and antioxidant capacity. Antiglycative capacity was evaluated by in vitro BSA-sugars (glucose, fructose, and ribose) and BSA-methylglyoxal (MGO) tests, formation of Amadori products assay, direct glyoxal (GO) and MGO trapping capacity. Results indicated both extracts as effective inhibitors of fructosamine formation and antiglycative agents. In particular, aqueous extract showed the best activity in the systems containing glucose and fructose, differently from ethanolic extract, that was demonstrated able to better inhibit AGEs formation when ribose or MGO act as precursors. Ethanolic extract was also shown to be able to trap MGO and GO, with efficiency increasing after 24hours of incubation time. These activities are partially correlated with the antioxidant effect of the extract, as demonstrated by the scavenger capacity against ABTS cation and DPPH stable radicals; this relationship is evident when the model system, containing protein incubated with ribose or MGO, is considered. The different activities of the tested extracts could probably be ascribed to the different composition in chlorogenic acids (CQAs), being aqueous extract richer in 1-CQA, 3-CQA, and 1,3-di-CQA, and ethanolic extract in 5-CQA, caffeic acid, 1,5-di-CQA. These findings support further investigations to study the stability of the different CQAs in simil-physiological conditions and the feasibility of artichoke waste as antiglycative agents in food or pharmacological preparations.

CHEMICAL COMPOUNDS

5-caffeoylquinic acid (PubChem CID 5280633); 3-caffeoylquinic acid (PubChem CID 1794427); 1-caffeoylquinic acid (PubChem CID 10155076); 1,3-di-caffeoylquinic acid (PubChem CID 24720973); 1,5 - di-caffeoylquinic acid (PubChem CID 122685); caffeic acid (PubChem CID 689043); apigenin-7-glucuronide (PubChem CID 5319484); methylglyoxal PubChem CID (880); aminoguanidine hydrochloride (PubChem CID 2734687).

Pharmacological Studies of Artichoke Leaf Extract and Their Health Benefits

Artichoke (Cynara scolymus) leaf extract was one of the few herbal remedies which the clinical and experimental trials have complemented each other. Both experimental and clinical effects have been verified through extensive biomedical herbal remedy research. Specifically, antioxidant, choleretic, hepatoprotective, bile-enhancing and lipid-lowering effects have been demonstrated, which corresponded with its historical use. Ongoing research seems to indicate that artichoke indeed have medicinal qualities. Most significant appears to be its beneficial effect on the liver. In animal studies, liquid extracts of the roots and leaves of artichoke have demonstrated an ability to protect the liver, with possibly even to help liver cells regenerate. Although research is not yet conclusive, scientists were optimistic that its long-standing use in humans for digestive and bowel problems was indeed justified. It may also play a role in lowering cholesterol and thus help to prevent heart disease. Boiled wild artichoke reduced postprandial glycemic and insulinemic responses in normal subjects but has no effect on metabolic syndrome patients. This article intended to review the wide ranging pharmacological effects of artichoke leaf extract.

Investigation of the in vivo antioxidative activity of Cynara scolymus (artichoke) leaf extract in the streptozotocin-induced diabetic rat

The in vivo antioxidant activity of a quantified leaf extract of Cynara scolymus (artichoke) was studied. The aqueous artichoke leaf extract (ALE), containing 1.5% caffeoylquinic acid with chlorogenic acid being most abundant (0.30%), and luteolin-7-O-glucoside as major flavonoid (0.15%), was investigated by evaluating the effect on different oxidative stress biomarkers, after 3 wk oral supplementation in the streptozotocin-induced diabetic rat model. Apart from two test groups (0.2 g ALE/kg BW/day and 1 g ALE/kg BW/day, where BW is body weight), a healthy control group, untreated oxidative stress group, and vitamin E treated group (positive control) were included. A 0.2 g/kg BW/day of ALE decreased oxidative stress: malondialdehyde and 8-hydroxydeoxyguanosine levels significantly diminished, whereas erythrocyte glutathione levels significantly increased. A 1.0 g/kg BW/day ALE did not show higher antioxidant activity.