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Context: The incidence of solar ultraviolet radiation (UV) on Earth has increased due to diminish of the ozone layer. This enviromental agent is highly genotoxic causing numerous damage in DNA molecule. Nowadays there is a growing interest in the search of compounds capable to minimize these effects. In particular, phytocompounds have been tested as excelent candidates for their antigenotoxic properties. Aims: To evaluate the protective effect of the aqueous extract of Pinus caribaea (EPC) against the damage induced by the UVB and UVC radiation. Methods: The cell-free plasmid DNA assay was employed. The forms of plasmid were separated electrophoretically in agarose gel. For genotoxic and photoprotective evaluation of P. caribaea, different concentrations of the extract (0.1 – 2.0 mg/mL) and exposure times were evaluated. The CPD lesions were detected enzymatically. Additionally, the transmittance of the aqueous extract against 254 nm and 312 nm was measured. Results: None of the concentrations were genotoxic in 30 min of treatment, for superior times a clastogenic effect was observed. The EPC despite inhibiting the activity of the enzyme T4 endo V, impedes photolesions formation in DNA at concentrations ≥ 0.1 mg/mL. Conclusions: The EPC has photoprotective properties, this effect could be related with its antioxidants and absorptives capacities.

Context: Sunlight ultraviolet (UV) radiation constitutes a significant physical carcinogen in nature. It could induce direct and indirect DNA damage, which if not properly repaired may generate mutations. Plants in the genus Phyllanthus (Phyllanthaceae) are widely used in traditional medicine and known as natural sources of antioxidant compounds. Recent investigations support their genoprotective activity against chemical and physical mutagens, among them UV radiation. Aims: To compare the antioxidant, photoprotective and antimutagenic activity of aqueous extracts obtained from three Cuban endemic Phyllanthus species: P. chamaecristoides Urb., P. microdictyus Urb., and P. williamioides Gr. Methods: DPPH radical scavenging assay was use for quantify the in vitro antioxidant capacity. Genoprotection against UVC radiation was measured at two levels: structural DNA damage and mutations, by means of the SOS Chromotest, Survival assay, and RifR mutagenicity test in Caulobacter crescentus cells. Results: P. chamaecristoides extract showed the highest antioxidant capacity (IC50 = 0.032 mg/mL), and together with P. microdictyus exhibited the greatest bioantimutagenic effects (RMF ≤ 5%), diminishing UVC-induced DNA damage in three and five times, respectively. Conclusions: The reduction in DNA damage is not founded in a Phyllanthus aqueous extracts desmutagenic effect. It is possible that the genoprotective activity detected could be due to modulation of DNA repair mechanisms, diminishing SOS response and related mutagenicity induced by UVC radiation. Moreover, high antioxidant capacity could also decrease UV radiation oxidative-damage. Altogether, these outcomes validate future pre-clinic research regarding Phyllanthus photoprotective capacities.

Objetivo: Evaluar el efecto protector del extracto acuoso de Cymbopogon citratus (DC) Stapf, ante el daño inducido por las radiaciones UVC. Material y Métodos: Para evaluar si el extracto acuoso de C. citratus era capaz de inducir roturas de cadenas en el ADN, moléculas de plásmido pBluescript SK II fueron tratadas con diferentes concentraciones del extracto (0,01 - 4,0 mg/mL), en los tiempos de exposición: 30, 60 y 90 min. El efecto fotoprotector fue evaluado aplicando el extracto vegetal antes, durante, y después de la irradiación del ADN plasmídico con 200 J/m² de UVC. La actividad enzimática de T4 endonucleasa V fue empleada para detectar formación de CPDs. Las formas superenrollada y relajada de las moléculas de plásmido fueron separadas electroforéticamente en gel de agarosa. Adicionalmente, se midió la transmitancia del extracto acuoso a la DO de 254 nm. Resultados: Ninguna de las concentraciones evaluadas resultó genotóxica con 30 min de tratamiento. Las concentraciones ≥ 2 mg/mL indujeron roturas de cadenas a los 90 min de incubación. El extracto de C. citratus a concentraciones ≥ 0,5 mg/mL protegió al ADN frente a las radiaciones UVC. Conclusiones: En nuestras condiciones experimentales, el extracto acuoso de C. citratus protege al ADN frente a la genotoxicidad inducida por la luz UVC, previniendo la generación de CPDs, pero no es capaz de eliminarlas una vez formadas.

The ultraviolet (UV) component of sunlight is high on the earth surface, especially at low latitudes, raising the risk of skin diseases, including cancer. The use of natural compounds is a strategy to protect people against UV damage. Seaweeds are becoming increasingly influential in the food industry, and are also used in the pharmacy and cosmetic industries, due to several bioactive demonstrated properties. This work analyzed the genotoxic and photoprotective effects of the aqueous extracts of two seaweed species: Bryothamnion triquetrum and Halimeda incrassata. A cell-free plasmid DNA assay was employed, allowing detection of DNA breaks. The plasmids were exposed to increasing concentrations of aqueous extracts. DNA break was produced at concentrations of 2.0 and 4.0 mg/mL in both seaweed extracts and, consequently, a genotoxic effect is postulated. This effect arises with higher exposure times. Additionally, different combinations of plasmid DNA, restriction enzymes (Eco RI, Bam HI, and Pvu II) and extracts were assayed. The extracts did not produce an interference effect in the reconnaissance of the specific restriction target sequences of each enzyme. Photoprotective activity of the extracts was evaluated in UVC-irradiated plasmids. None of the extracts displayed DNA protective effects in this assay.

Se estudió el efecto protector de una decocción de las hojas de la planta Cymbopogon citratus (DC.) Stapf. (caña santa o caña de limón) frente al daño genético inducido por los agentes oxidantes H2O2 y etilnitrosourea (ENU). Se utilizó para ello un modelo esperimental in vitro y otro in vivo: cultivo de células de ovario de Hamster chino (CHO) y el insecto Drosophila melanogaster, respectivamente. La capacidad de formar colonias de la línea celular CHO, fue el indicador de toxicidad utilizado para evaluar 5 concentraciones (0,1; 1; 5; 10; 15 %) de la decocción de caña santa, en tanto que el porcentaje de sobrevivencia de adultos se usó para evaluar el efecto tóxico de 4 concentraciones de esta (5; 25; 50; 100 %) sobre las larvas mwh + / + flr³ de Drosophila melanogaster; en ambos casos los resultados evidenciaron efectos tóxicos dependientes de las concentraciones utilizadas. Los estudios citofluorimétricos con diclorofluoresceína-diacetato en células CHO permitieron demostrar la capacidad antioxidante de la decocción de caña santa. Dosis no tóxicas de 0,1; 1 y 5 % produjeron reducciones significativas del estrés oxidativo causado por el H2O2. La genotoxicidad y antigenotoxicidad de diferentes concentraciones de la decocción fueron evaluadas mediante los ensayos de aberraciones cromosómicas en células CHO y el SMART de alas de Drosophila melanogaster. Los resultados de actividad mutagénica obtenidos fueron negativos, en tanto que los correspondientes a la acción protectora de las concentraciones probadas reafirmaron la capacidad antioxidante mostrada por el extracto vegetalThe protective effect of a decoction of Cymbopogon citratus (DC) Stapf. against genetic damage induced by oxidizing agents H2O2 and ethylnitrosourea was studied. To this end, was used an experimental model in vitro and another in vivo; Chinese Hamster ovary cell culture and Drosophila melanogarster respectively. The colony-forming capacity of CHO cell line was the toxicity indicator used to evaluate 5 Cymbopogon citratus (DC) Stap. decoction concentrations (0,1; 1; 5; 10; 15 %) whereas the percentage of surviving adult insects was used to asses the toxic effect of 4 concentrations of this extract (5; 25; 50; 100 %) on mwh + 1 + flr³ larvae of Drosophila melanogaster. In both cases, the results revealed concentration dependent toxic effects. The cytofluourimetric studies performed on CHO cells with dischlorofluorescein-diacetate showed the antioxidant capacity of the decoction. Non-toxic doses of 0,1; 1 and 5 % caused significant reductions of H2O2 induced oxidative stress. Genotoxicity and antigenotoxicity of the different decoction concentrations were evaluated by chromosomal aberration detection tests in CHO cell and the SMART of Drosophila melanogastes' wings. The results of the mutagenic activity were negative whereas those of the protective capacity of the tested concentrations confirmed the antioxidant capacity of this vegetal extract

Phyllanthus orbicularis (Phyllanthaceae) is an endemic evergreen tropical plant of Cuba that grows in the western part of the island and is used in traditional medicine as an infusion. The aqueous extract of this plant presents a wide range of pharmacological activitiessuch as antimutagenic, antioxidant and antiviral effects. Given the many beneficial effects and the great interest in the development of new pharmacological products from natural sources, the aim of this work was to investigate the phytochemistry of this species and to elucidate the structure of the main bioactive principles. Besides the presence of several known polyphenols, the major constituent was hitherto not described. The chemical structure of this compound, here named Fideloside, was elucidated by means of HR-ESIMS/MSn, 1D/2D NMR, FT-IR, and ECD as (2R,3R)-(−)-3’,4′,5,7-tetrahydroxydihydroflavonol-8-C-β-D-glucopyranoside. The compound, as well as the plant aqueous preparations, showed promising bioactive properties, i.e., anti-inflammatory capacity in human explanted monocytes, corroborating future pharmacological use for this new natural C-glycosyl flavanonol.

Homologous recombination is a DNA repair mechanism that additionally generates a biological diversity. Most of our knowledge about it was obtained from assays that used double strand ends as initiators of recombination. The present work is aimed at evaluating homologous recombination in bacteria, using an assay based on the segregation of chromosomal duplication. This assay measures exchanges between sister strands without favoring any pathway. A collection of strains of Salmonella enterica serovar typhimurium deficient in genes coding for proteins involved in homologous recombination was built. We evaluated spontaneous (SSR) and UV-induced segregation rate (UV-ISR). We demonstrated that the absence of RuvC resolvase did not affect SSR, while defects in RecA, RecQ and RecB/RecF decreased it and the lack of SbcCD or RuvAB stimulated it. In RecB null mutants, lesions that are not commonly sensed by RecFOR seem to have been recognized and repaired by this pathway. The methodology supported the corroboration of a RecA-independent pathway in Salmonella and suggests the existence of alternative recombination pathways in recB/recF double mutants.

Agents that can damage the DNA in vivo have potential adverse effects on human health. They may induce transmissible mutations and cancer. SOS Chromotest is a SOS transcriptional-fusion based assay, ß-galactosidase gene was located after a SOS promoter, thus its enzymatic activity indicates the level of induction of SOS response and the DNA damage produced by chemical and physical mutagens, can be estimated. We presented and evaluated a microanalytical variant of the original SOS Chromotest for detecting genotoxicity of pigmented samples. We introduced two main modifications: we changed the colorimetric substrates for fluorescent ones and we worked at micro-analytical scale. The optimal ß-galactosidase substrate concentration used was 1.8 mM and 40 minutes as time reaction. This variant detected efficiently the genotoxicity of known mutagen and the natural pigmented extracts. The results are discussed in relation to the advantages to work at micronalytical scale, costs reduction, automatization of reading and its usefulness for the screening of a large variety of samples.