María Eliana Hidalgo

Assessment of catalase activity, lipid peroxidation, chlorophyll-a, and growth rate in the freshwater green algae Pseudokirchneriella subcapitata exposed to copper and zinc

In this work, the effect of copper and zinc on green alga Pseudokirchneriella subcapitata was evaluated through catalase activity, lipid peroxidation by TBARS essay, growth rate, and the chlorophyll-a concentration. Catalase activity increased significantly (P < 0.05) in comparison to the control at 0.1 mg L -1 copper and 0.075 mg L -1 zinc, whereas the damage to the cell membrane expressed as nmols/10 6 cell of malondialdehyde increased significantly (P < 0.05) at 0.025 mg L -1 copper and 0.1 mg L -1 zinc. On the other hand, a significant (P < 0.05) decrease in chlorophyll-a concentration was found at 0.075 mg L -1 of both metals. The results showed that catalase activity, lipid peroxidation, and chlorophyll-a concentration were more sensitive to metals than the growth rate.

Induced and photoinduced dna damage by quinolones : Ciprofloxacin, ofloxacin and nalidixic acid determined by comet assay

Quinolones are degraded by light with loss of their antimicrobial activity, generating active species or radicals, Evidence exists that some fluoroquinolones (lomefloxacin, fleroxacin and enoxacin) induce damage to the cellular membrane and DNA cleavage by photosensitization. In this study, the genotoxic potential of the quinolones ofloxacin, nalidixic acid and ciprofloxacin (three antimicrobials frequently used in therapy) was evaluated upon irradiation with UV light by using the comet assay on cells of the Jurkat line. The results demonstrate that there are significant differences between the control groups (positive control with 50 μM H2O2, negative controls without drug and with and without irradiation) and the groups of irradiated quinolones (ofloxacin 2.76 × 10−5M, nalidixic acid 2.15 × 10−4M and ciprofloxacin 2.01 × 10−5M), indicating that, at the dose of irradiation employed (necessary to produce 50% photodegradation), the photodecomposition of the quinolones enhanced DNA damage. The unirradiated drugs also exhibited genotoxicity significantly different from that of the negative control.

ANTIOXIDANT CAPACITY OF EUGENOL DERIVATIVES

Toxicity and antioxidant capacity of eugenol derivatives (E2 = 2-Methoxy-4-[1-propenylphenyl]acetate, E3 = 4-Allyl-2-methoxyphenylacetate, E4 = 4-Allyl-2-methoxy-4-nitrophenol, E5 = 5-Allyl-3-nitrobenzene-1,2-diol, E6 = 4-Allyl-2-methoxy-5-nitrophenyl acetate) were evaluated in order to determine the influence of the sustituents. E2-E6 were synthesized from eugenol (E1). E1 was extracted from cloves oil, and E2-E6 were obtained through acetylation and nitration reactions. Antioxidant capacity evaluated by DPPH (1, 1-Diphenyl-2-picrylhydrazil) and ORAC fluorescein demonstrated that E1 and E5 have a higher capacity and the minor toxicity evaluated by red blood cells haemolysis and the Artemia saline test. In accordance with our results, the compounds (E1-E5) use in the pharmaceutical, cosmetic and or food industries could be suggested.

Comparative determination of photodegradation kinetics of quinolones

Abstract The photostabilities of several quinolones have been determined using high performance thin layer chromatography. On irradiation with UVA (350 nm), the photostability decreases in the order: ciprofloxacin (CP)> norfloxacin (NF) > pipemidic acid (PA) > nalidixic acid (NA) > M-193324 > rosoxacin (RS) > oxolinic acid (OA). The photo- degradation process in all cases follows first-order kinetics. Furthermore, the quantum yield of fluorescence was determined for each quinolone; these values vary from 0.15 x 10 −2 to 5.15 x 10 −2 . The highest Φ f value corresponds to CP and NF. These results show that quinolones which possess a piperazine ring at the C-7 position (CP, NF, PA) are less photostable and more fluorescent.

EFFECTS OF SOLAR UV-B RADIATION IN THE ACCUMULATION OF RHIZOCARPIC ACID IN A LICHEN SPECIES FROM ALPINE ZONES OF CHILE

En la especie liquenica Acarospora schleicheri, recolectada en gradientes altitudinales a 18o, 19o y 33o Lat. S, en zonas alpinas de Chile, se determinaron y compararon las concentraciones de acido rizocarpico. Se observaron incrementos significativos en la acumulacion del metabolito con la altura s.n.m. y el aumento en los niveles de radiacion UV-B en los gradientes seleccionados. Los resultados obtenidos sugieren que la sintesis de acido rizocarpico es inducida por la radiacion UV-B y que su presencia representa una adaptacion quimica frente a los elevados niveles de radiacion UV-B en los habitats de esta especie liquenica.

Lack of effects of 2,4-dichlorophenoxyacetic acid administration on markers of oxidative stress during early pregnancy in mice.

Induction of oxidative stress by 2,4-dichlorophenoxyacetic acid (2,4-D) both as a pure compound and in commercial formulation was investigated during early pregnancy in mice. Pregnant animals were exposed to increasing doses of the herbicide (0.01, 0.1 and 100mg/kg/d) during gestation days 0-9, after which animals were euthanized and their blood analyzed for catalase activity, thiobarbituric acid reactive substances (TBARs) and total antioxidant capacity (TAC). Number of corpora lutea and uterine implantations and resorptions were also determined. Herbicide exposure did not cause any overt signs of maternal toxicity at any of the doses administered; neither did it cause an effect on developmental parameters. Catalase activity and TBARs were not modified by herbicide exposure although TAC was significantly decreased at 100mg/kg/d of both pure and formulated compound. Thus, 2,4-D does not seem to induce oxidative stress during early pregnancy in mice at the doses administered, indicating that this mechanism is probably not involved in mediating herbicide toxicity at these dose levels. Furthermore, since no manifestations of developmental toxicity were observed after administration of the herbicide, it is also possible that 2,4-D may not produce any early developmental toxicity at the low environmentally relevant doses tested in this animal model.

Evaluación de la toxicidad de cobre en suelos a través de biomarcadores de estrés oxidativo en eisenia foetida

Copper toxicity in soil was evaluated using biomarkers of oxidative stress (catalase enzyme activity, superoxide dismutase and lipid peroxidation) in the earthworm Eisenia foetida. Agricultural topsoils from mining areas of the Aconcagua river basin were collected. Total copper concentrations were in the range of 94-959 mg kg-1, while the exchangeable copper concentrations were in the range of 46-2225 µg kg-1. Earthworms exposed to soil with exchangeable copper concentrations above 32 µg kg-1 showed an increase in catalase activity. Parameters of antioxidant activity were more sensitive than the weight change and thus can be used as appropriate biomarkers in Eisenia foetida.

Phototoxic potential of quinolones

The photohaemolytic potentials of the quinolones oxolinic acid, pipemidic acid, rosoxacin, norfloxacin, ciprofloxacin and M-193324 (synthesis intermediary) were evaluated and compared with the photohaemolysis induced by nalidixic acid. Quinolones with a piperazine group in position 7 (pipemidic acid, norfloxacin and ciprofloxacin) did not induce photohaemolysis. However, oxolinic acid, rosoxacin and M-193324 produced a concentration- and oxygen-dependent photohaemolysis. Ascorbic acid, histidine and thiourea inhibited the photohaemolysis induced by oxolinic acid, rosoxacin and M-193324, suggesting a photodynamic mechanism similar to that found with nalidixic acid. In addition, deuterium oxide increased the photohaemolysis induced by photohaemolytic quinolones, indicating that this process is mediated by singlet oxygen.

Effects of UV Radiation on Usnic Acid in Xanthoparmelia microspora (Müll. Arg. Hale)

An important decrease in the level of stratospheric ozone has been observed during the past decade (1), with accompanying increases in UV-B radiation (2) and some UV-A radiation (3), thus leading to probable damage to aquatic and terrestrial ecosystems (4–7). Inhabitants of terrestrial and aquatic ecosystems have developed strategies to cope with the potential stress induced by UV radiation. One of these strategies is the synthesis of photoprotector compounds derived mainly from the biosynthetic route of the polymalonate acetate (8–13). As levels of UV radiation increase, accumulation rates of some photoprotective compounds in lichen species from the Chilean Alpine zones also increase (14). Photodegradation of depsides may have accounted for the low levels of phenolics in lichens at higher elevations (15). It was observed that, in Xanthoparmelia lichens from the Alpine regions of Chile, the higher the altitude where the lichen was found, the greater amount of usnic acid it produced (16). This increase of usnic acid is the result of the lichen’s ability to adapt to radiation, which ensures its survival in extreme environmental conditions. In thalli from Xanthoparmelia oleosa collected at 4690 m no usnic acid was detected, which could be proof of the presence of a photodegradation product of usnic acid (17) but which has not been identified to date. In growth-chamber experiments lasting 1 week, thalli of Umbilicaria americana always produced smaller amounts of phenolic residue when exposed to both UV-B and UV-A radiation, compared with exposure to UV-A alone. In one field experiment exclusion of UV-B by light filtration produced significant increases in phenolic compounds. This increase occurs only during spring and autumn, when lichens are metabolically more active (18). In this article we evaluated the accumulation rates of usnic acid in Xanthoparmelia microspora (Mull. Arg. Hale) exposed to doses of solar radiation and to additional doses of UV-A and UV-B radiation. Furthermore, we report on the photolysis of usnic acid in nonnucleofilic solvents during exposure to higher doses of UV-A and UV-B radiation.

Applied Biological and Physicochemical Activity of Isoquinoline Alkaloids: Oxoisoaporphine and Boldine

The aim of this study was to determine the electronic influence of substituent groups and annelated rings such as oxazole-oxazinone on the physicochemical and photoprotection, antioxidant capacity, toxicity and singlet oxygen photosensitization biological properties of isoquinoline alkaloid frameworks. Thus, oxoisoaporphine derivatives 1–5 and 3-azaoxoisoaporphine (6), some of them with phenolic structures, did not present any antioxidant capacity, possibly either by formation of keto-enol tautomerism species or the formation of unstable free radicals. Due to the singlet oxygen quantum yields (ΦΔ) near to unity, and greater photostability than phenalenone, oxoisoaporphines 4–6 may be considered as photosensitizers for singlet oxygen production and can be used as new universal study tools. The biological application as antibacterial agents is an important and possible tool in the study of compounds with low cytotoxicity and high reactivity in antineoplastic chemotherapy. On the other hand, when boldine and its annelated derivatives B1–4 are irradiated, a photoprotector effect is observed (SPF = 2.35), even after 30 minutes of irradiation. They also act as photoprotectors in cell fibroblast cultures. No hemolysis was detected for boldine hydrochloride and its salts without irradiation. In solutions irradiated before incubation (at concentrations over 200 ppm) photoproducts were toxic to the nauplii of Artemia salina.