Antonio Nieto-Camacho

Oxidative stress, cytoxicity, and cell mortality induced by nano-sized lead in aqueous suspensions

This paper reports on the effect of aqueous and nano-particulated Pb on oxidative stress (lipid peroxidation), cytoxicity, and cell mortality. As determined by the Thiobarbituric Acid Reactive Substances (TBARS) method, only 6h after incubation aqueous suspensions bearing nano-sized PbO(2), soluble Pb(II), and brain-homogenate only suspensions, were determined to contain as much as ca. 7, 5, and 1 nmol TBARS mg protein(-1), respectively. Exposure of human cells (central nervous system, prostate, leukemia, colon, breast, lung cells) to nano-PbO(2) led to cell-growth inhibition values (%) ca. ≤18.7%. Finally, as estimated by the Artemia salina test, cell mortality values were found to show high-survival larvae rates. Microscopic observations revealed that Pb particles were swallowed, but caused no mortality, however.

Photoproduction of H2O2 and hydroxyl radicals catalysed by natural and super acid-modified montmorillonite and its oxidative role in the peroxidation of lipids

The reactivity of both natural montmorillonite and montmorillonite modified with super acids (CF3SO3H and HClO4) to generate hydrogen peroxide (H2O2) and hydroxyl radicals (˙OH) under both darkness and UV-light irradiation was investigated using EPR spin-trapping spectroscopy. We used the free-radical trapping action of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) to indicate the production of ˙OH from natural and modified clays. The recognition and characterisation of the formed DMPO–OH adduct established that super acid montmorillonites were able to generate hydroxyl radicals at 25 °C in the presence of O2 and H2O. When natural and acid montmorillonite were irradiated with UV light, hydroxyl radical generation was greater than under dark conditions. In addition, the peroxidation of lipids in biological matrices with natural and super acid montmorillonite was studied using a thiobarbituric acid reactive substances (TBARS) assay, which demonstrated that only ˙OH generated from the super acid montmorillonite induced the oxidative degradation of lipids. This study reports, for the first time, the generation of ˙OH and the peroxidation of lipids by a typical super acid-modified Mexican montmorillonite.

Anti-inflammatory and anti-bacterial activity, and CYTOTOXICITY of halloysite surfaces

Halloysite is a naturally-occurring nanomaterial occurring in the thousands of tons and that serves as biomaterial, with applications in the areas of biotechnology, pharmaceutical, and medical research. This study reports on the anti-inflammatory, cytotoxic, and anti-oxidant activity of halloysite Jarrahdale (collected at ∼ 45 km SE of Perth, Western Australia; JA), Dragon Mine (provided by Natural Nano Inc., Rochester, New York; NA), and Kalgoorie Archean (collected at Siberia, ∼ 85km NW of Kalgoorlie, West Australia; PA). Prior to biological testing, halloysites were characterized by 27Al and 29Si Nuclear Magnetic Resonance Spectroscopy, the anti-inflammatory activity was determined by (a) the mouse ear edema method, using 12-o-tetradecanoylphorbol-13-acetate (TPA) as anti-inflammatory agent; and (b) the myeloperoxidase enzymatic activity method (MPO). Cell viability was determined using the MTT method. Sample characterization by NMR method showed similar symmetry and atomic environments, with no evidence of distortion(s) due to shiftings in atomic ordering or electron density. The anti-inflammatory activity followed the order: PA>JA>NA, and remained invariant with time. Prolonged anti-inflammatory activity related inversely to surface area and lumen space. The low extent of infiltration at shorter reaction times confirmed a limiting number of active surface sites. EPR intensity signals followed the order: JA>NA>PA. The poor stabilization of RO species in PA suspensions was explained by tube alignment provoking occlusion, thus limiting transfer of H(+) or e(-) from-and-to the surface, and decreases in acidity associated to Al(oct). Cell viability (%) varied from one surface to the other, PA(92.3 ± 6.0), JA(84.9 ± 7.8), and NA(78.0 ± 5.6), but related directly to SBET values.

Synthesis, cytotoxic and antioxidant evaluations of amino derivatives from perezone

A series of eight amino derivatives (3a-h) from perezone 1 were prepared by nucleophilic addition of bioactive amines v.gr. melatonin, acetyl tryptamine, tryptophan and other amino acids esters (valine, leucine and methionine). Their structures were elucidated by spectroscopy data. The cytotoxic evaluation against four human tumor cell lines PC-3, K-562, HCT-15 and SKLU-1 was performed as well as the TBARS assay for antioxidant activity. The results suggest that 1 and its isomer 4 were highly active against all cell lines, 4 was twice as potent than 1 against PC-3 and HCT-15. The derivative 3a (IC(50)=7.5 ± 0.3 μM) was more active than 1 against HCT-15 whereas 3h was selective against K-562 with IC(50)=4.5 ± 0.4 μM. The TBARS assay has shown that 3c with IC(50)=5.564 ± 0.24 μM is a potent antioxidant with superior effect comparing to α-tocopherol and moreover was more active than the precursor molecule 1.

Determination of lipid peroxidation and cytotoxicity in calcium, magnesium, titanium and hectorite (SHCa-1) suspensions

This paper reports data on the relative ability of CaO, CaCl2, MgO, MgCl2, TiO2, and hectorite (SHCa-1) to induce oxidative stress (as determined by lipid peroxidation, LP) in biological matrices. The effectiveness of structural (oxide form) versus soluble Ca and Mg to induce LP is compared. An assessment on cytotoxicity as affected by soluble and structural Ca, Mg, TiO2 and SHCa-1 is also addressed. LP was screened and monitored using the Thiobarbituric Acid Reactive Substances (TBARS). The extent of TBARS production was found to vary with the type and initial concentration of the soluble or structural cation, Ca or Mg respectively. Obtained results showed higher magnitude values for the latter set of experiments. In the presence of TiO2 no significant TBARS production was detected pointing out a negligible effect of TiO2 on LP. At solid concentrations ca. 100 ppm, CaO appears to be more effective than SHCa-1 to induce LP. By contrast at ca. 25 ppm, MgO appears to be more effective than the clay mineral. The SHCa-1 LP-inducing activity has been proven to closely relate to structural Ca. The prevalence of mechanisms that may induce LP but not cytotoxicity (as determined by cell growth inhibition) was also addressed. Results on cell growth inhibition as affected by soluble and structural Ca, Mg, TiO2 and hectorite provide evidence to support that structural Ca or Mg brings about significantly higher variations than soluble Ca.

Oxidative stress induced by arsenopyrite and the role of desferrioxamine-B as radical scavenger.

Arsenopyrite (FeAsS) is one of the earths primary mineral sources of As, yet its effects on cell damage remain largely unknown. This paper addresses the question whether FeAsS induces lipid peroxidation (LP), a major indicator of oxidative stress. Screening and monitoring of LP was conducted using Thiobarbituric Acid Reactive Substances (TBARSs) assay. The lipid source was supernatant of rat brain homogenates. The formation of TBARS by FeAsS was rapid and took place just after 10 min. Maximum TBARS levels (ca. 14 nmol TBARS per mg of protein) were observed after 1h and remained constant thereafter. Suspension fraction separations showed that dissolved and structural components contributed to LP. The formation of TBARS by soluble As, As(III) or As(V), compared to basal levels. The initiation of LP by FeAsS was consistent with a mechanism initiated by the Fe(3+)/O(2)(-) redox system, and differed initiated by Fe(2+)/O(2). The effectiveness of FeAsS and FeSO(4) as inducer compared, and surpassed that of AAPH. On the other hand, the initiation of LP by FeAsS is consistent with a mechanism initiated by perferryl ion and Fe(3+)/O(2)(-), and differs from the mechanism characteristic of FeSO(4) initiated by the Fe(2+)/O(2) redox system. Proposedly, FeAsS surfaces contain a mixture of Fe(3+) and Fe(2+) that, along with O(2) and O(2)(-), participate in multiple mechanisms of electron transfer. EPR determinations show decreases in DMPO-OH adduct signal in FeAsS suspensions after adding desferrioxamine-B (DFO-B), consistent with the idea that DFO-B serves as a radical scavenger.

Anti-inflammatory, free radical scavenging and alpha-glucosidase inhibitory activities of Hamelia patens and its chemical constituents

Abstract Context Hamelia patens Jacq. (Rubiaceae) is traditionally used to treat wounds, inflammation and diabetes. However, there is still a lack of scientific evidence to support these applications. Objective The objective of this study is to evaluate the anti-inflammatory, antioxidant and antidiabetic activities of Hamelia patens, and identify its bioactive compounds. Materials and methods Four extracts were obtained by maceration and liquid–liquid extraction: HEX, DCM–EtOAc, MeOH–EtOAc and MeOH–Aq. The anti-inflammatory effect was evaluated orally on rat paw carrageenan-induced oedema over 6 h (50, 200 and 500 mg/kg), and topically in mouse ear oedema induced by 12-tetradecanoylphorbol-13-acetate (TPA) after 4 h (0.5 and 1 mg/ear). We also evaluated myeloperoxidase levels in ear tissue, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging ability, and in vitro α-glucosidase inhibition. The chemical compounds were separated by column chromatography and identified by spectroscopic analysis. Results We found that the oral administration of the HEX extract at 500 and 200 mg/kg significantly decreased the carrageenan-induced inflammation after 1 and 3 h, respectively. The MeOH–EtOAc extract significantly inhibited myeloperoxidase activity (83.5%), followed by the DCM–EtOAc extract (76%), β-sitosterol/stigmasterol (72.7%) and the HEX extract (55%), which significantly decreased oedema induced by TPA at both doses, giving a similar effect to indomethacin. We also found that the MeOH–EtOAc, MeOH–Aq and DCM–EtOAc extracts showed good DPPH scavenging activity (IC50 values of 18.6, 93.9 and 158.2 μg/mL, respectively). The HEX extract showed the lowest α-glucosidase inhibition (an IC50 value of 26.07 μg/mL), followed by the MeOH–EtOAc extract (an IC50 value of 30.18 μg/mL), β-sitosterol/stigmasterol (IC50 34.6 μg/mL) and compound A ((6E,10E,14E,18E)-2,6,10,14,18,23-hexamethyl-2,6,10,14,18,22-tetracosahexaene, an IC50 value of 114.6 μg/mL), which were isolated for the first time from Hamelia patens. Discussion and conclusion Hamelia patens possesses anti-inflammatory, antioxidant and α-glucosidase inhibitory activities, which support its traditional use. These effects can be attributed to the identified compounds.

Oxidative stress inhibition and oxidant activity by fibrous clays.

Fibrous clays (sepiolite, palygorskite) are produced at 1.2m tonnes per year and have a wide range of industrial applications needing to replace long-fibre length asbestos. However, information on the beneficial effects of fibrous clays on health remains scarce. This paper reports on the effect of sepiolite (Vallecas, Spain) and palygorskite (Torrejón El Rubio, Spain) on cell damage via oxidative stress (determined as the progress of lipid peroxidation, LP). The extent of LP was assessed using the Thiobarbituric Acid Reactive Substances assay. The oxidant activity by fibrous clays was quantified using Electron-Paramagnetic Resonance. Sepiolite and palygorskite inhibited LP, whereby corresponding IC50 values were 6557±1024 and 4250±289μgmL(-1). As evidenced by dose-response experiments LP inhibition by palygorskite was surface-controlled. Fibrous clay surfaces did not stabilize HO species, except for suspensions containing 5000μgmL(-1). A strong oxidant (or weak anti-oxidant) activity favours the inhibition of LP by fibrous clays.

Anti-Inflammatory and Cytotoxic Activities of Chichipegenin, Peniocerol, and Macdougallin Isolated from Myrtillocactus geometrizans (Mart. ex Pfeiff.) Con.

The oleanane-type triterpene chichipegenin and the sterols peniocerol and macdougallin, isolated from Myrtillocactus geometrizans, showed anti-inflammatory activities in both the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear edema model and the carrageenan- induced rat paw edema model. All tested compounds inhibited the TPA-induced edema in a dose-dependent manner, with ED50 values less than or equal to that shown by indomethacin. Among them, peniocerol was the most active compound. However, only peniocerol and macdougallin reduced carrageenan-induced rat paw edema. On the other hand, peniocerol and macdougallin showed cytotoxicity against several human cancer cell lines. These results indicate that compounds isolated from M. geometrizans possess antiinflammatory and cytotoxic properties, and the presence of chichipegenin in the aerial parts could justify the medicinal uses attributed to the plant.

Antioxidant and anti-inflammatory activities of Pittocaulon species from México

Context: Stems and leaves of Pittocaulon spp. (Asteraceae) are used in Mexican traditional medicine as an anti-inflammatory substance and for the treatment of skin injuries. Objective: This study evaluated the antioxidant activity of methanol (MeOH) and dichloromethane (DC) extracts of five Pittocaulon species. Materials and methods: DC and MeOH extracts from flowers, roots, and stems of Pittocaulon praecox (Cav.) H. Rob. & Brettell, P. bombycophole (Bullock) H. Rob. & Brettell, P. filare (Mc Vaugh) H. Rob. & Brettell, P. velatum (Greenm.) Rob. & Brettell and P. hintonii H. Rob. & Brettell. Result and Discussion: In the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the flower extracts obtained with MeOH were the most active with IC50 values ranging from 51.83 ± 4.08 to 154.19 ± 8.39 ppm. In the thiobarbituric acid reactive substances (TBARS) model, the best activity was shown by DC extracts of roots with IC50 values ranging from 55.54 ± 1.28 to 160.82 ± 5.37 ppm. The MeOH extract of flowers of P. bombycophole had the highest IC50 value in both DPPH (51.83 ± 4.08 ppm) and TBARS (39.78 ± 1.97 ppm). The samples with the best values in the antioxidant activity assays were evaluated in the anti-inflammatory tests. The DC root extract of P. velatum at a dose of 1 mg/ear produced the greatest reduction (84.96%) of the 2-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear edema. This extract also reduced the activity of the enzyme myeloperoxidase (MPO) (73.65%) at the same dose. In contrast, DC root extract of this species did not show significant inhibition of the increase in paw edema induced by carrageenan at the doses tested (100 mg/kg). Conclusion: These results support the traditional use of these plants as anti-inflammatory. DC extracts of P. velatum and MeOH extracts of P. bombycophole may be a potential resource of natural anti-inflammatory and antioxidant compounds, respectively. Additional studies must be done to identify the compounds responsible of the activity on these plants and to establish the mechanism of action.