Seasonal changes in the pro/antioxidant status of mussels Mytilus galloprovincialis (Lamarck, 1819) from Bulgarian Black Sea coastal habitats

The pro/antioxidant status of marine macrozoobentic organisms is being increasingly applied in environmental monitoring and conservation programs. The oxidative stress level in marine bivalves can provide valuable information not only on the health of the organisms and their populations, but also on the current state of habitats and ecosystems. The aim of the present study was to make the first comprehensive investigation of the seasonal changes in the antioxidant activity in different organs (gills, digestive gland and foot) of M. galloprovincialis from representative Bulgarian Black Sea coastal habitats. The lipid peroxidation and glutathione levels, as well as activities of the antioxidant enzymes catalase, superoxide dismutase, glutathion peroxidase, glutathion reductase, glucose-6-phosphate dehydrogenase and glutathione-S-transferase of the organs were measured spectrophotometrically. Our hypothesis was that enhanced environmental pressure during the summer season, induced by multiple factors (biogenic, abiogenic and anthropogenic) led to weakening of the antioxidant protection in mussels at the beginning of autumn. The reaction of the mussel organism to the multiple stress factors was specific for the target organ and the type of the biomarker. Significant differences were present in the activity of the antioxidant system in mussels from the northern and southern coastal locations. The seasonal changes in the pro/antioxidant status of mussels were primarily due to specific seasonal changes in factors concerning the marine environment at the concrete locality. Further research is obviously needed to confirm the present results and provide a more complete data of seasonal and spatial changes in the antioxidant defense system of mussels from the Bulgarian Black Sea coastal area and their implementation in biomonitoring programs

State of the antioxidant defense system in wedge clams from Bulgarian Black Sea as a measure of resistance to environmental impacts

Pollution and climate change can induce oxidative stress (OS) in aquatic organisms. Reduced activity or incoordination between antioxidant enzymes in marine bivalves may cause cellular impairment with effects on higher levels of ecological organization. The present study aims to assess the condition factor and the activity of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione concentration (GSH) in soft tissues of Donax trunculus (Linnaeus, 1758) as indicators of the state of marine ecosystems along the Bulgarian Black Sea coast. The wedge clams were sampled manually from different localities in June and in September. The activity of antioxidant enzymes and GSH concentrations varied both seasonally and among localities. Higher values of GSH, SOD and GPx were registered in wedge clams collected in autumn compared to those collected in summer. In wedge clams higher activity of the major phase II detoxification enzyme GST was observed in summer at localities with intensive tourism, suggesting an activation of the cell detoxification processes, presumably in response to increased environmental pressure. In conclusion, the observed presence of elevated enzyme activities suggested activation of the antioxidant protection system of the wedge clams in response to environmental pressure, indicating their ability to cope with induced OS and adapt to local conditions, and thus maintain ecosystem health

Comparative study on the oxidative stress of commercially important fish species from localities with different ecological conditions along the Bulgarian Black Sea coast

The aim of the present study was to perform a pilot assessment and analysis of the oxidative stress (OS) level in four commercially important fish species (round goby, red mullet, sprat and horse mackerel) from different localities of the Bulgarian Black Sea coast. The fish were sampled during trawl selectivity experiments. The OS level in the fish was assessed by measuring lipid peroxidation (LPO), glutathione concentration (GSH), activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST), as well as acetylcholine esterase (AChE) in gills and liver. Round goby and red mullet caught in the Nessebar Bay showed clear signs of OS with the highest levels of LPO and GST activities, accompanied by the lowest AChE activities in both liver and gills. On the contrary, round goby caught near Maslen Nos (a region with good ecological conditions) were least affected by OS with low LPO and high GSH concentrations and SOD activity. There were no significant differences in the OS bioindicators of horse mackerel from the different localities. Sprat caught in Nessebar Bay, compared to those caught from the other localities, showed presence of OS indicated by lower GSH levels and relatively higher CAT, GPx and GST activities, accompanied by low AChE activity in gills. It can be concluded that round goby and red mullet were more vulnerable to OS induced by marine environmental factors than the horse mackerel and sprat. However, their antioxidant defense system allows them to tolerate and adapt to the environment of their habitats. Further studies are needed for the assessment of OS in important fish species in the Bulgarian part of the Black Sea

Chromatographic Profile and Redox-Modulating Capacity of Methanol Extract from Seeds of Ginkgo biloba L. Originating from Plovdiv Region in Bulgaria

Oxidative stress underlies the pathogenesis of many diseases, which determines the interest in natural substances with antioxidant properties. Ginkgo biloba L. leaves are well known and widely used in the pharmaceutical industry, but the therapeutic properties of the seeds are less studied. This study aimed to identify the chromatographic profile and to evaluate the antioxidant properties of methanol extract from seeds of G. biloba (GBSE). In the GBSE, flavonoids and terpenes were found as terpenes predominated. The GBSE antioxidant capacity determined by 2,2 azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) and 1-diphenyl-2-picrylhydrazyl (DPPH) methods were equal to 1.34% and 0.58% of the activity of reference substance Trolox, respectively. The results of the ferric reducing antioxidant power method showed that the effect of concentration 1 mg/mL (w/v) GBSE was equal to 7.418 mM FeSO4 used as a standard. The cupric reducing antioxidant capacity activity of the GBSE was found to be 215.39 µmol Trolox/g GBSE and is presented as Trolox equivalent. The metal chelation effect of 1 mg/mL (w/v) GBSE was equal to that obtained for 0.018 mM EDTA. In conclusion, GBSE showed a good ability to neutralize ABTS and DPPH radicals and could have a beneficial effect in pathological conditions with oxidative stress etiology

Mitigation of the Oxidative Damage in Liver Caused by Influenza Virus Infection in Mice by an Effective Combination of Oseltamivir and S-adenosyl-L-methionine (SAM)

This study aimed to estimate the protective effect of a combination of S-Adenosyl-L-methionine (SAM) as a precursor of glutathione and oseltamivir as a specific inhibitor of virus replication on oxidative damages caused by influenza infection in the liver of infected mice. Albino mice were inoculated with 10×LD50 of influenza virus A/Aichi/2/68(H3N2). Oseltamivir was applied for five days after infection, twice per day, in a dose of 2.5 mg/kg. SAM was applied for ten days in a 100 mg/kg dose, starting five days before inoculation. Markers of oxidative stress, mortality rate, mean survival time, index, and protection coefficient were followed. Influenza infection causes severe oxidative damage to the liver. All combinations of SAM and oseltamivir restored the levels of the biochemical markers to those in healthy animals and improved the virological parameters. A combination of SAM 100 mg/kg and oseltamivir 2.5 mg/kg, which is 1/4 of the optimal therapeutic mice dose, exhibits protection index and affects most effectively all the tested parameters. This study provides an easy-to-apply approach with a good therapeutic potential for co-medicating influenza infection with a specific antiviral agent and an antioxidant precursor

In Vivo Toxicity, Redox-Modulating Capacity and Intestinal Permeability of Novel Aroylhydrazone Derivatives as Anti-Tuberculosis Agents

The emergence and spread of Mycobacterium tuberculosis strains resistant to many or all anti-tuberculosis (TB) drugs require the development of new compounds both efficient and with minimal side effects. Structure-activity-toxicity relationships of such novel, structurally diverse compounds must be thoroughly elucidated before further development. Here, we present the aroylhydrazone compounds (3a and 3b) regarding their: (i) acute and subacute toxicity in mice; (ii) redox-modulating in vivo and in vitro capacity; (iii) pathomorphology in the liver, kidney, and small intestine tissue specimens; and (iv) intestinal permeability. The acute toxicity test showed that the two investigated compounds exhibited low toxicity by oral and intraperitoneal administration. Changes in behavior, food amount, and water intake were not observed during 14 days of the oral administration at two doses of 1/10 and 1/20 of the LD50. The histological examination of the different tissue specimens did not show toxic changes. The in vitro antioxidant assays confirmed the ex vivo results. High gastrointestinal tract permeability at all tested pH values were demonstrated for both compounds. To conclude, both compounds 3a and 3b are highly permeable with low toxicity and can be considered for further evaluation and/or lead optimization

Effects of anthropogenic and environmental stressors on the current status of red mullet (Mullus barbatus L., 1758) populations inhabiting the Bulgarian Black Sea waters

The red mullet (Mullus barbatus Linnaeus, 1758) is a keynote species for the Bulgarian Black Sea ecosystem and fisheries; nevertheless, existing knowledge on population status is very scarce. The present study was intended to assess the health status and adaptive potential of M. barbatus populations inhabiting the Bulgarian waters of the Black Sea. Our findings revealed that populations of M. barbatus are exposed to a variety of anthropogenic and environmental stressors. The species’ status was assessed using representative genetic, morphological, biochemical and chemical biomarkers from specimens obtained in the research area’s northern and southern regions. Based on mtDNA markers, genetic analysis revealed low haplotype and nucleotide diversity, typically observed in overexploited or “threatened” populations. Examining the morphology of the specimens revealed no discernible pattern of differentiation. Except for aluminium and chrome, metal and PAH concentrations in fish were below the regulatory thresholds. The specimens from the southern region ingested more microplastics than those from the northern region. The majority of specimens collected from the southern region also exhibited elevated levels of oxidative stress and decreased antioxidant defence, which can be interpreted as an early indication that they had reached the limits of their adaptive potential. Further research on the composite effects of the stressogenic environment on the Black Sea biota are critically needed, as well as the introduction of new indicators and thresholds at molecular and cellular levels for adequate monitoring of both the ecological state of the marine environment and its biota

Effects of anthropogenic and environmental stressors on the current status of red mullet (Mullus barbatus L., 1758) populations inhabiting the Bulgarian Black Sea waters

The red mullet (Mullus barbatus Linnaeus, 1758) is a keynote species for the Bulgarian Black Sea ecosystem and fisheries; nevertheless, existing knowledge on population status is very scarce. The present study was intended to assess the health status and adaptive potential of M. barbatus populations inhabiting the Bulgarian waters of the Black Sea. Our findings revealed that populations of M. barbatus are exposed to a variety of anthropogenic and environmental stressors. The species’ status was assessed using representative genetic, morphological, biochemical and chemical biomarkers from specimens obtained in the research area’s northern and southern regions. Based on mtDNA markers, genetic analysis revealed low haplotype and nucleotide diversity, typically observed in overexploited or “threatened” populations. Examining the morphology of the specimens revealed no discernible pattern of differentiation. Except for aluminium and chrome, metal and PAH concentrations in fish were below the regulatory thresholds. The specimens from the southern region ingested more microplastics than those from the northern region. The majority of specimens collected from the southern region also exhibited elevated levels of oxidative stress and decreased antioxidant defence, which can be interpreted as an early indication that they had reached the limits of their adaptive potential. Further research on the composite effects of the stressogenic environment on the Black Sea biota are critically needed, as well as the introduction of new indicators and thresholds at molecular and cellular levels for adequate monitoring of both the ecological state of the marine environment and its biota