Redox homeostasis of albumin in relation to alpha-lipoic acid and dihydrolipoic acid

Albumin represents the predominant circulating antioxidant agent in plasma exposed to continuous oxidative stress and a change in serum albumin structure accounts for its antioxidant properties. Alterations in the redox status of albumin may result in impairments of its biological properties. Alpha-lipoic acid (LA), a naturally occurring thiol compound found in virtually all species, is a potent antioxidant with high efficacy which is also involved in the chelation of metal ions, regeneration of antioxidants, and repair of oxidatively damaged proteins. In human body LA is rapidly reduced to dihydrolipoic acid (DHLA) after intake into the cell. Both, LA and DHLA are amphipathic molecules which act as antioxidants both in hydrophilic and lipophilic environments. The present study aimed to investigate the antioxidant/pro-oxidant effects of LA and DHLA due to their concentrations in metal-catalyzed protein oxidation (MCO) of human serum albumin (HSA). Progressive oxidative modification of albumin was found in MCO system by an increased content of protein hydroperoxides (POOH), protein carbonyl groups (PCO) which is the former's major breakdown product, and other protein oxidation markers such as advanced oxidized protein products (AOPP) and protein thiol groups (P-SH). The possible antioxidant protective effects of LA and DHLA were observed with 25 µM and 50 µM; DHLA being more influential. Protein oxidation parameters were found to be lower and P-SH levels seemed higher. However, prooxidant effects of both LA and DHLA came on the scene with increased concentrations of 75 µM and 100 µM where the latter seemed the most hazardous with contradicted results. It is clear that the loss of biological activity of human serum albumin by MCO system appears of medical relevance and if LA exerts similar effects seen in the present study, it is possible that cellular prooxidant activity can also result consuming this unique antioxidant in certain doses

HİDROJEN PEROKSİT VE HİDROKSİL RADİKALİNİN SERUM PROTEİNLERİ ÜZERİNE ETKİSİNİN SİYALİK ASİD İÇERİĞİ AÇISINDAN İNCELENMESİ

ÖZET Dalo E. (2009). Hidrojen Peroksit ve Hidroksil Radikalinin Serum Proteinleri Üzerine Etkisinin Siyalik Asid İçeriği Açısından İncelenmesi. İstanbul Üniversitesi, Sağlık Bilimleri Enstitüsü, Biyokimya Anabilim Dalı. Yüksek Lisans Tezi. İstanbul. Son dönemlerdeki çalışmalarda SA’in in vitro hidrojen peroksit tutucu olduğu, radikal düzeylerindeki artışın desiyalilasyona neden olduğu, reaktif oksijen türlerinin SA’in glikokonjugatlara bağlandığı glikozidik bağı kırma eğiliminde olduğu şeklinde görüşler bulunmaktadır. Bu in vitro çalışmada hidrojen peroksit ve hidroksil radikali ile serum proteinlerinde oluşturulacak hasarın SA içeriğini nasıl etkileyeceği incelendi. Daha sonra ortama SA ilave edilerek oksidatif hasar tekrar incelendi. Protein oksidatif hasar belirteci olarak karbonil grupları ölçümü kullanıldı. Aynı zamanda poliakrilamid jel elektroforezi ile proteinler ayrılarak görüntülendi. Çalışmada SA’in oksidatif hasar göstergesi olabilirliği sorgulandı, artan siyalik asid düzeylerinin oksidatif hasarı azaltıcı/önleyici etkisi olup olmadığını incelendi. Literatürde invitro/invivo ortamda SA’in hidrojen peroksit tutucu özelliğinden faydalanılarak protein hasarının önlendiğini gösteren herhangi bir çalışma görülmemektedir. Çalışmada in vitro ortamda oksidatif stresin serum proteinlerindeki SA moleküllerini kopardığı, protein karbonilasyonunu arttırdığı tesbit edildi. Proteinlerin hasar etkenine eşdeğer siyalik asid ile buluşturulması SA ve karbonil grupları içeriğini yükseltmektedir. Albuminin SA ile inkübasyonunda SA tespit edilmesi de nonenzimatik bağlanmayı göstermektedir. Yüklü bir molekül olan SA’in proteinler üzerinde yer alışı karbonilasyona ve çapraz bağlanmalara katkıda bulunabileceğini düşündürmektedir. Sonuçta farklı nedenlerle SA düzeylerinin arttığı birçok patolojik durumda molekülün protein karbonilasyonunu artırması ve yeni bağ yapılanması proteinlere direnç kazandırırken ortaya çıkan yapısal değişiklik hücresel fonksiyonları da etkileyebilir. Protein SA kaybı oksidatif hasarın göstergesi olabilir. Anahtar kelimeler: Siyalik asid, oksidatif stres, radikal, protein karbonilasyonu, antioksidan. Bu çalışma, İstanbul Üniversitesi Bilimsel Araştırma Projeleri Birimi tarafından desteklenmiştir. Proje No:249

IN VITRO ANTIOXIDANT EFFECT OF SESAME OIL SEED ON THE PROTECTION OF PROTEINS FROM CARBONYLATION AND DESIALYLATION IN HUMAN BLOOD SERUM

Free radicals generated as a result of oxidative stress can cause protein oxidation. Protein damage can be assessed by determining the amount of carbonylation and desialylation of proteins. Meanwhile sesame oil has a good antioxidant effect in protecting proteins. Thus in this preliminary in vitro study, the influence of hydrogen peroxide (H2 O2 ) and hydroxyl (OH) radicals on the sialic acid bound to proteins and protein carbonylation was investigated. Also antioxidant effect of sesame oil in preventing protein oxidation and protein desialylation was investigated. Initially, H2 O2 was added to the human serum, respectively OH (Experiment 1 and 3) as well as sesame oil (Experiment 2 and 4) and then the serum was incubated on 40C for four hours, in which case the serum proteins reacted with these radicals but also with sesame oil. After incubation, oxidative damage was measured before and after the addition of sesame oil to the medium respectively, the amount of sialic acid (SA) bound to proteins as well as the amount of protein carbonylation as a marker of oxidative damage to proteins was determined. SA levels were determined by combined modification of the tiobarbituricacid method by Skozo-Mohos and dimethyl sulfoxide method by Aminoff, namely Tram method. Protein carbonyl group was determined by 2,4-dinitrophenyl hydrazine (DNPH) method by Levine. The statistical processing of the results was done with ANOVA Tuckey Test. The addition of H2 O2 respectively OH in serum, has caused a desialylation of proteins and also an increase in the amount of carbonylated proteins. Sesame seed oil has shown its antioxidant activity related to the sialic acid level (Experiment 2 and 4), and its amount in experimental groups is approximately as the untreated human serum with H2 O2 and hydroxyl radical that served as a control group. In contrast, this is not the case with protein carbonylation, as sesame seed oil has failed to protect proteins from oxidation caused by hydrogen peroxide and hydroxyl radicals. Consequently, it can be concluded that oxidative stress has caused a decrease in the amount of sialic acid bounded to proteins, as well as increase in carbonylation of proteins, while sesame oil with its antioxidant properties has affected the maintenance of sialic acid values, but has not achieved also in protecting proteins from carbonylation

Saliva profiles in children with congenital heart disease

Purpose The low salivary pH and buffering capacity are caused by using heart failure medications. For this reason oral health should be supported in cardiac patients, it is necessary that they attend dental clinics for regular follow up. The aim of this study is to evaluate the relationship between the salivary oxidative stress markers and salivary pH, salivary buffering capacity, salivary flow rate and dental caries of children with congenital heart disease (CHD). Material and Methods This cross sectional study was carried out with 42 CHD and 42 healthy children who applied to XXXXXXX. The participants’ gender, age, general health and medications, and caries scores (dfs/DMFS) were written down, then their unstimulated saliva samples were collected. These specimens were evaluated in terms of the salivary secretion rate, salivary buffering capacity, pH, protein levels, superoxide dismutase (SOD), ferric reducing antioxidant power (FRAP), the thiobarbituric acid reactive substances (TBARS), protein carbonyl, protein thiols, total sialic acid. Results Both groups showed caries at similar levels. The salivary pH and buffering capacity were significantly less in the children with CHD than in the controls. The levels of TBARS and protein carbonyl were significantly higher in the children with CHD than in the controls. There was not any significant difference relating to the mean salivary secretion rate, protein levels, SOD, FRAP, protein thiols and total sialic acid. Conclusion The elevated TBARS and protein carbonyl levels in the patients with CHD were observed as an indicator of the free radical damage leading to oxidative stress.Istanbul Universit

The investigation of biochemical effects of epigallocatechin-gallate and resveratrol in C6 glioma cells

İstanbul Bilim Üniversitesi, Sağlık Hizmetleri Meslek Yüksekokulu.Glioblastoma multiforme (GBM) nörolojik fonksiyon kaybına ve ölüme yol açan bir kanserdir. C6 glioma hücreleri malign glioblastoma özelliklerine sahip, GBM’nin araştırılmasında kullanılan bir soydur

A potential role of Sirtuin3 and its target enzyme activities in patients with ovarian endometrioma

Objective Sirtuin3 (SIRT3) is a NAD(+)-dependent major mitochondrial deacetylase. In this study, we aimed to investigate SIRT3 levels and their target enzyme activities, including glutamate dehydrogenase (GDH), succinate dehydrogenase (SDH), and manganese superoxide dismutase (MnSOD), also to determine the antioxidant capacity and oxidative stress in tissue, mitochondria and serum samples in ovarian endometrioma patients. Methods We collected serum and endometrioma tissue samples from 30 patients. In the control group, we collected serum and eutopic endometrial tissue samples from 26 women without endometriosis. Results SIRT3 levels were significantly decreased in endometrioma tissue samples compared to the control group. There was no statistically significant difference in SIRT3 levels between patient and control serum samples. Furthermore, there was a decrease in GDH and SDH enzyme activities in both endometrioma tissue homogenate and mitochondria. MnSOD activity was decreased in tissue homogenate but increased in mitochondria and there was no difference in serum. While total SOD activity was decreased, CuZnSOD activity was increased in both tissue and serum samples. Besides these, total antioxidant capacity and advanced oxidation protein products (AOPP) levels were decreased in endometrioma tissue and mitochondria, but there was no difference in serum. Conclusions Our results suggested that decreased levels of SIRT3 in endometrioma may be an important factor in the weakening of mitochondrial energy metabolism and antioxidant defense in endometriosis. We think that SIRT3 deficiency may be an important factor underlying the pathogenesis of endometriosis. More detailed studies are needed to reveal the relationship between SIRT3 and metabolism and oxidative stress in ovarian endometrioma