Investigation for natural extract inhibitors of bovine lens aldose reductase responsible for the formation of diabetis dependent cataract

Onay, Melih
In the polyol pathway, Aldose reductase (AR) is an important enzyme in reduction of aldehydes and aldosugars to their suitable alcohols. AR, using NADPH as a coenzyme, has a molecular weight of 37 000 dalton. AR in its activated form, known to increase the sorbitol accumulation in lens, is responsible for the cataract formation in diabetis diseases. Therefore, the inhibition of aldose reductase is important to prevent the incedence of cataract formation in diabetus mellitus. In the treatment of diabetis dependent cataract, chemically synthetized drugs were sometimes less than beneficial due to the severe side effects they cause. Recently a huge amount of study has been intensified on developing new drugs from natural compounds and even by utilizing plant extracts for their easily metabolizing polyphenolic compounds. In this study, BLAR, source of enzyme, was obtained as crude via differential centrifugation and ammonium sulfate precipitation. The enzyme assay conditions were optimized for the protein, substrate, coenzyme, and salt concentrations, also for the effects of pH and temperature. Ocimum basilicum, Lavandula stoechas, Melissa officinalis, Glycyrrhiza glabra L. and Tilia tomentosa were selected as commonly used alternative medicine plants. Plant extracts were prepared in ethanol and ethyl acetate and their inhibitory effects were tested on crude bovin lens aldose reductase enzyme. Fifty percent inhibitory concentrations (IC50) were found between values of 25.53 g/mL and 54.15 g/mL for ethanol extracts and between 41.55 g/mL and 82.96 g/mL for the ethyl acetate extracts of selected plants. In addition, the plant extracts were also characterized for their antioxidant activities by of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method and test of total phenolic content (TPC) .


Isolation and immunological characterization of theta class glutathione-s-transferase gstt2-2 from bovine liver
İşgör, Sultan Belgin; Çoruh, Nursen; Department of Biochemistry (2004)
The glutathione-S-transferases (GSTs) (EC. are enzymes that participate in cellular detoxification of endogenous as well as foreign electrophilic compounds, function in the cellular detoxification systems and are evolved to protect cells against reactive oxygen metabolites by conjugating the reactive molecules to the nucleophile scavenging tripeptide glutathione (GSH, ?-glu-cys-gly). The GSTs are found in all eukaryotes and prokaryotic systems, in the cytoplasm, on the microsomes, and in the mitoch...
Purification of glutathione S-transferases and genetic characterization of Zeta isozyme from Pinus brutia, Ten
Öztetik, Elif; İşcan, Mesude; Department of Biochemistry (2005)
Glutathione S-transferases (GST, EC2.5.1.18) are a family of multifunctional, dimeric enzymes that catalyse the nucleophilic attack of the tripeptide glutathione (?-L-glutamyl-L-cysteinyl-L-glycine) on lipophilic compounds with electrophilic centres. The primary function of GSTs is generally considered to be the detoxification of both endogenous and xenobiotic compounds. Cytosolic GSTs have been grouped into eleven distinct classes as: (A); Alpha, (M); Mu, (P); Pi, (S); Sigma, (T); Theta, (Z); Zeta, (F); Ph...
TURKOGLU, S; OZER, I (Elsevier BV, 1992-06-01)
1. Bovine liver arginase followed Michaelis-Menten kinetics in the pH range of 4.5-9.0. The variation of upsilon(i) pH implied that a basic group (pK(alpha) 8.7) functions at the catalytic site.
Sequences in the intracellular loops of the yeast pheromone receptor Ste2p required for G protein activation.
Celić, A; Martin, NP; Son, Çağdaş Devrim; Becker, JM; Naider, F; Dumont, ME (American Chemical Society (ACS), 2003-03-18)
The α-factor receptor of the yeast Saccharomyces cerevisiae encoded by the STE2 gene is a member of the large family of G protein-coupled receptors (GPCRs) that mediate multiple signal transduction pathways. The third intracellular loop of GPCRs has been identified as a likely site of interaction with G proteins. To determine the extent of allowed substitutions within this loop, we subjected a stretch of 21 amino acids (Leu228−Leu248) to intensive random mutagenesis and screened multiply substituted alleles...
Aromatic amino acid synthesis performance of bacillus acidocaldarius
Kocabaş, Pınar; Çalık, Pınar; Department of Chemical Engineering (2004)
In this study, the effects of bioprocess operation parameters on aromatic amino acid synthesis performance of Bacillus acidocaldarius were investigated. Firstly, in laboratory scale shake-bioreactors, a defined medium was designed in terms of its carbon and nitrogen sources, to achieve the highest cell concentration. Thereafter, the effects of bioprocess operation parameters, i.e., pH and temperature were investigated; and the optimum medium contained (kg m-3): fructose, 8; (NH4)2HPO4, 5; CaCl2, 0.2; KH2PO4...
Citation Formats
M. Onay, “Investigation for natural extract inhibitors of bovine lens aldose reductase responsible for the formation of diabetis dependent cataract,” M.S. - Master of Science, Middle East Technical University, 2008.