BackgroundDiabetes has become a serious health problem and a major risk factor associated with troublesome health complications, such as metabolism disorders and liver-kidney dysfunctions. The inadequacies associated with conventional medicines have led to a determined search for alternative natural therapeutic agents. The present study aimed to investigate and compare the hypoglycemic and antilipidemic effects of kombucha and black tea, two natural drinks commonly consumed around the world, in surviving diabetic rats.MethodsAlloxan diabetic rats were orally supplied with kombucha and black tea at a dose of 5 mL/kg body weight per day for 30 days, fasted overnight, and sacrificed on the 31st day of the experiment. Their bloods were collected and submitted to various biochemical measurements, including blood glucose, cholesterol, triglcerides, urea, creatinine, transaminases, transpeptidase, lipase, and amylase activities. Their pancreases were isolated and processed to measure lipase and α-amylase activities and to perform histological analysis.ResultsThe findings revealed that, compared to black tea, kombucha tea was a better inhibitor of α-amylase and lipase activities in the plasma and pancreas and a better suppressor of increased blood glucose levels. Interestingly, kombucha was noted to induce a marked delay in the absorption of LDL-cholesterol and triglycerides and a significant increase in HDL-cholesterol. Histological analyses also showed that it exerted an ameliorative action on the pancreases and efficiently protected the liver-kidney functions of diabetic rats, evidenced by significant decreases in aspartate transaminase, alanine transaminase, and gamma-glytamyl transpeptidase activities in the plasma, as well as in the creatinine and urea contents.ConclusionsThe findings revealed that kombucha tea administration induced attractive curative effects on diabetic rats, particularly in terms of liver-kidney functions. Kombucha tea can, therefore, be considered as a potential strong candidate for future application as a functional supplement for the treatment and prevention of diabetes.
Phospholipases are lipolytic enzymes that hydrolyze phospholipid substrates at specific ester bonds. Phospholipases are widespread in nature and play very diverse roles from aggression in snake venom to signal transduction, lipid mediator production, and metabolite digestion in humans. Phospholipases vary considerably in structure, function, regulation, and mode of action. Tremendous advances in understanding the structure and function of phospholipases have occurred in the last decades. This introductory chapter is aimed at providing a general framework of the current understanding of phospholipases and a discussion of their mechanisms of action and emerging biological functions.
The cytosolic (group IV) phospholipase A 2 (cPLA 2 s) family contains six members. We have prepared recombinant proteins for human ␣, mouse , human ␥, human ␦, human ⑀, and mouse cPLA 2 s and have studied their interfacial kinetic and binding properties in vitro. Mouse cPLA 2  action on phosphatidylcholine vesicles is activated by anionic phosphoinositides and cardiolipin but displays a requirement for Ca 2؉ only in the presence of cardiolipin. This activation pattern is explained by the effects of anionic phospholipids and Ca 2؉ on the interfacial binding of mouse cPLA 2  and its C2 domain to vesicles. Ca 2؉ -dependent binding of mouse cPLA 2  to cardiolipin-containing vesicles requires a patch of basic residues near the Ca 2؉ -binding surface loops of the C2 domain, but binding to phosphoinositide-containing vesicles does not depend on any specific cluster of basic residues. Human cPLA 2 ␦ also displays Ca 2؉ -and cardiolipin-enhanced interfacial binding and activity. The lysophospholipase, phospholipase A 1 , and phospholipase A 2 activities of the full set of mammalian cPLA 2 s were quantified. The relative level of these activities is very different among the isoforms, and human cPLA 2 ␦ stands out as having relatively high phospholipase A 1 activity. We also tested the susceptibility of all cPLA 2 family members to a panel of previously reported inhibitors of human cPLA 2 ␣ and analogs of these compounds. This led to the discovery of a potent and selective inhibitor of mouse cPLA 2 . These in vitro studies help determine the regulation and function of the cPLA 2 family members.It is well established that cytosolic phospholipase A 2 -␣ (cPLA 2 ␣) 2 (also known as group IVA cPLA 2 ) liberates arachidonic acid from the sn-2 position of membrane phospholipids in agonist-stimulated mammalian cells for the biosynthesis of eicosanoids. With the completion of the mouse and human genomes, it became clear that these mammals also contain other proteins homologous to cPLA 2 ␣, namely the , ␥, ␦, ⑀, and isoforms (groups IVB-F cPLA 2 s) (1, 2). This study is focused on the  isoform of mouse cPLA 2 (m-cPLA 2 ) and its comparison with the other isoforms. m-cPLA 2  and cPLA 2 ␣ have a similar modular structure with an N-terminal C2 domain linked to a catalytic domain containing the active site serine involved in the lipolytic catalysis. Human cPLA 2  differs in that it contains an N-terminal truncated JmJc domain of unknown function followed by a C2 domain and a catalytic domain. Furthermore, human cPLA 2  exists as two splice forms, human cPLA 2 1 and human cPLA 2 3, with the latter being the major protein form expressed in a large variety of human tissues (3). The differential splicing leads to a change in a portion of the catalytic domain that is probably not part of the active site cleft. As far as we know, m-cPLA 2  exists as a single splice form (4). An intriguing property of m-cPLA 2 , human cPLA 2 1, and human cPLA 2 3 is that they display specific activities for the hydrolysis of lysophosphatidylc...
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