X-Message-Number: 22572 Date: Wed, 24 Sep 2003 17:23:20 -0700 (PDT) From: Doug Skrecky <> Subject: luteolin may eliminate renal cell injury during preservation Bioflavonoids attenate renal proximal tubular cell injury during cold preservation in Euro-Collins and University of Wisconsin solutions Kidney International Vol. 63 2003; 554-563 Background. Cold ischemia and reperfusion during kidney transplantation are associated with release of free oxygen radicals and damage of renal tubular cells. Bioflavonoids may diminish cold storage-induced injury due to antioxidant and iron chelating activities. This study was designed to delineate the renoprotective mechanisms of bioflavonoids and to define the renoprotective mechanisms of bioflavonoids and to define the structural features conferring cytoprotection from cold injury. Methods. LLC-PK1 cells were preincubated for three hours with bioflavonoids and cold stored in University of Wisconsin (UW) or Euro-Collins (EC) solution for 20 hours. After rewarming, cell viability was assessed by the lactate dehydrogenase (LDH) release, MTT test and amino acid transport activity. Lipid peroxidation was assessed from the generation of thiobarbituric acid-reative substances. Results. Twenty hours of cold storage of LLC-PK1 cells resulted in a substantial loss of cell integrity that was more pronounced in the EC (LDH release, 93.6 +-1.6%) than the UW solution (67.2 +-6.9% ;P<0.0001). Pretreatment with quercetin significantly enhanced cell survival (LDH release, 5.4 +-2.7% for UW and 8.4 +-4.2% for EC) in a concentration dependant manner. Structure-activity studies revealed similar renoprotection for kaempferol, luteolin and fisetin, unlike myricetin, morin, apigenin, naringenin, catechin, silibinin and rutin. Lipid peroxidation was reduced (UW alone, 2.7 +-1.2 vs UW+quercetin 0.5 +-0.2 nmol/mg protein, P<0.01), and threonine uptake completely sustained by pretreatment with quercetin, kaempferol, luteolin, and fisetin. However, renoprotection by fisetin was rapidly lost during rewarming. Protective properties of bioflavonoids were governed by the number and arrangement of hydroxyl substitutes, electron-delocalization, sterical planarity, and lipophilicity of the basic diphenylpyran skeleton. Conclusion. Cold storage-induced renal tubular cell injury is ameliorated by bioflavonoids. Renoprotective effects of bioflavonoids are defined by structure, suggesting that flavonoids are incorporated into membrane lipid bilayers and interfere with membrane lipid peroxidation. Further quote: "Complete inhibition of LDH release was obtained with 25 micromol/L luteolin in both preservation solutions. At this concentration metabolic activity was sustained almost completely in the UW solution (91.4 +-11.9%), but only partially in the EC solution (64.1 +-5.2%). Full protection of metabolic activity in EC solution was achieved at 300 micromol/L luteolin." Additional comments by poster: It might be worth looking to see what the effect of luteolin is on cryoprotectant toxicity, and whether vitrified organs can maintain viability after liquid nitrogen storage. There exists a possibility of slowing human aging with luteolin, since it is a good inhibitor of human SIRT1, is nontoxic, and has a fairly low molecular weight. (Small molecule activators of sirtuins extend Saccharomyces cerevisiae lifespan; Nature, epub August 24, 2003) One source of luteolin is rooibos tea. Age-associated deteriorative changes in the brains of 24 month old Wistar rats were completely suppressed, if they were fed rooibos tea in place of water. (Neuroscience Letters Vol.196 1995; 85-88) Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=22572