089 Inhibitory effects on low temperature injury by flavonoids (glycosides)

Abstract

Our previous studies showed that xylem parenchyma cells (XPCs) in trees, which adapt to winter cold by deep supercooling, contained several kinds of supercooling promoting substances [Kasuga et al., Cryobiology, 55 (2007) 305–314; Wang et al., Planta, 235 (2012) 747–759]. It is suggested that the presence of supercooling-promoting substances keeps liquid state of water in XPCs near −40 °C. In the presence of such supercooling-promoting substances in XPCs, although occurrence of lethal intracellular freezing is prevented, it is noted that cells are subjected to extremely low temperature under liquid state of water. It is, thus, speculated that deep supercooling XPCs may also contain any substances which protect cellular components from such extremely low temperatures. It is thought that such inhibitory substances may be applied for an inhibitor of low temperature injury in a wide variety of biological materials. We examined effects of several compounds from deep-supercooling XPCs to find protection effect on low temperature injury using cultured mammal cells as experimental materials. Among the compounds examined, several kinds of flavonoids (glycosides) including quercetin 3-glycoside (Q3G), which existed in deep supercooling XPCs as supercooling-promoting substances, exhibited inhibitory effect of low temperature injury at 4 °C in very low concentrations ranging from 0.1 to 100 μ/mL to human promyelocytic leukemia cells (HL60), primary mouse embryo fibroblast, human foreskin fibroblast (Hs68) and human umbilical vein endothelial cells (HUVEC). It is worth to note, however, that inhibitory effect of low temperature injury by these flavonoids (glycosides) is greatly influenced depending on constituents of incubation medium. Although we examined relation between inhibitory effect of low temperature injury and degree of antioxidant activities in flavonoids (glycosides), no relation between them was found. Therefore, it is thought that inhibitory effect of low temperature injury by flavonoids (glycosides) is developed by mechanisms other than antioxidant effect. It is suggested that these flavonoids (glycosides) are useful to prevent low temperature injury of biological materials and we are currently examining their inhibitory effects under subzero-temperatures. Source of funding: None declared. Conflict of interest: None declared. sfuji@for.agr.hokudai.ac.jp