Flavonoid composition in frost-resistant Rhododendron cultivars grown in Poland

Influence of Two Fertilization Regimens on the Amounts of Organic Acids and Phenolic Compounds of Tronchuda Cabbage (Brassica oleracea L. Var. costata DC)

“…Additionally, the production of flavonoids was higher in January for the two agronomic practices, a fact that could be explained by the very low temperatures registered in Mirandela region during January (Figure 3). In fact, the existence of a positive correlation between high levels of flavonoid glycosides and increased frost resistance is well-known (17). As these compounds contain sugar residues, they can delay water crystallization by the formation of hydrogen bonds between their hydroxyl groups and water molecules.…”

“…As these compounds contain sugar residues, they can delay water crystallization by the formation of hydrogen bonds between their hydroxyl groups and water molecules. Also, the action of flavonoids as antioxidants can be invoked, as protectors of plant tissues against adverse effects of low-temperature oxidative stress (17). It seems that phenylalanine ammonia-lyase activity, a key enzyme of phenylpropanoid biosynthesis, is increased under low-temperature conditions (14), which may justify the production of flavonoids as defense agents.…”

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“…In turn, in the March-April period (LT 50 ) were -24.6°C, -37.6°C, -46.9°C, respectively. Similarly, Swiderski et al [2004] reported that cold hardiness of several cultivars of rhododendrons varied, especially at the beginning and end of winter. According to these authors, plants showed maximum cold hardiness in mid-winter, in January.…”

Chromatographic and electrophoretic methods for pharmaceutically active compounds in Rhododendron dauricum

“…Swiderski et al [65] studied the relationship between flavonoid concentration in rhododendron (Rhododendron L.) leaves and their frost resistance. The flavonoid content in various taxons of rhododendrons bred in Poland was compared with the extent of injury caused by the action of sub-zero temperatures.…”