Changes in content of major phenolic compounds during leaf development of sea buckthorn (Hippophae rhamnoides L.)

Content of total phenolic compounds and antioxidant capacity (FRAP) were investigated in the leaves of three sea buckthorn (Hippophae rhamnoides L.) cultivars: 'Otradnaja', 'Gibrid Pertjika' and 'Ljubitelskaja', at different dates. In addition, major phenolic compounds (catechin, kaempferol, quercetin, epigallocatechin, kaempferol-3-O-glucoside, quercetin-3-O-galactoside, isorhamnetin-3-O-glucoside, rutin, gallic acid, procyanidin monomer glycoside, procyanidin dimer aglycone and hydrolyzable tannins I-III) were determined in 'Ljubitelskaja'. Antioxidant capacity and the content of total phenolic compounds fluctuated during April, May and June, and then increased until the end of July, when the highest values were observed. Total phenolic compounds were strongly correlated with FRAP. Levels were generally higher in 'Ljubitelskaja' than in 'Otradnaja' and 'Gibrid Pertjika'. In 'Ljubitelskaja', hydrolyzable tannins I-III occurred in higher amounts than did any of the other studied phenolic compounds. The developmental stage of the leaves (harvesting date) had a strong influence on content of phenolic compounds and should be carefully considered when harvesting sea buckthorn leaves for different purposes.