Metabolism of Phenolic Compounds and Antioxidant Activity in Different Tissue Parts of Post-Harvest Chive (Allium schoenoprasum L.).

Chive (Allium schoenoprasum L.) has a strong antioxidant property as it contains abundant phenolic compounds and ascorbic acid. In the present study, we investigated the metabolism of phenolic compounds and the change in antioxidant activity in different tissue parts of post-harvest chives. The results showed that compared with the bottom white part (BW), the round green part (RG) exhibited significantly higher contents of phenolic compounds, increased enzyme activities and enhanced antioxidant activities, indicating that phenolic compounds were mainly synthesised in RG. The expression levels of genes such as phenylalanine ammonia-lyase, cinnamate 4-hydroxylase and 4-coumaroyl-CoA ligase and their corresponding enzyme activities rapidly decreased in RG, whereas they were maintained in BW, suggesting that senescence occurred more rapidly in RG than in BW. Our study provides a theoretical basis for further research into and development of different parts of Allium plants and offers a basis for consumers' nutritional considerations.

The dynamics of bioactive compounds and their contributions to the antioxidant activity of postharvest chive (Allium schoenoprasum L.).

Organosulfur compounds, phenolic compounds, and ascorbic acids (AsA) are known to account for the bulk of chive's (Allium schoenoprasum L.) antioxidant properties. This study uncovered the contribution of each of these compounds to the chive's antioxidant activity under different storage conditions. The results showed that room temperature (RT) accelerated the accumulation of reactive oxygen species, though phenolics, organosulfur compounds, activities of antioxidant enzymes, and scavenging activity toward hydroxyl radical (OH) and superoxide anion (O2-) were observed to be enhanced in chives stored at RT. In contrast, AsA content, DPPH (1,1-diphenyl-1-picrylhydrazyl) scavenging and FRAP (ferric reducing antioxidant power) activity of the chive were increased by LT on day 5. Furthermore, S-alk(en)ylcysteine sulfoxides (CSOs) showed OH scavenging and weak DPPH scavenging but had no O2- scavenging and FRAP capacity. Volatile organosulfur compounds showed no antioxidant activities. Conclusively, the data demonstrated that AsA was largely responsible for DPPH scavenging and FRAP activity of the chive, while phenolic compounds, especially vanillic acid and p-hydroxybenzoic acid, were primarily responsible for OH and O2- scavenging activity.