Characterization of polyphenol oxidase activity in a range of forage ecotypes with different phenol substrates. A new insight for PPO and protein‐bound phenol evaluation

Abstract

Plant phenols can influence utilization of forages by ruminants through binding with proteins either by complexing with oxidized phenols (products of polyphenol oxidase activity or formed in oxidizing conditions) or by hydrogen binding with tannins. These protein-bound phenols (PBPs) affect rumen metabolism by inhibition of both proteolysis and lipolysis. The aim of this work was to assess the level of polyphenol oxidase (PPO) activity (determined with a range of diphenolic substrates), PBP content, and to identify the main source of variation in different forage ecotypes harvested at different phenological stages. PPO activity was strongly influenced by substrate type with a significant effect of forage ecotype. Forage ecotype and phenological stage also influenced PPO and PBP content. PPO showed a strong relationship with dry matter and phenol content of plants.

Characterization of nitrogen transformation dynamics in alfalfa and red clover and their mixture silages

“…However, the epiphytic lactic acid bacteria biomass on the surface of all forages were found to be adequate, exceeding the satisfactory level 5 log 10 CFU/g FW (Silva et al., ). The PPO activity detected in red clover was within the range established in previous reports (Cabiddu et al., ).…”

Lipid metabolism in the rumen: New insights on lipolysis and biohydrogenation with an emphasis on the role of endogenous plant factors

“…For this reason, it is necessary to understand the interactions of UFA, PPO, coronaric acid and others PSM and clarify the role of each component on the ruminal biohydrogenation pathways. Preliminary results from Cabiddu et al (2011) showed that plant PPO activity could be affected by specific tannins with an interaction of forage species and plantphenological stage (Fig. 19).…”

“…When the PPO enzyme from red clover was incubated with a wide range of ortho-diphenols in the presence of oxygen, there was rapid conversion from the latent to the active form of PPO (Lee et al, 2008a), a conversion inhibited by adding ascorbic acid, suggesting that this mechanism requires formation of ortho-quinones. Other factors which influence the efficacy of PPO, to produce phenol-bound protein and/or PPO activation includes oxygen concentration, the phenological stage of the plant and the plant's NDF content (Lee et al, 2009b;Cabiddu et al, 2011).…”

Chemical composition and antioxidant capacity in edible biomass of tagasaste (Chamaecytisus proliferus var. palmensis)

“…The levels of TotP, NTP and TP in tagasaste leaves were 3 to 6 times higher than values found in a range of Mediterranean annual grass, legume and herb species such as Lolium rigidum Gaud., Medicago polymorpha L., Medicago arabica L., Plantago lanceolata L., Trifolium cherleri L. and T. resupinatum L. (Cabiddu et al, 2013). The levels of TotP, NTP found in Mediterranean populations of forage chicory (Piluzza et al, 2014) were half than those reported for tagasaste.…”