Proanthocyanidins Modulate Rumen Enzyme Activities and Protein Utilization In Vitro

Abstract

This study investigated the principal leaf protein (rubisco) solubilization and in vitro ruminal enzyme activity in relation to the molecular structure of proanthocyanidins extracted from leaves of Anogeissus pendula and Eugenia jambolana. Six proanthocyanidin fractions were extracted by 50% (v/v) methanol–water followed by 70% (v/v) acetone–water and then distilled water from leaves of A. pendula (AP) and E. jambolana (EJ) to yield EJ–70, EJ–50, EJ–DW, AP–70, AP–50 and AP–DW. Fractions were examined for their molecular structure and their effects on sheep ruminal enzymes and solubilization of rubisco in vitro. All fractions significantly (p < 0.05) inhibited the activity of ruminal glutamic oxaloacetic transaminase and glutamic pyruvic transaminase. The fractions AP–50 and EJ–50 significantly inhibited the activity of the R-cellulase enzyme. Most of the fractions inhibited R-glutamate dehydrogenase activity (p < 0.05) by increasing its concentration, while protease activity decreased by up to 58% with increasing incubation time and concentration. The solubilization of rubisco was observed to be comparatively higher in A. pendula (16.60 ± 1.97%) and E. jambolana (15.03 ± 1.06%) than that of wheat straw (8.95 ± 0.95%) and berseem hay (3.04 ± 0.08%). A significant (p < 0.05) increase in protein solubilization was observed when wheat straw and berseem hay were supplemented with A. pendula and E. jambolana leaves at different proportions. The efficiency of microbial protein was significantly (p < 0.05) greater with the supplementation of leaves of A. pendula in comparison to E. jambolana. The overall conclusion is that the proanthocyanidins obtained from E. jambolana exhibited greater inhibitory activities on rumen enzymes, whereas A. pendula recorded higher protein solubilization. Thus, PAs from A. pendula and E. jambolana appear to have the potential to manipulate rumen enzyme activities for efficient utilization of protein and fiber in ruminants.

The study of structure and effects of two new proanthocyanidins from Anogeissus pendula leaves on rumen enzyme activities

“…This inhibition effect of phenolic compounds could be a result of their antimicrobial nature and the release of other metabolites during the fermentation process. Similar observations were recorded in cow rumen kinetics ( 14 ) from phenolic extracts of Ficus species ( 17 ) and methanolic tree leaves extracts of A. pendula ( 25 ). The released or break-down products of phenolic compounds from the plant extracts can be turned into new antioxidants ( 45 ) and that could reduce ruminal enzymatic activities.…”

“…A ruminal cellulase extract was prepared from collected rumen liquor, and the effect of isolated compounds on its activities was estimated according to a described method ( 23 ). A protocol for determining the activity of the intracellular enzymes glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase (GOT) was used ( 24 ) while obtaining from the bacterial and protozoal fractions of the rumen liquor and then separation of bacteria and protozoal rich enzyme extracts in 0.1 M phosphate buffer of pH 6.8 were carried out according to our published methods ( 17 , 22 , 25 ). To measure proteolytic enzyme activities, the concentration of protein in enzyme extracts was estimated according to Lowry ( 26 ).…”

Proanthocyanidins isolated from the leaves of Ficus glomerata evaluated on the activities of rumen enzymes: in vitro and in silico studies

“…A similar observation of lowering the concentration of liberated rumen protein in the presence of isolated compounds 1 and 2 with elevated concentrations and incubation times with phenolic extracts of Lotus pendunculatus (McNabb et al, 1996), tannin-rich forage leaves (Aerts et al, 1999;Bhatta et al, 2012), proanthocyanidins obtained from Ficus (Koli et al, 2022) and Anogeissus species (Singh et al, 2022;Lata et al, 2023), phenolics extracted from pomegranate skin (Abarghuei et al, 2021). The movement of protein from the stomach to the intestine, where the animal can use it, depends on how strongly it binds.…”

“…A ruminal cellulase extract was prepared from the collected rumen liquor and the effect of isolated compounds on its activities was estimated according to a described method ( Mandels and Weber, 1969 ). A protocol for determining the activity of the intra-cellular enzymes’ glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase (GOT) was used ( Yatzidis, 1960 ), while the bacterial and protozoal fractions of the rumen liquor were obtained, and then, the separation of bacteria and protozoal-rich enzyme extracts in a 0.1 M phosphate buffer of pH 6.8 was carried out according to our published methods ( Singh and Kundu, 2010 ; Koli et al, 2022 ; Singh et al, 2022 ). To measure proteolytic enzyme activities, the concentration of protein in enzyme extracts was estimated according to a previous method ( Lowry et al, 1951 ).…”

Antioxidants in Animal Nutrition: UHPLC-ESI-QqTOF Analysis and Effects on In Vitro Rumen Fermentation of Oak Leaf Extracts

“…Therefore, a reduction of protein degradation in the rumen is associated with a lower production of ammonia and a greater flow of non-ammoniacal nitrogen to the duodenum and a higher amount of branched fatty acids. In this context, it has been observed that the proanthocyanidin fractions from the leaves of some species of Ficus or Anogeissus pendula and Eugenia jambolana , mainly composed of (epi)catechin, (epi)gallocatechin and their 4-phloroglucinol adducts, decrease the glutamic oxaloacetic ruminal and pyruvic transaminases as well as rumen R-Cellulase enzymes with consequent effects on the use of fibers and proteins [ 82 , 83 ]. Dietary condensed or hydrolysable tannins, supplied at adequate concentrations, are agreed to reduce in vitro concentrations of rumen NH 3 and branched-chain volatile fatty acids.…”