Sequential extraction of proanthocyanidin fractions from Ficus species and their effects on rumen enzyme activities in vitro

Three proanthocyanidin fractions per species were sequentially extracted by 50% (v/v) methanol–water, 70% (v/v) acetone–water, and distilled water from leaves of Ficus racemosa (fractions FR) and F. religiosa (fractions FRL) to yield fractions FR-50, FR-70, FR-DW, FRL-50, FRL-70, and FRL-DW. Fractions were examined for their molecular structure, effect on ruminal enzyme activities, and principal leaf protein (Rubisco) solubilization in vitro. All fractions except FRL-70 contained flavonoids including (+) catechin, (−) epicatechin, (+) gallocatechin, (−) epigallocatechin, and their -4-phloroglucinol adducts. The fractions FRL-50 and FRL-DW significantly (p < 0.05) inhibited the activity of ruminal glutamic oxaloacetic transaminase and glutamic pyruvic transaminase. All fractions inhibited glutamate dehydrogenase activity (p < 0.05) with increasing concentration, while protease activity decreased 15–18% with increasing concentrations. Fractions FRL-50 and FRL-DW completely inhibited the activity of cellulase enzymes. Solubilization of Rubisco was higher in F. religiosa (22.36 ± 1.24%) and F. racemosa (17.26 ± 0.61%) than that of wheat straw (WS) (8.95 ± 0.95%) and berseem hay (BH) (3.04 ± 0.08%). A significant (p < 0.05) increase in protein solubilization was observed when WS and BH were supplemented with FR and FRL leaves at different proportions. The efficiency of microbial protein was significantly (p < 0.05) greater in diets consisting of WS and BH with supplementation of F. racemosa leaves in comparison to those supplemented with F. religiosa leaves. The overall conclusion is that the fractions extracted from F. religiosa showed greater inhibitory effects on rumen enzymes and recorded higher protein solubilization in comparison to the F. racemosa. Thus, PAs from F. religiosa are potential candidates to manipulate rumen enzymes activities for efficient utilization of protein and fiber in ruminants

Proanthocyanidins modulate rumen enzyme activities and protein utilization In Vitro

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