Identification and bioactivity evaluation of flavan-3-ols in the milk of dairy sheep fed Cynomorium songaricum

Abstract

Cynomorium songaricum is a traditional medicine and also a food material that is eaten raw or processed as tea or beverages. As a featured plant in semi-desert grasslands, C. songaricum is also eaten by the cattle and sheep in the area. This research study fed dairy sheep C. songaricum to determine the flavan-3-ols in sheep milk. Catechin (Cat), epicatechin (Epi), procyanidin A1 (A1), procyanidin A2 (A2), and procyanidin B1 (B1) were detected in sheep milk with the concentration being Epi > A2 > Cat > B1 > A1 at 24 h after the administration of C. songaricum. Neither A1 nor A2 were detected in the methanol extract of C. songaricum. Cysteine degradation of the plant revealed that in addition to Epi, A2 was the extending unit of the polymeric flavan-3-ols in C. songaricum, indicating that A2 is released digestively from the polymers and enters the milk. Procyanidin B-1 was converted to A1 on incubation in raw but not heated milk, indicating that the A1 in milk is the enzymatically transformed product of B1. Accelerated oxidation showed that the flavan-3-ols, B1, Cat, and Epi significantly protects the unsaturated triacyglycerols in the milk from oxidation. The flavan-3-ol could slow down the oxidation of glutathione and the latter may play an important role in preventing the milk triglycerides from oxidation. Flavan-3-ols are polyphenols with many health benefits. The present research revealed the antioxidant activities of flavan-3-ols that could be absorbed to sheep milk, adding new evidences for the values of these flavan-3-ols and for the milk.

Biotransformation of Cynomorium flavan‐3‐ols in dairy sheep and their effects on inflammation and liver growth retardation

“…Previous study revealed that Epi, Cat, A1, A2, and B1 could enter the milk of sheep fed with C. songaricum stems (Duan et al., 2022). The present study found that these flavane‐3‐ols attenuated the recruitment of neutrophils in LPS‐treated or fin‐injured zebrafish larvae.…”

“…A2 was proved to be one of the extender units of the polymeric flavan‐3‐ols in C. songaricum and was speculated to be absorbed into the plasma after digestive degradation of the polymers (Duan et al., 2022). A2 and B1 have multiple peaks in the plasma concentration‐time curves, reflecting the ruminant digestion process of polymeric procyanidins in this plant.…”

“…As A2 and EPI were proved through chemical degradation to be the extender units of the polymeric flavan‐3‐ol in C. songaricum (Duan et al., 2022; Ma et al., 1999), it was speculated that most of the A2 and EPI in dairy sheep came from the digestive degradation of the polymers. However, it was unclear how and where EPI and A2 were released from the polymers in the sheep body.…”

“…Ewes for the study were produced by introducing DairyMeade embryos from New Zealand into the local breed as recipients. Over a period of 2 months, these ewes were provided twice daily the total mixed ration with reported ingredients and nutritional composition (Duan et al., 2022). The experiments were approved by the Animal Experiment Ethics Review Committee of Inner Mongolia University ([2018] 010) and conducted in accordance with animal welfare and handling guidelines.…”

“…Ewes for the study were produced by introducing DairyMeade embryos from New Zealand into the local breed as recipients. Over a period of 2 months, these ewes were provided twice daily the total mixed ration with reported ingredients and nutritional composition (Duan et al, 2022). The experiments were approved by the Animal Experiment Ethics Review After the gavage, 20 mL of the blood of was collected from each ewe at 1, 2, 4, 8, 12, 18, 24, and 36 h, and 50 mL of milk was collected from each ewe at 12, 24, and 36 h. To mitigate potential impact of prolonged fasting on sheep physiology, 36 h was used as the endpoint for fasting (Gaál et al, 1993).…”