Gastrointestinal biotransformation and tissue distribution of pterostilbene after long-term dietary administration in mice

Pterostilbene targets the molecular oscillator RORγ to restore circadian rhythm oscillation and protect against sleep restriction induced metabolic disorders

BACKGROUND

Considerable researches have directed toward metabolic disorders caused by sleep restriction (SR). SR-induced disruption of circadian metabolic rhythmicity is identified as an important pathophysiological mechanism. The flavonoid pterostilbene (PTE) is abundant in the traditional Chinese medicine dragon's blood with protective efficacy against obesity-related metabolic dysfunctions. Our previous study found that PTE ameliorates exercise intolerance and clock gene oscillation in the skeletal muscles subjected to SR.

PURPOSE

This study aimed to explore whether PTE improves SR-induced metabolic disorders and delineate the relationship between PTE and the circadian clock.

STUDY DESIGN AND METHODS

Two hundred male C57/B6J mice were kept awake for 20 h/d over five consecutive days and concurrently gavaged with 50, 100, or 200 mg/kg·bw/d PTE. Food consumption and body weight were monitored, and the metabolic status of the mice was evaluated by performing OGTT and ITT, measuring the serum lipid profiles and liver histopathology in response to SR. Daily behavior was analyzed by Clocklab™. The circadian rhythms of the liver clock genes and metabolic output genes were evaluated by cosine analysis. Binding between PTE and RORα/γ or NR1D1/2 was investigated by molecular docking. A luciferase reporter assay was used to determine the impact of PTE on Bmal1 transcription in SR-exposed mice co-transfected with Ad-BMAL1-LUC plus Ad-RORγ-mCherry or Ad-NR1D1-EGFP.

RESULTS

PTE significantly ameliorated abnormal glucose and lipid metabolism (p < 0.05) in SR-exposed mice. PTE improved circadian behavior (p < 0.05) and rescued the circadian rhythm oscillation of the liver clock (p < 0.05) and metabolic output genes (p < 0.05) under SR condition. Molecular docking disclosed that PTE might interact with RORs, and PTE was found to increase Bmal1 promoter luciferase activity with RORE elements in the presence of Ad-RORγ-mCherry (p < 0.05).

CONCLUSIONS

PTE may protect against SR-induced metabolic disorders by directly modulating RORγ to maintain circadian metabolic rhythm. The findings provide valuable insights into the potential use of PTE in the treatment of metabolic disorders associated with disruptions in the circadian rhythm.

Pterostilbene and Probiotic Complex in Chemoprevention of Putative Precursor Lesions for Colorectal Cancer in an Experimental Model of Intestinal Carcinogenesis with 1,2-Dimethylhydrazine

Dietary supplementation with pterostilbene (PS) and/or a probiotic (PRO) may ameliorate the intestinal microbiota in disease conditions. This study aims to evaluate PS and PRO for the chemoprevention of putative precursor lesions for colorectal cancer (CRC) in an experimental model of intestinal carcinogenesis with 1,2-dimethylhydrazine (1,2-DMH). Sixty male Wistar rats were equally divided into five groups: Sham, 1,2-DMH, 1,2-DMH + PS, 1,2-DMH + PRO, and 1,2-DMH + PS + PRO. PRO (5 × 10⁷/mL) was offered in water, and PS (300 ppm) was provided in the diet ad libitum. 1,2-DMH (20 mg/kg/week) was administered for 15 consecutive weeks. In the 25th week, proctocolectomy was conducted. PRO alone and PRO combined with PS were the best intervention strategies to improve experimental 1,2-DMH-induced CRC regarding several parameters of carcinogenesis. Our findings may contribute to the development of novel preventive strategies for CRC and may help to identify novel modulators of colon carcinogenesis.

Phase I Metabolism of Pterostilbene, a Dietary Resveratrol Derivative: Metabolite Identification, Species Differences, Isozyme Contribution, and Further Bioactivation

Pterostilbene (PTE), a dietary derivative of resveratrol, displayed pleiotropic health-promoting activities. This study aimed to explore the metabolic profiles and species differences of the phase I metabolism of PTE and to investigate subsequent detoxification after PTE bioactivation. PTE was found to be biotransformed to two pharmacologically active metabolites, pinostilbene and 3'-hydroxypterostilbene, in vivo and in vitro with substantial species differences. Human CYP1A2 was proved to be mainly responsible for the demethylation and 3'-hydroxylation of PTE, with its contribution to a demethylation of 94.5% and to a 3'-hydroxylation of 97.9%. An in vitro glutathione trapping experiment revealed the presence of an ortho-quinone intermediate formed by further oxidation of 3'-hydroxypterostilbene. Human glutathione S-transferase isoforms A2, T1, and A1 inactivated the ortho-quinone intermediate by catalyzing glutathione conjugation, implicating a potential protective pathway against PTE bioactivation-derived toxicity. Overall, this study provided a comprehensive view of PTE phase I metabolism and facilitated its further development as a promising nutraceutical.

Improving the in vitro and in vivo bioavailability of pterostilbene using Yesso scallop gonad protein isolates-epigallocatechin gallate (EGCG) conjugate-based emulsions: effects of carrier oil

This study investigated the influence of carrier oils on the in vitro and in vivo bioavailability of PTE encapsulated in scallop gonad protein isolates (SGPIs)-epigallocatechin gallate (EGCG) conjugate stabilized emulsions. The SGPIs-EGCG stabilized emulsions were subjected to an in vitro simulated digestion, and the resulting corn oil and MCT micelles were used to evaluate the PTE transportation using the Caco-2 cell model. Both emulsions remarkably improved the bioaccessibility of PTE in the micelle phase. Nevertheless, corn oil emulsions increased trans-enterocyte transportation of PTE more efficiently than MCT emulsions. Furthermore, the maximum plasma concentrations of PTE and its metabolites in mice fed with PTE emulsions were prominently higher than those in mice fed with PTE solution, while the in vivo metabolic patterns of PTE in different oil-stabilized emulsions were different. Therefore, SGPIs-EGCG stabilized emulsions could enhance the bioavailability of PTE through controlled release, in which corn oil is more suitable than MCT.

Gut Microbiota-Derived Resveratrol Metabolites, Dihydroresveratrol and Lunularin, Significantly Contribute to the Biological Activities of Resveratrol

Although resveratrol (RES) is barely detectable in the plasma and tissues upon oral consumption, collective evidence reveals that RES presents various bioactivities in vivo, including anti-inflammation and anti-cancer. This paradox necessitates further research on profiling and characterizing the biotransformation of RES, as its metabolites may contribute profound biological effects. After 4-week oral administration, 11 metabolites of RES were identified and quantified in mice by HPLC-MS/MS, including dihydro-resveratrol (DHR), lunularin (LUN), and conjugates (sulfates and glucuronides) of RES, DHR and LUN. Importantly, DHR, LUN, and their conjugates were much more abundantly distributed in tissues, gastrointestinal tract (GIT), and biological fluids compared to RES and its conjugates. Moreover, we established that DHR and LUN were gut bacteria-derived metabolites of RES, as indicated by their depletion in antibiotic-treated mice. Furthermore, the biological activities of RES, DHR, and LUN were determined at physiologically relevant levels. DHR and LUN exhibited stronger anti-inflammatory and anti-cancer effects than RES at the concentrations found in mouse tissues. In summary, our study profiled the tissue distribution of the metabolites of RES after its oral administration in mice and uncovered the important role of gut microbial metabolites of RES in the biological activities of RES in vivo.