Magnolia officinalis (Hou Po) bark extract stimulates the Nrf2-pathway in hepatocytes and protects against oxidative stress.

ETHNOPHARMACOLOGICAL RELEVANCE: The highly aromatic bark of Magnolia officinalis Rehder and EH Wilson, (magnolia bark) has been widely used in traditional Chinese medicine where it is known as Hou Po. Historically the bark of the tree has been used for treating variety of disorders the most common use of magnolia bark in traditional prescription has been to treat stress and anxiety disorders. Till date it is not clear regarding the fundamental cellular pathway it modulates. NRF2 signaling has emerged as the central pathway that protects cells from variety of stressors this led us to hypothesize that basis for magnolia bark's effects could be via activating NRF2 pathway. MATERIALS AND METHODS: We utilized variety of biochemical procedures like luciferase reporter assay, enzyme induction, gene expression to determine NRF2 inducing activity by magnolia bark extract and its significance. Further we identified the phytochemicals inducing this activity using bio-directed fractionation procedure. RESULTS: In this study, we demonstrate that magnolia bark extract activates Nrf2-dependent gene expression and protects against hydrogen peroxide mediated oxidative stress in hepatocytes. We further identified through HPLC fractionation and mass spectroscopy that magnolol, 4-methoxy honokiol and honokiol are the active phytochemicals inducing the Nrf2-mediated activity. This could be the molecular basis for its numerous beneficial activity.

Total Antioxidant Capacity and Characterization of Nitraria tangutorum Fruit Extract by Rapid Bioassay-Directed Fractionation.

In recent years, the role of reactive nitrogen and oxygen species (RNOS) in human disease has been the subject of considerable study. This has led to research on the potential benefit of natural products as dietary antioxidants to mitigate oxidative stress caused by increased RNOS associated with tissue damage. Five physiologically relevant reactive species include peroxyl radical, hydroxyl radical, peroxynitrite anion, superoxide radical anion, and singlet oxygen. Excessive amounts of these species can lead to the degradation of important biomolecules in vivo, and dietary antioxidants have been shown to inhibit damage both in vitro and in vivo. In this investigation, we have discovered that an extract of the fruit from Nitraria tangutorum Bobr. (Tangut white thorn) demonstrates significant antioxidant capacity against all five reactive species. Rapid bioassay-directed fractionation was used to identify antioxidant phytochemicals by collecting fractions from HPLC effluent into 96 well microplates and testing for antioxidant activity against the 2,2-diphenyl-1-picrylhydrazyl radical. Two different classes of phytochemicals, anthocyanins and flavonoids, were associated with antioxidant activity. Active components were further characterized by UV-Vis spectroscopy and high-resolution MS.

Identification of a botanical inhibitor of intestinal diacylglyceride acyltransferase 1 activity via in vitro screening and a parallel, randomized, blinded, placebo-controlled clinical trial.

BACKGROUND: Diacylglyceride acyltransferase 1 (DGAT1) is the enzyme that adds the final fatty acid on to a diacylglyceride during triglyceride (TG) synthesis. DGAT1 plays a key role in the repackaging of dietary TG into circulating TG rich chylomicrons. A growing amount of research has indicated that an exaggerated postprandial circulating TG level is a risk indicator for cardiovascular and metabolic disorders. The aim of this research was to identify a botanical extract that inhibits intestinal DGAT1 activity and attenuates postprandial hypertriglyceridemia in overweight and obese humans. METHODS: Twenty individual phytochemicals and an internal proprietary botanical extract library were screened with a primary cell-free DGAT1 enzyme assay that contained dioleoyl glycerol and palmitoleoyl Coenzyme A as substrates plus human intestinal microsomes as the DGAT1 enzyme source. Botanical extracts with IC50 values < 100 µg/mL were evaluated in a cellular DGAT1 assay. The cellular DGAT1 assay comprised the analysis of (14)C labeled TG synthesis in cells incubated with (14)C-glycerol and 0.3 mM oleic acid. Lead botanical extracts were then evaluated in a parallel, double-blind, placebo-controlled clinical trial. Ninety healthy, overweight and obese participants were randomized to receive 2 g daily of placebo or individual botanical extracts (the investigational product) for seven days. Serum TG levels were measured before and after consuming a high fat meal (HFM) challenge (0.354 L drink/shake; 77 g fat, 25 g carbohydrate and 9 g protein) as a marker of intestinal DGAT1 enzyme activity. RESULTS: Phenolic acids (i.e., gallic acid) and polyphenols (i.e., cyanidin) abundantly found in nature appeared to inhibit DGAT1 enzyme activity in vitro. Four polyphenolic rich botanical extracts were identified from in vitro evaluation in both cell-free and cellular model systems: apple peel extract (APE), grape extract (GE), red raspberry leaf extract (RLE) and apricot/nectarine extract (ANE) (IC50 = 1.4, 5.6, and 10.4 and 3.4 µg/mL, respectively). In the seven day clinical trial, compared to placebo, only GE significantly reduced the baseline subtracted change in serum TG AUC following consumption of the HFM (AUC = 281 ± 37 vs. 181 ± 30 mg/dL*h, respectively; P = 0.021). Chromatographic characterization of the GE revealed a large number of closely eluting components containing proanthocyanidins, catechins, anthocyanins and their secondary metabolites that corresponded with the observed DGAT1 enzyme inhibition in the cell-free model. CONCLUSION: These data suggest that a dietary GE has the potential to attenuate postprandial hypertriglyceridemia in part by the inhibition of intestinal DGAT1 enzyme activity without intolerable side effects. TRIAL REGISTRATION: This trial was registered with ClinicalTrials.gov NCT02333461.

Identification of glabridin as a bioactive compound in licorice (Glycyrrhiza glabra L.) extract that activates human peroxisome proliferator-activated receptor gamma (PPARγ).

Licorice, the root and stolons of the Glycyrrhiza plant (Fabaceae), has been used for centuries as a food additive (sweetener), in cosmetics, and in traditional medicine. In this research, we provide evidence that licorice extract activates peroxisome proliferator-activated receptor gamma (PPARγ) and, as identified through HPLC fractionation and mass spectroscopy, one of the activating phytochemicals is glabridin. Glabridin was shown to bind to and activate PPARγ. It was also shown to activate PPARγ-regulated gene expression in human hepatoma cells similar to known PPARγ ligands and that the expression was blocked by a PPARγ specific antagonist.

Identification of evodiamine as the bioactive compound in evodia (Evodia rutaecarpa Benth.) fruit extract that activates human peroxisome proliferator-activated receptor gamma (PPARγ).

The dried unripe fruit from Evodia rutaecarpa Benth., known as Wu zhu yu in China, has long been used in traditional Chinese medicine. In this research, we provide evidence that evodia fruit extract activates peroxisome proliferator-activated receptor gamma (PPARγ) and, as identified through HPLC fractionation and mass spectroscopy, the activating phytochemical is evodiamine. Evodiamine was shown to bind to and activate PPARγ. It was also shown to activate PPARγ-regulated gene expression in human hepatoma cells similar to known PPARγ ligands and that the expression was blocked by a PPARγ specific antagonist.