Defining the Cholesterol Lowering Mechanism of Bergamot (Citrus bergamia) Extract in HepG2 and Caco-2 Cells.

Bergamot, a Mediterranean citrus fruit native to southern Italy, has been reported to have cholesterol-lowering properties; however, the mechanism of action is not well understood. Due to structural similarities with 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) inhibitors, it has been proposed that the phenolic compounds in bergamot may also inhibit HMGCR. Statins are widely used for their cholesterol-lowering properties; however, they are not universally well tolerated, suggesting there is a need to identify novel cholesterol-lowering strategies. In the present study, we investigated bergamot fruit extract (BFE) and its principal components (neoeriocitrin, naringin, neohesperidin, melitidin, and brutieridin) for their ability to regulate cholesterol levels in HepG2 and Caco-2 cells. BFE at increasing concentrations decreased the levels of total and free cholesterol in HepG2 cells. BFE and its constituents did not directly inhibit HMGCR activity. However, BFE and neohesperidin decreased HMGCR levels in HepG2 cells, suggesting that neohesperidin and BFE may downregulate HMGCR expression. An increase in AMP-kinase phosphorylation was observed in BFE and neohesperidin-treated cells. In Caco-2 cells, brutieridin exhibited a significant reduction in cholesterol uptake and decreased the level of Niemann-Pick C1 Like 1, an important cholesterol transporter. Taken together, our data suggest that the cholesterol-lowering activity of bergamot is distinct from statins. We hypothesize that BFE and its principal constituents lower cholesterol by inhibiting cholesterol synthesis and absorption.

Pharmacokinetic Analysis of Carnosic Acid and Carnosol in Standardized Rosemary Extract and the Effect on the Disease Activity Index of DSS-Induced Colitis.

Rosemary extract (RE) is an approved food preservative in the European Union and contains dietary phytochemicals that are beneficial for gastrointestinal health. This study investigated the effects of RE on dextran sodium sulfate (DSS)-induced colitis and also determined the pharmacokinetics of dietary phytochemicals administered to mice via oral gavage. Individual components of rosemary extract were separated and identified by LC-MS/MS. The pharmacokinetics of two major diterpenes from RE, carnosic acid (CA) and carnosol (CL), administered to mice via oral gavage were determined. Then, the effect of RE pre-treatment on the disease activity index (DAI) of DSS-induced colitis in mice was investigated. The study determined that 100 mg/kg RE significantly improved DAI in DSS-induced colitis compared to negative control. Sestrin 2 protein expression, which increased with DSS exposure, was reduced with RE treatment. Intestinal barrier integrity was also shown to improve via fluorescein isothiocyanate (FITC)-dextran administration and Western blot of zonula occludens-1 (ZO-1), a tight junction protein. Rosemary extract was able to improve the DAI of DSS-induced colitis in mice at a daily dose of 100 mg/kg and showed improvement in the intestinal barrier integrity. This study suggests that RE can be an effective preventative agent against IBD.

Prenylated xanthones from mangosteen (Garcinia mangostana) activate the AhR and Nrf2 pathways and protect intestinal barrier integrity in HT-29 cells.

Xanthones from the tropical fruit mangosteen (Garcinia mangostana) display anti-inflammatory and anti-oxidative activities. Here, we isolate and identify potential inducers of the aryl hydrocarbon receptor (AhR) and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways from mangosteen using a bioassay-guided strategy. Mangosteen fruit pericarp extracts were subjected to sequential solvent extractions, followed by chromatography coupled with NMR spectroscopy and mass spectrometric analyses for identification and isolation of pure compounds. Isolation of active fractions led to seven prenylated xanthones that were identified and subsequently evaluated for bioactivity. In vitro luciferase reporter cellular assays using H1L6.1c3 (AhR induction) and HepG2-ARE (Nrf2 induction) were used to identify AhR and Nrf2 activators. All seven prenylated xanthones displayed AhR inducing activity, whereas only five xanthones activated Nrf2. Garcinone D (GarD) significantly upregulated AhR/Cyp1a1 and Nrf2/HO-1 protein expression and enhanced zonula occludens-1 and occludin protein levels in HT-29 cells. In addition, GarD inhibited oxidative stress-induced intestinal epithelial barrier dysfunction by enhancing tight junction (TJ) proteins and inhibition of reactive oxygen species production. Inhibition of AhR by pretreating cells with an AhR antagonist revealed that the AhR pathway is required for the improved epithelial barrier functions of GarD. These results highlight a dual mechanism by GarD that confers protection against intestinal epithelial barrier dysfunction.

Valorization of pomelo (Citrus grandis Osbeck) peel: A review of current utilization, phytochemistry, bioactivities, and mechanisms of action.

Citrus grandis Osbeck, commonly known as "pomelo" or "shaddock," is the largest citrus fruit, the peel of which is a well-known agricultural residual waste. Pomelo peel offers a wide range of components such as essential oils, polysaccharides, and phytochemicals with potential food applications. Utilization of pomelo peel to recover these components is an important step toward agricultural sustainability. This review covers pomelo peel utilization opportunities beyond conventional composting and animal feed production, and critically examines value-added uses via the recovery of potentially bioactive components. The peel of pomelo accounts for approximately 30% of the total fruit weight and contains phytochemicals, including aroma-active volatiles, pectin, flavonoids, phenolic acids, carotenoids, coumarins, and polysaccharides. Recovery of these phytochemicals offers an opportunity for value-added utilization such as the development of enriched or functional foods and nutraceuticals. The health-promoting and therapeutic potential of pomelo peel extracts and isolated pure compounds have been evaluated through numerous in vitro and in vivo studies that revealed a wide range of bioactivities, including hypolipidemic, hypoglycemic, antioxidant, antimicrobial, anti-inflammatory, and anticancer effects. Preclinical evidence highlights multifaceted molecular and signaling events that possibly underlie the said bioactive potential. Overall, the pomelo processing industry offers a great opportunity to recover or produce valuable products from the large amounts of residual wastes it generates. It is envisaged that a thorough understanding of the bioactive components of pomelo peel, their functional and nutraceutical applications, and mode of actions will benefit the food industry.

Boiling enriches the linear polysulfides and the hydrogen sulfide-releasing activity of garlic.

Garlic is rich in polysulfides, and some of them can be H2S donors. This study was conducted to explore the effect of cooking on garlic's organopolysulfides and H2S-releasing activity. Garlic bulbs were crushed and boiled for a period ranging from 3 to 30min and the solvent extracts were analyzed by GC-MS/FID and HPLC. A cell-based assay was used to measure the H2S-releasing activity of the extracts. Results showed that the amounts of allyl polysulfides increased in crushed garlic boiled for 6-10min; however, prolonging the thermal treatment to 20 or 30min decreased their concentrations. Data of the H2S-releasing activity, expressed as diallyl trisulfide equivalents (DATS-E), parallel this trend, being significantly higher at 6 and 10min boiling. Our results showed enhancement of H2S-releasing activity upon moderate boiling, suggesting that shorter cooking time may maximize its health benefits as a dietary source of natural H2S donors.

Organosulfide profile and hydrogen sulfide-releasing capacity of stinky bean (Parkia speciosa) oil: Effects of pH and extraction methods.

Stinky beans (Parkia speciosa) were hydrodistilled and solvent-extracted and the oil obtained was analyzed by GC-MS/FID. Nine cyclic and one acyclic organosulfides were identified comprising 36% of total volatiles. Solvent extracts contained significantly (p < 0.05) higher total organosulfides (680 ppm) as compared to distilled oil (444 ppm). The concentrations of organosulfides are highly dependent on the pH values of the matrix, with control sample (pH 5.40) giving the highest total organosulfides (424 ppm) followed by that of pH 7.0 (234 ppm), pH 9.0 (195 ppm), and pH 3.0 (152 ppm). The H2S-releasing capacity, expressed as diallyl trisulfide equivalents (DATS-E in mmol DATS/g), corresponded well with the differences in organosulfide concentrations as affected by pH with control having the highest value (24.35) followed pH 7.0 (7.27), pH 9.0 (3.27), and pH 3.0 (1.80). We conclude that stinky bean oil is a potent H2S-releasing agent that could have health-beneficial properties.

Effect of processing conditions on the organosulfides of shallot (Allium cepa L. Aggregatum group).

There is a growing account of the health benefits of H2S as an endogenous cell-signaling molecule. H2S from organic polysulfides, in particular, is increasingly gaining attention for their beneficial effects to cardiovascular health. Here, we studied shallot as a potential dietary source of organic polysulfides and examined the effects of processing conditions on its polysulfide profiles. Boiling, autoclaving, and freeze-drying were tested on whole and crushed shallot bulbs, analyzing their effect on the yield of organosulfides. Seventeen organosulfides, including disulfides, trisulfides, and cyclic polysulfides, were identified. Significant differences in the quantitative and qualitative profiles of organosulfides in the hydrodistilled and solvent extracted oils were observed. Freeze-drying retained the majority of the organosulfides, but the whole-autoclaved and whole-boiled shallots lost more than 95% of their organic polysulfides. Crushed-boiled and crushed-autoclaved shallot lost 76-80% of their organosulfides, likely due to the thermal sensitivity of these compounds. The organosulfide profiles are sensitive to the pH values of the processing media. In general, disulfides increased at basic pH (pH 9.0) while trisulfides and cyclic organosulfides are much higher at the acidic to neutral pH values (pH 3.0-5.0). Our results provide important information on the effects of processing conditions that are relevant for optimizing extraction of organosulfides from shallot for further studies evaluating their H2S-releasing activity.