Hepatoprotective Activity and Mechanisms of Prenylated Stilbenoids.

Dietary prenylated stilbenoids, found in various food sources, offer multiple health benefits, including liver protection. However, the underlying mechanisms of hepatoprotection remain unclear. In this study, we synthesized 13 natural prenylated stilbenoids and examined their hepatoprotective activities, with silent mating type information regulation 2 homologue-1 (SIRT1) as the primary target for screening. Among all of the prenylated stilbenoids tested, 4-C-geranyl oxyresveratrol demonstrated superior performance. It activated SIRT1 activity more effectively than resveratrol, a well-known SIRT1 activator. To further investigate the mechanism of liver protection, two in vitro models were used: the palmitic acid-induced lipid accumulation model and the H2O2-induced apoptosis model. Our findings suggested that 4-C-geranyl oxyresveratrol mitigated lipid accumulation through the SIRT1-PGC1α pathway, reduced apoptosis via the SIRT1-p53-p21 pathway, and exerted antioxidant effects through the SIRT1-Nrf2 pathway. These findings provide new insights into the chemical basis of the health benefits of prenylated stilbenoids and their potential use as functional food additives.

The structure characteristics, biosynthesis and health benefits of naturally occurring rare flavonoids.

Rare flavonoids, a special subclass of naturally occurring flavonoids with diverse structures including pterocarpans, aurones, neoflavonoids, homoisoflavones, diphenylpropanes, rotenoids and 2-phenylethyl-chromones. They are mainly found in legumes with numerous health benefits. Rare flavonoids are regarded as minor flavonoids due to their very limited abundance in nature. This review gives an overview of the natural occurrences of rare flavonoids from previous literatures. Recent findings on the biosynthesis of rare flavonoids have been updated by describing their structural characteristics and classifications. Recent findings on the health benefits of rare flavonoids have also been compiled and discussed. Natural rare flavonoids with various characteristics from different subclasses from plant-based food sources are stated. They show a wide range of health benefits, including antibacterial, anticancer, anti-osteoporosis and antiviral activities. Studies reviewed suggest that rare flavonoids possessing different skeletons demonstrate different characteristic bioactivities by discussing their mechanism of actions and structure-activity relationships. Besides, recent advances on the biosynthesis of rare flavonoids, such as pterocarpans, rotenoids and aurones are well-known, while the biosynthesis of other subclasses remain unknown. The perspectives and further applications of rare flavonoids using metabolic engineering strategies also be expected.

Effect of γ-irradiation on structure, physicochemical property and bioactivity of soluble dietary fiber in navel orange peel.

Soluble dietary fibers are widely used in functional food. In this work, the effects of γ-irradiation on molecular weight, structure, physicochemical properties and bioactivities of soluble dietary fiber in navel orange peel (OSDF) were investigated. Γ-irradiation enhanced the extraction yield of OSDF. The molar ratio of glucose and galacturonic acid was increased. The molecular weight profile of OSDF was modified. Γ-irradiation (3-6 kGy) improved the water holding capacity, water swelling capacity, oil holding capacity, cation-exchange capacity, nitrite adsorption capacity and total antioxidant capacity of OSDF. Glucose adsorption capacity and bifidobacterium proliferation capacity of OSDF were improved in a dose-dependent behaviour. Moreover, γ-irradiation promoted the cracking of microstructure. FT-IR spectra showed that more carboxyl groups were newly formed by γ-irradiation. These findings indicated that γ-irradiation treatment was an efficient technique for improving physicochemical properties and health benefits.

Structure identification of a polysaccharide in mushroom Lingzhi spore and its immunomodulatory activity.

Ganoderma lucidum spore serves as a well-known immunomodulatory functional food in Asia. The polysaccharides in G. lucidum spore are responsible for the claimed immunomodulatory activity. However, the structural information of polysaccharides remains unclear. In this work, the leading water-soluble polysaccharide in G. lucidum spore (GLSP-I) with a molecular weight of 128.0 kDa was isolated and purified. The monosaccharide composition analysed by gas chromatography indicated that GLSP-I was a glucan. Three side chains, including Glc-(1 â†’ 3)-Glc-(1 â†’ 3)-Glc-(1 â†’ 6)-Glc, Glc-(1 â†’ 6)-Glc-(1 â†’ 6)-Glc-(1 â†’ 6)-Glc and Glc-(1 â†’ 3)-Glc-(1 â†’ 3)-Glc-(1 â†’ 3)-Glc-(1 â†’ 3)-Glc, were identified by UPLC-MS/MS. The structural characteristics were further identified by NMR spectra. The results indicated that the backbone of GLSP-I was (1 â†’ 3)-ß-D-glucan, with side chains linking at O-6. The proposed structure was drawn as below. The immunomodulatory activity assay indicated that GLSP-I could activate macrophages in a dose-dependent manner.

Structure of water-soluble polysaccharides in spore of Ganoderma lucidum and their anti-inflammatory activity.

Ganoderma lucidum spore is widely accepted as functional food. Polysaccharides are the predominant bioactive components in G. lucidum spore and contribute much to its health benefits. However, their structural characteristics remain unclear. In this work, water-soluble polysaccharides (GLSP) were obtained by hot water extraction. Three monosaccharides, including arabinose (Ara), glucose (Glc) and galactose (Gal), were presented in GLSP. 1D and 2D NMR data revealed that GLSP were composed mainly by two polysaccharides, ß-glucan and arabinogalactan. The arabinogalactan had a backbone of galactan with Araf in the side chain. ß-Glucan was the dominant polysaccharide in G. lucidum spore. The molecular weight was measured. GLSP could induce IEC-6 cells proliferation in a concentration-dependent manner. Moreover, GLSP possessed a strong anti-inflammatory activity through inhibiting the overproduction of NO and pro-inflammatory cytokines, like interleukin-6 (IL-6) and interleukin-1ß (IL-1ß) induced by LPS. These results implied the potential of GLSP on gut barrier protection.

UHPLC-MS/MS Analysis on Flavonoids Composition in Astragalus membranaceus and Their Antioxidant Activity.

Astragalus membranaceus is a valuable medicinal plant species widely distributed in Asia. Its root is the main medicinal tissue rich in methoxylated flavonoids. Origin can highly influence the chemical composition and bioactivity. To characterize the principal chemicals influenced by origin and provide more information about their antioxidant profile, the extracts of A. membranaceus roots from four origins were analysed by UHPLC-MS/MS. Thirty-four flavonoids, including thirteen methoxylated flavonoids, fifteen flavonoid glycosides and six flavonols, were identified. By principal component analysis, eighteen identified compounds were considered to be principal compounds. They could be used to differentiate A. membranaceus from Shanxi, Inner Mongolia, Heilongjiang and Gansu. The antioxidant activity was analysed by ORAC assay, DPPH radical scavenging activity assay and cell antioxidant activity assay. 'Inner Mongolia' extract showed the highest antioxidant activity. These results were helpful to understand how origin influenced the quality of A. membranaceus.

Effect of pinolenic acid on oxidative stress injury in HepG2 cells induced by H2O2.

To investigate the effect and mechanism of pinolenic acid (PNA) on H2O2-induced oxidative stress injury in HepG2 cells. Methods: PNA was used to regulate oxidative stress injury of HepG2 cells induced by H2O2. Quantification of cell survival rate, accumulation of intracellular reactive oxygen species (ROS), and expression levels of anti-oxidation-related genes were determined using MTT, fluorescent probe technology (DCFH-DA), and real-time quantitative reverse transcription polymerase chain technology (qRT-PCR) method, respectively. Meanwhile, the activity of intracellular antioxidant enzymes was determined by biochemical methods. The results showed that PNA improved the survival rate of HepG2 cells induced by H2O2 (29.59%, high-dose group), reduced the accumulation of intracellular ROS (65.52%, high-dose group), and reduced the level of intracellular malondialdehyde (MDA; 65.52%, high-dose group). All these results were dose-dependent, which indicated that PNA can improve oxidative stress damage of cells. Furthermore, the mechanism of PNA regulating oxidative stress was investigated from the gene level. Results showed that under supplementation of PNA, the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) had been improved (39.74%, 17.58%, and 23.83%, high-dose group). Further studies on gene expression which controls the activity of antioxidant enzymes showed that under the regulation of PNA, the expression level of Keap1 gene was decreased, while Nrf2 gene was increased. The expression levels of HO-1 and NQO1 in the downstream of Nrf2 were increased. Results indicated that under the regulation of PNA, Nrf2 was separated from Keap1, entered the nucleus, bound to ARE, and up-regulated the expression levels of HO-1 and NQO1 genes. Conclusion: PNA has a conspicuous improvement effect on oxidative stress damage induced by H2O2 in HepG2 cells. We also found the antioxidant mechanisms of PNA where it protected cells from oxidative stress damage by causing nuclear translocation of Nrf2 gene and up-regulated the expression levels of antioxidant enzymes in the downstream. This shows that PNA prevented oxidative stress by mediating the Keap1/Nrf2 transcriptional pathway and down-regulating enzyme activities.

Structure Differences of Water Soluble Polysaccharides in Astragalus membranaceus Induced by Origin and Their Bioactivity.

Astragalus membranaceus is a functional food with multiple bioactivities. It presents differentiated health benefits due to origins. Polysaccharides (APS) are the leading bioactive macromolecules of A. membranaceus, which are highly related to its health benefits. However, the effect of origin on the structural characteristics of APSs remains unclear. In this work, polysaccharides from four origins were isolated and identified by NMR. The results showed APSs of four origins had identical monosaccharide composition and glycosidic linkage. Rhamnogalacturonan II pectins and α-(1→4)-glucan were the dominant polysaccharides. However, the level of methyl ester in pectins varied to a large extent. The molecular weight profiles of APSs were also different. Inner Mongolia APS had the largest percentage of 20-40 kDa polysaccharides. Molecular weight and methyl ester level were two important parameters determining the difference of APSs from four origins. These results were helpful to recognize the origin-related quality of A. membranaceus.