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Sasa quelpaertensis Nakai extract (SQE) has long been used as a traditional medicine and health drink. The present study aims to examine the properties and antioxidant activity of the phytochemicals isolated from S. quelpaertensis. Therefore, the SQE was fractionated with n-hexane, chloroform (CHCl3), ethyl acetate (EtOAc), and n-butanol (BuOH). Phytochemicals present in the solvent fraction were also isolated using a high-performance liquid chromatography (HPLC) system. In addition, their DPPH radical scavenging ability and NO production inhibitory effect were compared. The results showed that phytochemicals p-hydroxybenzaldehyde (1), salicylic acid (2), syringaldehyde (3), methyl cis-p-hydroxycinnamate (4), methyl trans-p-hydroxycinnamate (5), p-coumaric acid (6), 2,3-dihydrozypropyl 9Z,12Z-octadecadienoate (7), (+)-(6S,7aS)-epilolide (8), (-)-(6 R,7aS)-loliolide (9), naringenin (10), 3-O-p-coumaroyl-1-(4-hydroxy-3,5-dimethoxyphenyl)-1-O-β-glucopyranosylpropanol (11), tricin (12), and tricin 7-O-b-D-glucopyranoside (13) were isolated from CHCl3, EtOAc, and BuOH fractions and then identified using nuclear magnetic resonance (NMR) spectrometry. This is an initial study on compounds 2, 3, 4, 5, 7, 8, and 9 obtained from S. quelpaertensis. Compounds 11 (IC50 120.3 μM) and 7 (IC50 43.62 μM) showed significant DPPH radical scavenging activity and anti-inflammatory activity, respectively. We believe these results may provide the basic data for developing effective antioxidants using the SQE.

Polymethoxyflavones (PMFs) are flavonoids exclusively found in certain citrus fruits and have been reported to be beneficial to human health. Most studies have been conducted with PMFs isolated from citrus peels, while there is no study on PMFs isolated from leaves. In this study, we prepared a PMF-rich fraction (PRF) from the leaves of Citrus sunki Hort ex. Tanaka (Jinkyool) and investigated whether the PRF could improve metabolic decline in obese mice induced by a high-fat diet (HFD) for 5 weeks. The HFD-induced obese mice were assigned into HFD, OR (HFD + orlistat at 15.6 mg/kg of body weight/day), and PRF (HFD + 50, 100, and 200 mg/kg of body weight/day) groups. Orlistat and PRF were orally administered for 5 weeks. At the end of the experiment, the serum biochemical parameters, histology, and gene expression profiles in the tissues of each group were analyzed. The body weight gain of the obese mice was significantly reduced after orlistat and PRF administration for 5 weeks. PRF effectively improved HFD-induced insulin resistance and dyslipidemia. Histological analysis in the liver demonstrated that PRF decreased adipocyte size and potentially improved the liver function, as it inhibited the incidence of fatty liver. PRF activated AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), and hormone-sensitive lipase (HSL) in HFD-induced obese mice. Moreover, liver transcriptome analysis revealed that PRF administration enriched genes mainly related to fatty-acid metabolism and immune responses. Overall, these results suggest that the PRF exerted an anti-obesity effect via the modulation of lipid metabolism.

Sasa quelpaertensis Nakai is a dwarf bamboo grass suitable for food and health-related applications as it is a rich source of antioxidants. In this study, the leaves and culms of this plant were harvested from May to December, and the ethanol extracts of leaves (ESL) and culms (ESC), and the hot water extracts of leaves (HSL) and culms (HSC) were prepared. Extracts were evaluated for the seasonal changes in the content of p-coumaric acid, tricin, total phenolics (TP), and total flavonoids (TF) content; as well as for the antioxidant and anti-inflammatory activities. The p-coumaric acid in HSL and tricin contents in ESL rapidly decreased from June to October, and remained relatively constant until December. TP and TF contents in ESL were gradually increased from October and reached the highest level in December. The phenolic compounds (p-coumaric acid, tricin, TP and TF contents) in ESL showed an excellent correlation with antioxidant activities, indicating that ESL contained the highest levels of antioxidant and anti-inflammatory substances. Taken together, these results suggest that the optimal time to harvest this plant is from October to December.

Background: Increased dietary fructose consumption is closely associated with lipid and glucose metabolic disorders. Sasa quelpaertensis Nakai possesses various health-promoting properties, but there has been no research on its protective effect against fructose-induced metabolic dysfunction. In this study, we investigated the effects of S. quelpaertensis leaf extract (SQE) on metabolic dysfunction in high-fructose-diet-fed rats. Methods: Animals were fed a 46% carbohydrate diet, a 60% high-fructose diet, or a 60% high-fructose diet with SQE (500 mg/kg of body weight (BW)/day) in drinking water for 16 weeks. Serum biochemical parameters were measured and the effects of SQE on hepatic histology, protein expression, and transcriptome profiles were investigated. Results: SQE improved dyslipidemia and insulin resistance induced in high-fructose-diet-fed rats. SQE ameliorated the lipid accumulation and inflammatory response in liver tissues by modulating the expressions of key proteins related to lipid metabolism and antioxidant response. SQE significantly enriched the genes related to the metabolic pathway, namely, the tumor necrosis factor (TNF) signaling pathway and the PI3K-Akt signaling pathway. Conclusions: SQE could effectively prevent dyslipidemia, insulin resistance, and hepatic lipid accumulation by regulation of metabolism-related gene expressions, suggesting its role as a functional ingredient to prevent lifestyle-related metabolic disorders.

The aim of this study was to investigate the relationship between the chemical composition and antioxidant activity of roasted jinpi extract (RJE) under various roasting conditions (e.g., 100–155 °C). The total phenolic contents, flavonoid content, and antioxidant activities in RJE increased with increased roasting temperature, and the highest efficacy was observed at 155 °C. The narirutin and hesperidin contents in RJE reached 15.32 and 11.50 mg/g, respectively, under this optimal temperature (155 °C). The roasting process caused the Maillard reaction to occur which increased the amounts of 2,4-diamino-5-(3′,4′-dichlorophenyl)-6-methyl pyrimidine (DDMP) and 5-hydroxymethlyfurfural (5-HMF) but decreased the total sugar content in RJE. Among the compounds contained in RJE, DDMP had the strongest diethylene glycol, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, which was determined by DPPH-HPLC analysis. These results suggest that roasting jinpi under optimal conditions increases the amount of phenolics and flavonoids and thereby enhances the antioxidant activity of jinpi.

The peel of Citrus sunki is a rich source of polymethoxyflavones (PMFs). In this study, a PMF-rich fraction (PRF) was obtained from the peels of C. sunki by hot-water extraction and subsequent fractionation with n -hexane. Six PMFs and two demethylated PMFs were isolated by semi-preparative HPLC, and their structures were identified by 1 H NMR and 13 C NMR. To define the synergistic effects of PRF, the PRF and its eight individual components were assessed for antiproliferative activity using HL-60 cells. The PRF showed greater growth inhibitory activity ( IC 50 value = 25.14 μg/ml), compared with its individual components. Flow cytometric analysis confirmed that the PRF significantly increased the percentage of sub-G 1 cells (30.1% at 25 μg/ml). Our study provides an efficient method for preparing a PRF for use as a functional food ingredient.