Lingguang Yang

Tyrosol Prevents Ischemia/Reperfusion-Induced Cardiac Injury in H9c2 Cells: Involvement of ROS, Hsp70, JNK and ERK, and Apoptosis

Ischemia-Reperfusion (I/R) injury causes ROS overproduction, creating oxidative stress, and can trigger myocyte death, resulting in heart failure. Tyrosol is an antioxidant abounded in diets and medicine. Our objective was to investigate the protective effect of tyrosol on I/R-caused mortality in H9c2 cardiomyocytes through its influence on ROS, Hsp70, ERK, JNK, Bcl-2, Bax and caspase-8. A simulated I/R model was used, myocytes loss was examined by MTT, and ROS levels were measured using DCFH-DA. Nuclear condensation and caspase-3 activity were assessed by DAPI staining and fluorometric assay. Phosphorylated ERK and JNK were determined by electrochemiluminescent ELISA, and Hsp70, Bcl-2, Bax and caspase-8 were examined by Western blotting. Results show that tyrosol salvaged myocyte loss, inhibited nuclear condensation and caspase-3 activity dose-dependently, indicating its protection against I/R-caused myocyte loss. Furthermore, tyrosol significantly inhibited ROS accumulation and activation of ERK and JNK, augmenting Hsp70 expression. Besides, tyrosol inhibited I/R-induced apoptosis, associated with retained anti-apoptotic Bcl-2 protein, and attenuated pro-apoptotic Bax protein, resulting in a preservation of Bcl-2/Bax ratio. Finally, tyrosol notably decreased cleaved caspase-8 levels. In conclusion, cytoprotection of tyrosol in I/R-caused myocyte mortality was involved with the mitigation of ROS, prohibition of the activation of ERK, JNK and caspase-8, and elevation of Hsp70 and Bcl-2/Bax ratio.

Response Surface Methodology Optimization of Ultrasonic-Assisted Extraction of Acer Truncatum Leaves for Maximal Phenolic Yield and Antioxidant Activity

This study is the first to report the use of response surface methodology to improve phenolic yield and antioxidant activity of Acer truncatum leaves extracts (ATLs) obtained by ultrasonic-assisted extraction. The phenolic composition in ATLs extracted under the optimized conditions were characterized by UPLC-QTOF-MS/MS. Solvent and extraction time were selected based on preliminary experiments, and a four-factors-three-levels central composite design was conducted to optimize solvent concentration (X1), material-to-liquid ratio (X2), ultrasonic temperature (X3) and power (X4) for an optimal total phenol yield (Y1) and DPPH• antioxidant activity (Y2). The results showed that the optimal combination was ethanol:water (v:v) 66.21%, material-to-liquid ratio 1:15.31 g/mL, ultrasonic bath temperature 60 °C, power 267.30 W, and time 30 min with three extractions, giving a maximal total phenol yield of 7593.62 mg gallic acid equivalent/100 g d.w. and a maximal DPPH• antioxidant activity of 74,241.61 μmol Trolox equivalent/100 g d.w. Furthermore, 22 phenolics were first identified in ATL extract obtained under the optimized conditions, indicating that gallates, gallotannins, quercetin, myricetin and chlorogenic acid derivatives were the main phenolic components in ATL. What’s more, a gallotannins pathway existing in ATL from gallic acid to penta-O-galloylglucoside was proposed. All these results provide practical information aiming at full utilization of phenolics in ATL, together with fundamental knowledge for further research.

Urolithin C, a gut metabolite of ellagic acid, induces apoptosis in PC12 cells through a mitochondria-mediated pathway

Urolithins (Uros), metabolites of ellagitannins (ET) and ellagic acid (EA) produced by gut microbiota, showed better bioavailability and extensive bioactivity, and were considered as the active compounds responsible for the health benefits exerted by ET-containing foodstuffs. Here, we chemically synthesized three Uros including Uros A, B, and C and compared their anti-proliferative activities with that of EA in PC12 cells. MTT assay showed that EA significantly promoted, while Uros significantly inhibited the proliferation of PC12 cells, among which UroC showed the strongest anti-proliferation. UroC treatment actively increased the lactate dehydrogenase (LDH) release and lipid peroxidation malondialdehyde (MDA), stimulated reactive oxygen species (ROS) formation and mitochondrial membrane depolarization, and caused calcium dyshomeostasis. Furthermore, flow cytometry analysis showed that UroC treatment induced apoptosis and S phase cell cycle arrest with increasing UroC concentrations. Consequently, UroC also induced imbalance in the Bcl-2/Bax ratio, which triggered the caspase cascade, thereby shifting the balance in favor of apoptosis, as evidenced by western blotting and real-time PCR. These observations indicated that UroC possessed significantly different anti-proliferation activities from EA, and actively induced cell apoptosis through a mitochondria-mediated pathway.

Comparative evaluations on phenolic antioxidants of nine adulterants and anti-inflammation of four alternatives with their original herb Erycibe schmidtii

Erycibe schmidtii is widely used as folk medicine in China for treatments of various inflammations. Recently, with reduction of its wild sources, various adulterants have been misused as substitutes. To distinguish reliable alternatives from various adulterants, total phenolics and antioxidant activities of E. schmidtii and its nine adulterants, as well as three marker compounds of E. schmidtii defined by Chinese Pharmacopoeia were simultaneously quantified. And HPLC fingerprints of these ten herbs were established. Compared with E. schmidtii (S1), Porana sinensis (S2), Porana sinensis var. delavayi (S3), Celastrus hindsii (S4), and Morinda umbellata (S5) exhibited similar or higher total phenols, flavonoids and tannins along with similar or greater capacities scavenging DPPH˙, ABTS+˙ and AAPH˙, contained similar or higher total amounts of the three marker compounds, and possessed higher similarities in HPLC profiles. The other five adulterants (S6–S10, i.e., Illigera parviflora, Morinda parvifolia, Piper puberulum, Piper kadsura and Iodes seguini in sequence) were identified as absolute fakes, thus were excluded from alternatives of S1. Further anti-inflammatory experiments with LPS-induced RAW264.7 macrophages cells on NO release and transcriptions of inflammatory factors iNOS, COX-2, IL-6 and IL-1β showed that S2 and S3 possessed higher anti-inflammation activities than and similar mechanisms to those of S1. Taken together, S2 and S3 could be the best potentially alternatives of E. schmidtii among the nine adulterants. S4 and S5 might be also considered as alternatives for they contained similar fundamental compounds and equally impressive anti-inflammatory potential with E. schmidtii concerning iNOS and COX-2.

Effects of thermal treatments on 10 major phenolics and their antioxidant contributions in Acer truncatum leaves and flowers

This study aimed to investigate effects of thermal treatments on major phenolics and their antioxidant contributions in Acer truncatum leaves and flowers (ATL and ATF, respectively). With ultra performance liquid chromatography-diode array detector-quadrupole time-of-flight-mass spectrometer/mass spectrometer, phenolic compositions of ATF were first characterized and compared with those of ATL. An optimized high performance liquid chromatography fingerprint was then established, and 10 major phenolics existing in both ATL and ATF were quantified. Gallic acid derivatives and flavonol-3-O-glycosides were found to be their dominant phenolic constituents, with the former being key constituents which was affected by thermal treatments and further influencing the variations of total phenols. Moreover, the mechanism underlining the changes of phenolics in ATL and ATF by the treatments was characterized as a thermolhydrolysis process. During thermal treatments, polymerized gallotannins were hydrolysed to 1,2,3,4,6-pentakis-O-galloyl-β-d-glucose, ethyl gallate and gallic acid, resulting in more than fivefold and twofold increase of their contents in ATL and ATF, respectively. By contrast, contents and antioxidant contributions of flavonol-3-O-glycosides gradually decreased during the process.\absbreak Overall, this is, to our knowledge, the first report on the effects of thermal treatments on phenolics and their antioxidant contributions in ATL and ATF, and the three gallic acid derivatives with potentially higher bioactivity could be efficiently achieved by thermal treatments.

Hypoglycemic Effects in Alloxan-Induced Diabetic Rats of the Phenolic Extract from Mongolian Oak Cups Enriched in Ellagic Acid, Kaempferol and Their Derivatives

Our previous reports showed that crude extract prepared with 50% ethanol (ethanol crude extract, ECE) from Mongolian oak cups possessed excellent in vitro antioxidant capacities as well as inhibitory activities against α-glucosidase, α-amylase and protein glycation caused by its enrichment in phenolics, including mainly ellagic acid, kaempferol and their derivatives. Nevertheless, few in vivo studies on antidiabetic activities of these phenolics were conducted. The present study investigated hypoglycemic effects with normal and diabetic rats being administrated orally without or with ECE at 200 and 800 mg/kg for 15 days. In normal rats, no significant differences were exhibited after ECE administration in body weight, fasting blood glucose level, levels of cholesterol, triglyceride, LDL and AST in serum, organ indexes, and levels of GSH and MDA in organs. In diabetic rats, the fasting blood glucose level, indexes of heart and liver, and levels of cholesterol and triglyceride in serum and MDA in heart tissue were significantly decreased. Moreover, HDL levels in serum and SOD activities in the four organs of diabetic rats were significantly improved after ECE administration at 800 mg/kg. Thus, in addition to inhibiting α-glucosidase, α-amylase and protein glycation reported previously, oak cups might contain novel dietary phytonutrients in preventing abnormal changes in blood glucose and lipid profile and attenuating oxidant stress in vivo. The results also implied that it is ellagic acid, kaempferol and their derivatives enriched in ECE that might play vital roles in managing type 1 as well as type 2 diabetes.

Inhibitory effects against α-glucosidase and α-amylase of the flavonoids-rich extract from Scutellaria baicalensis shoots and interpretation of structure–activity relationship of its eight flavonoids by a refined assign-score method

A flavonoids-rich extract of Scutellaria baicalensis shoots and its eight high content flavonoids were investigated for their inhibitory effects against α-glucosidase and α-amylase. Results show that abilities of the extract in inhibiting the two enzymes were obviously higher than those of acarbose. Moreover, inhibitory abilities of all the eight individual flavonoids against the two enzymes show exactly a same order (i.e., apigenin > baicalein > scutellarin > chrysin > apigenin-7-O-glucuronide > baicalin > chrysin-7-O-glucuronide > isocarthamidin-7-O-glucuronide), and their structure–activity relationship could be well-interpretated by the refined assign-score method. Furthermore, based on the inhibitory abilities and their contents in the extract, it was found that the eight flavonoids made predominant contributions, among which baicalein and scutellarin played roles as preliminary contributors, to overall inhibitory effects of the extract against the two enzymes. Beyond these, contributions of the eight flavonoids to the overall enzyme inhibitory activity were compared with those to the overall antioxidant activity characterized in our recent study, and it could be inferred that within the basic flavonoid structure the hydroxyl on C-4′ of ring B was more effective than that on C-6 of ring A in enzyme inhibitory activities while they behaved inversely in antioxidant activities; scutellarin and apigenin contributed more to the overall enzyme inhibitory activity, and baicalin and scutellarin, to the overall antioxidant activity of the extract; and flavonoids of the extract, apart from directly inhibiting enzymes, might also be conducive to curing type 2 diabetes via scavenging various free radicals caused by increased oxidative stresses.