Bihong Hong

Preparation and antioxidant properties of selenium nanoparticles-loaded chitosan microspheres

Selenium nanoparticles (SeNPs), as a special form of selenium (Se) supplement, have attracted worldwide attention due to their favorable properties and unique bioactivities. Herein, an eco-friendly and economic way to prepare stable SeNPs is introduced. SeNPs were synthesized in aqueous chitosan (CTS) and then embedded into CTS microspheres by spray-drying, forming selenium nanoparticles-loaded chitosan microspheres (SeNPs-M). The physicochemical properties including morphology, elemental state, size distribution and surface potential were investigated. Institute of Cancer Research mice were used as model animal to evaluate the bioactivities of SeNPs-M. Trigonal-phase SeNPs of ~35 nm were synthesized, and SeNPs-M physically embedding those SeNPs were successfully prepared. Amazingly, acute toxicity test indicated that SeNPs-M were much safer than selenite in terms of Se dose, with a LD50 of around 18-fold of that of selenite. In addition, SeNPs-M possessed powerful antioxidant activities, as evidenced by a dramatic increase of both Se retention and the levels of glutathione peroxidase, superoxide dismutase and catalase. The design of SeNPs-M can offer a new way for further development of SeNPs with a higher efficacy and better biosafety. Thus, SeNPs-M may be a potential candidate for further evaluation as an Se supplement with antioxidant properties and be used against Se deficiency in animals and human beings.

Docosahexaenoic acid attenuates carbon tetrachloride-induced hepatic fibrosis in rats

Abstract Fish oil containing docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) has been reported to exert beneficial health effects, including hepatoprotection. However, the effect of DHA alone has not been well studied, and the mechanism is not fully understood. In the present study, we reported the protective effect of DHA on carbon tetrachloride (CCl4) induced hepatic fibrosis. Compared with the control group, the CCl4 group showed hepatic damage as evidenced by histological changes and elevation in serum transaminase activity, fibrosis, inflammation and oxidative stress levels. These pathophysiological changes were attenuated by chronic DHA supplementation. The anti‐fibrotic effect of DHA was accompanied by reductions in gene and protein expression of &agr;‐smooth muscle actin (&agr;‐SMA), fibronectin, and collagen in the liver tissue. DHA also attenuated CCl4‐induced elevation of lipid peroxidation (LPO) and decrease of glutathione (GSH)/oxidized GSH (GSSG) ratio. The upregulated inflammatory cytokines tumor necrosis factor (TNF)‐&agr;, interferon (IFN)‐&ggr; and interleukin (IL)‐6 by CCl4 were also ameliorated by DHA. Peroxisome proliferator‐activated receptor (PPAR)‐&ggr; upregulation and type I and II receptors for transforming growth factor (TGF)‐&bgr; (T&bgr;‐RI and T&bgr;‐RII) and platelet‐derived growth factor (PDGF)‐&bgr; receptor (PDGF‐&bgr;R) downregulation on both mRNA and protein levels were observed by DHA treatment compared to CCl4 group. Moreover, in vitro study showed that DHA inhibited HSC activation, being associated with elevating PPAR&ggr; level and reducing the phosphorylation levels of Smad2/3 and ERKs, which are downstream intermediates of TGF&bgr; and PDGF receptors, respectively. Taken together, the hepatoprotective, anti‐inflammatory and anti‐fibrotic effects of DHA appeared to be multifactorial. Further, one of the mechanisms of the anti‐fibrotic effect of chronic DHA supplementation is probably through PPAR&ggr; signaling to interrupt TGF&bgr;/Smad and PDGF/ERK pathways in HSCs. HighlightsThe effect of DHA free acid to attenuate CCl4‐induced hepatic fibrosis in a rat model was observed.DHA inhibited HSC activation accompanied by elevating PPAR&ggr; and interfering with the TGF&bgr;/Smad and PDGF/ERK signaling.DHA might attenuate hepatic fibrosis via regulating PPAR&ggr; to interrupt TGF&bgr; and PDGF pathways in HSCs.

Processing Optimization and Characterization of Angiotensin-Ι-Converting Enzyme Inhibitory Peptides from Lizardfish (Synodus macrops) Scale Gelatin

Hypertension can cause coronary heart disease. Synthetic angiotensin-converting enzyme (ACE) inhibitors are effective antihypertensive drugs but often cause side effects. The aim of this study was to prepare potential ACE inhibitors from scales. Gelatin was extracted from lizardfish scales. Then, scale gelatin was enzymolyzed to prepare ACE inhibitory peptides using response surface methodology. Proteolytic conditions after optimization were as follows: pH 7.0, enzyme substrate ratio 3.2%, temperature 47 °C, and proteolysis lasting 2 h and 50 min. The experimental ACE inhibitory activity under optimal conditions was 86.0 ± 0.4%. Among the 118 peptides identified from gelatin hydrolysates, 87.3% were hydrophilic and 93.22% had a molecular weight <2000 Da. Gelatin peptides had high stability upon exposure to high temperature and pH as well as gastrointestinal tract enzymes. Gelatin peptides showed an antihypertensive effect in spontaneously hypertensive rats at a dosage of 2 g/kg in the long-term experiments. A new ACE inhibitory peptide was isolated from gelatin hydrolysates, and was identified as AGPPGSDGQPGAK with an IC50 value of 420 ± 20 μM. In this way, ACE inhibitory peptides derived from scale gelatin have the potential to be used as healthy ACE-inhibiting drug raw materials.

A Study of 11-[3H]-Tetrodotoxin Absorption, Distribution, Metabolism and Excretion (ADME) in Adult Sprague-Dawley Rats

Tetrodotoxin (TTX) is a powerful sodium channel blocker that in low doses can safely relieve severe pain. Studying the absorption, distribution, metabolism and excretion (ADME) of TTX is challenging given the extremely low lethal dose. We conducted radiolabeled ADME studies in Sprague-Dawley rats. After a single dose of 6 μg/(16 μCi/kg) 11-[3H]TTX, pharmacokinetics of plasma total radioactivity were similar in male and female rats. Maximum radioactivity (5.56 ng Eq./mL) was reached in 10 min. [3H]TTX was below detection in plasma after 24 h. The area under the curve from 0 to 8 h was 5.89 h·ng Eq./mL; mean residence time was 1.62 h and t½ was 2.31 h. Bile secretion accounted for 0.43% and approximately 51% of the dose was recovered in the urine, the predominant route of elimination. Approximately 69% was recovered, suggesting that hydrogen tritium exchange in rats produced tritiated water excreted in breath and saliva. Average total radioactivity in the stomach, lungs, kidney and intestines was higher than plasma concentrations. Metabolite analysis of plasma, urine and feces samples demonstrated oxidized TTX, the only identified metabolite. In conclusion, TTX was rapidly absorbed and excreted in rats, a standard preclinical model used to guide the design of clinical trials.

Effect of Tetrodotoxin Pellets in a Rat Model of Postherpetic Neuralgia

Postherpetic neuralgia (PHN) is nerve pain caused by a reactivation of the varicella zoster virus. Medications are used to reduce PHN but their use is limited by serious side effects. Tetrodotoxin (TTX) is a latent neurotoxin that can block neuropathic pain, but its therapeutic index is only 3–5 times with intravenous or intramuscular injection. Therefore, we prepared oral TTX pellets and examined their effect in a rat model of PHN induced by resiniferatoxin (RTX). Oral TTX pellets were significantly effective at preventing RTX-induced mechanical and thermal allodynia, and similar to pregabalin. Moreover, oral administration of TTX pellets dose-dependently inhibited RTX-induced PHN compared with intramuscular administration of TTX injection. We also studied the pharmacokinetic profile of TTX pellets. Our results showed that the blood concentration of TTX reached a maximum plasma concentration (Cmax) at around 2 h, with an elimination half-life time (t1/2) of 3.23 ± 1.74 h after intragastric administration. The median lethal dose (LD50) of TTX pellets was 517.43 μg/kg via oral administration to rats, while the median effective dose (ED50) was approximately 5.85 μg/kg, and the therapeutic index was 88.45. Altogether, this has indicated that oral TTX pellets greatly enhance safety when compared with TTX injection.

Determination of trehalose by ion chromatography and its application to a pharmacokinetic study in rats after intramuscular injection

An ion chromatography method was established for detecting trehalose in rat plasma. The samples were analyzed using a CPMA1 column (250 × 4.0 mm, Thermo) with 120 mm NaOH as eluent at a flow rate of 0.7 mL/min. The standard curve was y = 1.4316x - 0.0654 (R = 0.9992), and the linear range was 0.2-10 mg/L. The relative standard deviations of within-run and between-run precisions at low, medium and high concentrations were within 0.96-8.33%, and the accuracy was within 80.09-114.99%. The method was verified by rigorous methods, and applied to a pharmacokinetic study in rats after intramuscular injection (20 mg/kg, n = 6). The pharmacokinetic parameters, specifically AUC0-t , AUC0-∞ , t1/2 , CL and Vd , were 15.542 ± 3.122 mg h/L, 15.599 ± 3.141 mg h/L, 0.73 ± 0.347 h, 1.331 ± 0.293 L/h kg and 1.403 ± 0.735 L/kg, respectively. The developed ion chromatography method met the requirements of biological sample measurement, and will be helpful for future pharmacological studies of trehalose.