Modulating intestinal health: Impact of chitooligosaccharide molecular weight on suppressing RAGE expression and inflammatory response in methylglyoxal-induced advanced glycation end-products

The accumulation of methylglyoxal (MGO) produced in high-temperature processed foods and excessive production in the body contributes to intestinal barrier dysfunction. In this study, we investigated the effects of chitooligosaccharides (COSs) of different molecular weights (<1 kDa, 1-3 kDa, 3-5 kDa, 5-10 kDa, and >10 kDa) on MGO-induced intestinal barrier dysfunction. We investigated the effect of COSs on inhibiting intracellular MGO accumulation/MGO-derived AGEs production and regulating the receptor for AGE (RAGE)-mediated downstream protein expression, including proteins related to apoptosis and inflammation, intestinal barrier integrity, and paracellular permeability. Pretreatment with COSs ameliorated MGO-induced increased RAGE protein expression, activation of apoptotic cascade/inflammatory response, loss of intestinal epithelial barrier integrity, and increased paracellular permeability, ameliorating intestinal dysfunction through MGO scavenging. 1-3 kDa COSs most effectively ameliorated MGO-induced intestinal dysfunction. Our results suggest the potential of COSs in improving intestinal health by ameliorating intestinal barrier dysfunction by acting as an MGO scavenger and highlighting the need for the optimization of the molecular weight of COSs to optimize its protective effects.

Brown Algae Dictyopteris divaricata Attenuates Adipogenesis by Modulating Adipocyte Differentiation and Promoting Lipolysis through Heme Oxygenase-1 Activation in 3T3-L1 Cells

The present study aims to explore the probable anti-adipogenesis effect of Dictyopteris divaricata (D. divaricata) in 3T3-L1 preadipocytes by regulating heme oxygenase-1 (HO-1). The extract of D. divaricata retarded lipid accretion and decreased triglyceride (TG) content in 3T3-L1 adipocytes but increased free glycerol levels. Treatment with the extract inhibited lipogenesis by inhibiting protein expressions of fatty acid synthase (FAS) and lipoprotein lipase (LPL), whereas lipolysis increased by activating phosphorylation of hormone-sensitive lipase (p-HSL) and AMP-activated protein kinase (p-AMPK). The extract inhibited adipocyte differentiation of 3T3-L1 preadipocytes through down-regulating adipogenic transcription factors, including peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), and sterol regulatory element-binding protein 1 (SREBP1). This is attributed to the triggering of Wnt/β-catenin signaling. In addition, this study found that treatment with the extract activated HO-1 expression. Pharmacological approaches revealed that treatment with Zinc Protoporphyrin (ZnPP), an HO-1 inhibitor, resulted in an increase in lipid accumulation and a decrease in free glycerol levels. Finally, three adipogenic transcription factors, such as PPARγ, C/EBPα, and SREBP1, restored their expression in the presence of ZnPP. Analysis of chemical constituents revealed that the extract of D. divaricata is rich in 1,4-benzenediol, 7-tetradecenal, fucosterol, and n-hexadecanoic acid, which are known to have multiple pharmacological properties.

Poly(vinyl alcohol)/chitosan hydrogel incorporating chitooligosaccharide-gentisic acid conjugate with antioxidant and antibacterial properties as a potential wound dressing

The design and development of wound dressing with antioxidant and antibacterial properties to accelerate wound healing remain challenging. In this study, we synthesize a chitooligosaccharide-gentisic acid (COS-GSA) conjugate using the free-radical grafting method, and fabricate a poly(vinyl alcohol) (PVA)/chitosan (CH)/COS-GSA (PVA/CH/CG) hydrogel using a freeze-thaw method. We characterize the synthesized COS-GSA conjugates using through polyphenol assay, absorbance, and 1H NMR spectroscopy and evaluate their antioxidant properties. The COS-GSA conjugates are successfully synthesized and exhibit better antioxidant properties than pristine COSs. Subsequently, the fabricated hydrogel is characterized based on its morphological analysis, rheological properties, water contact angle, swelling, degradation, water retention properties, and COS-GSA release profiles. Finally, the biocompatibility of the fabricated hydrogel is evaluated on HDF and HaCaT cells through indirect and direct cytotoxicity. The PVA/CH/CG hydrogel exhibited significantly higher antioxidant properties (DPPH, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and hydrogen peroxide (H2O2) scavenging activities) and antibacterial activities (Staphylococcus aureus and Pseudomonas aeruginosa) compared to other fabricated hydrogels such as PVA, PVA/CH, and PVA/CH/COS (PVA/CH/C). These results provide evidence that PVA/CH/CG hydrogels with antioxidant, antibacterial, and non-cytotoxic properties have great potential for wound-dressing applications.

Angiotensin I-Converting Enzyme (ACE) Inhibition and Molecular Docking Study of Meroterpenoids Isolated from Brown Alga, Sargassum macrocarpum

Angiotensin I-converting enzyme (ACE) is an important blood pressure regulator. In this study, we aimed to investigate the ACE-inhibitory effects of meroterpenoids isolated from the brown alga, Sargassum macrocarpum, and the molecular mechanisms underlying ACE inhibition. Four fractions of S. macrocarpum were prepared using hexane, chloroform, ethyl acetate, and water as solvents and analyzed for their potential ACE-inhibitory effects. The chloroform fraction showed the strongest ACE-inhibitory effect, with an IC50 value of 0.18 mg/mL. Three meroterpenoids, sargachromenol, 7-methyl sargachromenol, and sargaquinoic acid, were isolated from the chloroform fraction. Meroterpenoids isolated from S. macrocarpum had IC50 values of 0.44, 0.37, and 0.14 mM. The molecular docking study revealed that the ACE-inhibitory effect of the isolated meroterpenoids was mainly attributed to Zn-ion, hydrogen bonds, pi-anion, and pi-alkyl interactions between the meroterpenoids and ACE. These results suggest that S. macrocarpum could be a potential raw material for manufacturing antihypertensive nutraceutical ingredients.

Antioxidant potential of hydrolysate-derived seahorse (Hippocampus abdominalis) peptide: Protective effects against AAPH-induced oxidative damage in vitro and in vivo

In this study, seahorse peptide (SHP) was isolated from an alcalase-treated hydrolysate from Hippocampus abdominalis and assessed for its antioxidant potential against AAPH-induced oxidative stress damage. AAPH stimulation significantly decreased cell viability and increased intracellular reactive oxygen species (ROS) production in Vero cells. SHP treatment increased cell viability and remarkably lowered ROS production under AAPH-induced oxidative stress. Furthermore, it protected against AAPH-induced apoptotic DNA damage. Western blot analysis demonstrated that SHP treatment remarkably increased the protein expression levels of catalase and SOD in AAPH-induced Vero cells. A zebrafish study revealed that SHP-treated zebrafish embryos resulted in lower cell death, ROS generation, and lipid peroxidation than the AAPH-treated group. These results suggest that SHP is a potent functional antioxidant that could be developed as a natural antioxidant in the food and functional food industries.

Antifibrosis Efficacy of Apo-9-Fucoxanthinone-Contained Sargassum horneri Ethanol Extract on Nasal Polyp: An In Vitro and Ex Vivo Organ Culture Assay

Sargassum horneri is a seaweed species with diverse bioactivities. However, its antifibrotic effects during nasal polyp (NP) formation are not clearly understood. Therefore, we investigated the inhibitory effect of S. horneri on fibrosis progression in NP-derived fibroblasts (NPDFs) and NP tissues ex vivo. NPDFs were stimulated with TGF-β1 in the presence or absence of S. horneri ethanol extract (SHE). The extracellular matrix (ECM) protein production levels, myofibroblast differentiation (α-smooth muscle actin, α-SMA), and phosphorylation of Smad 2/3 and -ERK in TGF-β1-stimulated NPDFs were investigated using western blotting. Further, the contractile activity of SHE was assessed by performing a collagen gel contraction assay. The expression levels of collagen-1, fibronectin, and α-SMA were investigated in NP organ cultures treated with SHE. TGF-β1 stimulated ECM protein expression, myofibroblast differentiation, and collagen contractile activity while these were attenuated by pretreatment with SHE. We also found antifibrotic effect of SHE on ex vivo NP tissues. The antifibrotic effects of SHE were modulated through the attenuation of Smad 2/3 and ERK signaling pathways in TGF-β1-stimulated NPDFs. In conclusion, SHE inhibited ECM protein accumulation and myofibroblast differentiation during NP remodeling. Thus, SHE may be helpful as a treatment for NP recurrence after endoscopic sinus surgery.

Sargassumin C, a Novel Butenolide from Sargassum micracanthum

Objective: In our ongoing effort to search for the novel secondary metabolites from the marine algae, chemical investigation of a methanolic extract of Sargassum micracanthum led to the isolation of a novel butenolide (1) and a known compound (2). Methods: The methanolic extract of S. micracanthum was partitioned and subjected to medium pressure column chromatography and preparative-HPLC to yield two compounds (1 and 2). Their structures were established based on comprehensive spectroscopic data (1D NMR, 2D NMR, and HRESIMS). These compounds (1 and 2) were evaluated for the production of the NO in lipopolysaccharide (LPS)-induced RAW264.7 cells and pro-inflammatory cytokines such as IL-6, IL-1 β, TNF- α, and IL-10. Results: A new compound (1) was determined to be a new butenolide derivative, and a known compound (2) were identified as 2-hydroxy-(5 E,9 E)-6,10,14-trimethylpentadeca-5,9-dien-12-one. Compounds 1 and 2 showed inhibitory activities in a dose-dependent manner on LPS-induced NO production in RAW264.7 cells and pro-inflammatory cytokines. Conclusion: A new butenolide, sargassumin C (1), and 2-hydroxy-(5 E,9 E)-6,10,14-trimethylpentadeca-5,9-dien-12-one (2) were isolated from the brown alga, S. micracanthum. Compound 2 was more effective than 1 on NO production and pro-inflammatory cytokines.

Isolation and Characterization of Efficient Active Compounds Using High-Performance Centrifugal Partition Chromatography (CPC) from Anti-Inflammatory Activity Fraction of Ecklonia maxima in South Africa

Ecklonia maxima is a brown seaweed, which is abundantly distributed in South Africa. This study investigated an efficient approach using high-performance centrifugal partition chromatography (HPCPC), which has been successfully developed for the isolation and purification of phlorotannins, eckmaxol, and dieckol from the ethyl acetate fraction of E. maxima (EEM). We evaluated EEM for its inhibitory effect against lipopolysaccharide (LPS)-induced inflammatory responses in zebrafish embryos. The separation of eckmaxol and dieckol from samples of EEM using HPCPC was found to be of high purity and yield under an optimal solvent system composed of n-hexane:ethyl acetate:methanol:water (2:7:3:7, v/v/v/v). To evaluate the anti-inflammatory efficacy of EEM containing active compounds, zebrafish embryos exposed to LPS were compared with and without EEM treatment for nitric oxide (NO) production, reactive oxygen species (ROS) generation, and cell death two days after fertilization. These evaluations indicate that EEM alleviated inflammation by inhibiting cell death, ROS, and NO generation induced by LPS treatment. According to these results, eckmaxol and dieckol isolated from brown seaweed E. maxima could be considered effective anti-inflammatory agents as pharmaceutical and functional food ingredients.

A new Butenolide Derivative from the Brown Alga Sargassum micracanthum

A new butenolide derivative (1), along with three known compounds (2-4) were isolated from the MeOH extract of brown alga Sargassum micracanthum. The structures of 1 to 4 were determined by the analyses of 1D and 2D NMR and mass spectroscopic data. The known compounds (2-4) were identified as (5 E,10 Z)-6,10,14-trimethylpentadeca-5,10-dien-2,12-dione (2), (5 E,9 E)-6,10,14-trimethylpentadeca-5,9-dien-2,12-dione (3), and (-)-loliolide (4) by comparing with their published spectroscopic data. The antioxidant activities of compounds 1 to 4 were evaluated based on using 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities. Compounds 1 to 4 were inactive at the concentration of 200 μM.

Sargachromenol Purified from Sargassum horneri Inhibits Inflammatory Responses via Activation of Nrf2/HO-1 Signaling in LPS-Stimulated Macrophages

In this study, we isolated sargachromenol (SC) from Sargassum horneri and evaluated its anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. SC did not show cytotoxicity at all concentrations and effectively increased the cell viability by reducing the nitric oxide (NO) and intracellular reactive oxygen species (ROS) production in LPS-stimulated RAW 264.7 macrophages. In addition, SC decreased the mRNA expression levels of inflammatory cytokines (IL-1β, IL-6, and TNF-α) and inflammatory mediators (iNOS and COX-2). Moreover, SC suppressed the activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) and mitogen-activated protein kinase (MAPK) signaling, whereas activated the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling in LPS-stimulated RAW 264.7 macrophages. Interestingly, the anti-inflammatory effect of SC was abolished by the inhibition of HO-1 in LPS-stimulated RAW 264.7 macrophages. According to the results, this study suggests that the antioxidant capacity of SC leads to its anti-inflammatory effect and it potentially may be utilized in the nutraceutical and pharmaceutical sectors.

Effects of Ethanol Extracts from Grateloupia elliptica, a Red Seaweed, and Its Chlorophyll Derivative on 3T3-L1 Adipocytes: Suppression of Lipid Accumulation through Downregulation of Adipogenic Protein Expression

Grateloupia elliptica (G. elliptica) is a red seaweed with antioxidant, antidiabetic, anticancer, anti-inflammatory, and anticoagulant activities. However, the anti-obesity activity of G. elliptica has not been fully investigated. Therefore, the effect of G. elliptica ethanol extract on the suppression of intracellular lipid accumulation in 3T3-L1 cells by Oil Red O staining (ORO) was evaluated. Among the eight red seaweeds tested, G. elliptica 60% ethanol extract (GEE) exhibited the highest inhibition of lipid accumulation. GEE was the only extract to successfully suppress lipid accumulation among ethanol extracts from eight red seaweeds. In this study, we successfully isolated chlorophyll derivative (CD) from the ethyl acetate fraction (EA) of GEE by high-performance liquid chromatography and evaluated their inhibitory effect on intracellular lipid accumulation in 3T3-L1 adipocytes. CD significantly suppressed intracellular lipid accumulation. In addition, CD suppressed adipogenic protein expression such as sterol regulatory element-binding protein-1 (SREBP-1), peroxisome proliferator-activated receptor-γ (PPAR-γ), CCAAT/enhancer-binding protein-α (C/EBP-α), and fatty acid binding protein 4 (FABP4). Taken together, our results indicate that CD from GEE inhibits lipid accumulation by suppressing adipogenesis via the downregulation of adipogenic protein expressions in the differentiated adipocytes. Therefore, chlorophyll from G. elliptica has a beneficial effect on lipid metabolism and it could be utilized as a potential therapeutic agent for preventing obesity.

Inhibitory Effects of a Sargassum miyabei Yendo on Cutibacterium acnes-Induced Skin Inflammation

Acne vulgaris is a chronic inflammatory condition of skin sebaceous follicles. To explore its effects on acne vulgaris, we investigated the antibacterial and anti-inflammatory activities of Sargassum miyabei Yendo (a brown alga) ethanolic extract (SMYEE) on Cutibacterium acnes (C. acnes)-stimulated inflammatory responses, both in vivo and in vitro. To induce inflammation in vivo, C. acnes was intradermally injected into the dorsal skin of mice, to which SMYEE was applied. The antimicrobial activity of SMYEE was evaluated by the determination of minimum inhibitory concentrations (MICs). To explore in vitro anti-inflammatory effects, HaCaT cells were stimulated with C. acnes after treatment with SMYEE. The levels of IL-8 and the underlying molecular effects in C. acnes-stimulated HaCaT cells were assessed by enzyme-linked immunosorbent assay, Western blotting, and an electrophoretic mobility shift assay. Mouse skin lesions improved after treatment with SMYEE (50 μg/mouse). Neutrophil infiltration was significantly reduced in SMYEE-treated compared to SMYEE-untreated skin lesions. SMYEE reversed the C. acnes-induced increase in IL-8 levels in HaCaT cells and suppressed dHL-60 cell migration. SMYEE also inhibited C. acnes-induced phosphorylation of the extracellular signal-regulated kinase and inhibited activator protein-1 signaling. SMYEE may be a useful treatment for C. acnes-induced acne vulgaris.

Inhibitory Effect of Tricyclic Antidepressant Doxepin on Voltage-Dependent K+ Channels in Rabbit Coronary Arterial Smooth Muscle Cells

Doxepin, tricyclic antidepressant, is widely used for the treatment of depressive disorders. Our present study determined the inhibitory effect of doxepin on voltage-dependent K⁺ (Kv) channels in freshly isolated rabbit coronary arterial smooth muscle cells using a whole-cell patch clamp technique. Vascular Kv currents were inhibited by doxepin in a concentration-dependent manner, with a half-maximal inhibitory concentration (IC₅₀) value of 6.52 ± 1.35 μM and a Hill coefficient of 0.72 ± 0.03. Doxepin did not change the steady-state activation curve or inactivation curve, suggesting that doxepin does not alter the gating properties of Kv channels. Application of train pulses (1 or 2 Hz) slightly reduced the amplitude of Kv currents. However, the inhibition of Kv channels by train pulses were not changed in the presence of doxepin. Pretreatment with Kv1.5 inhibitor, DPO-1, effectively reduced the doxepin-induced inhibition of the Kv current. However, pretreatment with Kv2.1 inhibitor (guangxitoxin) or Kv7 inhibitor (linopirdine) did not change the inhibitory effect of doxepin on Kv currents. Inhibition of Kv channels by doxepin caused vasoconstriction and membrane depolarization. Therefore, our present study suggests that doxepin inhibits Kv channels in a concentration-dependent, but not use-, and state-dependent manners, irrespective of its own function.

Sargassum serratifolium Extract Attenuates Interleukin-1β-Induced Oxidative Stress and Inflammatory Response in Chondrocytes by Suppressing the Activation of NF-κB, p38 MAPK, and PI3K/Akt

Osteoarthritis (OA) is a degenerative joint disease that is characterized by irreversible articular cartilage destruction by inflammatory reaction. Among inflammatory stimuli, interleukin-1β (IL-1β) is known to play a crucial role in OA pathogenesis by stimulating several mediators that contribute to cartilage degradation. Recently, the marine brown alga Sargassum serratifolium has been reported to exhibit antioxidant and anti-inflammatory effects in microglial and human umbilical vein endothelial cell models using lipopolysaccharide and tumor necrosis factor-α, but its beneficial effects on OA have not been investigated. This study aimed to evaluate the anti-osteoarthritic effects of ethanol extract of S. serratifolium (EESS) in SW1353 human chondrocytes and, in parallel, primary rat articular chondrocytes. Our results showed that EESS effectively blocked the generation of reactive oxygen species in IL-1β-treated SW1353 and rat primary chondrocytes, indicating that EESS has a potent antioxidant activity. EESS also attenuated IL-1β-induced production of nitric oxide (NO) and prostaglandin E₂, major inflammatory mediators in these cells, which was associated with the inhibition of inducible NO synthase and cyclooxygenase-2 expression. Moreover, EESS downregulated the level of gene expression of matrix metalloproteinase (MMP)-1, -3 and -13 in SW1353 chondrocytes treated with IL-1β, resulting in their extracellular secretion reduction. In addition, the IL-1β-induced activation of nuclear factor-kappa B (NF-κB) was restored by EESS. Furthermore, EESS reduced the activation of p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathways upon IL-1β stimulation. These results indicate that EESS has the potential to exhibit antioxidant and anti-inflammatory effects through inactivation of the NF-κB, p38 MAPK, and PI3K/Akt signaling pathways. Collectively, these findings demonstrate that EESS may have the potential for chondroprotection, and extracts of S. serratifolium could potentially be used in the prevention and treatment of OA.

The anti-diabetic drug dapagliflozin induces vasodilation via activation of PKG and Kv channels

AIM

Considering the clinical efficacy of dapagliflozin in patients with type 2 DM and the pathophysiological relevance of Kv channels for vascular reactivity. We investigate the vasodilatory effect of dapagliflozin and related mechanisms using phenylephrine (Phe)-induced contracted aortic rings.

MATERIAL AND METHODS

Arterial tone measurement was performed in aortic smooth muscle.

KEY FINDINGS

Application of dapagliflozin induced vasodilation in a concentration-dependent manner. Pre-treatment with the BK_Ca channel inhibitor paxilline, the K_ATP channel inhibitor glibenclamide, and the Kir channel inhibitor Ba²⁺ did not change dapagliflozin-induced vasodilation. However, application of the Kv channels inhibitor 4-AP effectively inhibited dapagliflozin-induced vasodilation. Application of the Ca²⁺ channel inhibitor nifedipine and the sarcoplasmic/endoplasmic reticulum Ca²⁺-ATPase (SERCA) pump inhibitor thapsigargin did not alter the vasodilatory effect of dapagliflozin. Moreover, the adenylyl cyclase inhibitor SQ 22536 and the protein kinase A (PKA) inhibitor KT 5720 had no effect on dapagliflozin-induced vasodilation. Although guanylyl cyclase inhibitors, NS 2028 and ODQ, did not reduce the vasodilatory effect of dapagliflozin, the protein kinase G (PKG) inhibitor KT 5823 effectively inhibited dapagliflozin-induced vasodilation. The vasodilatory effect of dapagliflozin was not affected by elimination of the endothelium. Furthermore, pretreatment with the nitric oxide synthase inhibitor L-NAME or the small-conductance Ca²⁺-activated K (SKCa) channel inhibitor apamin did not change the vasodilatory effect of dapagliflozin.

SIGNIFICANCE

We concluded that dapagliflozin induced vasodilation via the activation of Kv channels and PKG, and was independent of other K⁺ channels, Ca²⁺ channels, intracellular Ca²⁺, and the endothelium.

Anti-inhibitory potential of an ethanolic extract of Distromium decumbens on pro-inflammatory cytokine production in Pseudomonas aeruginosa lipopolysaccharide-stimulated nasal polyp-derived fibroblasts

Marine algae are rich sources of biologically active compounds that may present useful leads in the development of pharmaceuticals, nutraceuticals, and functional foods. The main aim of this study was to identify the possible anti-inflammatory effects of Distromium decumbens in nasal polyp-derived fibroblasts (NPDFs) and its associated mechanism of action. NPDFs were stimulated by Pseudomonas aeruginosa lipopolysaccharide (PA-LPS) and treated with an ethanolic extract of Distromium decumbens (DDE). The production of interleukin-6 (IL-6) and IL-8 in the supernatant, the phosphorylation of mitogen-activated protein kinase (MAPK) molecules [extracellular signal-related kinase 1/2 (ERK1/2), c-Jun N-terminal kinase and p38 MAPK] and Akt, and the activation of nuclear factor-κB (NF-κB) were assayed in the PA-LPS-stimulated NPDFs untreated or treated with DDE. The expression levels of IL-6 and IL-8 in PA-LPS-exposed NPDFs were detected using enzyme-linked immunosorbent assays. The mechanisms by which DDE regulates cellular signaling cascades were investigated using electrophoretic mobility shift assays and western blot analysis. Functional validation was performed by measuring the inhibitory effects of DDE on neutrophil migration in vitro. DDE reduced the expression of IL-6 and IL-8 stimulated by PA-LPS in NPDFs. The activation of ERK1/2, Akt and NF-κB by PA-LPS was inhibited by DDE. Inhibitors of ERK1/2, Akt and NF-κB inhibited the expression of IL-6 and IL-8. In addition, DDE significantly attenuated PA-LPS-induced migration of differentiated HL-60 cells. The present findings suggest that DDE potently inhibits inflammation through the ERK1/2, Akt and NF-κB signaling pathways in NPDFs.

Inhibitory effect of the tricyclic antidepressant amitriptyline on voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells

Amitriptyline, a tricyclic antidepressant (TCA) drug, is widely used in treatment of psychiatric disorders. However, the side effects of amitriptyline on vascular K⁺ channels remain to be determined. Therefore, we investigated the effect of the tricyclic antidepressant and serotonin reuptake inhibitor amitriptyline on voltage-dependent K⁺ (Kv) channels in freshly isolated rabbit coronary arterial smooth muscle cells, using the whole-cell patch clamp technique. The Kv current amplitudes were inhibited by amitriptyline in a concentration-dependent manner, with an apparent IC₅₀ value of 2.2 ± 0.14 μmol/L and a Hill coefficient of 0.87 ± 0.03. Amitriptyline shifted the activation curve to a more positive potential, but had no significant effect on the inactivation curve, suggesting that amitriptyline altered the voltage sensitivity of Kv channels. Pretreatment with Kv1.5 and Kv1.2 channel inhibitors did not alter the inhibitory effect of amitriptyline on Kv channels. Additionally, application of train pulses (1 and 2 Hz) did not affect amitriptyline-induced inhibition of Kv currents, which suggested that the action of amitriptyline on Kv channels was not use (state)-dependent. From these results, we concluded that amitriptyline inhibited the channels in a concentration-dependent, but state-independent manner.

Fucoxanthin inhibits profibrotic protein expression in vitro and attenuates bleomycin-induced lung fibrosis in vivo

Pulmonary fibrosis, a potentially fatal disease, results from acute and chronic interstitial lung diseases. Fucoxanthin (Fx), a carotenoid found in brown seaweed, shows a wide range of pharmacological activities. In this study, we investigated the antifibrotic effects of fucoxanthin and their underlying molecular mechanisms in transforming growth factor-beta1 (TGF-β1)-stimulated human pulmonary fibroblasts (HPFs). Thus, the effects of Fx on TGF-β1-induced expression of fibrotic factors, such as alpha-smooth muscle actin (α-SMA), type 1 collagen, fibronectin, and interleukin-6 (IL-6), in HPFs were investigated. We performed an enzyme-linked immunosorbent assay (ELISA), and a western blot analysis to elucidate the mechanisms underlying the antifibrotic effects of Fx in TGF-β1-stimulated cells. The contractile activity of HPFs was measured using a collagen gel contraction assay. We also investigated the effects of Fx on inflammation and fibrosis in bleomycin (BLM)-induced pulmonary fibrosis mouse model. We observed that Fx inhibited the TGF-β1-induced expression of α-SMA, type 1 collagen, fibronectin, and IL-6 in HPFs. Similarly, markedly inhibition of TGF-β1-induced phosphorylation of p-38 mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K)/Akt, and Smad2/Smad3 (Smad2/3) was observed after Fx treatment. Collagen contraction also significantly decreased on fucoxanthin treatment. Intraperitoneal injection of Fx (10mg/kg) in mice inhibited BLM-induced lung fibrosis and type I collagen protein expression. Overall, our findings suggest that Fx may be effective in the treatment of pulmonary fibrosis owing to its potent antifibrotic activity.

Benzyl isothiocyanate inhibits inflammasome activation in E. coli LPS-stimulated BV2 cells

Inflammasomes are multi-protein complexes that play a crucial role in innate immune responses. Benzyl isothiocyanate (BITC) is a naturally occurring compound found in cruciferous vegetables, and BITC exhibits potential as a chemopreventive agent. However, whether BITC exerts inflammasome-mediated regulatory effects on neuroinflammation is unknown. In this study, we examined the effects of BITC on inflammasome-mediated interleukin-1β (IL-1β) production in E. coli lipopolysaccharide (LPS)-stimulated BV2 microglial cells. IL-1β production is tightly regulated at the post-translational level through the inflammasoume. We measured the levels of IL-1β produced from the LPS-exposed BV2 microglial cells using enzyme-linked immunosorbent assays (ELISAs). The BITC regulatory mechanisms in inflammasome-mediated cellular signaling pathways were examined by RT-PCR, western blot analysis and electrophoretic mobility shift assays. BITC inhibited the secretion of IL-1β induced by LPS in the BV2 microglial cells. BITC inhibited inflammasome activation and NLR family, pyrin domain containing 3 (NLRP3)-mediated caspase-1 activation, and decreased the levels of inflammasome activation pro-inflammatory mediators, including mitochondrial reactive oxygen species (ROS) and adenosine triphosphate (ATP) secretion in the LPS-stimulated BV2 microglial cells. Furthermore, we demonstrated that nuclear factor-κB (NF-κB) activation induced by LPS was inhibited by BITC, which may contribute to the attenuated secretion of IL-1β. These BITC-mediated inhibitory effects on IL-1β expression may thus regulate neuroinflammation through the inflammasome-mediated signaling pathway.

Studies on antimicrobial activity of Poncirus trifoliata ethyl extract fraction against methicillin-resistant Staphylococcus aureus and to elucidate its antibacterial mechanism

Traditional medicinal plants contain a wide variety of chemicals that have potent antibacterial activity. To find an alternative agent of overcoming the problems of methicillin-resistant Staphylococcus aureus (MRSA), the antibacterial mechanism of Ponciruss trifoliata against MRSA was investigated. Ethyl acetate (EtOAc)-soluble extract of P. trifoliata methanolic extract was evaluated for antibacterial activity using minimum inhibitory concentration (MIC). An EtOAc sub-fraction 08 (EA08) from silica-gel open column chromatography exhibited strong anti-MRSA activity. Apart from the study to isolate single compound from EA08, a synergistic antibacterial effect between the sub-fraction and β-lactam antibiotics against MRSA was determined. In order to elucidate the antibacterial restoring mechanism of EA08 on MRSA, mRNA expression of mecA gene and production penicillin-binding protein 2a (PBP2a) encoded by mecA gene were monitored. EA 08 showed the strongest antibacterial activity with MIC value of 256 μg ml(-1). MIC of oxacillin against MRSA was dramatically reduced from 512 to 16 μg ml(-1) in combination with 256 μg ml(-1) of EA08. The fractional inhibitory concentration index of oxacillin was measured at 0.53 in combination with EA08 against MRSA, suggesting that EA08-oxacillin combinations exert synergetic effect against MRSA. The analysis of RT-PCR and Western blotting profiles revealed that EA08 inhibited mRNA expression of mecA gene and production PBP2a, which is a key determinant for β-lactam antibiotic resistance, in a dose-dependent manner. These results indicated that EA08 eventually led to the reduction or inhibition of PBP2a production through translational inhibition in MRSA.

Anti-allergic effects of a nonameric peptide isolated from the intestine gastrointestinal digests of abalone (Haliotis discus hannai) in activated HMC-1 human mast cells

The aim of the present study was to examine whether the intestine gastrointestinal (GI) digests of abalone [Haliotis discus hannai (H. discus hannai)] modulate inflammatory responses and to elucidate the mechanisms involved. The GI digests of the abalone intestines were fractionated into fractions I (>10 kDa), II (5-10 kDa) and Ⅲ (<5 kDa). Of the abalone intestine GI digests (AIGIDs), fraction Ⅲ inhibited the passive cutaneous anaphylaxis (PCA) reaction in mice. Subsequently, a bioactive peptide [abalone intestine GI digest peptide (AIGIDP)] isolated from fraction Ⅲ was determined to be 1175.2 Da, and the amino acid sequence was found to be PFNQGTFAS. We noted that the purified nonameric peptide (AIGIDP) attenuated the phorbol‑12‑myristate 13-acetate plus calcium ionophore A23187 (PMACI)-induced histamine release and the production of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 in human mast cells (HMC-1 cells). In addition, we also noted that AIGIDP inhibited the PMACI‑induced activation of nuclear factor‑κB (NF-κB) by suppressing IκBα phosphorylation and that it suppressed the production of cytokines by decreasing the phosphorylation of JNK. The findings of our study indicate that AIGIDP exerts a modulatory, anti-allergic effect on mast cell-mediated inflammatory diseases.

3,3'-Diindolylmethane inhibits VEGF expression through the HIF-1α and NF-κB pathways in human retinal pigment epithelial cells under chemical hypoxic conditions

Oxidative stress in the retinal pigment epithelium (RPE) can lead to the pathological causes of age-related macular degeneration (AMD). Hypoxia induces oxidative damage in retinal pigment epithelial cells (RPE cells). In this study, we investigated the capacity of 3,3'-diindolylmethane (DIM) to reduce the expression of vascular endothelial growth factor (VEGF) under hypoxic conditions, as well as the molecular mechanisms involved. Human RPE cells (ARPE-19 cells) were treated with cobalt chloride (CoCl2, 200 µM) and/or DIM (10 and 20 µM). The production of VEGF was measured by enzyme-linked immunosorbent assay. The translocation of hypoxia-inducible factor-1α (HIF-1α) and nuclear factor-κB (NF-κB) was determined by western blot analysis. The binding activity of HIF-1α and NF-κB was analyzed by electrophoretic mobility shift assay. The phosphorylation levels of mitogen-activated protein kinases (MAPKs) were measured by western blot analysis. The levels of mitochondrial reactive oxygen species (ROS) were detected by fluorescence microplate assay. The results revealed that DIM significantly attenuated the CoCl2-induced expression of VEGF in the ARPE-19 cells. The CoCl2-induced translocation and activation of HIF-1α and NF-κB were also attenuated by treatment with DIM. In addition, DIM inhibited the CoCl2-induced activation of p38 MAPK in the ARPE-19 cells. Pre-treatment with YCG063, a mitochondrial ROS inhibitor, led to the downregulation of the CoCl2-induced production of VEGF by suppressing HIF-1α and NF-κB activity. Taken together, the findings of our study demonstrate that DIM inhibits the CoCl2-induced production of VEGF by suppressing mitochondrial ROS production, thus attenuating the activation of HIF-1α and p38 MAPK/NF-κB.

The mechanism of antibacterial activity of phlorofucofuroeckol-A against methicillin-resistant Staphylococcus aureus

To find more effective ways of overcoming methicillin-resistant Staphylococcus aureus (MRSA), there has been considerable interest in the use of marine-derived constituents as alternatives to control pathogenic microorganisms. In this study, we investigated whether phlorofucofuroeckol-A (PFF) isolated from the edible brown alga Eisenia bicyclis suppressed production or function of penicillin-binding protein 2a (PBP2a). The antimicrobial mode of action of PFF in MRSA was identified by measuring cell membrane integrity and using the time-kill curve method. We attempted to determine the antimicrobial effects of PFF on the expression level of the resistance determinants mecA and its regulatory genes mecI and mecR1 in MRSA by reverse transcriptase polymerase chain reaction. PFF suppressed mecI, mecR1, and mecA gene expression in a dose-dependent manner. In addition, we revealed PFF mediates the suppressive effect of PBP2a expression in MRSA by Western blot analysis. PFF suppressed production of the PBP2a protein, suggesting that PFF probably acts by controlling the methicillin resistance-associated genes involved in the cell wall and production of PBP2a. These results demonstrate that PFF isolated from E. bicyclis significantly suppressed the expression of the methicillin resistance-associated genes and production of PBP2a, which is considered the primary cause of methicillin resistance.

Antibacterial and synergic effects of gallic acid-grafted-chitosan with β-lactams against methicillin-resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA) is spreading worldwide, emphasizing the need to search for new antibiotics. The anti-MRSA activities of gallic acid-grafted-chitosans (GA-g-chitosans) were investigated against 2 MRSA standards and 10 MRSA clinical isolates by determining the minimum inhibitory concentrations (MICs). GA-g-chitosan (I), which has the highest gallic acid content, exhibited the strongest anti-MRSA activities, with MICs of 32–64 μg/mL. A time-kill investigation revealed that GA-g-chitosan (I) exhibited a bactericidal effect at twice the MIC, also demonstrating good thermal and pH stability. Investigation of cell envelope integrity showed the release of intracellular components with an increasing absorbance value at 260 nm, indicating cell envelope damage caused by the GA-g-chitosan (I), which was further confirmed by transmission electron microscopy. When GA-g-chitosans were combined with β-lactams, including ampicillin and penicillin, synergistic effects were observed on the 2 standard MRSA strains and on the 10 clinical isolates, with fractional inhibitory indices ranging from 0.125 to 0.625. In the time-kill dynamic confirmation test, synergistic bactericidal effects were observed for the combinations of GA-g-chitosans with β-lactams, and over 4.0 log CFU/mL reductions were observed after 24 h when combination treatment was used. These results may prove GA-g-chitosans to be a potent agent when combined with ampicillin and penicillin for the elimination of MRSA.

Suppressive effects of Amarouciaxanthin A on 3T3-L1 adipocyte differentiation through down-regulation of PPARγ and C/EBPα mRNA expression

Fucoxanthin is converted to fucoxanthinol and amarouciaxanthin A in mice. It was previously reported that fucoxanthinol attenuated the adipogenesis of 3T3-L1 cells. However, the effects of amarouciaxanthin A on adipocyte differentiation have not been clarified. This study examined the effects of amarouciaxanthin A on 3T3-L1 adipogenesis by comparing the effects of fucoxanthinol, isofucoxanthinol, and amarouciaxanthin B. Amarouciaxanthin A significantly decreased glycerol-3-phosphate dehydrogenase (GPDH) activity, which was measured as an indicator of adipocyte differentiation. The suppressive effect of amarouciaxanthin A was stronger than that of fucoxanthinol, amarouciaxanthin B, and isofucoxanthinol. The mRNA expressions of adipocyte fatty acid-binding protein (aP2), lipoprotein lipase (LPL), and glucose-transporter 4 (Glut4) in 3T3-L1 cells were markedly down-regulated by amarouciaxanthin A compared to fucoxanthinol. Furthermore, the expression levels of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT-enhancer-binding protein α (C/EBPα),, which are the key adipogenic transcriptional factors, were also decreased by amarouciaxanthin A during adipocyte differentiation. These results show that amarouciaxanthin A, which is a dominant metabolite of fucoxanthin in white adipose tissue, suppressed 3T3-L1 adipocyte differentiation.

New C37 skeletal carotenoid from the clam, Paphia amabillis

Carotenoids in the muscle of Paphia amabillis (Veneridae) were investigated. Amarouciaxanthin 3-ester (1a) was found to be a major carotenoid along with amarouciaxanthin A (1b), fucoxanthinol 3-ester (2), peridininol 3'-ester (3), and a new C(37) skeletal carotenoid, named hydratopyrrhoxanthinol 3'-ester. This structure was determined to be 3'-acyloxy-3,5,6-trihydroxy-7',8'-didehydro-5,6-dihydro-12',13',20'-trinor-beta,beta-caroten-19,11-olide (4) by UV-vis, NMR, and FAB-MS spectral data. The absolute configuration of 4 was postulated to be (3S,5R,6R,3'R) on the bases of CD and ROESY data. The fatty acids esterified with hydratopyrrhoxanthinol were assigned as C22:6, C20:1, C20:4, C20:5, C18:0, C18:1, C17:0, C16:0, C16:1, and C14:0 on the basis of FAB-MS data.

Correlation of plasma homocysteine and mitochondrial DNA content in peripheral blood in healthy women

Hyperhomocysteinemia is an independent risk factor of cardiovascular disease and associated with insulin resistance, although their causal relationship remains unclear. A previous report has shown that high concentration of homocysteine damages mitochondrial gene expression, function and structure. As we found recently, the mitochondrial DNA (mtDNA) contents are inversely correlated with insulin resistance parameters. Thus there is possibility that plasma total homocysteine (tHcy) level is somewhat correlated with mtDNA content. Sixty healthy women (mean age 40.3+/-20.9 yr, range 18-78 yr) were recruited to investigate the correlation of plasma tHcy level and mtDNA content in peripheral blood. A significant negative correlation was found between plasma tHcy levels and mtDNA content (r=-0.507, P<0.01). Plasma tHcy and mtDNA content have an independent effect on each other and on insulin resistance (HOMA-insulin resistance (IR) score) respectively in multiple regression model. Plasma tHcy showed positive correlations with age (r=0.407), W/H ratio (r=0.370), total cholesterol (r=0.338), LDL-cholesterol (r=0.317) and insulin resistance (HOMA-IR score) (r=0.261); and a negative correlation with folate (r=-0.273). MtDNA content showed negative correlations with age (r=-0.407), BMI (r=-0.440), W/H ratio (r=-0.659), SBP (r=-0.350), total cholesterol (r=-0.340), triglyceride (r=-0.376), LDL-cholesterol (r=-0.349), fasting plasma insulin (r=-0.483), and insulin resistance (HOMA-IR score) (r=-0.423); and a positive correlation with folate (r=0.299). In this study, there was a significant inverse correlation between plasma tHcy level and mtDNA content. Further study will be warranted to elucidate the mechanism by which two factors are associated.

Effect of exercise on the mitochondrial DNA content of peripheral blood in healthy women

Exercise decreases insulin resistance and increases maximal exercise capacity as estimated from maximal oxygen uptake (VO2max). Recent reports have demonstrated that the mitochondrial DNA (mtDNA) content of blood is correlated with VO2max in healthy subjects (mean age 31 years) and is inversely correlated with insulin resistance parameters. The aim of this study was to determine the effect of regular exercise on the mtDNA content in the peripheral blood of 16 healthy young women of mean age 24.8 (SD 6.2) years and 14 healthy older women of mean age 66.7 (SD 5.8) years. The exercise programme lasted for 10 weeks and consisted of three sessions a week, each of 1 h and aiming to attain 60%-80% of VO2max. The mtDNA content of peripheral blood was measured by competitive polymerase chain reaction. The VO2max had significantly increased following the exercise programme [from 33.1 (SD 3.4) to 35.2 (SD 3.4) ml x kg(-1) min(-1) in the young and from 24.3 (SD 5.3) to 30.3 (SD 7.3) ml x kg(-1) x min(-1) in the older women, both P < 0.05]. Exercise decreased systolic blood pressure, and concentrations of triglyceride, low density lipoprotein-cholesterol (LDL-C), glucose and insulin in the blood of the young and of total cholesterol, LDL-C and glucose in that of the older women. High density lipoprotein-cholesterol (HDL-C) in the young women was increased by exercise. The mtDNA content significantly increased following the exercise programme in both groups [from 27.1 (SD 17.9) to 52.7 (SD 44.6) amol x 5 ng(-1) genomic DNA in the young and from 15.3 (SD 10.2) to 32.1 (SD 30.0) amol x 5 ng(-1) genomic DNA in the older women, both P < 0.05]. There was a significant positive correlation between the change in mtDNA content and the change in VO2max (r = 0.74 in the young and r = 0.71 in the older women, both P < 0.01). In conclusion, 10 weeks of moderate intensity, regular exercise increased the mtDNA content in peripheral blood and decreased insulin resistance parameters. This data suggests that increase in the mtDNA content may be associated with increased insulin sensitivity.