Protein tyrosine phosphatase 1B and α-glucosidase inhibitory Phlorotannins from edible brown algae, Ecklonia stolonifera and Eisenia bicyclis.

The present work investigates protein tyrosine phosphatase 1B (PTP1B) and the α-glucosidase inhibitory activities of two edible brown algae, Ecklonia stolonifera and Eisenia bicyclis, as well as in their isolated phlorotannins. Since the individual extracts and fractions showed significant inhibitory activities, column chromatography was performed to isolate six phlorotannins, phloroglucinol (1), dioxinodehydroeckol (2), eckol (3), phlorofurofucoeckol-A (4), dieckol (5), and 7-phloroeckol (6). Phlorotannins 3-6 were potent and noncompetitive PTP1B inhibitors with IC(50) values ranging from 0.56 to 2.64 µM; 4-6 exhibited the most potent α-glucosidase inhibition with IC(50) values ranging from 1.37 to 6.13 µM. Interestingly, 4 and 6 were noncompetitive, while 5 exhibited competitive inhibition in an α-glucosidase assay. E. stolonifera and E. bicyclis as well as their isolated phlorotannins therefore possessed marked PTP1B and α-glucosidase inhibitory activities; this could lead to opportunities in the development of therapeutic agents to control the postprandial blood glucose level and thereby prevent diabetic complications.

Anti-inflammatory activity of edible brown alga Eisenia bicyclis and its constituents fucosterol and phlorotannins in LPS-stimulated RAW264.7 macrophages.

Although individual phlorotannins contained in the edible brown algae have been reported to possess strong anti-inflammatory activity, the responsible components of Eisenia bicyclis have yet to be fully studied. Thus, we evaluated their anti-inflammatory activity via inhibition against production of lipopolysaccharide (LPS)-induced nitric oxide (NO) and tert-butylhydroperoxide (t-BHP)-induced reactive oxygen species (ROS), along with suppression against expression of inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), in RAW 264.7 cells. The anti-inflammatory activity potential of the methanolic extract and its fractions of E. bicyclis was in the order of dichloromethane>methanol>ethyl acetate>n-butanol. The strong anti-inflammatory dichloromethane fraction was further purified to yield fucosterol. From the ethyl acetate fraction, six known phlorotannins were isolated: phloroglucinol, eckol, dieckol, 7-phloroeckol, phlorofucofuroeckol A and dioxinodehydroeckol. We found that these compounds, at non-toxic concentrations, dose-dependently inhibited LPS-induced NO production. Fucosterol also inhibited t-BHP-induced ROS generation and suppressed the expression of iNOS and COX-2. These results indicate that E. bicyclis and its constituents exhibited anti-inflammatory activity which might attribute to inhibition of NO and ROS generation and suppression of the NF-κB pathway and can therefore be considered as a useful therapeutic and preventive approach to various inflammatory and oxidative stress-related diseases.

Neuroprotective effect of edible brown alga Eisenia bicyclis on amyloid beta peptide-induced toxicity in PC12 cells.

Amyloid beta peptide (Aß) oligomers increase intracellular reactive oxygen species (ROS) and calcium cation (Ca(2+)) concentrations, which causes neuronal cell death in Alzheimer's disease (AD). Thus, the use of neuroprotective agents with antioxidative activity might be effective in the treatment of AD. In the present study, the neuroprotective effects of the methanol extract from edible brown alga Eisenia bicyclis (Laminariaceae) and its solvent soluble fractions together with the isolated phlorotannins on Aß-induced toxicity were assessed by cell viability, intracellular ROS, and Ca(2+) levels in PC12 cells. The addition of the methanol extract as well as its ethyl acetate and n-butanol fractions of E. bicyclis markedly reversed the Aß-induced toxicity. Among six phlorotannins, including phloroglucinol (1), dioxinodehydroeckol (2), eckol (3), phlorofucofuroeckol A (4), dieckol (5), and 7-phloroeckol (6), isolated from the most active ethyl acetate fraction, 3-6 significantly decreased Aß-induced cell death. Furthermore, these compounds also inhibited intracellular ROS generation and Ca(2+) generation, indicating the neuroprotective effects may be mediated through reduced intracellular ROS and Ca(2+) generation. Thus, the results of the present study imply that E. bicyclis and its active components attenuated the oxidative stress and reduced neuronal cell death, suggesting that it may be used as a dietary neuroprotective agent in AD.

In vitro antioxidant and anti-inflammatory activities of Angelica decursiva.

Mounting evidences continue to support the involvement of oxidative/nitrosative stress and inflammation in the pathogenesis of many diseases. Plant constituents having antioxidant activities together with anti-inflammatory activities may provide better opportunities to develop anti-inflammatory agents. In view of this, we evaluated the antioxidant and antiinflammatory activities of methanolic extract of whole plants of Angelica decursiva, and its solvent soluble fractions via in vitro activities against lipopolysaccharide-induced nitric oxide (NO) production in RAW 264.7 cells, as well as in vitro scavenging activities against 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid, NO, and peroxynitrite. Among the tested fractions, the ethyl acetate fraction was found as the most active antioxidant fraction together with significant anti-inflammatory effect. From the active ethyl acetate fraction, four coumarin derivatives consisting of nodakenin, nodakenetin, umbelliferone, and umbelliferone-6-carboxylic acid, along with a phenolic compound, vanillic acid, were isolated. Among them, umbelliferone 6-carboxylic acid and vanillic acid were isolated for the first time from this plant. In all antioxidant assays, vanillic acid showed the highest antioxidant potential followed by umbelliferone 6-carboxylic acid among the isolated compounds. In the anti-inflammatory assay, umbelliferone 6-carboxylic acid exhibited the highest inhibitory activity against lipopolysaccharide-induced NO production in RAW 264.7 cells with an IC(50) value of 72.98 µg/mL. Therefore, the present study reveals the potential antioxidant and antiinflammatory activities of whole plants of A. decursiva and its constituents, mainly umbelliferone 6-carboxylic acid, which could be used in the development of therapeutic and preventive agents for oxidative stress-related inflammatory diseases.

Mechanism of anti-inflammatory activity of umbelliferone 6-carboxylic acid isolated from Angelica decursiva.

AIMS OF THE STUDY: We recently reported the potential antioxidant and anti-inflammatory activities of umbelliferone 6-carboxylic acid (UMC) isolated from the whole plants of Angelica decursiva. In this study, we elucidated the anti-inflammatory mechanisms of UMC in vitro and in vivo. METHODS: The inhibitory effects of UMC on the production of nitric oxide (NO), prostaglandin E(2) (PGE(2)), and tumor necrosis factor-α (TNF-α), the expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), the activation of nuclear factor kappa B (NF-κB) were evaluated using lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. The reactive oxygen species (ROS) generation inhibitory activity of UMC was evaluated using t-butyl hydroperoxide (t-BHP)-induced RAW 264.7 cells. Furthermore, the in vivo anti-inflammatory activity of UMC was evaluated using carrageenan induced mouse paw edema model. RESULTS: UMC dose-dependently inhibited NO and PGE(2) production by down-regulating iNOS and COX-2 protein expression in LPS-stimulated RAW 264.7 macrophages. UMC also suppressed the production of the proinflammatory cytokine TNF-α in LPS stimulated RAW 264.7 cells in a concentration dependent manner. In addition, UMC dose-dependently prevented LPS-induced nuclear translocation of NF-κB in RAW 264.7 macrophages. Furthermore, UMC exhibited the inhibitory activity against t-BHP-induced ROS generation in RAW 264.7 cells with an IC(50) value of 705.1 µg/ml. Moreover, UMC inhibited λ-carrageenan induced mouse paw edema by 70.40 and 60.20% at doses of 50 and 25 mg/kg body weight, respectively. CONCLUSION: The combined results of this study indicate that UMC is an important anti-inflammatory constituent of A. decursiva and its anti-inflammatory effect was due to its ability to inhibit the production of inflammatory mediators via inhibition of NF-κB activation pathway.

Anti-tumorigenic activity of sophoflavescenol against Lewis lung carcinoma in vitro and in vivo.

This study examined the in vitro cytotoxic activity and in vivo antitumor activity as well as intracellular apoptotic capacities of a prenylated flavonol, sophoflavescenol from Sophora flavescens, to evaluate prospective anti-tumorigenic drugs, and antitumor potential. In addition, the in vitro antioxidant and anti-inflammatory capacities were evaluated. Despite the small effect on human breast adenocarcinoma (MCF-7), sophoflavescenol showed cytotoxicity against human leukaemia (HL-60), Lewis lung carcinoma (LLC), and human lung adenocarcinoma epithelial (A549) cells. Interestingly, it also exerted potent in vivo antitumor activity by tumor growth inhibition in the LLC tumor model as well as apoptotic activity by caspase-3 activation in HL-60 cells. In addition, it exhibited potent antioxidant activities in 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radicals and lipid peroxidation assays. Sophoflavescenol exerted notable anti-inflammatory activity by inhibiting nitric oxide generation and tert-butylhydroperoxide-induced ROS generation rather than inhibiting nuclear factor kappa B activation in RAW 264.7 cells. The findings show that the antioxidant, anti-inflammatory, and apoptotic activities of sophoflavescenol might contribute to the antitumor activity without severe side effects, highlighting its potential for chemoprevention and/or anticancer drugs due to multi-effective targets in almost all stages of tumorigenesis, including initiation, promotion, and progression.