Brown Alga Ecklonia Cava Research Articles

Optimization of protoplast isolation and subsequent regeneration from the economically important brown alga Ecklonia cava using response surface methodology

Ecklonia cava is an edible kelp species distributed in Korea and Japan with diverse uses in ecological restoration, traditional medicine, and the pharmaceutical and abalone industries. These features make E. cava a good candidate for cellular biotechnology research, which is often dependent on protoplasts. To date, however, there have been no studies that have focused on the isolation of protoplast from E. cava. In this study, we sought to optimize the yield of protoplasts from cultured young sporophytes of E. cava using commercial enzymes, with a particular focus on identifying the key conditions for achieving high protoplast yield, including enzyme concentration, chelation pre-treatment, growth, temperature, incubation time, pH, and osmolarity. Protoplast production conditions were modeled using response surface methodology (RSM) via Box–Behnken design (BBD), and the practical utility of these conditions was experimentally verified. We found that an enzyme composition of 1.67 % cellulase RS and 4 U mL−1 alginate lyase without chelation pre-treatment, at 1570 mOsm L−1 H2O and pH 6 produced the highest protoplast yield of 4.45 ± 2.16 × 107 protoplasts g−1 fresh weight when incubated at 20 °C for 4 h using young (2-week-old) cultures. Our data revealed a strong positive correlation between growth rate and protoplast yield, thereby indicating that growth rate could serve as an index for determining the optimal timing of protoplast isolation from cultured material. The optimized protocol resulted in protoplasts capable of cell wall formation, division, and regeneration. These findings indicate the efficacy of commercial enzymes in protoplast isolation and that BBD-mediated RSM is a useful approach for the production of viable protoplasts from kelp sporophytes.

Evaluation of Protective Effects of Polyphenols of the Marine Brown Alga Ecklonia cava against Potassium Bromate Induced Nephrotoxicity in Rats

Pharmacognosy Research,2023,15,3,544-550.DOI:10.5530/pres.15.3.057Published:June 2023Type:Original Article Authors:Moqbel Ali Moqbel Redhwan, Suman Samaddar, Hariprasad MG, Sumaia Abdulbari Ahmed Ali Hard, Gitima Deka, and Anyembe Godfrey Author(s) affiliations:Moqbel Ali Moqbel Redhwan1,*, Suman Samaddar2, Hariprasad MG3, Sumaia Abdulbari Ahmed Ali Hard4, Gitima Deka5, Anyembe Godfrey6 1Department of Pharmacology, KLE College of Pharmacy, Bangalore, Karnataka, INDIA. 2BGS GIMS Research Institute, BGS Global Institute of Medical Sciences, Bengaluru, Karnataka, INDIA. 3Department of Pharmacology, KLE College of Pharmacy, Bangalore, Karnataka, INDIA. 4Department of Pharmaceutics, KLE College of Pharmacy, Bangalore, Karnataka, INDIA. 5Department of Pharmacy, Yeungnam University, Gyeongsangbuk-do, SOUTH KOREA. 6Department of Pharmacology, Karnataka College of Pharmacy, Bangalore, Karnataka, INDIA. Abstract:Background: Ecklonia cava is a kelp (brown algae) genus belonging to Lessoniaceae with plenty of Eckol-type phlorotannins. It exhibits antioxidant, anti-inflammatory, and antibacterial activity. Objectives: This study investigated Ecklonia cava (EC) polyphenols for their protective effects against KBrO3-induced nephrotoxicity in rats. Materials and Methods: The polyphenolic fraction was isolated from EC. Group, I was control (untreated), and group II was administered KBrO3 (135 mg/kg b.w) intragastric for four weeks. Group III was administered ECPP (200 mg/kg b.w) concurrently with KBrO3 (135 mg/kg b.w) orally, and Group VI was administered Rutin (100 mg/ kg b.w) along with KBrO3 (135 mg/kg b.w) orally. The protective effects of ECPP on KBrO3-induced nephrotoxicity in rats were assessed for the biochemical parameters of serum, various antioxidant enzymes, and histopathological changes in kidneys. Results: The level of serum of Blood Urea Nitrogen (BUN), uric acid, and creatinine was suggestively augmented (p<0.001) when treated by KBrO3. The activity of antioxidant enzymes, superoxide dismutase, catalase, glutathione peroxidase, and FRAP (ferric ion reducing antioxidant parameter) were diminished (p<0.001). At the same time, lipid peroxidation and nitric oxide were raised (p<0.001) with KBrO3 treatment in the kidneys. In addition, the protein carbonyl level was amplified (p<0.001) with KBrO3 administration. Histological studies presented renal damage in KBrO3-treated animals where tissue injury was abridged in ECPP pretreatment groups. Conclusion: These results suggest that ECPP functions as an antioxidant in vivo by scavenging reactive oxygen species, which helps preclude oxidative renal injury in rats treated with KBrO3. Keywords:Antioxidant, Ecklonia cava, Nephroproductive activity, Polyphenols, Potassium bromate.View:PDF (1.04 MB)

Effect of Phlorofucofuroeckol A and Dieckol Extracted from Ecklonia cava on Noise-induced Hearing Loss in a Mouse Model.

One of the well-known causes of hearing loss is noise. Approximately 31.1% of Americans between the ages of 20 and 69 years (61.1 million people) have high-frequency hearing loss associated with noise exposure. In addition, recurrent noise exposure can accelerate age-related hearing loss. Phlorofucofuroeckol A (PFF-A) and dieckol, polyphenols extracted from the brown alga Ecklonia cava, are potent antioxidant agents. In this study, we investigated the effect of PFF-A and dieckol on the consequences of noise exposure in mice. In 1,1-diphenyl-2-picrylhydrazyl assay, dieckol and PFF-A both showed significant radical-scavenging activity. The mice were exposed to 115 dB SPL of noise one single time for 2 h. Auditory brainstem response(ABR) threshold shifts 4 h after 4 kHz noise exposure in mice that received dieckol were significantly lower than those in the saline with noise group. The high-PFF-A group showed a lower threshold shift at click and 16 kHz 1 day after noise exposure than the control group. The high-PFF-A group also showed higher hair cell survival than in the control at 3 days after exposure in the apical turn. These results suggest that noise-induced hair cell damage in cochlear and the ABR threshold shift can be alleviated by dieckol and PFF-A in the mouse. Derivatives of these compounds may be applied to individuals who are inevitably exposed to noise, contributing to the prevention of noise-induced hearing loss with a low probability of adverse effects.

Correlation between the seasonal variations in phlorotannin content and the antiallergic effects of the brown alga Ecklonia cava subsp. stolonifera

Here, we investigated the antiallergic effects of brown algae (Ecklonia cava subsp. stolonifera) harvested on the coast of Nishinoshima Town, Oki Islands, Shimane Prefecture, Japan. Specifically, we investigated whether the active components of E. cava ssp. stolonifera vary seasonally and whether such variation correlates with seasonal variation in the antiallergic effects of the algae. High-performance liquid chromatography, liquid chromatography–mass spectrometry, and nuclear magnetic resonance spectra were used to analyze 80% methanol (80M) extract from E. cava ssp. stolonifera and to isolate eckol, 6,6′-bieckol, 8,8′-bieckol, dieckol, and phlorofucofuroeckol-A as the major active compounds in the species' phlorotannins. Monthly measurements of phlorotannin content and the isolated phlorotannins in the 80M extract showed that the crude phlorotannin and isolated phlorotannin content was higher in the summer–autumn period than in the winter–spring period. The antiallergic effects of the monthly 80M extracts and the isolated phlorotannins were confirmed by measuring inhibition of inflammation-related enzymatic activity, suppression of degranulation in rat basophile leukemia-2H3 cells, and effects on allergic inflammation in Institute of Cancer Research strain mice. There was partial seasonal variation in the effect of 80M extract in combination with the amount of isolated phlorotannin and the antiallergic effects. When phlorotannin was removed from the extracts using polyvinylpolypyrrolidone, the antiallergic effects were no longer observed; thus, phlorotannins are the active components. Overall, these results show that correlations exist between the seasonal variations in the suppressive effect of 80M extract on enzymatic activities, allergic inflammation in mice, and the amount of isolated phlorotannins.

Effects of Ecklonia cava Extract on Neuronal Damage and Apoptosis in PC-12 Cells against Oxidative Stress.

Marine algae (seaweed) encompass numerous groups of multicellular organisms with various shapes, sizes, and colors, and serve as important sources of natural bioactive substances. The brown alga Ecklonia cava Kjellman, an edible seaweed, contains many bioactives such as phlorotannins and fucoidans. Here, we evaluated the antioxidative, neuroprotective, and anti-apoptotic effects of E. cava extract (ECE), E. cava phlorotannin-rich extract (ECPE), and the phlorotannin dieckol on neuronal PC-12 cells. The antioxidant capacities of ECPE and ECE were 1,711.5 and 1,050.4 mg vitamin C equivalents/g in the ABTS assay and 704.0 and 474.6 mg vitamin C equivalents/g in the DPPH assay, respectively. The dieckol content of ECPE (58.99 mg/g) was approximately 60% higher than that of ECE (36.97 mg/g). Treatment of PC-12 cells with ECPE and ECE increased cell viability in a dose-dependent manner. Intracellular oxidative stress in PC-12 cells due to ECPE and ECE decreased dose-independently by up to 63% and 47%, respectively, compared with the stress control (323%). ECPE reduced the production of the pro-apoptotic proteins Bax and caspase-3 more effectively than ECE. Early and late apoptosis in PC-12 cells were more effectively decreased by ECPE than ECE treatments. From the results obtained in this study, we concluded that ECPE, which is rich in phlorotannins, including the marker compound dieckol, may be applied to the development of functional materials for improving cognition and memory.

Dieckol, a Major Marine Polyphenol, Enhances Non-Rapid Eye Movement Sleep in Mice via the GABAA-Benzodiazepine Receptor.

We had previously demonstrated that phlorotannins, which are marine polyphenols, enhance sleep in mice via the GABAA-benzodiazepine (BZD) receptor. Among the constituents of phlorotannin, dieckol is a major marine polyphenol from the brown alga Ecklonia cava. Although phlorotannins are known to exert hypnotic effects, the sleep-enhancing effect of dieckol has not yet been determined. We evaluated the effect of dieckol on sleep-wake state of mice by analyzing electroencephalograms (EEGs) and electromyograms. Flumazenil, a GABAA-BZD antagonist, was used to investigate the molecular mechanism underlying the effects of dieckol on sleep. The polygraphic recordings and corresponding hypnograms revealed that dieckol accelerated the initiation of non-rapid eye movement sleep (NREMS); it shortened sleep latency and increased NREMS duration. According to the change in time-course, dieckol showed sleep-enhancing effects by increasing the amount of NREMS and decreasing wakefulness during the same hours. Additionally, sleep quality was evaluated by analyzing the EEG power density, and dieckol was found to not affect sleep intensity while zolpidem was found to reduce it. Finally, we treated mice with zolpidem or dieckol in combination with flumazenil and found the latter to inhibit the sleep-enhancing effect of dieckol and zolpidem, thereby indicating that dieckol exerts sleep-enhancing effects by activating the GABAA-BZD receptor, similar to zolpidem. These results implied that dieckol can be used as a promising herbal sleep aid with minimal side effects, unlike the existing hypnotics.

Using organic compounds to assess the dominant controls on seasonal iodine variability in the brown alga Ecklonia cava in the northwestern Pacific coast of central Japan

Brown algal species are among the most efficient iodine accumulators and thus heavily influence the biogeochemical cycling of iodine in coastal environments. Previously, we reported seasonal variability in iodine concentrations in the brown alga Ecklonia cava collected from the Japanese coast over a 2-year period. In this study, we sought to identify the factors controlling this observed variability by investigating the relationships between the concentrations of iodine and major organic compounds (carbohydrates and fatty acids). The concentrations of total carbohydrates and individual constituent monosaccharides showed no significant correlations with iodine concentration, implying that carbohydrate concentration and composition are not the dominant controls on iodine concentration in E. cava. However, fucose concentrations were significantly correlated when data points of highest iodine concentrations were removed, potentially suggesting some influence of structural carbohydrate on iodine variability. Significant positive correlations with iodine concentration were only observed in odd-chain fatty acids, which are known to be bacterial biomarkers; in particular, the C17:1 fatty acid showed the highest correlation (r = 0.83). The concentrations of the remaining fatty acids, as well as total concentration of fatty acids, did not correlate significantly with iodine concentrations. Our results suggest that, in general, the concentration and composition of fatty acids do not directly influence iodine variability and that iodine concentrations in E. cava are predominantly controlled by bacteria living on its surface.

Phlorofucofuroeckol A from Edible Brown Alga Ecklonia Cava Enhances Osteoblastogenesis in Bone Marrow-Derived Human Mesenchymal Stem Cells.

The deterioration of bone formation is a leading cause of age-related bone disorders. Lack of bone formation is induced by decreased osteoblastogenesis. In this study, osteoblastogenesis promoting effects of algal phlorotannin, phlorofucofuroeckol A (PFF-A), were evaluated. PFF-A was isolated from brown alga Ecklonia cava. The ability of PFF-A to enhance osteoblast differentiation was observed in murine pre-osteoblast cell line MC3T3-E1 and human bone marrow-derived mesenchymal stem cells (huBM-MSCs). Proliferation and alkaline phosphatase (ALP) activity of osteoblasts during differentiation was assayed following PFF-A treatment along extracellular mineralization. In addition, effect of PFF-A on osteoblast maturation pathways such as Runx2 and Smads was analyzed. Treatment of PFF-A was able to enhance the proliferation of differentiating osteoblasts. Also, ALP activity was observed to be increased. Osteoblasts showed increased extracellular mineralization, observed by Alizarin Red staining, following PFF-A treatment. In addition, expression levels of critical proteins in osteoblastogenesis such as ALP, bone morphogenetic protein-2 (BMP-2), osteocalcin and β-catenin were stimulated after the introduction of PFF-A. In conclusion, PFF-A was suggested to be a potential natural product with osteoblastogenesis enhancing effects which can be utilized against bone-remodeling imbalances and osteoporosis-related complications.

Fabrication and biological activity of polycaprolactone/phlorotannin endotracheal tube to prevent tracheal stenosis: An in vitro and in vivo study

Prolonged endotracheal intubation is the most common cause of tracheal stenosis, which may lead to serious airway obstruction. Development of an endotracheal tube coated with biomaterials that exhibit anti-inflammatory or anti-fibrogenic effects may prevent tracheal stenosis. This study demonstrates that an endotracheal tube coated with phlorotannin, which is present in extracts of the brown alga Ecklonia cava, can prevent tracheal stenosis in a rabbit model. An in vitro study shows that phlorotannin inhibits proliferation of human tracheal fibroblasts treated with transforming growth factor β1. Phlorotannin-coated endotracheal tubes show steady release of phlorotannin for up to 7 days, and removal of the tube 1 week after insertion reveals a reduction in both fibrogenesis and thickening of tracheal submucosa. Western blot analysis of tracheal tissues after removal of the phlorotannin-coated tube shows decreased protein expression levels of phenotypic markers of fibrosis such as collagen type I and α-smooth muscle actin. The ability of phlorotannin-coated endotracheal tube to prevent tracheal stenosis caused by endotracheal intubation indicates that phlorotannin may be considered as a candidate biomaterial for coating the cuff of endotracheal tubes to prevent tracheal stenosis.

Enrichment of bacteria and alginate lyase genes potentially involved in brown alga degradation in the gut of marine gastropods

Gut bacteria of phytophagous and omnivorous marine invertebrates often possess alginate lyases (ALGs), which are key enzymes for utilizing macroalgae as carbon neutral biomass. We hypothesized that the exclusive feeding of a target alga to marine invertebrates would shift the gut bacterial diversity suitable for degrading the algal components. To test this hypothesis, we reared sea hare (Dolabella auricularia) and sea snail (Batillus cornutus) for two to four weeks with exclusive feeding of a brown alga (Ecklonia cava). Pyrosequencing analysis of the gut bacterial 16S rRNA genes revealed shifts in the gut microbiota after rearing, mainly due to a decrease in the variety of bacterial members. Significant increases in six and four 16S rRNA gene phylotypes were observed in the reared sea hares and sea snails, respectively, and some of them were phylogenetically close to known alginate-degrading bacteria. Clone library analysis of PL7 family ALG genes using newly designed degenerate primer sets detected a total of 50 ALG gene phylotypes based on 90% amino acid identity. The number of ALG gene phylotypes increased in the reared sea hare but decreased in reared sea snail samples, and no phylotype was shared between them. Out of the 50 phylotypes, 15 were detected only after the feeding procedure. Thus, controlled feeding strategy may be valid and useful for the efficient screening of genes suitable for target alga fermentation.

Neuroprotective mechanisms of dieckol against glutamate toxicity through reactive oxygen species scavenging and nuclear factor-like 2/heme oxygenase-1 pathway.

Glutamate toxicity-mediated mitochondrial dysfunction and neuronal cell death are involved in the pathogenesis of several neurodegenerative diseases as well as acute brain ischemia/stroke. In this study, we investigated the neuroprotective mechanism of dieckol (DEK), one of the phlorotannins isolated from the marine brown alga Ecklonia cava, against glutamate toxicity. Primary cortical neurons (100 µM, 24 h) and HT22 neurons (5 mM, 12 h) were stimulated with glutamate to induce glutamate toxic condition. The results demonstrated that DEK treatment significantly increased cell viability in a dose-dependent manner (1–50 µM) and recovered morphological deterioration in glutamate-stimulated neurons. In addition, DEK strongly attenuated intracellular reactive oxygen species (ROS) levels, mitochondrial overload of Ca2+ and ROS, mitochondrial membrane potential (ΔΨm) disruption, adenine triphosphate depletion. DEK showed free radical scavenging activity in the cell-free system. Furthermore, DEK enhanced protein expression of heme oxygenase-1 (HO-1), an important anti-oxidant enzyme, via the nuclear translocation of nuclear factor-like 2 (Nrf2). Taken together, we conclude that DEK exerts neuroprotective activities against glutamate toxicity through its direct free radical scavenging property and the Nrf-2/HO-1 pathway activation.

Seasonal variations in iodine concentrations in a brown alga (Ecklonia cava Kjellman) and a seagrass (Zostera marina L.) in the northwestern Pacific coast of central Japan

Seasonal variations in iodine concentrations were investigated for two years in a brown alga (Ecklonia cava Kjellman) and a seagrass (Zostera marina L.) occurring in the northwestern Pacific coast of central Japan. The iodine concentration in E. cava was 0.92–5.6 mg per gram dry weight (g‒ 1 DW) (mean ± SD:2.3 ± 1.1 mg g‒1 DW), and its variation was similar to that of other brown algae. In Z. marina, the iodine concentration was 17–110 μg g‒1 DW (61 ± 28 μg g‒ 1 DW) and displayed seasonal variation, as it was high in winter and spring and low in autumn.

Dioxinodehydroeckol Enhances the Differentiation of Osteoblasts by Regulating the Expression of Phospho-Smad1/5/8.

Lack of bone formation-related health problems are a major problem for the aging population in the modern world. As a part of the ongoing trend of developing natural substances that attenuate osteoporotic bone loss conditions, dioxinodehydroeckol (DHE) from edible brown alga Ecklonia cava was tested for its effects on osteoblastogenic differentiation in MC3T3-E1 pre-osteoblasts. DHE was observed to successfully enhance osteoblast differentiation, as indicated by elevated cell proliferation, alkaline phosphatase activity, intracellular cell mineralization, along with raised levels of osteoblastogenesis indicators at the concentration of 20 μM. Results suggested a possible intervening of DHE on the bone morphogenetic protein (BMP) signaling pathway, according to elevated protein levels of BMP-2, collagen-I, and Smads. In addition, the presence of DHE was also able to raise the phosphorylated extracellular signal–regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) levels which are also activated by the BMP signaling pathway. In conclusion, DHE is suggested to be a potential bioactive compound against bone loss that could enhance osteoblastogenesis with a suggested BMP pathway interaction.

Protective Effect of Brown Alga Phlorotannins against Hyper-inflammatory Responses in Lipopolysaccharide-Induced Sepsis Models.

Brown algae have been recognized as a food ingredient and health food supplement in Japan and Korea, and phlorotannins are unique marine phenol compounds produced exclusively by brown algae. Sepsis is a whole-body inflammatory condition with a mortality rate of 30-40%. Here, we investigated the effects of a phlorotannin-rich extract of the edible brown alga Ecklonia cava against hyper-inflammatory response in LPS-induced septic shock mouse model. E. cava extract significantly increased the survival rate and attenuated liver and kidney damage in the mice. In addition, E. cava attenuated serum levels of NO, PGE2, and HMGB-1. In macrophages, treatment with E. cava extract down-regulated iNOS, COX-2, TNF-α, IL-6, and HMGB-1. In addition, E. cava suppressed the NIK/TAK1/IKK/IκB/NFκB pathway. Moreover, E. cava increased Nrf2 and HO-1 expression. HO-1 knockdown using siRNA restored the extract-suppressed NO and PGE2 production. Dieckol, a major compound in the extract, reduced mortality, tissue toxicity, and serum levels of the inflammatory factors in septic mice. These data suggest that brown algae phlorotannins suppress septic shock through negative regulation of pro-inflammatory factors via the NIK/TAK1/IKK/IκB/NFκB and Nrf2/HO-1 pathways.

Flavobacterium jejuensis sp. nov., isolated from marine brown alga Ecklonia cava.

A bacterial strain, designated EC11(T) was isolated from brown alga Ecklonia cava collected from Jeju Island, Korea. EC11(T) was identified as a Gram-negative, rod-shaped and yellow-pigmented bacterial strain. The strain EC11(T) grew over a temperature range of 10 °C to 30 °C (optimally at 25 °C), and a pH range of 6.0-10.5 (optimally at pH 7.5). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain EC11(T) belongs to the genus Flavobacterium. Strain EC11(T) shared close similarity with Flavobacterium jumunjinense HME7102(T) (96.4%), Flavobacterium dongtanense LW30(T) (95.8%), Flavobacterium haoranii LQY-7(T) (95.3%), and Flavobacterium urocaniciphilum (95.1%). The major fatty acids (> 5%) were iso-C17:0 3-OH (22.4%), iso-C15:0 3-OH (19.0%), C15:0 (12.4%), summed feature 3 (comprising C16:1 ω7c/ C16:1 ω6c; 9.78%), iso-C15:1 G (9.6%), and iso-C16:0 3-OH (9.0%). The DNA G+C content was 28.1 mol% and the strain contained MK-6 as the predominant menaquinone. The major polar lipids were phosphatidylethanolamine, two unknown aminolipids and three unknown polar lipids. Based on phenotypic, chemotaxonomic and phylogenetic analysis, strain EC11T represents a novel species of the Flavobacterium genus, for which the name Flavobacterium jejuensis sp. nov. is proposed. The type strain of F. jejuensis is EC11(T) (=KCTC 42149(T) = JCM 30735(T)).

Clinical Trial of the Hypolipidemic Effects of a Brown Alga Ecklonia cava Extract in Patients with Hypercholesterolemia

Clinical Trial of the Hypolipidemic Effects of a Brown Alga Ecklonia cava Extract in Patients with Hypercholesterolemia

Winogradskyella eckloniae sp. nov., a marine bacterium isolated from the brown alga Ecklonia cava.

A novel bacterial strain, designated EC29(T), was isolated from the brown alga Ecklonia cava collected on Jeju Island, Republic of Korea. Cells of strain EC29(T) were Gram-stain-negative, aerobic, rod-shaped and motile by gliding. Growth was observed at 10-30 °C (optimum, 20-25 °C), at pH 6.0-9.5 (optimum, pH 7.5) and in the presence of 1-5% (w/v) NaCl. Phylogenetic analyses based on the 16S rRNA gene sequence revealed that the strain belonged to the genus Winogradskyella. Strain EC29(T) exhibited the highest 16S rRNA gene sequence similarities, of 96.5-97.8%, to the type strains of Winogradskyella pulchriflava EM106(T), Winogradskyella echinorum KMM 6211(T) and Winogradskyella ulvae KMM 6390(T). Strain EC29(T) exhibited < 27% DNA-DNA relatedness with Winogradskyella pulchriflava EM106(T) and Winogradskyella echinorum KMM 6211(T). The predominant fatty acids of strain EC29(T) were iso-C15 : 0, iso-C15 : 1 G, C15 : 0, iso-C17 : 0 3-OH, iso-C15 : 0 3-OH and anteiso-C15 : 0. The DNA G+C content was 31.1 mol% and the major respiratory quinone was menaquinone-6 (MK-6). Based on a polyphasic study, strain EC29(T) is considered to represent a novel species of the genus Winogradskyella, for which the name Winogradskyella eckloniae sp. nov. is proposed. The type strain is EC29(T) ( = KCTC 32172(T) = JCM 18703(T)).

Multifunctional activity of polyphenolic compounds associated with a potential for Alzheimer's disease therapy from Ecklonia cava.

Five polyphenols were isolated and purified from a brown alga Ecklonia cava. These compounds showed diverse biological activities such as antioxidative, antiinflammatory, and enzyme inhibitory activities. This led us to investigate the potential of these compounds as Alzheimer's disease drugs. All of the compounds showed moderate acetylcholinesterase inhibitory activity in a micromolar range (IC50 from 16.0 to 96.3 μM). For butyrylcholinesterase, a new target for the treatment of Alzheimer's disease, phlorofucofuroeckol-A (PFF-A), showed a particularly potent inhibitory activity (IC50 0.95 μM), which is over 100-fold greater than for acetylcholinesterase. These compounds inhibited glycogen synthase kinase 3 beta, which is related to the formation of hyperphosphorylated tau and generation Aβ. Bieckol and PFF-A inhibited amyloid precursor protein biosynthesis. PFF-A also showed very strong β-secretase inhibitory activity with IC50 of submicromole. These results render these compounds as interesting potential drug candidates for Alzheimer's disease.

Dieckol Attenuates Microglia-mediated Neuronal Cell Death via ERK, Akt and NADPH Oxidase-mediated Pathways.

Excessive microglial activation and subsequent neuroinflammation lead to synaptic loss and dysfunction as well as neuronal cell death, which are involved in the pathogenesis and progression of several neurodegenerative diseases. Thus, the regulation of microglial activation has been evaluated as effective therapeutic strategies. Although dieckol (DEK), one of the phlorotannins isolated from marine brown alga Ecklonia cava, has been previously reported to inhibit microglial activation, the molecular mechanism is still unclear. Therefore, we investigated here molecular mechanism of DEK via extracellular signal-regulated kinase (ERK), Akt and nicotinamide adenine dinuclelotide phosphate (NADPH) oxidase-mediated pathways. In addition, the neuroprotective mechanism of DEK was investigated in microglia-mediated neurotoxicity models such as neuron-microglia co-culture and microglial conditioned media system. Our results demonstrated that treatment of anti-oxidant DEK potently suppressed phosphorylation of ERK in lipopolysaccharide (LPS, 1 µg/ml)-stimulated BV-2 microglia. In addition, DEK markedly attenuated Akt phosphorylation and increased expression of gp91phox, which is the catalytic component of NADPH oxidase complex responsible for microglial reactive oxygen species (ROS) generation. Finally, DEK significantly attenuated neuronal cell death that is induced by treatment of microglial conditioned media containing neurotoxic secretary molecules. These neuroprotective effects of DEK were also confirmed in a neuron-microglia co-culture system using enhanced green fluorescent protein (EGFP)-transfected B35 neuroblastoma cell line. Taken together, these results suggest that DEK suppresses excessive microglial activation and microglia-mediated neuronal cell death via downregulation of ERK, Akt and NADPH oxidase-mediated pathways.

Brown algae phlorotannins enhance the tumoricidal effect of cisplatin and ameliorate cisplatin nephrotoxicity

ObjectiveThe clinical application of cisplatin is limited due to its drug resistance and side effects. We investigated the effect of a phlorotannin-rich extract from the edible brown alga Ecklonia cava (PREC) and its major phlorotannin (dieckol) on cisplatin responsiveness and side effects. MethodsThe A2780 and SKOV3 ovarian cancer cell lines and the SKOV3-bearing mouse model were used. The MTT assay was applied to assess cell viability, and the annexin V assay was employed for apoptosis analysis. Reactive oxygen species (ROS) production and protein expression were assessed by H2DCFDA staining and Western blotting, respectively. ResultsWe found that PREC enhanced the tumor growth-inhibitory effect of cisplatin and diminished cisplatin-induced nephrotoxicity and weight loss in SKOV3-bearing mice. PREC augmented cisplatin-induced apoptosis by activating caspases in SKOV3 and A2780 ovarian cancer cells. In addition, a combination of PREC and cisplatin-induced ovarian cancer cell apoptosis by downregulating the Akt and NFκB pathways. We further demonstrated that PREC increased intracellular ROS and that antioxidants significantly attenuated Akt-NFκB activation and apoptosis in ovarian cancer cells. In contrast, PREC inhibited cisplatin-induced ROS production and cell death in normal HEK293 kidney cells. Dieckol, a major compound in PREC, significantly enhanced the inhibition of tumor growth by cisplatin with less weight loss and kidney damage in a mouse model. ConclusionThese data suggest that brown algae phlorotannins may improve the efficacy of platinum drugs for ovarian cancer by enhancing cancer cell apoptosis via the ROS/Akt/NFκB pathway and reduce nephrotoxicity by protecting against normal kidney cell damage.