Tortile Research Articles

Seven undescribed meroterpenoids from Sargassum siliquastrum and their inhibitory activity against amyloid β aggregation.

The inhibition of amyloid β (Aβ) aggregation and degradation of Aβ aggregates are promising approaches for treating and preventing Alzheimer's disease. In our search for Aβ42 aggregation inhibitors, we isolated seven undescribed meroterpenoids, sargasilides A (1)‒G (7), from brown alga (Sargassum siliquastrum) collected at Noto Peninsula in Japan. We structurally elucidated the isolated meroterpenoids using spectroscopic data and evaluated their activities using Thioflavin T assay and transmission electron microscopy. Among the seven compounds isolated, sargasilide B had the strongest inhibitory activity. From the comparison of structure and activity, the geometric isomerism of olefins and length of isoprene side chains are important for the activity of meroterpenoids isolated from brown alga.

Sustainable synthesis of magnetic Sargassum siliquastrum activated carbon loaded with NiS nanorods for adsorption of 2,4-D herbicide

The upgrade of sustainable resource waste into a valuable and beneficial material is an urgent task. The current paper outlines the development of an economical, sustainable, and prolonged adsorbent derived from Sargassum siliquastrum biomass and its use for potent 2,4-dichlorophenoxyacetic acid (2,4-D) removal. A simple carbonization approach was applied to obtain the highly functionalized carbon structure, which was subsequently transformed into a novel magnetic nanoadsorbent. The magnetic nanoadsorbent was characterized using Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Brunauer Emmett Teller (BET)-specific surface area, and vibrating sample magnetometer (VSM). The characterization results confirm the successful formation of a high specific surface area and a uniform distribution of Fe3O4/NiS NPs grafted activated carbon. The adsorption kinetics was more accurately described via the pseudo-second order model; nevertheless, the isothermal data showed that the Langmuir model was most suitable. The monolayer adsorption capacity for 2,4-D was 208.26 ± 15.75 mg/g at 328 K. The favourability and spontaneity of the adsorption process were demonstrated by thermodynamic studies. The adsorbent displayed exceptional selectivity for 2,4-D and high stability in multi-cycle use. Electrostatic attraction, π-π stacking, and hydrogen bonding were all believed to have an impact on the sorbent’s robust 2,4-D adsorption. Analyses of real tap and Nile River water samples showed little effect of the sample matrix on 2,4-D adsorption. This study presents an innovative approach for developing highly efficient adsorbent from natural biomass and offers an affordable way to recycle algal waste into beneficial materials.Graphical

Mannitol as a resource for the growth and reproduction of Sargassum siliquastrum (Mertens ex Turner) C. Agardh

Mannitol as a resource for the growth and reproduction of Sargassum siliquastrum (Mertens ex Turner) C. Agardh

Facile and green synthesis of CuS-activated carbon nanocomposite from Sargassum siliquastrum biomass for fast and efficient removal of eosin yellow dye

AbstractSargassum spp. comprise significant amounts of biomass which can be risky for environmental and economic activities; thus, taking the advantage of this underutilized raw material could make a significant contribution to long-term sustainability. In this study, Sargassum siliquastrum (SS) brown alga was successfully transformed into CuS nanoparticles–activated carbon (CuS NPs–AC) composite for adsorption of the hazardous dye eosin yellow (EY) from aqueous solutions. The CuS NPs–AC sorbent was characterized through FTIR, XRD, SEM-EDX, and SBET analyses. Characterization results revealed the successful formation of CuS NPs–AC nanocomposite. Results of the adsorption process indicated that EY was efficiently removed with a percentage of 99.6% at the optimum conditions; pH 7, 120 min contact time, 2 g/L CuS NPs–AC dose, and 300 mg/L initial EY concentration. Adsorption data fitted well with pseudo-second-order kinetics and Langmuir isotherm model with a monolayer adsorption capacity of 303.03 mg/g at 328 K. Thermodynamic analyses revealed that the adsorption process was spontaneous and endothermic. The adsorbent showed high selectivity towards EY and followed a three-stage intraparticle diffusion mechanism. The potent adsorption of EY by CuS NPs–AC nanocomposite was attributed to electrostatic attraction, π-π stacking, halogen bonding, and hydrogen bonding. This study developed a reliable and cost-effective adsorbent for removing EY dye from water. Graphical Abstract

The Anti-Inflammatory Effect of Low Molecular Weight Fucoidan from Sargassum siliquastrum in Lipopolysaccharide-Stimulated RAW 264.7 Macrophages via Inhibiting NF-κB/MAPK Signaling Pathways.

Brown seaweed is a rich source of fucoidan, which exhibits a variety of biological activities. The present study discloses the protective effect of low molecular weight fucoidan (FSSQ) isolated from an edible brown alga, Sargassum siliquastrum, on lipopolysaccharide (LPS)-stimulated inflammatory responses in RAW 264.7 macrophages. The findings of the study revealed that FSSQ increases cell viability while decreasing intracellular reactive oxygen species production in LPS-stimulated RAW 264.7 macrophages dose-dependently. FSSQ reduced the iNOS and COX-2 expression, inhibiting the NO and prostaglandin E2 production. Furthermore, mRNA expression of IL-1β, IL-6, and TNF-α was downregulated by FSSQ via modulating MAPK and NF-κB signaling. The NLRP3 inflammasome protein complex, including NLRP3, ASC, and caspase-1, as well as the subsequent release of pro-inflammatory cytokines, such as IL-1β and IL-18, release in LPS-stimulated RAW 264.7 macrophages was inhibited by FSSQ. The cytoprotective effect of FSSQ is indicated via Nrf2/HO-1 signaling activation, which is considerably reduced upon suppression of HO-1 activity by ZnPP. Collectively, the study revealed the therapeutic potential of FSSQ against inflammatory responses in LPS-stimulated RAW 264.7 macrophages. Moreover, the study suggests further investigations on commercially viable methods for fucoidan isolation.

Anti-Neuroinflammatory Meroterpenoids from a Chinese Collection of the Brown Alga Sargassum siliquastrum.

Nine new chromane-type meroterpenoids, including the rare nor-meroterpenoid sargasilol A (1) and the eight meroditerpenoids sargasilols B-I (2-9), were isolated from a China Sea collection of the brown alga Sargassum siliquastrum, together with six known analogues (10-15). The structures of the new chromanes were identified by extensive spectroscopic analysis and by comparison with previously reported data. Compounds 1-3 and 6-15 exhibited inhibition against LPS-induced NO production in BV-2 microglial cells, and 1, with a shorter carbon chain, was the most active one. Compound 1 was established as an anti-neuroinflammatory agent through targeting the IKK/IκB/NF-κB signaling pathway. As such, the chromanes from brown algae could provide promising anti-neuroinflammatory lead compounds for further structural modification.

A novel Sargassum siliquastrum-stabilized MnS nanospheres for malachite green adsorption from aqueous solutions

ABSTRACT In this study, the marine alga Sargassum siliquastrum was used for the first time as a stabilizer for the preparation of manganese sulfide nanoparticles (MnS NPs). After characterization, the resulting MnS NPs were literature-first applied for adsorption of malachite green (MG) cationic dye. Characterizations indicated the formation of a spherical, monodispersed, mesoporous mixture of γ-MnS (56%) and α-MnS (46%) with a small crystallite size of 19 nm and a high surface area of 156.7 m2/g. After stepwise optimization of various parameters affecting the adsorption process, MG was 99.7% removed within 60 min from neutral solution by 0.2 g/L of MnS NPs at 298 K. The data of MG adsorption are best fitted by Langmuir isotherm (R2 ≥ 0.99) with a maximum adsorption capacity of 432.2 mg/g at 328 K. Pseudo-second order (R2 = 0.99) is the most appropriate to describe adsorption kinetics. In addition, thermodynamic results revealed that the adsorption is endothermic and spontaneous. Stability and interference studies showed that MnS NPs are highly stable and more selective for MG removal than other dyes. Upon these results, MnS NPs can be applied for the effective removal of MG from various water samples.

Suppression of adipogenesis by Au nanostructures-conjugated Sargassum seaweed extracts in 3 T3-L1 adipocytes

Recently, with the development of metal nanostructure synthesis technology, Au nanostructures (AuNPs) are synthesized using seaweed extract without using an organic solvent and applied to the pharmaceutical field. In this regard, in this study, AuNPs biosynthesis was mediated through extracts of two brown algae (Sargassum siliquastrum [SS] and Sargassum horneri [SH]) without the use of stabilizers or surfactants. In addition, we investigated the effects of SS-AuNPs (SS-functionalized AuNPs) and SH-AuNPs (SH-functionalized AuNPs) on adipogenesis in adipocytes and their underlying molecular mechanisms. A rapid and simplified synthesis of SS-AuNP and SH-AuP was achieved using aqueous extracts of SS and SH. The morphology, structure and composition of SS-AuNPs and SH-AuNPs were characterized by DLS, FTIR, UV–Vis spectroscopy, HR-TEM and EDS analysis. The stable monodisperse SS-AuNPs and SH-AuPs were synthesized with mean sizes of 17.47 ± 0.13 nm and 21.0 ± 2.74 and zeta potentials of −31.9 ± 0.75 and −34.57 ± 4.43, the biosynthetic AuNPs with the face-centered structure of SS-AuNPs and SH-AuPs had crystalline characteristics, and many functional groups that play an important role in the biological reduction present in the SS and SH extracts were adsorbed on the surfaces of the SS-AuNPs and SH-AuPs. This study was conducted to investigate the effect of SS-AuNPs and SH-AuPs on adipogenesis in adipocytes. SS-AuNPs and SH-AuPs reduced morphological changes and increased lipid accumulation by approximately 80% compared with that in mature adipocytes (MDI-induced). This result was accompanied by a reduction in the triglyceride content. SS-AuNPs and SH-AuPs suppressed lipid accumulation by downregulating C/EBPα, PPARγ, SREBP 1, FAS, and aP2 mRNA and protein expression. Furthermore, SS-AuNPs and SH-AuPs induced the mRNA and protein expression of UCP1, PRDM16, and PGC1α to increase mitochondrial biogenesis in mature adipocytes and effectively induced brown adipogenesis. SS-AuNPs and SH-AuPs have potent anti-adipogenic effects and can be used as potential therapeutic agents for obesity.

Ethanol Extract of Sargassum siliquastrum Inhibits Lipopolysaccharide-Induced Nitric Oxide Generation by Downregulating the Nuclear Factor-Kappa B Signaling Pathway.

Sargassum siliquastrum (SS) is an edible brown seaweed widely consumed in Korea and considered a functional food source. Previous studies have reported various biological activities of SS extracts, including antioxidant and hepatoprotective properties. In the present study, we examined the anti-inflammatory effects of the SS extract and assessed the underlying mechanism of action. The SS extract significantly inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO) production in a dose-dependent manner (% of NO production at 500 μg/mL: 60.1 ± 0.9%), with no obvious toxicity. Furthermore, the SS extract inhibited mRNA and protein expression levels of inducible NO synthase, as well as LPS-induced expression and production of proinflammatory cytokines such as IL-1β, IL-6, or TNF-α (IL-6 production (ng/mL) : LPS−: 0.7 ± 0.3; LPS+: 68.1 ± 2.8; LPS + SS extract: 51.9 ± 1.2; TNF-α production (ng/mL) : LPS−: 0.3 ± 0.1; LPS+: 23.0 ± 0.1; LPS + SS extract: 18.2 ± 10.8). Mechanistically, the SS extract attenuated LPS-induced activation of the nuclear factor kappa-light-chain-enhancer of activated B cells (nuclear factor-kappa B, NF-κB) signaling pathway such as phosphorylation of NF-κB p65 and degradation of IκB-α, thereby blocking LPS-induced activation of NF-κB transcriptional activity. The SS extract also enhanced LPS-induced heme oxygenase-1 expression and attenuated LPS-induced cellular reactive oxygen species production (% of ROS production at 500 μg/mL: 52.2 ± 1.3%). Collectively, these findings suggest that the SS extract elicits anti-inflammatory effects in mouse macrophage cells.

The Effect of Sargassum siliquastrum Supplementation on Growth Performance, Cecal Fermentation, Intestine Histomorphology, and Immune Response of Japanese Quails.

Simple SummaryMarket demand is predicted to rise as the growing scope of seaweed-based applications, as feed additives for poultry, expands. Seaweeds are a rich source of essential nutrients and bioactive substances, including polysaccharides and trace elements. Seaweeds also have prebiotic properties that help birds perform better and could be utilised instead of antibiotics. Only a few studies have examined the effect of brown seaweed (Sargassum siliquastrum) supplementation on bird performance, but to our knowledge, there have been no studies regarding the effect of S. siliquastrum supplementation on the bird’s cecal fermentation and microbial populations. Hence, this research aimed to evaluate the impact of S. siliquastrum supplementation on performance, cecal fermentation, and microbial populations, as well as on the immunological response in Japanese quails. The results indicated that the studied S. siliquastrum supplement improved the performance, cecal fermentation, microbial populations, intestinal morphology, and immunological response in Japanese quails. Hence, this research implies that a dietary S. siliquastrum supplement for quails could be a viable feed additive alternative.This study aimed to investigate the dietary effects of Sargassum siliquastrum on the growth performance, nutrient digestibility, cecal fermentation, microbial populations, antioxidant status, immune response, and intestine histomorphology of Japanese quails. A total of 450 Japanese quails, aged 7 days, weighing 27.35 ± 0.23 g, were randomly distributed to three dietary groups in a 42-day feeding experiment. Five replicates were prepared per group, with each replicate consisting of 30 chicks in a cage. The three dietary groups consisted of a basal diet (0% supplementation, which was the control) and diets supplemented with 1% and 2% of S. siliquastrum. The results showed that the S. siliquastrum-supplemented groups and the control group had similar final body weight (FBW), average body gain (ADG), and average feed intake (ADFI). However, the S. siliquastrum-supplemented groups had a better feed conversion ratio (FCR), as well as a lower mortality rate, compared to the control group. S. siliquastrum supplementation improved the nutrient digestibility of dry matter (DM), organic matter (OM), crude protein (CP), and crude fiber (CF) (p < 0.05). The S. siliquastrum-supplemented groups exhibited the heaviest empty intestine and cecum weights, as well as the longest intestinal and cecal length. Furthermore, the total volatile fatty acid (VFA) and the propionic acid concentrations increased significantly in quails fed S. siliquastrum-supplemented diets (p < 0.05), although the concentration of NH3-N decreased (p < 0.05). The dietary inclusion of S. siliquastrum had a beneficial effect on cecal microbial populations, where the Lactobacillus sp. counts increased, and the E. coli and Clostridium perfringens counts decreased. The histopathological examination of the duodenum confirmed that S. siliquastrum dietary supplementation enhanced the height and width of the villi. Quails fed S. siliquastrum-supplemented diet exhibited the highest total antioxidant capacity, superoxide dismutase, glutathione peroxidase, and glutathione reductase activities, but the thiobarbituric acid reactive substance was decreased (p < 0.05). Serum IgA, IgG, and IgM concentrations increased considerably (p < 0.05) in S. siliquastrum-supplemented groups. In conclusion, S. siliquastrum supplementation in the diet of Japanese quail can provide beneficial effects on performance, cecal fermentation, beneficial bacteria populations, and the immune response, and could be considered as an alternative feed additive in poultry production.

Effect of water velocity on the physiology of a collapsing Sargassum siliquastrum canopy under a controlled environment

SUMMARYSeaweed beds form a canopy affecting water flow in and around them, and therefore affect mass transport processes between the canopy and the surrounding seawater. Nutrients and physiological byproducts are transferred to and from the bulk seawater and the macroalgae surface, where they are absorbed or released. A change in the canopy structure caused by the interaction of the canopy with water motion affects mass transport and therefore affects physiological rates. Many previous studies reported that photosynthesis and nutrient uptake rates increase as water velocity increases, and recent studies have begun to examine how the interaction between water velocity and canopies affects mass transport. To elucidate how this interaction can affect the physiology of macroalgae, we measured the spatial distribution of water velocity around and in a Sargassum siliquastrum canopy and examined its impact on photosynthesis and dark respiration in a re‐circulating flume. We examined eight water velocities ranging from 0.5 to 40 cm s−1 and three canopy densities, where the spacings between individuals were 4, 6, and 8 cm. Dissolved oxygen concentrations were measured at each velocity for 2 h under dark conditions and for 1 h under 800 μmol photons m−2 s−1. As water velocity increased, the canopy began to bend with the flow and collapse, which was quantified by digital images. The gross photosynthesis rate and the dark respiration rate of the canopy increased as water velocity increased. However, the gross photosynthesis rates began to decrease beyond 9 cm s−1, whereas the dark respiration rates began to decrease beyond 4 cm s−1. Canopy density did not influence either of the rates. We conclude that increasing water velocities led to a collapse of the canopy, which inhibited water exchange between the canopy exterior and interior, and further led to the decline in physiological rates at high water velocity.

Potent inhibition of acetylcholinesterase by sargachromanol I from Sargassum siliquastrum and by selected natural compounds

Six hundred forty natural compounds were tested for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities. Of those, sargachromanol I (SCI) and G (SCG) isolated from the brown alga Sargassum siliquastrum, dihydroberberine (DB) isolated from Coptis chinensis, and macelignan (ML) isolated from Myristica fragrans, potently and effectively inhibited AChE with IC50 values of 0.79, 1.81, 1.18, and 4.16 µM, respectively. SCI, DB, and ML reversibly inhibited AChE and showed mixed, competitive, and noncompetitive inhibition, respectively, with Ki values of 0.63, 0.77, and 4.46 µM, respectively. Broussonin A most potently inhibited BChE (IC50 = 4.16 µM), followed by ML, SCG, and SCI (9.69, 10.79, and 13.69 µM, respectively). In dual-targeting experiments, ML effectively inhibited monoamine oxidase B with the greatest potency (IC50 = 7.42 µM). Molecular docking simulation suggested the binding affinity of SCI (−8.6 kcal/mol) with AChE was greater than those of SCG (−7.9 kcal/mol) and DB (−8.2 kcal/mol). Docking simulation indicated SCI interacts with AChE at Trp81, and that SCG interacts at Ser119. No hydrogen bond was predicted for the interaction between AChE and DB. This study suggests SCI, SCG, DB, and ML be viewed as new reversible AChE inhibitors and useful lead compounds for the development for the treatment of Alzheimer’s disease.

A novel antihypertension agent, sargachromenol D from marine brown algae, Sargassum siliquastrum, exerts dual action as an L-type Ca2+ channel blocker and endothelin A/B2 receptor antagonist

We isolated the novel vasoactive marine natural products, (5E,10E)-14-hydroxy-2,6,10-trimethylpentadeca-5,10-dien-4-one (4) and sargachromenol D (5), from Sargassum siliquastrum collected from the coast of the East Sea in South Korea by using activity-guided HPLC purification. The compounds effectively dilated depolarization (50mMK+)-induced basilar artery contraction with EC50 values of 3.52±0.42 and 1.62±0.63μM, respectively, but only sargachromenol D (5) showed a vasodilatory effect on endothelin-1 (ET-1)-induced basilar artery contraction (EC50=9.8±0.6μM). These results indicated that sargachromenol D (5) could act as a dual antagonist of l-type Ca2+ channel and endothelin A/B2 receptors. Moreover, sargachromenol D (5) lowered blood pressure in spontaneous hypertensive rats (SHRs) 2h after oral treatment at a dose of 80mg/kg dose and the effect was maintained for 24h. Based on our ex vivo and in vivo experiments, we propose that sargachromenol D (5) is a strong candidate for the treatment of hypertension that is not controlled by conventional drugs, in particular, severe-, type II diabetes-, salt-sensitive, and metabolic disease-induced hypertension.

New Chromene Derivatives with Radical Scavenging Activities from the Brown Alga Sargassum Siliquastrum

The organic extract of Sargassum siliquastrum exhibited in vitro radical scavenging activity in our screening of marine brown algae collected in Jeju Island, Korea. Bioactivity-guided fractionation of the organic extract led to the isolation of two new meroterpenoids, named sargachromanols S and T, along with the known meroterpenoids, isopolycerasoidol, nahocol D2, and sargachromanols D, E, G, and I. The planar structures of the new compounds were determined by the analysis of spectroscopic data obtained by HREIMS and 1D and 2D NMR. The structures of the new compounds sargachromanols S and T were closely related to those of previously isolated sargachromanols D and A, respectively. The isolated compounds showed radical scavenging activities in vitro against 1,1-diphenylpicrylhydrazyl and 2,2'-azidobis(3-ethylbenzothiazoline-6-sulfonate) radicals.

New chromene derivatives with radical scavenging activities from Brown Alga Sargassum siliquastrum

New chromene derivatives with radical scavenging activities from Brown Alga Sargassum siliquastrum

Defense mechanisms of sargassacean species against the epiphytic red alga Neosiphonia harveyi.

Flora diversity and abundance of epiphytes are specific to their basiphyte species and may relate to variations in the defensive abilities of basiphytes. Thus, investigating the interactions between epiphytes and basiphytes is useful for a better understanding of the biological impact of epiphytism and the survival strategies of basiphytes. We examined the epiphyte density on five sargassacean species at six locations between two study sites, which showed that the epiphytic red alga Neosiphonia harveyi was remarkably less abundant on Sargassum siliquastrum at all locations. To assess its defense mechanism against N.harveyi, we performed bioassays of phlorotannins, which are considered effective in deterring fouling, by culturing sargassacean blades with N.harveyi carpospores and observed the process by which sargassacean blades remove epiphytes. When the carpospores were incubated with various concentrations of dissolved phlorotannins, settlement and germination were inhibited only at the highest concentrations (>0.1g·L(-1) ), and this effect did not significantly differ among the five sargassacean species. When the carpospores were combined with blades from the five species, many of the spores attached and germinated on every blade. Because N.harveyi penetrated rhizoids into basiphyte tissues, cuticle peeling observed in all five sargassacean species could not remove this epiphyte after germination. However, in S.siliquastrum, the blade tissues around the germlings became swollen and disintegrative, and were removed together with the germlings. The spores normally grew on the dead blades, suggesting that the tissue degradation of S.siliquastrum is triggered by the infection of N.harveyi.

Isolation of Two New Meroterpenoids from Sargassum siliquastrum

Ocean Science & Technology School, Korea Maritime and Ocean University, Busan 606-791, KoreaReceived April 24, 2014, Accepted May 30, 2014Key Words : Sargassum siliquastrum , Chromanol, Meroterpenoid, CytotoxicityIn the course of our continuing phytochemical investi-gation of the algal genus Sargassum, we have recentlypublished antioxidant and cytotoxic effects of organic ex-tract of S. siliquastrum,

Novel isonahocol E3 exhibits anti-inflammatory and anti-angiogenic effects in endothelin-1-stimulated human keratinocytes

Endothelin-1 (ET-1) is reported to be a potent mitogenic and pro-angiogenic factor that plays a vital role in both physiological and pathological processes. ET-1 is implicated in dermal cell proliferation and skin disorders, such as psoriasis and atopic dermatitis. ET-1, endothelin ETA receptor, and endothelin ETB receptor could be potential targets for developing specific therapeutics to treat such disorders. Here, we provide the first report that an isonahocol [2,-5-dihydroxy-3-(13-hydroxy-3,-7,-11,-15-tetramethyl-12-oxo-hexadeca-2,-6,-14-trienyl)-phenyl]-acetic acid methyl ester (isonahocol E3) from the brown algae Sargassum siliquastrum has functional antagonistic activities against ET-1 induced inflammatory and pro-angiogenic effects. Isonahocol E3 significantly inhibited ET-1-induced cell proliferation, as well as inflammatory mediators, such as interleukin-6 (IL-6) and interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α), and pro-angiogenic factors including metalloproteinases in immortalized human keratinocytes. We also found that isonahocol E3 reduced expression level of endothelin ETA receptor, and endothelin ETB receptor as well as suppressed ET-1-induced extracellular signal-regulated kinase (ERK) phosphorylation. Taken together, our results suggest that isonahocol E3 can exert anti-inflammatory and anti-angiogenic activities at least by regulating the expression of ET-1 receptors and ERK signaling pathway.

Assessing the potential for recovery of a Sargassum siliquastrum community in Hong Kong

Tung Ping Chau Marine Park in Hong Kong was designated in 2001 with aims to protect its highly-diverse marine habitats from destructive human activities. Sargassum spp. (mainly Sargassum siliquastrum) formed a dense canopy in Lung Lok Shiu (LLS) in southwestern side of the Marine Park. This Sargassum bed, however, disappeared and a barren ground developed 7 years after the marine park designation. The increase in density of the short-spined sea urchin Anthocidaris crassispina, and thus the grazing pressure, as a result of restriction on its commercial fishery within the Marine Park was hypothesized as the immediate cause of the barren ground formation. In this study, we tested this hypothesis and manipulated the density of A. crassispina in exclusion cages underwater in LLS, where S. siliquastrum canopy originally existed. Transplantation of S. siliquastrum thalli and ceramic tiles with their recruits was carried out in these cages in February–May 2012 and May 2013. The results showed that the transplanted Sargassum thalli could not survive outside exclusion cages, whereas the induced recruits were almost wiped out in all tiles even inside exclusion cages. This provides evidence that the sea urchin A. crassispina could have overgrazed S. siliquastrum thalli and decimated the Sargassum canopy in LLS. It also suggested that other than A. crassispina, other grazers also contributed to the removal of S. siliquastrum recruits. Therefore, natural recovery of Sargassum bed seems unlikely if the grazing pressure remains high in this site. Proactive management strategies may need to be adapted to restore this Sargassum bed.

Preparative isolation of sargachromanol E from Sargassum siliquastrum by centrifugal partition chromatography and its anti-inflammatory activity.

Centrifugal partition chromatography (CPC) can be used to isolate various bioactive compounds from natural materials by one-step. We confirmed antioxidative compounds existed in chloroform (CHCl3) fraction of Sargassum siliquastrum using online-HPLC. Fractions (A, B, C, D and E) were separated from the CHCl3 fraction by preparative CPC (n-hexane:ethyl acetate:methanol:water, 5:5:7:3, v/v). In this study, we proved that the isolated compounds exhibit anti-inflammatory activities using lipopolysaccharide (LPS) stimulated RAW 264.7 macrophages. The fraction A which exhibited the strongest inhibitory effect on nitric oxide (NO) production level, was confirmed as sargachromanol E by LC-MS-ESI, (1)H NMR and (13)C NMR data. The sargachromanol E significantly reduced the inflammatory response in LPS induced macrophages, decreasing LPS-induced transcription factor of pro-inflammatory cyclooxygenase-2, NO synthase, phosphate P38, phosphate ERK1/2, LPS-stimulated tumor-necrosis factor alpha, interleukin-1 beta and prostaglandin E2 release. In conclusion, it was suggested that sargachromanol E inhibited inflammation in LPS induced RAW 264.7 cells via MAPK pathway.