The dynamics and geographic disjunction of the kelp Eisenia arborea along the west coast of Canada

Eisenia arborea has a disjunct distribution along the west coast of North America. We detail the current distribution of E. arborea and use long-term records to examine how present-day shifts in E. arborea prevalence and abundance in British Columbia (BC), relative to the dominant stipitate kelp Pterygophora californica, may be driven by interactions between changing grazing pressure and warming water. We further speculate on how the disjunction of E. arborea arose. The ancestor of E. arborea likely dispersed from Japan to North America where glaciation disrupted its distribution and speciation occurred. As glaciers retreated E. arborea likely dispersed into BC from warmer waters in the south and/or expanded from refugia off Vancouver Island and Haida Gwaii. While E. arborea is uncommon, our records extend its range into Alaska and Washington State. Along western Vancouver Island, BC, under warming conditions, E. arborea prevalence and abundance increased where once-extirpated sea otters (Enhydra lutris) removed urchins. Where otters were absent, however, reduced summer wave heights, associated with warming, apparently allowed urchins to graze shallow-water kelps, which declined. We suggest that under warming conditions, sea otters may increase kelp resilience, with E. arborea becoming more prevalent in NE Pacific kelp forests.

Revisiting a DNA barcode survey of Haida Gwaii kelp: the quest for Eisenia arborea (Arthrothamnaceae, Laminariales)

Eisenia arborea Areschoug is a temperate kelp first described from California, and commonly reported as far south as Mexico. Floristic surveys in cold-temperate waters of the Northeast Pacific, however, have revealed its presence on the Canadian archipelago of Haida Gwaii (at latitude 53.3799o N), last reported from the area in 2000 by Sloan and Bartier. Here, we present COI-5P data for E. arborea and confirm its presence at two sites on the west coast of Haida Gwaii in the years 2015 and 2018. These collections update a recently published list of genetically confirmed kelp species from Haida Gwaii. Our surveys suggest that northern populations of E. arborea are likely scattered throughout the western portions of the archipelago. The Haida Gwaii populations reported here represent potential monitoring sites for ecological and evolutionary investigations of E. arborea.

Virucidal and Synergistic Activity of Polyphenol-Rich Extracts of Seaweeds against Measles Virus

Although preventable by vaccination, Measles still causes thousands of deaths among young children worldwide. The discovery of new antivirals is a good approach to control new outbreaks that cause such death. In this study, we tested the antiviral activity against Measles virus (MeV) of Polyphenol-rich extracts (PPs) coming from five seaweeds collected and cultivated in Mexico. An MTT assay was performed to determine cytotoxicity effect, and antiviral activity was measured by syncytia reduction assay and confirmed by qPCR. PPs from Ecklonia arborea (formerly Eisenia arborea, Phaeophyceae) and Solieria filiformis (Rhodophyta) showed the highest Selectivity Index (SI), >3750 and >576.9 respectively. Both PPs extracts were selected to the subsequent experiments owing to their high efficacy and low cytotoxicity compared with ribavirin (SI of 11.57). The combinational effect of PPs with sulphated polysaccharides (SPs) and ribavirin were calculated by using Compusyn software. Synergistic activity was observed by combining both PPs with low concentrations of Solieria filiformis SPs (0.01 µg/mL). The antiviral activity of the best combinations was confirmed by qPCR. Virucidal assay, time of addition, and viral penetration evaluations suggested that PPs act mainly by inactivating the viral particle. To our knowledge, this is the first report of the virucidal effect of Polyphenol-rich extracts of seaweeds.

Orally Administered Phlorotannins from Eisenia arborea Suppress Chemical Mediator Release and Cyclooxygenase-2 Signaling to Alleviate Mouse Ear Swelling

Phlorotannin is the collective term for polyphenols derived from brown algae belonging to the genera Ascopyllum, Ecklonia, Eisenia, Fucus and Sargassum etc. Since the incidence of allergies is currently increasing in the world, there is a focus on phlorotannins having anti-allergic and anti-inflammatory effects. In this study, six purified phlorotannins (eckol; 6,6′-bieckol; 6,8′-bieckol; 8,8′-bieckol; phlorofucofuroeckol (PFF)-A and PFF-B) from Eisenia arborea, orally administered to mice, were examined for their suppression effects on ear swelling. In considering the suppression, we also examined whether the phlorotannins suppressed release of chemical mediators (histamine, leukotriene B4 and prostaglandin E2), and mRNA expression and/or the activity of cyclooxygenase-2 (COX-2), using RBL-2H3 cells, a cultured mast cell model. Results showed that the phlorotnannins exhibited suppression effects in all experiments, with 6,8′-bieckol, 8,8′-bieckol and PFF-A showing the strongest of these effects. In conclusion, orally administered phlorotannins suppress mouse ear swelling, and this mechanism apparently involves suppression of chemical mediator release and COX-2 mRNA expression or activity. This is the first report of the anti-allergic effects of the orally administered purified phlorotannins in vivo. Phlorotannins show potential for use in functional foods or drugs.

Evaluation of Anti-glycation Activities of Phlorotannins in Human and Bovine Serum Albumin-glyceraldehyde Models

The anti-glycation activities of phlorotannins contained in the Japanese Lessoniaceae ( Ecklonia cava, Eck. kurome, Eck. stolonifera, Eisenia arborea, and Eis. bicyclis) were tested using serum albumin-glyceraldehyde (GA) models. In the human serum albumin (HSA)-GA model and the bovine serum albumin (BSA)-GA model, the concentrations of crude phlorotannins at 50% inhibition (IC50) of fluorescent advanced glycation end products (AGEs) formation was in the range of 0.48 to 0.70 mg/mL and 0.52 to 0.75 mg/mL, respectively. In tests using phloroglucinol and purified phlorotannins (eckol, fucofuroeckol A, phlorofucofuroeckol A, dieckol, and 8,8'-bieckol), dieckol had the highest inhibitory activity (IC50: 5.5 × 102 μM) against fluorescent AGEs formation in HSA-GA model and showed about 18 times inhibition compared with aminoguanidine hydrochloride of positive control. In the BSA albumin model, 8,8'-bieckol had about 27 times AGEs formation inhibitory activity (IC50: 6.2 × 102 μM) against aminoguanidine hydrochloride. In tests on GA scavenging activity, it was shown that compounds with phloroglucinol tetramer or higher had a scavenging rate of 70%, or more, with a reaction time of 120 minutes. These results suggest that among the phlorotannins, in particular the dimers of eckol (dieckol and 8,8'-bieckol), there are effective compounds for inhibiting the formation of AGEs derived from GA.

Evaluation of Anti-glycation Activities of Phlorotannins in Human and Bovine Serum Albumin-methylglyoxal Models

In this study, the anti-glycation activities of phlorotannins contained in the Japanese Lessoniaceae ( Ecklonia cava, Eck. kurome, Eck. stolonifera, Eisenia arborea, and Eis. bicyclis) were tested using serum albumin-methlglyoxal (MGO) models. In the human serum albumin (HSA)-MGO model and the bovine serum albumin (BSA)-MGO model, the concentrations of crude phlorotannins at 50% inhibition (IC50) of fluorescent advanced glycation end products (AGEs) formation was in the range of 0.45 to 0.53 mg/mL and 0.43 to 0.53 mg/mL, respectively. Among the purified phlorotannins, phlorofucofuroeckol A with the benzobisbenzofuran skeleton had the highest inhibitory activities (IC50: 4.8 × 102 μM in HSA-MGO model and 4.1 × 102 μM in BSA-MGO model) against fluorescent AGEs formation, and showed about 13 times the inhibition in the HSA-MGO model, and about 20 times the inhibition in the BSA-MGO model, with respect to aminoguanidine hydrochloride, which was used as a positive control. In the test on MGO-scavenging activity using HPLC analysis, it showed that eckol and its simple dimers (dieckol and 8,8′-bieckol) had higher scavenging rate than aminoguanidine hydrochloride. In addition, it was revealed by liquid chromatography-electrospray ionization-mass spectrometry that eckol reacted with MGO and formed two adducts with it. These results strongly suggest that phlorotannins are novel and effective anti-glycation substances derived from natural plants.