Bromophenols of Rhodomela larix: Chemotaxonomy of morphological forms

The bromophenols of two morphological forms of Rhodomela larix were examined. GLC-MIS analyses revealed five bromophenols in a low intertidal form of the alga and four of the same compounds in a tidepool form. The results are discussed in relation to the chemotaxonomy of the species.     

Correlations between primary and secondary metabolites in Ceramiales (Rhodophyta)

A correlation between the presence of terpenes and floridosides and between the presence of bromophenols and digeneaside was observed in species of red algae belonging to the order Ceramiales. This observation suggests a division in Ceramiales that can be easily detected through the presence of the secondary metabolites, terpenes and bromophenols.     

Bromophenol accumulation and sediment contamination by the marine annelids Notomastus lobatus and Thelepus crispus

The occurrence of bromophenols in Notomastus lobatus and Thelepus crispus and associated sediment and porewater was determined. 4-Bromophenol, 2,4-dibromophenol, and 2,4,6-tribromophenol were identified in N. lobatus with the highest concentrations occurring in the anterior and posterior abdomen and substantially less in the thorax (345, 209, and 6.6 μg/ml of worm, respectively). The concentration of dibromobenzyl alcohol was highest in the tail (last 15 setigers) of T. crispus (1.02 mg/ml of worm), but did not differ among body parts as the bromophenols did in N. lobatus. Concentrations in sediments were significantly reduced from those in the worms and decreased from the inner burrow lining out to 5 cm from N. lobatus burrows. Similarly for T. crispus, concentrations of dibromobenzyl alcohol in the surrounding sediments and porewater were low and increased with proximity to the burrow. For both species, concentrations in surface sediment (upper 1 cm) did not differ from those at 6 cm depth. Several lines of evidence indicate that these compounds are produced by the worms and hence their presence in sediments is derived from the worms. The contamination of sediment by these bromophenols has important implications for the structure and activities of benthic-associated communities.     

Screening marine algae from China for their antitumor activities

Thirty-nine species of marine algae collected from the coast of China were screened for their antitumor activities, and eight species Leathesia difformes, Polysiphonia urcedata, Scytosiphon lomentarius, Gloiopeliis furcata, Punctaria latifolia, Symphyocladia latiuscula, Rhodomela confervoides and Ulva pertusa showed potent cytotoxic activities. Three, Rhodomela confervoides, Scytosiphon lomentarius and Gloiopeliis furcata, were used for further investigation. More than 30 compounds were isolated and purified, and 14 bromophenols, 1 steroid and 1 carotene were identified by advanced spectroscopic methods including IR, MS, and NMR techniques. Amongst the 16 identified compounds, 7 showed vigorously selective activities against KB, Bel7402 and A549 cancer cells, and 6 bromophenols were new compounds.     

Metabolism of 4-hydroxybenzaldehyde, 3-bromo-4-hydroxybenzaldehyde and bromide by cell-free fractions of the marine red alga Odonthalia floccosa

Cell-free fractions from Odonthalia floccosa incubated with 4-hydroxybenzaldehyde-[U-¹⁴C], 3-bromo-4-hydroxybenzaldehyde-[U-¹⁴C] and ⁸²Br^? formed the dibromo-dihydroxybenzaldehyde derivatives of the bromophenols (brominated benzylalcohols) which were also identified as naturally occurring products.     

Potent alpha-glucosidase inhibitors purified from the red alga Grateloupia elliptica

Diabetes mellitus is a most serious and chronic disease whose incidence rates are increasing with incidences of obesity and aging of the general population over the world. One therapeutic approach for decreasing postprandial hyperglycemia is to retard absorption of glucose by inhibition of α-glucosidase. Two bromophenols, 2,4,6-tribromophenol and 2,4-dibromophenol, were purified from the red alga Grateloupia elliptica. IC₅₀ values of 2,4,6-tribromophenol and 2,4-dibromophenol were 60.3 and 110.4 μM against Saccharomyces cerevisiae α-glucosidase, and 130.3 and 230.3 μM against Bacillus stearothermophilus α-glucosidase, respectively. In addition, both mildly inhibited rat-intestinal sucrase (IC₅₀ of 4.2 and 3.6 mM) and rat-intestinal maltase (IC₅₀ of 5.0 and 4.8 mM). Therefore, bromophenols of G. elliptica have potential as natural nutraceuticals to prevent diabetes mellitus because of their high α-glucosidase inhibitory activity.     

Red algal exotics on North Sea coasts

A total of ten red seaweed species are recognized as introduced into the North Sea from other parts of the world. These areAsparagopsis armata andBonnemaisonia hamifera (Bonnemaisoniales),Grateloupia doryphora (Halymeniales),Antithamnionella spirographidis, Antithamnionella ternifolia, Anotrichium furcellatum, Dasya baillouviana, ?Dasysiphonia sp.,Polysiphonia harveyi andPolysiphonia senticulosa (Ceramiales). The oldest of these isB. hamifera, introduced prior to 1890, while the most recent,?Dasysiphonia sp., was first found in 1994 and still requires taxonomic investigation. A variety of distribution patterns is seen, with geographical ranges varying from general within the North Sea to very restricted. The diversity of introduced red algae on eastern coasts of the North Sea is much greater than in the west. The most likely explanation for this pattern is that French coasts were the initial site of introduction for many of the seaweeds, which were then distributed northwards by the residual surface currents. Their increasing success in the Netherlands has probably been promoted by the drastically changed local hydrodynamic conditions which have also permitted the recent introduction of many native European species. Of the biological features of species that may favour their success as introductions, clonal vegetative propagation, often with specialized propagules or fragmentation mechanisms, is almost ubiquitous. Low-temperature tolerances can be inferred, but data are sparse. Many of the alien red algae in the North Sea contain anti-grazing compounds such as bromophenols, which may contribute to their invasive potential by deterring grazing sufficiently to permit establishment of an inoculum.     

Synthesis and characterization of novel bromophenols: Determination of their anticholinergic,antidiabetic and antioxidant activities

In this paper, a series of novel bromophenol derivatives were synthesized and evaluated for their acetylcholinesterase and α-glycosidase enzymes inhibition properties and antioxidant activity. Diarylmethanones were synthesized and their bromination was carried out. During bromination, some compounds gave new bromophenols via regioselective O-demethylation. Demethylation of brominated diarylmethanones was also performed with BBr₃ to give novel bromophenols. In addition, we examines the antioxidant capacity of novel bromophenol derivatives using several in vitro bioanalytical methodologies such as 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS⋅⁺) and 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) radical scavenging activity, Fe³⁺ and Cu²⁺ reducing activities and ferrous (Fe²⁺) ions chelating activities. Also, novel bromophenols and methoxylated bromophenols derivatives were tested against acetylcholinesterase and α-glycosidase, which associated with some metabolic diseases. The novel bromophenols showed Ki values in range of 8.94 ± 0.73–59.45 ± 14.97 nM against AChE and 4.31 ± 1.93–44.14 ± 2.19 nM against α-glycosidase.     

Bromochlorophenols and a brominated diphenylmethane in red algae

Identification of chlorinated bromophenols and a 2,3,2′,3′-tetrabromo-4,5,4′,5′-tetrahydroxydiphenylmethane in Polysiphonia nigrescens and Rhodomela confervoides was made by stepwise extraction followed by GC-MS analysis. Four different forms of the brominated and brominated-chlorinated benzyl alcohols in red algae are suggested (i) free phenols, (ii) sulphated potassium salts, (iii) constituents of brominated diphenylmethanes and (iv) part of the red pigment floridorubin.     

Synthesis and Biological Activity of Some Bromophenols and Their Derivatives Including Natural Products

In addition to the first synthesis of the natural bromophenol butyl 2-(3,5-dibromo-4-hydroxyphenyl)acetate ( 1 ), indene derivatives 34 and 35 were synthesized from 3-phenylpropenal derivatives in BBr₃ medium. Five known natural bromophenols and some derivatives were synthesized by known methods. Cholinesterase (ChEs) inhibitors reduce the breakdown of acetylcholine and are used in the treatment of Alzheimer's disease (AD) and dementia symptoms. The inhibition effects of all obtained compounds were examined towards acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and α-glycosidase enzymes. All synthesized compounds demonstrated the strong inhibition effects against both cholinergic enzymes. For determination of Ki values of novel bromophenols Lineweaver-Burk graphs were obtained. Ki values were found in the ranging of 0.13–14.74 nM for AChE, 5.11–23.95 nM for BChE, and 63.96–206.78 nM for α-glycosidase, respectively. All bromophenols and their derivatives exhibit effective inhibition profile when compared to positive controls.     

Fishborne Trematode Metacercariae in Freshwater Fish from Guangxi Zhuang Autonomous Region, China

A survey was performed to investigate the infection status of fishborne trematode (FBT) metacercariae in freshwater fish from Guangxi Zhuang Autonomous Region, China. A total of 307 freshwater fish of 31 species were collected from 5 administrative regions of Guangxi Zhuang Autonomous Region. They were examined by artificial digestion method from July 2003 to August 2004. No metacercariae were detected in fish from Fusui-xian. In fish from Mashan-xian and a market in Nanning, 3 species of metacercariae, Haplorchis taichui, Haplorchis pumilio, and Centrocestus formosanus, were mainly detected. Metacercariae (8 in number) of Clonorchis sinensis were found in 1 Chanodichthys dabryi purchased from a market in Nanning. In fish from Yangshuo, Metagonimus yokogawai metacercariae were detected from all 18 fish species examined. Total 13 C. sinensis metacercariae were found in 3 out of 10 Hemibarbus maculatus from Yangshuo. All 7 Zacco platypus from Yangshuo were infected with 8-112 Echinochasmus perfoliatus metacercariae. In fish from Binyang-xian, H. pumilo metacercariae were mainly detected in all 5 fish species examined, and only 1 metacercaria of C. sinensis was found in a Hemiculter leucisculus. From the above results, it was confirmed that some species of freshwater fish play a role of second intermediate hosts for FBT in Guangxi Zhuang Autonomous Region, China. In particular, 4 species of intestinal flukes, M. yokogawai, H. taichui, H. pumilio, and C. formosanus, were prevalent in fish hosts, whereas C. sinensis metacercariae were detected only in 3 fish species.     

Extracellular secretion of phenolic substances from living brown algae

The chemical structures of ultraviolet (UV)- absorbing substances secreted from the healthy living brown algae, Eisenia bicyclis and Ecklonia kurome, were demonstrated. The living activity of algal cells was critically examined using a confocal laser-scanning microscope after incorporation of fluorescein diacetate (FDA) into the cells. Using thin-layer chromatography (TLC), reversed-phase three-dimensional high-performance liquid chromatography (RP-3D-HPLC) and gas chromatography-mass spectrometry (GC-MS), it was found that the UV-absorbing substances (λ_max 265–270 nm) secreted from the living brown algae mainly consisted of the three monomeric bromophenols, 2,4-dibromophenol, 2,4,6-tribromophenol and dibromo-iodophenol, but not phloroglucinol or phlorotannins. The other minor compounds detected in the secretions were as follows: benzothiazole, fatty acids (14:1, 16:0 and 18:0 acids), franesol, 3-hydroxy-2,4,4-trimethylpentyl 2-methylpropanoate and squalene. Exudation of phloroglucinol and phlorotannins was ascertained to take place only after the cell death of these algae. These results indicate that, whilst the algae are alive, polymeric phlorotannins are strictly kept within the algal body, and only monomeric bromophenols are secreted into the seawater medium.     

Infection Status of Zoonotic Trematode Metacercariae in Fishes from Vientiane Municipality and Champasak Province in Lao PDR

The infection status of fishborne zoonotic trematode (FZT) metacercariae was investigated in fishes from 2 localities of Lao PDR. Total 157 freshwater fishes (17 species) were collected in local markets of Vientiane Municipality and Champasak Province in December 2010 and July 2011, and each fish was examined by the artificial digestion method. Total 6 species of FZT metacercariae, i.e., Opisthorchis viverrini, Haplorchis taichui, Haplorchis yokogawai, Haplorchis pumilio, Centrocestus formosanus, and Procerovum varium, were detected in fishes from Vientiane Municipality. The metacercariae of O. viverrini were detected in 50 (49.5%) out of 101 fishes (6 species), and their average number was 154 per fish infected. The remaining 5 species of heterophyid metacercariae were detected in 36.8%, 65.8%, 9.4%, 23.9%, and 5.1% fishes examined, and their average densities were 12, 1,038, 4, 15, and 13 per infected fish, respectively. In fishes from Champasak Province, 3 species of FZT metacercariae, i.e., O. viverrini, H. taichui, and H. yokogawai, were detected. Only 2 O. viverrini metacercariae were found in only 1 Barbonymus schwanefeldi. The metacercariae of H. taichui and H. yokogawai were detected in 60.0% and 50.0% of fishes examined, and their average densities were 47 and 28 per fish infected. By the present study, it has been confirmed that several species of FZT metacercariae are prevalent in fishes from Vientiane Municipality, with P. varium being a new member of FZT in Lao PDR. In comparison, FZT metacercariae are less prevalent in fishes from Champasak Province.     

Structure based design of compounds from natural sources for diabetes and inflammation

Medicinal plants and marine sources are important elements of indigenous medical systems worldwide. The natural drugs from medicinal plants and marine sources have received considerable interest in treatment of diabetes and inflammation. Based on literature, alpha glucosidase, aldose reductase and PTP1B enzymes were chosen as anti-diabetes targets and PLA₂ was chosen for the anti-inflammatory target. In our study, plant and bromophenols (BPs) inhibitors were screened using High Throughput Virtual screening (HTVS) followed by Induced Fit Docking (IFD) studies were carried out against diabetes and inflammation targets. The IFD result of natural inhibitors has showed favorable docking score, glide energy and hydrogen bonds interactions with the active site residues. Some of the natural inhibitors successively satisfied all the in silico parameters among the others and seem to be potent inhibitors against diabetes and inflammation.     

Using genetic analysis to determine the distribution,prevalence and diversity of Eimeria species in pest rabbits (Oryctolagus cuniculus) in Australia

To genetically assess the Australian distribution and frequency of Eimeria species in wild rabbits, with a primary focus on Eimeria intestinalis and Eimeria flavescens as possible additional agents of rabbit biocontrol, the distal colon and faecal samples from wild rabbits sourced from 26 Australian locations with mean annual rainfalls of between 252 mm and 925 mm were analysed using amplicon sequencing of the ITS1 region. Contrary to previous microscopy studies which had only detected E. flavescens on mainland Australia at Wellstead in south-west Western Australia, we detected this species at all 23 effectively sampled sites. The more pathogenic E. intestinalis was only found at 52.2% of sites. Three unique Eimeria genotypes were detected that did not align to the 11 published sequences using a pairwise-match threshold of 90%, and may represent unsequenced known species or novel species. One genotype we termed E. Au19SH and was detected at 20 sites, E. Au19CO was detected at eight sites, and E. Au19CN was detected in one rabbit at Crows Nest (Qld). Site diversity ranged from only five Eimeria species at Boboyan (ACT) to 13 unique sequences at Cargo (NSW). Eimeria diversity in individual rabbits ranged from 11 unique sequences in a rabbit at Wellstead (WA) and a rabbit at Cargo (NSW), to one in 17 rabbits and zero in six rabbits. The three rabbit age classes averaged 4.3 Eimeria species per rabbit. No relationship was found between the number of Eimeria species detected and mean annual rainfall. As Eimeria species were found to be fairly ubiquitous at most sites they appear to be an unlikely additional candidate to assist the control of pest rabbits in Australia.     

Ellagitannins of the casuarinaceae,stachyuraceae and myrtaceae

Eight ellagitannins and related polyphenols, found in Casuarina stricta and Stachyurus praecox, were detected in the leaf of Psidium species. Five of them and a new polyphenol, named isostrictinin, were isolated from Psidium guajava. Most of these compounds were detected in several species of Myrtaceae, and 2, 3-hexahydroxydiphenoylglucose and 4, 6-hexahydroxydiphenoylglucose were found in some.     

Antimicrobial activities of the bromophenols from the red alga Odonthalia corymbifera and some synthetic derivatives

A series of bromophenols was obtained by isolation from red alga Odonthalia corymbifera and by reactions of bis(hydroxyphenyl)methanes with bromine. New bromophenols including 3,3',5,5'-tetrabromo-2,2',4,4'-tetrahydroxydiphenylmethane (10), a regioisomer of the potent antimicrobial natural product, together with known derivatives were synthesized in high yield. All of the isolated and synthesized compounds were tested for antimicrobial activity against gram-negative, gram-positive bacteria and fungi. The preliminary structure-activity relationship, to elucidate the essential structure requirements for antimicrobial activity, has been described. Among the isolated natural products 2,2',3,3'-tetrabromo-4,4',5,5'-tetrahydroxydiphenylmethane (4) was found to be the most active derivative against Candida albicans, Aspergillus fumigatus, Trichophyton rubrum, and Trichophyton mentagrophytes. The synthetic bromophenols 3,3'-dibromo-6,6'-dihydroxydiphenylmethane (13) and 3,3',5,5'-tetrabromo-6,6'-dihydroxydiphenylmethane (14) showed potent antibacterial effect against Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus, Proteus vulgaris, and Salmonella typhimurium.     

High Endemicity with Clonorchis sinensis Metacercariae in Fish from Yongjeon-cheon (Stream) in Cheongsong-gun,Gyeongsangbuk-do,Korea

The infection status with Clonorchis sinensis metacercariae (CsMc) was examined in freshwater fishes from Yongjeon-cheon (a branch of Nakdong-gang) located in Cheongsong-gun, Gyeongsangbuk-do, the Republic of Korea (Korea). A total of 750 fishes in 19 species were examined by the artificial digestion method for 2 years (2019 and 2020). CsMc were detected in 378 (51.4%) out of 735 fishes in 14 species (73.7%), and the infection intensity was 666 per fish infected. In 2019, CsMc were found in 172 (68.0%) out of 253 fishes in 10 species, and the infection intensity was 565 per fish infected. In 2020, CsMc were detected in 206 (62.2%) out of 331 fishes in 10 species, and the infection intensity was 751 per fish infected. The other zoonotic trematode, ie. Metagonimus spp., Centrocestus armatus, Echinostoma spp. and Clinostomum complanatum, metacercariae were also detected in fishes from the survey streams, but their endemicities were relatively low. Conclusively, it was first confirmed that CsMc are highly endemic in fishes from Yongjeon-cheon in Cheongsong-gun, Gyeongsangbuk-do, Korea.     

Bromine, Bromophenols and Floridorubin in the Red Alga Lenormandia prolifera

The pigment floridorunin was localized to the cuticle of the red alga Lenormandia prolifera (C. Ag.) J. Agardh by x-ray micro-analysis in Ihe transmission electron microscope and by its colour reactions in the light microscope. The pigment was set free from the cell wall by a pectinase. Bromine was also identified in the chloro-plasts. the middle lamellae, the intercellulars and the pore plugs of the alga. The content of bromophenols in the alga increases with increasing age. The cell walls of old plants are stratified and their outer parts are apparently shed. The bromophenols could have a function as regulators of the epiphytes or the shedding of parts of the outer cell wall.     

Toxic HAB species from the Sea of Okhotsk detected by a metagenetic approach,seasonality and environmental drivers

During recent decades, the distribution of harmful algal bloom (HAB) species has expanded worldwide together with the increase of blooms and toxicity events. In this study, the presence of toxic HAB species in the Sea of Okhotsk was investigated based on metagenetic data collected during 6 years of weekly monitoring. Operational taxonomic units (OTUs) associated with the toxic HAB species were detected based on amplifying 18S V7-V9 and 28S D1 rRNA gene regions. In total, 43 unique OTUs associated with toxic HAB species were revealed, with 26 of those previously not reported from the Sea of Okhotsk. More OTUs belonging to dinoflagellates were detected by 18S, whereas a similar number of OTUs associated with dinoflagellates and diatoms were detected by targeting the 28S region. Species belonging to genera Alexandrium, Karenia and Karlodinium were mainly associated with OTUs under Dinophyceae, whereas Bacillariophyceae was represented by the species belonging to genus Pseudo-nitzschia. From the detected OTUs, 22 showed a clear seasonal pattern with the majority of those appearing during summer-autumn. For Alexandrium pacificum, Aureococcus anophagefferens, and Pseudo-nitzschia pungens, the seasonal pattern was detected based on both rRNA regions. Additionally, 14 OTUs were detected during all seasons and two OTUs appeared sporadically. OTUs associated with the toxic species had low relative read abundances, which together with other factors such as similar and variable morphology as well as usage of fixatives, may explain why those species have previously not been detected by light microscopy. Environmental parameters, especially water temperature, significantly (<0.05) influenced the variability in OTU relative abundances and displayed significant (<0.05) correlations with the unique OTUs. The results of this study demonstrate the usefulness of the metagenetic approach for phytoplankton monitoring, which is especially relevant for detecting toxic HAB species.