Marine-derived Phoma—the gold mine of bioactive compounds

The genus Phoma contains several species ubiquitously present in soil, water, and environment. There are two major groups of Phoma, viz., terrestrial and marine. After 1981 researchers all over the world have focused on marine-derived Phoma for their bioactive compounds. The marine Phoma are very rich sources for novel bioactive secondary metabolites, which could potentially be used as drugs. Recently, a large number of structurally unique metabolites with potential biological and pharmacological activities have been isolated from the marine Phoma species particularly Phoma herbarum, P. sorghina, and P. tropica. These metabolites mainly include diterpenes, enolides, lactones, quinine, phthalate, and anthraquinone. Most of these compounds possess antimicrobial, anticancer, radical scavenging, and cytotoxic properties. The present review has been focused on the general background of Phoma, current approaches used for its identification and their limitations, difference between terrestrial and marine Phoma species. In addition, this review summarizes the novel bioactive compounds derived from marine Phoma and their biological activities.

     

Active Nematocyst Isolation Via Nudibranchs

Cnidarian venoms are potentially valuable tools for biomedical research and drug development. They are contained within nematocysts, the stinging organelles of cnidarians. Several methods exist for the isolation of nematocysts from cnidarian tissues; most are tedious and target nematocysts from specific tissues. We have discovered that the isolated active nematocyst complement (cnidome) of several sea anemone (Cnidaria: Anthozoa) species is readily accessible. These nematocysts are isolated, concentrated, and released to the aqueous environment as a by-product of aeolid nudibranch Spurilla neapolitana cultures. S. neapolitana feed on venomous sea anemones laden with stinging nematocysts. The ingested stinging organelles of several sea anemone species are effectively excreted in the nudibranch feces. We succeeded in purifying the active organelles and inducing their discharge. Thus, our current study presents the attractive possibility of using nudibranchs to produce nematocysts for the investigation of novel marine compounds.     

Expression and mutagenesis of the sea anemone toxin Av2 reveals key amino acid residues important for activity on voltage-gated sodium channels

Type I sea anemone toxins are highly potent modulators of voltage-gated Na-channels (Na(v)s) and compete with the structurally dissimilar scorpion alpha-toxins on binding to receptor site-3. Although these features provide two structurally different probes for studying receptor site-3 and channel fast inactivation, the bioactive surface of sea anemone toxins has not been fully resolved. We established an efficient expression system for Av2 (known as ATX II), a highly insecticidal sea anemone toxin from Anemonia viridis (previously named A. sulcata), and mutagenized it throughout. Each toxin mutant was analyzed in toxicity and binding assays as well as by circular dichroism spectroscopy to discern the effects derived from structural perturbation from those related to bioactivity. Six residues were found to constitute the anti-insect bioactive surface of Av2 (Val-2, Leu-5, Asn-16, Leu-18, and Ile-41). Further analysis of nine Av2 mutants on the human heart channel Na(v)1.5 expressed in Xenopus oocytes indicated that the bioactive surfaces toward insects and mammals practically coincide but differ from the bioactive surface of a structurally similar sea anemone toxin, Anthopleurin B, from Anthopleura xanthogrammica. Hence, our results not only demonstrate clear differences in the bioactive surfaces of Av2 and scorpion alpha-toxins but also indicate that despite the general conservation in structure and importance of the Arg-14 loop and its flanking residues Gly-10 and Gly-20 for function, the surface of interaction between different sea anemone toxins and Na(v)s varies.     

Do the Anemonefish Amphiprion ocellaris (Pisces: Pomacentridae) Imprint Themselves to Their Host Sea Anemone Heteractis magnifica (Anthozoa: Actinidae)?

Juvenile anemonefishes detect their host sea anemone by olfactory stimuli; in order to investigate whether this behaviour is innate or acquired, the anemonefish species Amphiprion ocellaris was bred in two different ways: 1. With no host sea anemone present at all (–A); and 2. With the specific host sea anemone Heteractis magnifica present in the hatching aquarium, so that these eggs were laid and hatched close to the sea anemone, as in nature (+A). The two different types of juvenile A. ocellaris were presented to the odours of the host sea anemone H. magnifica in two sets of short-term experiments with the host (a) visually hidden in a net cage, and (b) visible but physically separated from the anemonefishes. In both cases, a water flow was established between fishes and host. The +A-fishes found their host by olfactory and not by visual stimuli. In both series, the –A-fishes showed a significantly lower affinity behaviour towards the odour compounds from the host sea anemone than the +A-fishes did. A third type of experiment was a direct confrontation between fishes and host; here, the –A-fishes were indifferent towards the host sea anemone for almost 48 h, while the +A-fishes acclimated to the host sea anemone within the first 5 min of the direct confrontation. The results of this study suggest that Amphiprion ocellaris imprints itself olfactorily to its species-specific host sea anemone Heteractis magnifica, and, furthermore, may be genetically disposed towards olfactory recognition of the host sea anemone.     

Effects of neurotoxins (veratridine, sea anemone toxin, tetrodotoxin) on transmitter accumulation and release by nerve terminals in vitro.

Two of the tree toxic compounds used in this work, veratridine and the sea anemone toxin, provoke neurotransmitter release from synaptosomes; the third one, tetrodotoxin, prevents the action of both veratridine and the sea anemone toxin. The half-maximum effects of veratridine and sea anemone toxin actions on synaptosomes are K0.5 = 10 and 0.02 micronM, respectively. Although veratridine and the sea anemone toxin similarly provoke neurotransmitter release, they act on different receptor structures in the membrane. Tetrodotoxin antagonizes the effects of both veratridine and the sea anemone toxin. The half-maximum inhibitory concentration of tetrodotoxin is K0.5 = 4 nM for veratridine and 7.9 nM for ATXII. It is very similar to the dissociation constant measured from direct binding experiments with the radioactive toxin. The analysis of this antagonistic action offers an easy in vitro assay for tetrodotoxin interaction with its receptor.     

Materials on fauna of anemonefishes (Perciformes, Pomacentridae, Amphiprioninae) and host sea anemones (Cnidaria, Actiniaria) from Con Son Islands (South China Sea, Southern Vietnam)

The species composition of anemonefishes (Amphiprioninae) and host sea anemones (Actiniaria: Actiniidae, Stichodactylidae) from the Con Son Islands is given for the first time. The investigations carried out in archipelago waters revealed four species of the anemonefishes associated with four species of the host sea anemones: Amphiprion freanatus in the symbiosis with sea anemone Entacmaea quadricolor (Actiniidae), A. perideraion with sea anemone Heteractis magnifica (Stichodactylidae), A. sandaracinos with sea anemone Stichodactyla mertensii (Stichodactylidae), and A. polymnus with sea anemone S. haddoni. The possibility of larval carrying in one more species of anemonefishes, i.e., A. clarkii, into the water area of the Con Son Islands from the nearby regions of the South China Sea is discussed. The view on the probable revealing of this species in the investigated region in the future is expressed.     

Life in cellulose houses: symbiotic bacterial biosynthesis of ascidian drugs and drug leads

Ascidians (tunicates; sea squirts) are sources of diverse, bioactive natural products, one of which is an approved drug and many of which are potent drug leads. It has been shown that symbiotic bacteria living with ascidians produce some of the bioactive compounds isolated from whole animals, and indirect evidence strongly implicates symbiotic bacteria in the synthesis of many others. However, for the majority the producing organism has not been identified. In cases where a symbiotic origin has been definitively assigned, the resulting data lead to improved paths to drug discovery and development from marine animals. This review traces evidence for symbiotic production where such evidence exists and describes the strengths and limitations of that evidence.     

Unique carotenoid lactoside, P457, in Symbiodinium sp. of dinoflagellate

The dinoflagellates are a large group of unicellular alge in marine and fresh water. Some are an endosymbiont of marine animals. Photosynthetic dinoflagellates have peridinin, a light-harvesting carotenoid. In addition, a unique carotenoid, P457, was found from Amphinidium. The presence of P457 in Symbiodinium derived from marine animals has not been reported. We reconfirmed the molecular structure of P457, a neoxanthin-like carotenoid with an aldehyde group and a lactoside, from Symbiodinium sp. NBRC 104787 isolated from a sea anemone. In addition, we investigated the distribution of P457 and peridinin in various Symbiodinium and scleractinian coral species, and possible biosynthetic pathways of these carotenoids are proposed.     

Novel Group I Introns Encoding a Putative Homing Endonuclease in the Mitochondrial <Emphasis Type="Italic">cox1</Emphasis> Gene of Scleractinian Corals

Analyses of mitochondrial sequences revealed the existence of a group I intron in the cytochrome oxidase subunit 1 (cox1) gene in 13 of 41 genera (20 out of 73 species) of corals conventionally assigned to the suborder Faviina. With one exception, phylogenies of the coral cox1 gene and its intron were concordant, suggesting at most two insertions and many subsequent losses. The coral introns were inferred to encode a putative homing endonuclease with a LAGLI-DADG motif as reported for the cox1 group I intron in the sea anemone Metridium senile. However, the coral and sea anemone cox1 group I introns differed in several aspects, such as the intron insertion site and sequence length. The coral cox1 introns most closely resemble the mitochondrial cox1 group I introns of a sponge species, which also has the same insertion site. The coral introns are also more similar to the introns of several fungal species than to that of the sea anemone (although the insertion site differs in the fungi). This suggests either a horizontal transfer between a sponge and a coral or independent transfers from a similar fungal donor (perhaps one with an identical insertion site that has not yet been discovered). The common occurrence of this intron in corals strengthens the evidence for an elevated abundance of group I introns in the mitochondria of anthozoans. [Reviewing Editor: Dr. Niles Lehman]     

Seasonal production of primmorphs from the marine sponge Petrosia ficiformis (Poiret, 1789) and new culturing approaches

The need to produce bioactive compounds from marine sponges leads several groups of research to the culture of primmorphs from different species, which are generally maintained in aquaria for long time before processing. Here we present a study where the importance of several parameters on primmorphs production from the symbiotic sponge Petrosia ficiformis has been evaluated: (i) the sterility of sea water, (ii) the maintenance in aquarium before processing, (iii) the seasonal cycle. Sterility of sea water does not improve primmorphs production in this species. The maintenance of sponges in aquaria before processing negatively affects cell cultures. Regarding seasonality, it is evident that both the number and the size of primmorphs can deeply change depending on the period of the year the sponge is collected. April and July are the months that lead to the highest number of primmorphs, May and June are the months that lead to their biggest sizes. Possible relationships of these results with the life cycle of P. ficiformis are discussed.     

The amino acid sequence of toxin RpIII from the sea anemone, Radianthus paumotensis

The amino acid sequence of the sodium channel toxin RpIII from the sea anemone Radianthus paumotensis has been determined. The protein is homologous with five analogous toxins from three anemone species, and is most similar to a less toxic protein, RpII, from the same organism. Twelve residues are conserved in all six toxins, one of which is an arginine residue thought to be essential for toxicity. The others (Cys, Gly, Pro and Trp) tend to be conserved in other sets of homologous proteins to maintain functional folds. Comparisons of the sequences suggest the existence of two separate but related classes of toxins cumon the three species of anemone.     

海绵生物活性物质及海绵细胞离体培养

介绍了来自海绵的生物活性物质种类、分布及其潜在的应用价值。讨论了其作为抗癌、抗病毒、抗细菌等药用的生物活性物质及其相关的海绵种属 ;强调海绵生物活性物质的商业化和临床应用所面临的“供给短缺问题”。作为解决这一问题的途径之一 ,海绵细胞离体培养是最有前景的技术。讨论了海绵细胞离体培养技术的研究现状 ,存在的问题及未来的发展趋势。对我国海域的海绵生物活性物质的研究开发现状进行总结 ,强调海绵研究对开发具有我国自主知识产权的新药、新化合物的必要性及重要性 ,并提出进行研发的可能优先领域     

Biologically active polypeptides of sea anemones: Structure, function, and prospects for application

This paper presents the results of a structure-functional study of neurotoxins, actinoporins, and proteinase inhibitors from the tropical sea anemone Heteractis crispa (= Radianthus macrodactylus) and the low boreal sea anemone Oulactis orientalis. The new data significantly contribute to the knowledge of the mechanisms of action of polypeptides from marine coelenterates and can be useful for solving practical problems of the biotechnological development of medicines.     

Wound healing Activities of the bioactive compounds from Micrococcus sp. OUS9 isolated from marine water

Marine species are increasingly important as a source of specific biological active metabolites. Marine species comprise almost half of global biodiversity. Oceans and sea are thus the biggest source of positive natural compounds that could be utilized in the pharmaceutical industry as functional constituents. In the present study was to find out the wound healing property of the bioactive compounds from Micrococcus sp. OUS9 isolated from marine source. The in vivo wound healing activity was studied using excision wound model. The KLUF 10 and KLUF13 ointment was prepared and used to determine wound healing activity in albino rats. Topical application of the ointment enhanced the contraction of wound in contrast with rat control group. KLUF13 had shown strong healing ability in wounds and had a positive influence on the various phases of wound repair.     

Adaptable defense: a nudibranch mucus inhibits nematocyst discharge and changes with prey type

Nudibranchs that feed on cnidarians must defend themselves from the prey's nematocysts or risk their own injury or death. While a nudibranch's mucus has been thought to protect the animal from nematocyst discharge, an inhibition of discharge by nudibranch mucus has never been shown. The current study investigated whether mucus from the aeolid nudibranch Aeolidia papillosa would inhibit nematocyst discharge from four species of sea anemone prey. Sea anemone tentacles were contacted with mucus-coated gelatin probes, and nematocyst discharge was quantified and compared with control probes of gelatin only. Mucus from A. papillosa inhibited the discharge of nematocysts from sea anemone tentacles. This inhibition was specifically limited to the anemone species on which the nudibranch had been feeding. When the prey species was changed, the mucus changed within 2 weeks to inhibit the nematocyst discharge of the new prey species. The nudibranchs apparently produce the inhibitory mucus rather than simply becoming coated in anemone mucus during feeding. Because of the intimate association between most aeolid nudibranchs and their prey, an adaptable mucus protection could have a significant impact on the behavior, distribution, and life history of the nudibranchs.     

Biodiversity and potentials of marine-derived microorganisms

The marine environment is a prolific resource for the isolation of less exploited microorganisms. As a matter of fact, in the sea, untapped habitats exist with unique characteristics. In addition, the potential contribution of marine sources to the discovery of new bioactive molecules was recently recognized. Biosearch Italia possesses a collection of about 40 000 microorganisms, isolated from different ecological niches. In the search of new bioactive entities, investigations were expanded to marine habitats including marine sediments and organisms. More then 800 microorganisms have been isolated. About half belong to fungal genera, the others being actinomycetes. The frequency of antibiotic activities produced by these marine strains has been determined. Initial data are encouraging: marine isolates produce antibiotic activities with frequencies comparable to terrestrial ones. These activities probably represent a mixture of novel metabolites and known products previously discovered from terrestrial isolates. Further investigations are ongoing to assess the novelty of these observed microbiological activities.     

The sodium channel in non-impulsive cells Interaction with specific neurotoxins

The cell line C₉ used in this paper has a resting potential of ?50 mV (±10 mV) but is unable to generate an action potential upon electrical stimulation. The cell membrane has receptors for the selectivity filter toxin tetrodotoxin as well as for the gating system toxins, veratridine, scorpion toxin and sea anemone toxin. The Na⁺ channel which remains silent to electrical stimulation in the absence of toxins can be chemically activated by the gating system toxins. This has been demonstrated by electrophysiological techniques and by ²²Na⁺ flux studies. The electrophysiological approach has shown that the sea anemone toxin is able to induce a spontaneous slow-wave activity inhibited by tetrodotoxin. ²²Na⁺ influx analyses have shown that veratridine and the sea anemone toxin produce an important increase of the initial rate of ²²Na⁺ influx into the C₉ cell. The stimulation of ²²Na⁺ entry by these gating system toxins is similar to that found using spiking neuroblastoma cells. Veratridine and the sea anemone toxin on one hand as well as veratridine and the scorpion toxin on the other hand are synergistic in their action to stabilize an open and highly permeable form of the sodium channel. Stimulation of ²²Na⁺ entry into the cell through the sodium channel maintained open by the gating system neurotoxins is completely suppressed by tetrodotoxin.     

Searching for a Toxic Key to Unlock the Mystery of Anemonefish and Anemone Symbiosis

Twenty-six species of anemonefish of the genera Amphiprion and monospecific Premnas, use only 10 species of anemones as hosts in the wild (Families: Actiniidae, Stichodactylidae and Thalassianthidae). Of these 10 anemone species some are used by multiple species of anemonefish while others have only a single anemonefish symbiont. Past studies have explored the different patterns of usage between anemonefish species and anemone species; however the evolution of this relationship remains unknown and has been little studied over the past decade. Here we reopen the case, comparing the toxicity of crude venoms obtained from anemones that host anemonefish as a way to investigate why some anemone species are used as a host more than others. Specifically, for each anemone species we investigated acute toxicity using Artemia francisca (LC₅₀), haemolytic toxicity using ovine erythrocytes (EC₅₀) and neurotoxicity using shore crabs (Ozius truncatus). We found that haemolytic and neurotoxic activity varied among host anemone species. Generally anemone species that displayed greater haemolytic activity also displayed high neurotoxic activity and tend to be more toxic on average as indicated by acute lethality analysis. An overall venom toxicity ranking for each anemone species was compared with the number of anemonefish species that are known to associate with each anemone species in the wild. Interestingly, anemones with intermediate toxicity had the highest number of anemonefish associates, whereas anemones with either very low or very high toxicity had the fewest anemonefish associates. These data demonstrate that variation in toxicity among host anemone species may be important in the establishment and maintenance of anemonefish anemone symbiosis.     

海洋曲霉来源的新天然产物

海洋真菌由于其遗传背景复杂、代谢产物种类多且产量高,已成为海洋微生物新天然产物的主要来源,从我们对2010–2013年初的海洋微生物来源新天然产物的统计来看,研究最多的是曲霉属(Aspergillus)真菌,占海洋真菌来源新天然产物的31%。本文从菌株来源、化合物结构及其生物活性等方面,综述了自1992年第一个海洋曲霉天然产物到2014年8月已报道的共512个海洋曲霉来源的新天然产物。这些海洋天然产物具有丰富的化学多样性,且36%的化合物表现出细胞毒、抑菌、抗氧化和抗寄生虫等生物活性;含氮化合物是其主要的结构类型、约占曲霉源海洋天然产物总数的52%,也是出现活性化合物比例最高的结构类型、约40%的含氮化合物具有生物活性,其中脱氢二酮哌嗪生物碱halimide的化学衍生物plinabulin已结束II期临床研究,并于2015年第三季度开始在美国和中国进行III期临床研究,用于治疗转移性的晚期非小细胞肺癌。     

Toxicity and speciation analysis of organotin compounds

Abstract

The use of antifouling paints in shipbuilding has led to a significant concentration of organotin compounds in the marine environment. Antifouling paints have become the main source of tributyltin and triphenyltin derivatives loaded into the sea. The toxicity of organotin compounds has been of great concern. High concentrations of organotin compounds are associated with growth abnormalities in mussels and oysters and have also resulted to the decline in their abundance. High concentration of organotin compounds have also been found in the tissues of marine mammals and its presence has been linked to mass mortalities of marine mammals. It causes imposex and calcification anomalities in mollusks. Seafood is thought to be a possible source of organotin compounds in human. Therefore, to evaluate the environmental distribution and fate of these compounds and to determine the effectives of legal provisions adopted by a number of countries, a variety of analytical methods have been developed for the speciation of organotin compounds in the environment. A detailed review of the toxicity and chemical speciation of organotin compounds is given.