Marine-Derived Leads as Anticancer Candidates by Disrupting Hypoxic Signaling through Hypoxia-Inducible Factors Inhibition

The inadequate vascularization seen in fast-growing solid tumors gives rise to hypoxic areas, fostering specific changes in gene expression that bolster tumor cell survival and metastasis, ultimately leading to unfavorable clinical prognoses across different cancer types. Hypoxia-inducible factors (HIF-1 and HIF-2) emerge as druggable pivotal players orchestrating tumor metastasis and angiogenesis, thus positioning them as prime targets for cancer treatment. A range of HIF inhibitors, notably natural compounds originating from marine organisms, exhibit encouraging anticancer properties, underscoring their significance as promising therapeutic options. Bioprospection of the marine environment is now a well-settled approach to the discovery and development of anticancer agents that might have their medicinal chemistry developed into clinical candidates. However, despite the massive increase in the number of marine natural products classified as 'anticancer leads,' most of which correspond to general cytotoxic agents, and only a few have been characterized regarding their molecular targets and mechanisms of action. The current review presents a critical analysis of inhibitors of HIF-1 and HIF-2 and hypoxia-selective compounds that have been sourced from marine organisms and that might act as new chemotherapeutic candidates or serve as templates for the development of structurally similar derivatives with improved anticancer efficacy.

Visible light promoted polyhalomethylation of alkenes: alkylation and cyclization

The report describes a visible light promoted carbochloromethylation of 2-bromomethyl acrylate and N-arylmethacrylamide, and a series of trihalomethyl substituted allylic acid esters and indolone derivatives were synthesized.

Antiprotozoal and Antitumor Activity of Natural Polycyclic Endoperoxides: Origin, Structures and Biological Activity

Polycyclic endoperoxides are rare natural metabolites found and isolated in plants, fungi, and marine invertebrates. The purpose of this review is a comparative analysis of the pharmacological potential of these natural products. According to PASS (Prediction of Activity Spectra for Substances) estimates, they are more likely to exhibit antiprotozoal and antitumor properties. Some of them are now widely used in clinical medicine. All polycyclic endoperoxides presented in this article demonstrate antiprotozoal activity and can be divided into three groups. The third group includes endoperoxides, which show weak antiprotozoal activity with a reliability of up to 70%, and this group includes only 1.1% of metabolites. The second group includes the largest number of endoperoxides, which are 65% and show average antiprotozoal activity with a confidence level of 70 to 90%. Lastly, the third group includes endoperoxides, which are 33.9% and show strong antiprotozoal activity with a confidence level of 90 to 99.6%. Interestingly, artemisinin and its analogs show strong antiprotozoal activity with 79 to 99.6% confidence against obligate intracellular parasites which belong to the genera Plasmodium, Toxoplasma, Leishmania, and Coccidia. In addition to antiprotozoal activities, polycyclic endoperoxides show antitumor activity in the proportion: 4.6% show weak activity with a reliability of up to 70%, 65.6% show an average activity with a reliability of 70 to 90%, and 29.8% show strong activity with a reliability of 90 to 98.3%. It should also be noted that some polycyclic endoperoxides, in addition to antiprotozoal and antitumor properties, show other strong activities with a confidence level of 90 to 97%. These include antifungal activity against the genera Aspergillus, Candida, and Cryptococcus, as well as anti-inflammatory activity. This review provides insights on further utilization of polycyclic endoperoxides by medicinal chemists, pharmacologists, and the pharmaceutical industry.

Radical-mediated alkoxypolyhaloalkylation of styrenes with polyhaloalkanes and alcohols via C(sp3)–H bond cleavage

A radical-mediated alkoxypolyhaloalkylation of styrenes with polychloroalkanes and alcohols for the facile synthesis of complex polyhaloalkanes with excellent functional-group compatibility and a broad substrate scope.

High-value compounds from the molluscs of marine and estuarine ecosystems as prospective functional food ingredients: An overview

Extensive biodiversity and availability of marine and estuarine molluscs, along with their their wide-range of utilities as food and nutraceutical resources developed keen attention of the food technologists and dieticians, particularly during the recent years. The current review comprehensively summarized the nutritional qualities, functional food attributes, and bioactive properties of these organisms. Among the phylum mollusca, Cephalopoda, Bivalvia, and Gastropoda were mostly reported for their nutraceutical applications and bioactive properties. The online search tools, like Scifinder/Science Direct/PubMed/Google Scholar/MarinLit database and marine natural product reports (1984-2019) were used to comprehend the information about the molluscs. More than 1334 secondary metabolites were reported from marine molluscs between the periods from 1984 to 2019. Among various classes of specialized metabolites, terpenes were occupied by 55% in gastropods, whereas sterols occupied 41% in bivalves. The marketed nutraceuticals, such as CadalminTM green mussel extract (Perna viridis) and Lyprinol® (Perna canaliculus) were endowed with potential anti-inflammatory activities, and were used against arthritis. Molluscan-derived therapeutics, for example, ziconotide was used as an analgesic, and elisidepsin was used in the treatment of cancer. Greater numbers of granted patents (30%) during 2016-2019 recognized the increasing importance of bioactive compounds from molluscs. Consumption of molluscs as daily diets could be helpful in the enhancement of immunity, and reduce the risk of several ailments. The present review comprehended the high value compounds and functional food ingredients from marine and estuarine molluscs.

Regiospecific and Stereoselective Ene Reaction of the A-Ring Methylcyclohexene Moiety of Polycyclic Terpenoid Systems with Dimethyl Acetylenedicarboxylate

Polycyclic terpenoid compounds with a methylcyclohexene moiety at the A-ring, such as 1 and 7, give a regio- and stereoselective ene reaction when heated at low temperatures with dimethyl acetylenedicarboxylate. The structure and stereochemistry of the compound formed in the case of 1, e.g. 5, is determined by X-ray analysis.

From Marine Origin to Therapeutics: The Antitumor Potential of Marine Algae-Derived Compounds

Marine environment has demonstrated to be an interesting source of compounds with uncommon and unique chemical features on which the molecular modeling and chemical synthesis of new drugs can be based with greater efficacy and specificity for the therapeutics. Cancer is a growing public health threat, and despite the advances in biomedical research and technology, there is an urgent need for the development of new anticancer drugs. In this field, it is estimated that more than 60% of commercially available anticancer drugs are natural biomimetic inspired. Among the marine organisms, algae have revealed to be one of the major sources of new compounds of marine origin, including those exhibiting antitumor and cytotoxic potential. These compounds demonstrated ability to mediate specific inhibitory activities on a number of key cellular processes, including apoptosis pathways, angiogenesis, migration and invasion, in both in vitro and in vivo models, revealing their potential to be used as anticancer drugs. This review will focus on the bioactive molecules from algae with antitumor potential, from their origin to their potential uses, with special emphasis to the alga Sphaerococcus coronopifolius as a producer of cytotoxic compounds.

Axonal Transport and Neurodegeneration: How Marine Drugs Can Be Used for the Development of Therapeutics

Unlike virtually any other cells in the human body, neurons are tasked with the unique problem of transporting important factors from sites of synthesis at the cell bodies, across enormous distances, along narrow-caliber projections, to distally located nerve terminals in order to maintain cell viability. As a result, axonal transport is a highly regulated process whereby necessary cargoes of all types are packaged and shipped from one end of the neuron to the other. Interruptions in this finely tuned transport have been linked to many neurodegenerative disorders including Alzheimer's (AD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) suggesting that this pathway is likely perturbed early in disease progression. Therefore, developing therapeutics targeted at modifying transport defects could potentially avert disease progression. In this review, we examine a variety of potential compounds identified from marine aquatic species that affect the axonal transport pathway. These compounds have been shown to function in microtubule (MT) assembly and maintenance, motor protein control, and in the regulation of protein degradation pathways, such as the autophagy-lysosome processes, which are defective in many degenerative diseases. Therefore, marine compounds have great potential in developing effective treatment strategies aimed at early defects which, over time, will restore transport and prevent cell death.

Alternative and efficient extraction methods for marine-derived compounds

Marine ecosystems cover more than 70% of the globe’s surface. These habitats are occupied by a great diversity of marine organisms that produce highly structural diverse metabolites as a defense mechanism. In the last decades, these metabolites have been extracted and isolated in order to test them in different bioassays and assess their potential to fight human diseases. Since traditional extraction techniques are both solvent- and time-consuming, this review emphasizes alternative extraction techniques, such as supercritical fluid extraction, pressurized solvent extraction, microwave-assisted extraction, ultrasound-assisted extraction, pulsed electric field-assisted extraction, enzyme-assisted extraction, and extraction with switchable solvents and ionic liquids, applied in the search for marine compounds. Only studies published in the 21st century are considered.

Statistical research on the bioactivity of new marine natural products discovered during the 28 years from 1985 to 2012

Every year, hundreds of new compounds are discovered from the metabolites of marine organisms. Finding new and useful compounds is one of the crucial drivers for this field of research. Here we describe the statistics of bioactive compounds discovered from marine organisms from 1985 to 2012. This work is based on our database, which contains information on more than 15,000 chemical substances including 4196 bioactive marine natural products. We performed a comprehensive statistical analysis to understand the characteristics of the novel bioactive compounds and detail temporal trends, chemical structures, species distribution, and research progress. We hope this meta-analysis will provide useful information for research into the bioactivity of marine natural products and drug development.

Diversity oriented synthesis and IKK inhibition of aminobenzimidazole tethered quinazoline-2,4-diones, thioxoquinazolin-4-ones, benzodiazepine-2,3,5-triones, isoxazoles and isoxazolines

The derivatization of resin-bound aminobenzimidazole toward the parallel solid-phase synthesis of aminobenzimidazole tethered pharmacologically important heterocycles such as quinazoline-2,4-diones, thioxoquinazolin-4-ones, benzodiazepine-2,3,5-triones, isoxazoles and isoxazolines is reported. All the compounds were tested for IKK inhibition. Only one compound elicited significant inhibition of IKKε, TBK-1 and IKK2.

Synthesis of α-tribromomethylamines via Mg-mediated addition of bromoform to imines

Mg-mediated addition of bromoform to electron deficient imines such as N-sulfonylimines affords α-tribromomethylated N-sulfonylamines in good to excellent yields. The procedure could be further simplified by transforming the imine precursors, α-sulfonyl-N-tosyl- and Boc-amines, in one pot to the corresponding α-tribromomethyl derivatives. Facile removal of the Boc protecting group in nearly quantitative yield and a silver carbonate mediated monodebromination have also been demonstrated.

A Model Study toward the Concise Synthesis of Bromotyrosine Derived Spiroisoxazoline Natural Products and Analogous Core Structures

A model study of the first non-aromatic ring based approach toward α-hydroxyspiroisoxazolines resembling the bromotyrosine derived natural product and analogous spiroisoxazoline core structures were implemented. The desired molecular architecture was achieved through the multifunctionalization of a key 1,3-diketo spiroisoxazoline. Our strategy could serve as an efficient alternative of previously developed approaches that utilize an aromatic ring oxidation as the essential step to synthesize this class of natural products.

Placotylene A, an inhibitor of the receptor activator of nuclear factor-κB ligand-induced osteoclast differentiation, from a Korean sponge Placospongia sp

A new inhibitor, placotylene A (1), of the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation, and a regioisomer of placotylene A, placotylene B (2), were isolated from a Korean marine sponge Placospongia sp. The chemical structures of placotylenes A and B were elucidated on the basis of 1D and 2D NMR, along with MS spectral analysis and revealed as an iodinated polyacetylene class of natural products. Placotylene A (1) displayed inhibitory activity against RANKL-induced osteoclast differentiation at 10 μM while placotylene B (2) did not show any significant activity up to 100 μM, respectively.

1,2-Alkylarylation of activated alkenes with dual C–H bonds of arenes and alkyl halides toward polyhalo-substituted oxindoles

Alkylarylation of N-arylacrylamides with alkyl halides through selective scission of the C(sp³)–H bond adjacent to halide atoms is presented.

Base-dependent stereodivergent intramolecular aza-Michael reaction: asymmetric synthesis of 1,3-disubstituted isoindolines

The nucleophilic addition (A(N)) / intramolecular aza-Michael reaction (IMAMR) process on Ellman's tert-butylsulfinyl imines, bearing a Michael acceptor in the ortho position, is studied. This reaction affords 1,3-disubstituted isoindolines with a wide range of substituents in good yields and diastereoselectivities. Interestingly, careful choice of the base for the aza-Michael step allows either the cis or the trans diastereoisomers to be exclusively obtained. This stereodivergent cyclization has enabled the synthesis of C2-symmetric bisacetate-substituted isoindolines. In addition, bisacetate isoindolines bearing two well-differentiated ester moieties are also noteworthy because they may allow for the orthogonal synthesis of β,β'-dipeptides using a single nitrogen atom as a linchpin.

Solid Phase Synthesis of Isoxazole and Isoxazoline-carboxamides via [2+3]-Dipolar Cycloaddition Using Resin-bound Alkynes or Alkenes

An efficient approach for the parallel solid phase synthesis of isoxazole and isoxazoline derivatives has been developed. The isoxazoles and isoxazolines were constructed through a 1,3-dipolar cycloaddition reaction of nitrile oxides, with resin-bound alkynes or alkenes. The cycloaddition reaction conditions performed on solid phase supports was optimized, and an array of resin bound carboxylic acid building blocks were utilized for distinct conversions. This methodology presents a new alternative to the diversity oriented synthesis of disubstituted isoxazoles and isoxazolines different from existing routes which are limited in structural diversity.

Synthetic strategies to terpene quinones/hydroquinones

The cytotoxic and antiproliferative properties of many natural sesquiterpene-quinones and -hydroquinones from sponges offer promising opportunities for the development of new drugs. A review dealing with different strategies for obtaining bioactive terpenyl quinones/hydroquinones is presented. The different synthetic approches for the preparation of the most relevant quinones/hydroquinones are described.

Trends in the discovery of new marine natural products from invertebrates over the last two decades--where and what are we bioprospecting?

It is acknowledged that marine invertebrates produce bioactive natural products that may be useful for developing new drugs. By exploring untapped geographical sources and/or novel groups of organisms one can maximize the search for new marine drugs to treat human diseases. The goal of this paper is to analyse the trends associated with the discovery of new marine natural products from invertebrates (NMNPI) over the last two decades. The analysis considers different taxonomical levels and geographical approaches of bioprospected species. Additionally, this research is also directed to provide new insights into less bioprospected taxa and world regions. In order to gather the information available on NMNPI, the yearly-published reviews of Marine Natural Products covering 1990-2009 were surveyed. Information on source organisms, specifically taxonomical information and collection sites, was assembled together with additional geographical information collected from the articles originally describing the new natural product. Almost 10000 NMNPI were discovered since 1990, with a pronounced increase between decades. Porifera and Cnidaria were the two dominant sources of NMNPI worldwide. The exception was polar regions where Echinodermata dominated. The majority of species that yielded the new natural products belong to only one class of each Porifera and Cnidaria phyla (Demospongiae and Anthozoa, respectively). Increased bioprospecting efforts were observed in the Pacific Ocean, particularly in Asian countries that are associated with the Japan Biodiversity Hotspot and the Kuroshio Current. Although results show comparably less NMNPI from polar regions, the number of new natural products per species is similar to that recorded for other regions. The present study provides information to future bioprospecting efforts addressing previously unexplored taxonomic groups and/or regions. We also highlight how marine invertebrates, which in some cases have no commercial value, may become highly valuable in the ongoing search for new drugs from the sea.

Synthesis of (±)-14-epi-hydroxydolasta-1(15),7,9-triene and (±)-7-epi-acetoxy-14-epi-hydroxydolasta-1(15),8-diene*Taken in part from the Ph.D. dissertation of Jianhua Yu, University of Georgia, Athens, Georgia, USA, 2009

1,3-Dimethyl-2-nitrobenzene was converted to the key intramolecular Friedel–Crafts intermediate 24 in ten steps. Treatment of 24 with TiCl4 produced tricyclic enone 25 in 61%–75% yield, having the requisite trans relationship of the two angular methyl groups and many of the salient features of the dolastane diterpenes. The structure of enone 25 was verified by X-ray crystallography analysis. Cyclization product 25 permitted the facile synthesis of (±)-14-epi-hydroxydolasta-1(15),7,9-triene and (±)-7-epi-acetoxy-14-epi-hydroxydolasta-1(15),8-diene, which are detailed in this article.

Bioactive secondary metabolites from marine microbes for drug discovery

The isolation and extraction of novel bioactive secondary metabolites from marine microorganisms have a biomedical potential for future drug discovery as the oceans cover 70% of the planet's surface and life on earth originates from sea. Wide range of novel bioactive secondary metabolites exhibiting pharmacodynamic properties has been isolated from marine microorganisms and many to be discovered. The compounds isolated from marine organisms (macro and micro) are important in their natural form and also as templates for synthetic modifications for the treatments for variety of deadly to minor diseases. Many technical issues are yet to overcome before wide-scale bioprospecting of marine microorganisms becomes a reality. This chapter focuses on some novel secondary metabolites having antitumor, antivirus, enzyme inhibitor, and other bioactive properties identified and isolated from marine microorganisms including bacteria, actinomycetes, fungi, and cyanobacteria, which could serve as potentials for drug discovery after their clinical trials.

Cnidarians as a source of new marine bioactive compounds--an overview of the last decade and future steps for bioprospecting

Marine invertebrates are rich sources of bioactive compounds and their biotechnological potential attracts scientific and economic interest worldwide. Although sponges are the foremost providers of marine bioactive compounds, cnidarians are also being studied with promising results. This diverse group of marine invertebrates includes over 11,000 species, 7500 of them belonging to the class Anthozoa. We present an overview of some of the most promising marine bioactive compounds from a therapeutic point of view isolated from cnidarians in the first decade of the 21st century. Anthozoan orders Alcyonacea and Gorgonacea exhibit by far the highest number of species yielding promising compounds. Antitumor activity has been the major area of interest in the screening of cnidarian compounds, the most promising ones being terpenoids (monoterpenoids, diterpenoids, sesquiterpenoids). We also discuss the future of bioprospecting for new marine bioactive compounds produced by cnidarians.

One Pot Spiropyrazoline Synthesis via Intramolecular Cyclization/Methylation

Regioisomeric spiropyrazolines were synthesized through a tandem intramolecular cyclization/methylation reaction of a functionalized 5,5-disubstituted pyrazoline in one reaction vessel. The 5,5-pyrazolines were constructed through a 1,3-dipolar cycloaddition reaction of aromatic ring containing nitrile imines and a disubstituted geminal alkene. An evaluation of the relative location of the nucleophilic and electrophilic functional groups on the pyrazoline was performed in order to ascertain the best pyrazoline system for the intramolecular cyclization/methylation reaction. Higher spiropyrazoline isolated yields were realized from pyrazolines with the electrophilic ester located further away from the pyrazoline when compared to pyrazolines with a directly bonded ester.

Statistical research on marine natural products based on data obtained between 1985 and 2008

Since the 1960s, more than 20,000 compounds were discovered from marine organisms. In this paper we performed a quantitative analysis for the novel marine natural products reported between 1985 and 2008. The data was extracted mainly from the reviews of Faulkner and Blunt [1–26]. The organisms producing these marine natural products are divided into three major biological classes: marine microorganisms (including phytoplankton), marine algae and marine invertebrate. The marine natural products are divided into seven classes based on their chemical structure: terpenoids, steroids (including steroidal saponins), alkaloids, ethers (including ketals), phenols (including quinones), strigolactones, and peptides. The distribution and the temporal trend of these classes (biological classes and chemical structure classes) were investigated. We hope this article provides a comprehensive perspective on the research of marine natural products.

Molluscan biological and chemical diversity: secondary metabolites and medicinal resources produced by marine molluscs

The phylum Mollusca represents an enormous diversity of species with eight distinct classes. This review provides a taxonomic breakdown of the published research on marine molluscan natural products and the medicinal products currently derived from molluscs, in order to identify priority targets and strategies for future research. Some marine gastropods and bivalves have been of great interest to natural products chemists, yielding a diversity of chemical classes and several drug leads currently in clinical trials. Molluscs also feature prominently in a broad range of traditional natural medicines, although the active ingredients in the taxa involved are typically unknown. Overall secondary metabolites have only been investigated from a tiny proportion (<1%) of molluscan species. At the class level, the number of species subject to chemical studies mirrors species richness and our relative knowledge of the biology of different taxa. The majority of molluscan natural products research is focused within one of the major groups of gastropods, the opisthobranchs (a subgroup of Heterobranchia), which are primarily comprised of soft-bodied marine molluscs. Conversely, most molluscan medicines are derived from shelled gastropods and bivalves. The complete disregard for several minor classes of molluscs is unjustified based on their evolutionary history and unique life styles, which may have led to novel pathways for secondary metabolism. The Polyplacophora, in particular, have been identified as worthy of future investigation given their use in traditional South African medicines and their abundance in littoral ecosystems. As bioactive compounds are not always constitutively expressed in molluscs, future research should be targeted towards biosynthetic organs and inducible defence reactions for specific medicinal applications. Given the lack of an acquired immune system, the use of bioactive secondary metabolites is likely to be ubiquitous throughout the Mollusca and broadening the search field may uncover interesting novel chemistry.

Chemical constituents of the deep reef caribbean sponges Plakortis angulospiculatus and Plakortis halichondrioides and their anti-inflammatory activities

Chemical investigations of two collections of the deep reef Caribbean sponge Plakortis angulospiculatus resulted in the isolation of a new compound (1) along with the known compound spiculoic acid B (2) belonging to the spiculoic acid class and four other new compounds (3-6) belonging to the zyggomphic acid class. Three new aromatic compounds (7-9) were isolated from the Caribbean sponge Plakortis halichondrioides. The structural determination of the compounds was based on extensive NMR and mass spectroscopic analysis. The isolated compounds 1-7 were tested for their anti-inflammatory activity using in vitro assays for inhibition of inducible nitric oxide synthase and nuclear factor kappa B (NFκB) activity, as well as inhibition of intracellular reactive oxygen species generation as a result of oxidative stress. The cytotoxicity of these compounds was also evaluated to determine the selectivity index of their bioactivity with respect to cytotoxicity. Compounds 1 and 4 were more potent than the positive control in inhibiting NFκB activity and had IC(50) values of 0.47 and 2.28 μM, respectively.

Bioactive compounds from marine bacteria and fungi

Marine bacteria and fungi are of considerable importance as new promising sources of a huge number of biologically active products. Some of these marine species live in a stressful habitat, under cold, lightless and high pressure conditions. Surprisingly, a large number of species with high diversity survive under such conditions and produce fascinating and structurally complex natural products. Up till now, only a small number of microorganisms have been investigated for bioactive metabolites, yet a huge number of active substances with some of them featuring unique structural skeletons have been isolated. This review covers new biologically active natural products published recently (2007-09) and highlights the chemical potential of marine microorganisms, with focus on bioactive products as well as on their mechanisms of action.

Biological importance of marine algae

Marine organisms are potentially prolific sources of highly bioactive secondary metabolites that might represent useful leads in the development of new pharmaceutical agents. Algae can be classified into two main groups; first one is the microalgae, which includes blue green algae, dinoflagellates, bacillariophyta (diatoms)… etc., and second one is macroalgae (seaweeds) which includes green, brown and red algae. The microalgae phyla have been recognized to provide chemical and pharmacological novelty and diversity. Moreover, microalgae are considered as the actual producers of some highly bioactive compounds found in marine resources. Red algae are considered as the most important source of many biologically active metabolites in comparison to other algal classes. Seaweeds are used for great number of application by man. The principal use of seaweeds as a source of human food and as a source of gums (phycocollides). Phycocolloides like agar agar, alginic acid and carrageenan are primarily constituents of brown and red algal cell walls and are widely used in industry.

Effects of dissolved oxygen levels on survival and growth in vitro of Haliclona pigmentifera (Demospongiae)

In vitro sponge cultures are considered as legitimate alternatives for utilizing marine sponges (Porifera) to yield bioactive molecules. Optimization of culture methodologies for enhancing sponge survival is in progress for the identification of the factors regulating sponge survival in vitro. Dissolved oxygen (DO) is an essential factor promoting sponge survival. However, the effects of variable DO levels on the in vitro survival responses of sponges are not fully understood. Hence, we have investigated the effects of variable DO levels on the survival of the marine sponge, Haliclona pigmentifera (Demospongiae), with no external nutritional supplementation in closed type incubator chambers. Our results indicate that, under hypoxic conditions (1.5-2.0 ppm DO), H. pigmentifera with intact ectodermal layers and subtle oscula show adherent growth for 42+/-3 days. Sponges with prominent oscula, foreign material, and damaged pinacoderm exhibit poor survival under similar conditions. Complete mortality occurs within 2 days under anoxia (<0.3 ppm DO), and survival for a few days has been observed at >4.0 ppm DO without adhesion. Cellular differences between the outer and inner zones and collagen-like extracellular matrix have been identified in adherent sponges. Based on the hypothesis that hypoxia-inducible factor1-alpha (HIF-1alpha) is a ubiquitous protein promoting hypoxic survival in animals, we have detected, by Western blot, a protein band corresponding to human HIF-1alpha-like protein from sponges exposed to hypoxia and to hypoxia-mimicking agents. We thus report, for the first time, adhesive growth and a protein band corresponding to human HIF-1alpha-like protein in sponges surviving hypoxia in vitro.