Sediment toxicity assessment: comparison of standard and new testing designs

Standard methods of sediment toxicity testing are fairly well accepted; however, as with all else, evolution of these methods is inevitable. We compared a standard ASTM 10-day amphipod toxicity testing method with smaller, 48- and 96-h test methods using very toxic and reference sediments. In addition we compared parallel exposures of single species, either the amphipod Ampelisca abdita or the mysid Americamysis bahia, to multiple species, mysid, and amphipod, cohabiting the same types of chambers. These comparisons were performed for both water-only and sediment-water tests. Results of the comparison of the standard ASTM 10-day amphipod test with the smaller, 48- and 96-h test chambers indicate that survival was high in both test designs using the reference sediment. With toxic sediments, complete mortality occurred in less than 48 h using the smaller experimental chambers and only after 96 h in the larger experimental chambers. We concluded that although time to death is shorter in the smaller, shorter exposure chambers, there was no overall change in mortality for the organisms, and that the smaller chambers were predictive of the results obtained with larger chambers and longer exposures. For multiple species testing in whole sediment exposures there was no change in toxicity to either the amphipod or the mysid when they cohabited the same chamber. In contrast, for water-only exposures, A. bahia demonstrated less sensitivity when cohabiting the same chamber as A. abdita. Therefore, during whole sediment testing we can add A. bahia and A. abdita to the same test chamber without changing the toxicity to either species; however, in our 10-ml water-only exposures, the species should be tested separately.

DNA strand breaks (comet assay) and embryo development effects in grass shrimp (Palaemonetes pugio) embryos after exposure to genotoxicants

Grass shrimp embryos develop in egg sacs (stages 1-10) attached to the female for 14-20 days after which they 'hatch' from the egg sacs into a swimming zoea stage (stage 11). Until they emerge from the egg sacs, embryos depend on lipids and lipovitellin stored within the egg. The percent of embryos which hatch after exposure to toxicants relative to controls was the basis of an embryo development assay. Exposure of embryos to chromium(III) chloride, sodium chromate, mercuric chloride, and 2-methyl-1,2-naphthoquinone (MNQ) resulted in a reduced hatching rate. In addition to effects on embryo development, DNA strand damage tests were carried out on contaminant-exposed embryos, using the single-cell electrophoresis method often referred to as comet assay. Development of stage 4 embryos was more affected by MNQ exposure than stage 7 embryos. The hatching rates of stages 4 and 7 embryos exposed to MNQ (172 micrograms/l) were 0 and 90%, respectively. DNA strand damage, measured as DNA tail moments, were 3.4 and 4.4, respectively. Thus, exposure of an early embryo stage to MNQ prevented full embryo development while development of later embryo stages was not affected. It may be that the DNA repair systems are more efficient in later embryo stages than in early stages and thus DNA damaged in the early stages affects development.

Coordinated changes of adenylate energy charge and ATP/ADP: use in ecotoxicological studies

The coordinated variations of the adenylate energy charge and ATP/ADP ratio were modeled and a function that depends on the numerical value of the adenylate kinase-catalyzed reaction has been derived. The model allows sensitive detection of the effects of xenobiotics on adenylate kinase and its cellular environment and offers a robust estimation of the direct or indirect effects of pollutants on the adenylate kinase system: data obtained in laboratory studies on shrimp exposed to cadmium and in field studies on oysters either exposed to polychloro-biphenyl compounds or located in a heavily polluted area indicate that xenobiotics affect the adenylate kinase reaction directly or by changing its cellular environment. These results demonstrate that application of the model to the treatment of ecotoxicological data allows detection of energetic changes that would have been missed by simple analysis of the usual energetic parameters, and should overcome problems encountered in using energetic parameters during assessment of pollution monitoring.

Brine shrimp bioassay of ethanol extracts of Sesuvium verrucosum, Salsola baryosma and Zygophyllum quatarense medicinal plants from Bahrain

Ethanol whole plant extracts of three halophytic plants from Bahrain Sesuvium verrucosum, Salsola baryosma, Zygophyllum quatarense have been tested for their cytotoxic activity by the brine shrimp method. Only S. verrucosum showed a marked significant activity (LC(50) = 102.7 microg/mL)

Solution-phase combinatorial synthesis and evaluation of piperazine-2,5-dione derivatives

An efficient one-pot synthesis of a 61-membered combinatorial chemistry library of piperazine-2,5-diones was accomplished. Results of combinatorial synthesis, purification, analysis, and biological evaluation are described.

Purification and partial characterization of a toxic serine protease produced by pathogenic Vibrio alginolyticus

An extracellular lethal toxin produced by Vibrio alginolyticus strain Swy originally isolated from diseased kuruma prawn (Penaeus japonicus) was purified using the AKTA purifier system with hydrophobic interaction chromatography, anion exchange and gel filtration columns. The toxin is an alkaline serine protease, inhibited by phenyl methylsulphonyl fluoride (PMSF), antipain and shows maximal activity at pH 8 to 11, having a pI of 4.3 and a molecular weight of approximately 33 kD. The toxin was completely inhibited by FeCl2 but partially inhibited by 3,4-dichloroisocoumarin (3,4-DCI), ethylenediamine tetraacetic acid (EDTA), ethylene glycol-bis(beta-amino-ethyl ether) N,N,N',N'-tetraacetic acid (EGTA), CuCl2 and ZnCl2. The purified protease was lethal for kuruma prawn at an LD50 of 0.29 microgram protein/g body weight. The haemolymph withdrawn from the moribund prawns injected with the toxic protease was unable to clot. The coagulogen in the kuruma prawn plasma showed an increased migration rate after incubation with this serine protease, and a plasma colour change from blue to pink was recorded. The addition of PMSF completely inhibited the lethal toxicity of the purified protease, indicating that this serine protease was a lethal toxin produced by the bacterium. The 33 kD protease was therefore a toxic protease produced by V. alginolyticus strain Swy.

Field efficacy and nontarget effects of the mosquito larvicides temephos, methoprene, and Bacillus thuringiensis var. israelensis in Florida mangrove swamps

We compared the efficacy and nontarget effects of temephos, Bacillus thuringiensis var. israelensis (B.t.i.), and methoprene applied by helicopter to control mosquito larvae in mangrove swamps on Sanibel Island, FL, in May 1997. Three sites per treatment and 3 untreated sites were used. Temephos (Abate) was applied at 37 ml/ha (43% active ingredient [AI]), B.t.i. granules (Vectobac G) were applied at 5.606 kg/ha (200 International Toxic Units/mg), and methoprene (Altosid ALL) was applied at 213 ml/ha (5% AI). Efficacy was quantified by monitoring the survival of caged and uncaged larval Aedes taeniorhynchus. We quantified mortality of sentinel nontarget amphipods (Talitridae) at all sites, monitored the effect of temephos on flying arthropods using light traps, and collected dead insects in tarps suspended under mangroves in areas treated with either temephos or methoprene. Each pesticide showed good overall efficacy but occasional failures occurred. No detectable mortality of amphipods or flying insects attributable to pesticides was found. The inconsistent field efficacies of the pesticides indicate a need for reinspection of treated sites in this habitat.

A bioassay using Artemia salina for detecting phototoxicity of plant coumarins

Artemia salina (brine shrimp) has been successfully used for toxicity testing, and a screening test for phototoxicity has been developed based on this method. The ability of the method to test the phototoxic potential of seven known compounds was investigated. Athamantin (an angular furanocoumarin) and umbelliferone (a simple coumarin) showed no phototoxicity, while linear furanocoumarins exhibited phototoxic activity in the following order: psoralen > bergapten > peucedanin > xanthotoxin. The applicability of this method was also tested in screening the phototoxicity of plant material. Six plants from Apiaceae [Aegopodium podagraria L., Anethum graveolens L., Angelica archangelica L., Levisticum officinalis Koch, Petroselinum crispum (P. Mill) A. W. Hill., and Peucedanum palustre (L.) Moench] and one from Rutaceae (Ruta graveolens L.) were selected, all of them known to contain furanocoumarins. Extracts from leaves collected at different times during the growth period were used in the screening. Our results were in accordance with the furanocoumarin content of these plants and with the results of other phototoxicity tests. The Artemia salina method proved to be rapid, simple and inexpensive, and is therefore ideal in the initial biological screening of large numbers of samples for simultaneous detection of both toxicity and phototoxicity.

Environmental conditions and pesticide pollution of two coastal ecosystems in the Gulf of California, Mexico

In December 1997 and April and September 1998, water temperature, salinity, dissolved oxygen, nutrients, chlorophyll, and pesticide residues were determined in two coastal ecosystems of Sinaloa, NW Mexico: Ensenada del Pabellón and Bahía de Santa María. These two are considered to be among the greatest shrimp producers in the region. Temperature, salinity, and dissolved oxygen were similar to those of other ecosystems of this region: high temperatures and salinity in spring and summer (dry season) and lower in winter and the rainy season. Levels of nitrites and phosphates and chlorophyll concentration were relatively higher than those of other ecosystems nearby, probably due to fertilizers used in the agricultural lands surrounding the water bodies studied. The pesticides more frequently detected were BHCalpha, aldrin, endosulfan and parathion. In some cases, pesticides forbidden by Mexican regulations were detected. These results indicate that the ecosystems studied are in a warning condition, because severe biochemical and physiological alterations have been reported in crustaceans exposed to pesticides. Therefore these pesticides could be one cause of the slow growth, diverse pathologies, and mortality in shrimp that have been reported in recent years.

Methanol adduct of puupehenone, a biologically active derivative from the marine sponge Hyrtios species

A methanol adduct of puupehenone (1), 15alpha-methoxypuupehenol (2), an artifact resulting from the action of MeOH on puupehenone, was isolated during purification of the CH(2)Cl(2) extract of the New Caledonian marine sponge Hyrtios sp., as the major constituent. Its chemical structure was elucidated by 2D NMR experiments. Compound 2 displayed similar antimicrobial and antifungal activity as puupehenone and a lower cytotoxic activity toward KB cells with ED(50) values of 6 and 0.5 microg/mL, respectively. Compound 2 was slightly more active against three strains of Plasmodium falciparum than puupehenone.

Tanikolide, a toxic and antifungal lactone from the marine cyanobacterium Lyngbya majuscula

A new brine-shrimp toxic and antifungal compound, tanikolide 1, has been isolated from the lipid extract of a Madagascan collection of the marine cyanobacterium Lyngbya majuscula. The structure of tanikolide was determined by spectroscopic methods, relying heavily on 2D NMR spectroscopy. The absolute configuration at C-5 of tanikolide was established as R by oxidizing the primary alcohol to an acid and analyzing the corresponding (R)- and (S)-PGME amide derivatives by (1)H NMR.

A new antiviral and antimicrobial sesquiterpene from Glyptopetalum sclerocarpum

Sclerocarpic acid, a new sesquiterpene with a novel carbon skeleton, was isolated from the stem bark of Glyptopetalum sclerocarpum Laws. (Celastraceae). The compound exhibited antiviral activity against herpes simplex virus types 1 and 2, and antimicrobial activity against Gram-positive bacteria and a fungus.

Asitrilobins A and B: cytotoxic mono-THF annonaceous acetogenins from the seeds of Asimina triloba

The seeds of Asimina triloba have yielded two novel cytotoxic mono-tetrahydrofuran (THF) Annonaceous acetogenins, asitrilobins A (1) and B (2). In addition, annonacin, asimin and asiminacin, which are known, and annomontacin and xylomaticin, which are known but are new in this species, were obtained. Compounds 1 and 2 have a relative stereochemical relationship of erythro/cis/threo across the mono-THF ring with its two flanking hydroxyls and they, thus, represent a new type of acetogenin. Their structures were established on the basis of chemical and spectral evidence. 1 and 2 showed potent bioactivities in the brine shrimp lethality test (BST) and among six human solid tumor cell lines with notable selectivity for the pancreatic cell line (MIA PaCa-2) at ten to one-hundred times the potency of adriamycin.

Biological activities of 7-epiclusianone

7-Epiclusianone, isolated from Rheedia gardneriana, was tested in several biological assays. It was active in vitro against trypomastigotes of Trypanosoma cruzi but inactive in vivo in experimentally infected mice. It was also active against Artemia salina, but inactive against the fungus Cladosporium sphaerospermum and the snail Biomphalaria glabrata.

Degradation of weathered oil by mixed marine bacteria and the toxicity of accumulated water-soluble material to two marine crustacea

Artificially weathered crude oil was degraded by four diverse cultures of mixed marine bacteria under optimized conditions for 7 and 14 days. Loss in total weight of starting oil (30 g) ranged from 6.8-17.3% in biologically active incubations compared with only 0. 9-1.1% in sterile and nutrient-limited controls. In all incubations, both neutral and acidic water-soluble fractions (WSF) were accumulated. In biologically active systems, 50.9-249.0 mg neutral and 63.3-406.8 mg acidic WSF were accumulated whereas only 6.5-11.1 mg neutral and 1.7-2.2 mg acidic WSF were accumulated in control incubations. Analysis by gas chromatography demonstrated that accumulated WSF in biologically active systems contained compounds different from those washed from the starting crude oil. Exposure of grass shrimp (Palaemonetes pugio) embryos to neutral WSF from each of the biologically active cultures resulted in high embryo mortalities relative to sterile and nutrient-limited controls which exhibited >90% hatching success and larval survival. Toxicity of neutral WSF was also demonstrated on larvae of mysids (Mysidopsis bahia). In both cases, toxicity occurred only on exposure to neutral material accumulated by active, oil-degrading cultures and not with material washed from the weathered crude oil. These results imply that unique compounds were accumulated during degradation that may have been responsible for increased toxicity.

Evaluation of toxicity of some saponins on brine shrimp

Toxicity of several types of saponins (1-11) against brine shrimp (Artemia salina) were evaluated. As a result, it was found that most tested compounds were not toxic to brine shrimp at high enough concentration. The most toxic saponin (1) to brine shrimp showed also cytotoxicity towards HL-60 tumor cell line using MTT assay. Brine shrimp model may thus be used as bench-top assay in finding cytotoxic components from saponin-containing fractions of plant extracts.

Preliminary antifungal and cytotoxicity studies of extracts of Ritchiea capparoides var. longipedicellata

Crude extracts obtained from the leaves, stem bark and roots of Ritchiea capparoides var. longipedicellata were screened for in vitro antifungal activity using the agar tube dilution method. The leaf hexane, leaf methanol, stem bark methanol and root methanol extracts were tested using ten clinical strains of fungi at a concentration of 200 and 400 microg/ml, respectively. At 400 microg/ml, all four extracts inhibited the growth of six of the ten test fungi used in the study. Inhibition of the growth of Aspergillus niger by the extracts was also seen but the activity was low and the leaf hexane and root methanol extracts inhibited the growth of Drechslera rostrata. Only the leaf hexane extract was active against Curvularia lunata, while the growth of Candida albicans was not inhibited by any of the extracts. The inhibition of growth of almost all the microorganisms decreased at 200 microg, griseofulvin was included as a reference compound and methanol as the control. Preliminary cytotoxicity tests were done with the four extracts using the larvae of the brine shrimp, Artemia saline. The extracts were however found to be relatively non-toxic as each extract had an LD50 value greater than 1000 microg/ml.

Purpurediolin and purpurenin, two new cytotoxic adjacent bis-tetrahydrofuran annonaceous acetogenins from the seeds of Annona purpurea

Two novel cytotoxic acetogenins, purpurediolin (1) and purpurenin (2), were isolated from the seeds of Annona purpurea. Their structures were elucidated by a combination of chemical and spectral methods including MS and NMR measurements. In addition, six known acetogenins were obtained, namely, bullatacin, squamocin (annonin I), motrilin (squamocin C), annoglaucin, xylomatenin, and annonacin A. Compounds 1 and 2 exhibited potent cytotoxic activity in vitro against six human solid tumor cell lines.

Grenadadiene and grenadamide, cyclopropyl-containing fatty acid metabolites from the marine cyanobacterium Lyngbya majuscula

Grenadadiene (1), debromogrenadiene (2), and grenadamide (3), three structurally unique cyclopropyl-containing metabolites, were isolated from the organic extract of a Grenada collection of the marine cyanobacterium Lyngbya majuscula. The structures and the relative stereochemistries of these compounds were determined using spectroscopic methods. These are the first reported cyclopropyl-containing fatty acid derivatives from a Lyngbya sp. Grenadadiene (1) has an interesting profile of cytotoxicity in the NCI 60 cell line assay, while grenadamide (2) exhibited modest brine shrimp toxicity (LD50 = 5 microg/mL) and cannabinoid receptor binding activity (Ki = 4.7 microM).

Kalkipyrone, a toxic gamma-pyrone from an assemblage of the marine cyanobacteria Lyngbya majuscula and Tolypothrix sp

Kalkipyrone, a novel alpha-methoxy-beta,beta'-dimethyl-gamma-pyrone possessing an alkyl side chain, was isolated from an assemblage of the marine cyanobacteria Lyngbyamajuscula and Tolypothrix sp. Its structure, including stereochemistry, was determined by NMR, UV, and IR analysis and by GC-MS of the natural product and key derivatives. Kalkipyrone is toxic to brine shrimp (LD50 1 microg/mL) and gold fish (LD50 2 microg/mL) and is structurally related to the actinopyrones that were previously isolated from Streptomyces spp.