Ecotoxicological assessment of pesticides towards the plant growth promoting activities of Lentil (<Emphasis Type="Italic">Lens</Emphasis><Emphasis Type="Italic">esculentus</Emphasis>)-specific <Emphasis Type="Italic">Rhizobium</Emphasis> sp. strain MRL3

This study was designed to evaluate the effect of the selected pesticides [herbicides (metribuzin and glyphosate), insecticides (imidacloprid and thiamethoxam) and fungicides (hexaconazole, metalaxyl and kitazin)] at the recommended and the higher dose rates on plant growth promoting traits of Rhizobium sp. strain MRL3 isolated from lentil-nodules. Strain MRL3 was explicitly selected owing to its high pesticide-tolerance ability and substantial production of indole acetic acid, siderophores (salicylic acid and 2, 3 dihydroxy benzoic acid), exo-polysaccharides, HCN and ammonia. A trend of pesticide-concentration dependent progressive-decline for plant growth promoting properties of Rhizobium sp. strain MRL3 was observed excluding exo-polysaccharides which was regularly augmented on exceeding the concentration of each tested pesticide from the recommended dose. Commonly, the maximum toxicity to plant growth promoting traits of Rhizobium was shown by glyphosate, imidacloprid and hexaconazole at three times the recommended rate among herbicides, insecticides and fungicides, respectively.     

Growth rate of <Emphasis Type="Italic">Pseudokirchneriella subcapitata</Emphasis> exposed to herbicides found in surface waters in the Alqueva reservoir (Portugal): a bottom-up approach using binary mixtures

Previous work showed the existence of ecotoxicity of water samples from the Alqueva reservoir due to the presence of the herbicides atrazine, simazine, terbuthylazine and metolachlor. In the present study we examine the effects of these herbicides singly and as binary mixtures on the growth rate of the microalgae Pseudokirchneriella subcapitata. Usually, the toxicity of mixtures is evaluated in relation to the reference models CA (concentration addiction) and IA (independent action). In this study CA model was selected to evaluate the joint effects of s-triazine herbicides on the growth of algae due to their similar mode of action. Moreover, IA reference model was chosen to evaluate the joint toxicity of the chloroacetanilide metolachlor and the s-triazine herbicides due to their different mode of action. In this study dose ratio was the common deviation obtained on both reference models. In the binary mixtures between atrazine/simazine and atrazine/terbuthylazine the increase of the mixtures toxicity (synergism) was mainly due to atrazine. Also, in the binary mixture between atrazine and metolachlor, atrazine was responsible for the increase (synergism) of the mixture toxicity. In the cases of the binary mixtures between simazine/metolachlor and terbuthylazine/metolachlor, the increase of the mixtures toxicity (synergism) was detected when metolachlor was the herbicide dominant, and antagonism was detected when simazine and terbuthylazine were dominant in both mixtures. This study represents an important step to understand the interactions among herbicides detected previously in the waters of the Alqueva reservoir.     

Acute effects of binary mixtures of Type II pyrethroids and organophosphate insecticides on <Emphasis Type="Italic">Oreochromis niloticus</Emphasis>

Pyrethroid and organophosphate insecticides have been used for more than 20 years worldwide to control a variety of insect pest in different settings. These pesticides have been detected in a variety of environmental samples, including surface waters and sediments and therefore there is significant concern about their potential toxic effects on non-target organisms. Mixtures of compounds from these groups of pesticides have been found to frequently show enhanced toxicity but it has been a challenge to predict whether or not enhanced toxicity will occur for a given combination of compounds. This study therefore studied the effects of binary pyrethroid-organophosphate mixtures using cypermethrin, deltamethrin and dimethoate in an acute toxicity test system with Oreochromis niloticus. The 96?h LC50s for individual insecticides were 9.13?µg/l, 9.42?µg/l and 45.52?mg/l for cypermethrin, deltamethrin and dimethoate respectively. These showed that the pyrethroid insecticides were highly toxic to Oreochromis niloticus and were far more toxic than dimethoate. All mixtures were also more toxic than single insecticides throughout the concentration-response curve with mixtures resulting in mortality at concentrations which the individual pesticides in the mixture were below their respective NOECs. In addition, observed mixture toxicities deviated from the predicted mixture effects based either on the Concentration Addition (CA) or Independent Action (IA) models independent of mixture ratio. However, the extent of observed mixture mortality deviation was dependent on the effect level. Significant deviations (MDR?>?2.0) were observed at lower concentrations indicating synergistic effects at lower and possibly environmentally relevant concentrations. This is not unexpected since organophosphate insecticides are known to inhibit acetylcholinesterase as well as inactivate esterase, resulting in reduced detoxification of pyrethroid insecticides and consequently greater toxicity than would be expected. This has important implications for risk assessment of mixtures since the risk of pyrethroid-organophosphate mixtures may be underestimated if either the CA or IA model is employed.     

Joint toxicity of cadmium and SDBS on <Emphasis Type="Italic">Daphnia magna</Emphasis> and <Emphasis Type="Italic">Danio rerio</Emphasis>

Information on joint toxicity is limited. To clarify the joint toxicity and the interactions among toxicants on different aquatic organisms, we investigated the acute toxicity of cadmium and sodium dodecyl benzene sulfonate, two chemicals with high concerns in Chinese waters, on the immobilization of Daphnia magna (D. magna) and the swimming behavior of Danio rerio (D. rerio). Our results illustrated that cadmium and sodium dodecyl benzene sulfonate expressed a synergistic effect on the immobilization of D. magna; and an antagonistic effect on the swimming speed D. rerio, but a synergistic effect on its vertical position in the water column. Based on the observed data, we found the independent action model was more appropriate than the concentration addition model in the prediction of their joint toxicity. Our results gave an example of the joint toxicity investigation, and aided to comprehensive the toxicity action mode of chemical mixtures.     

Assessing the environmental hazard of individual and combined pharmaceuticals: acute and chronic toxicity of fluoxetine and propranolol in the crustacean <Emphasis Type="Italic">Daphnia magna</Emphasis>

Pharmaceuticals are widespread emerging contaminants and, like all pollutants, are present in combination with others in the ecosystems. The aim of the present work was to evaluate the toxic response of the crustacean Daphnia magna exposed to individual and combined pharmaceuticals. Fluoxetine, a selective serotonin re-uptake inhibitor widely prescribed as antidepressant, and propranolol, a non-selective β-adrenergic receptor-blocking agent used to treat hypertension, were tested. Several experimental trials of an acute immobilization test and a chronic reproduction test were performed. Single chemicals were first tested separately. Toxicity of binary mixtures was then assessed using a fixed ratio experimental design. Five concentrations and 5 percentages of each substance in the mixture (0, 25, 50, 75, and 100%) were tested. The MIXTOX model was applied to analyze the experimental results. This tool is a stepwise statistical procedure that evaluates if and how observed data deviate from a reference model, either concentration addition (CA) or independent action (IA), and provides significance testing for synergism, antagonism, or more complex interactions. Acute EC50 values ranged from 6.4 to 7.8?mg/L for propranolol and from 6.4 to 9.1?mg/L for fluoxetine. Chronic EC50 values ranged from 0.59 to 1.00?mg/L for propranolol and from 0.23 to 0.24?mg/L for fluoxetine. Results showed a significant antagonism between chemicals in both the acute and the chronic mixture tests when CA was adopted as the reference model, while absence of interactive effects when IA was used.     

Impairment of trophic interactions between zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) and midge larvae (<Emphasis Type="Italic">Chironomus riparius</Emphasis>) by chlorpyrifos

The effects of chemicals on biotic interactions, such as competition and predation, have rarely been investigated in aquatic ecotoxicology. This study presents a new approach for the investigation of predator–prey interactions between zebrafish (Danio rerio) and midge larvae (Chironomus riparius) impaired by chlorpyrifos (CHP), a neurotoxic insecticide. With a simple experimental design including four different treatments: (1) control, (2) predator exposed, (3) prey exposed and (4) both, predator and prey, exposed, we were able to detect by visual observation an increase in the feeding rate of zebrafish preying on exposed chironomids after acute (2 h) exposure to 6 μg/l CHP. Previously, a decrease in the burrowing behaviour of exposed chironomid larvae was observed. However, when pre-exposing simultaneously both predators and prey, no significant differences in the feeding rate of zebrafish were observed. This suggests an impairment in prey recognition of the exposed zebrafish. At a lower CHP concentration (1 μg/l), no differences in feeding rate of zebrafish were observed. We therefore propose the use of trophic interactions as parameters in higher tier studies for chemical testing and evaluation of ecotoxicological risk assessment.     

Chromosomal Damage in Two Species of Aquatic Turtles (<Emphasis Type="Italic">Emys orbicularis</Emphasis> and <Emphasis Type="Italic">Mauremys caspica</Emphasis>) Inhabiting Contaminated Sites in Azerbaijan

The Caspian region and specifically the Apsheron peninsula of Azerbaijan are known to be polluted with a variety of environmental contaminants. These complex mixtures of contaminants make risk assessment difficult. We used the flow cytometry method (FCM) and the micronucleus assay (MN) to assess chromosomal damage in aquatic turtles (Emys orbicularis, the European pond turtle; and Mauremys caspica, the Caspian turtle) inhabiting contaminated wetlands in Azerbaijan. Evidence of genetic damage was found for two sites, Neftchala and Sumgayit, relative to a reference site, Ali Bairamly. Sediment samples from each site were analyzed for PAHs and mercury to evaluate potential contaminant associations with genetic damage. A significant positive correlation was documented between three-ring PAH sediment concentrations and FCM estimates of chromosomal damage in E. orbicularis. These data combine to show that the contaminated wetlands in Sumgayit and Neftchala are genotoxic and that three-ring PAHs are likely a significant influence on observed genotoxicity.     

Combined effects of malathion and nitrate on early growth,abnormalities, and mortality of wood frog (<Emphasis Type="Italic">Rana sylvatica</Emphasis>) tadpoles

Use of pesticides and other agro-chemicals adversely influence amphibians either directly by killing them or by inducing sublethal, chronic effects. Many studies have investigated the effect of mixtures of pesticides or fertilizers. We studied the combined effects of nitrate and malathion ([(dimethoxy phosphino thioyl] butanediotae) on the early growth, expression of abnormalities, and mortality of Wood Frog (Rana sylvatica) tadpoles in a laboratory experiment. Tadpoles were treated with factorial combinations of 0, 8, and 16 mg NO₃–N l⁻¹ and 0, 250, 500, and 1,000 μg malathion l⁻¹ for a period of 14 days. Feeding behaviour, total length, mean tadpole mass, frequencies of abnormalities, and survivorship in each treatment were recorded. Malathion showed a significant negative influence on all parameters and strongly influenced the frequencies of morphological anomalies. In contrast, nitrate alone did not produce any significant effects on behavior, total length, tadpole mass, or the frequency of abnormalities during the experiment. Malathion and nitrate had an interactive effect on tadpole length and mass, but did not affect any other parameters. Our results suggest that exposure to malathion, even at relatively low concentrations can have serious negative consequences for Wood Frog tadpoles. In addition, our results also indicate that there was little synergistic interaction between malathion and nitrate exposure under laboratory conditions.     

Detection of insecticide resistance in <Emphasis Type="Italic">Bradysia odoriphaga</Emphasis> Yang <Emphasis Type="Italic">et</Emphasis> Zhang (Diptera: Sciaridae) in China

Bradysia odoriphaga Yang et Zhang is a destructive insect pest of Chinese chives. To understand the current status of insecticide resistance of B. odoriphaga in China, the sensitivity variation of eight field populations to six commonly used insecticides, including chlorpyrifos, phoxim, imidacloprid, thiamethoxam, clothianidin and beta-cypermethrin were evaluated. The results showed that almost all the tested B. odoriphaga populations had developed moderate to high resistance to chlorpyrifos and phoxim. There were different resistance levels found in the eight field populations among the three neonicotinoids, imidacloprid, thiamethoxam and clothianidin. Imidacloprid was very effective against B. odoriphaga in most tested populations except those from Yangzhou (10.35-fold) and Tangshan (14.56-fold). While four populations kept susceptible to thiamethoxam, the other four populations showed decreased susceptibility or low resistance. To clothianidin, five populations displayed moderate resistance, two populations displayed low resistance, and one population exhibited susceptibility, respectively. All the tested populations were resistance to beta-cypermethrin, the highest resistance was found in the Tangshan population with a resistance ratio of 172.56-fold. The results of this study provided valuable information for choosing insecticides for control and integrated resistance management of B. odoriphaga.     

Demographic responses of <Emphasis Type="Italic">Daphnia magna</Emphasis> fed transgenic <Emphasis Type="Italic">Bt</Emphasis>-maize

The food/feed quality of a variety of genetically modified (GM) maize expressing Cry1Ab Bt-toxin was tested over the life-cycle of Daphnia magna, an arthropod commonly used as model organism in ecotoxicological studies. Demographic responses were compared between animals fed GM or unmodified (UM) near isogenic maize, with and without the addition of predator smell. Age-specific data on survival and birth rates were integrated and analysed using life tables and Leslie matrices. Survival, fecundity and population growth rate (PGR) data generally disfavoured transgenic Bt-maize as feed for D. magna compared to animals fed the unmodified (UM) near isogenic line of maize. Decomposition of age-specific effects revealed that the most important contributions to a reduced PGR in the GM-fed group came from both fecundity and survival differences early in life. We conclude that juvenile and young adult stages are the most sensitive experimental units and should be prioritized in future research. These stages are often omitted in toxicological/ecotoxicological studies and in feeding trials.     

Identification of medicinal <Emphasis Type="Italic">Dendrobium</Emphasis> species by phylogenetic analyses using <Emphasis Type="Italic">matK</Emphasis> and <Emphasis Type="Italic">rbcL</Emphasis> sequences

Species identification of five Dendrobium plants was conducted using phylogenetic analysis and the validity of the method was verified. Some Dendrobium plants (Orchidaceae) have been used as herbal medicines but the difficulty in identifying their botanical origin by traditional methods prevented their full modern utilization. Based on the emerging field of molecular systematics as a powerful classification tool, a phylogenetic analysis was conducted using sequences of two plastid genes, the maturase-coding gene (matK) and the large subunit of ribulose 1,5-bisphosphate carboxylase-coding gene (rbcL), as DNA barcodes for species identification of Dendrobium plants. We investigated five medicinal Dendrobium species, Dendrobium fimbriatum, D. moniliforme, D. nobile, D. pulchellum, and D. tosaense. The phylogenetic trees constructed from matK data successfully distinguished each species from each other. On the other hand, rbcL, as a single-locus barcode, offered less species discriminating power than matK, possibly due to its being present with little variation. When results using matK sequences of D. officinale that was deposited in the DNA database were combined, D. officinale and D. tosaense showed a close genetic relationship, which brought us closer to resolving the question of their taxonomic identity. Identification of the plant source as well as the uniformity of the chemical components is critical for the quality control of herbal medicines and it is important that the processed materials be validated. The methods presented here could be applied to the analysis of processed Dendrobium plants and be a promising tool for the identification of botanical origins of crude drugs.     

<Emphasis Type="Italic">In Vitro</Emphasis> antioxidant and anti-inflammatory activities of Jaceosidin from <Emphasis Type="Italic">Artemisia princeps</Emphasis> Pampanini <Emphasis Type="Italic">cv.</Emphasis> Sajabal

Oxidized low-density lipoprotein (oxLDL) plays a key role in the inflammatory processes of atherosclerosis. Jaceosidin isolated from the methanolic extracts of the aerial parts of Artemisia princeps Pampanini cv. Sajabal was tested for antioxidant and anti-inflammatory activities. Jaceosidin inhibited the Cu²⁺-mediated LDL oxidation with IC₅₀ values of 10.2 μM in the thiobarbituric acid-reactive substances (TBARS) assay as well as the macrophage-mediated LDL oxidation. The antioxidant activities of jaceosidin were exhibited in the conjugated diene production, relative electrophoretic mobility, and apoB-100 fragmentation on copper-mediated LDL oxidation. Jaceosidin also inhibited the generation of reactive oxygen species (ROS) concerning in regulation of NF-κB signaling. And jaceosidin inhibited nuclear factor-kappa B (NF-κB) activity, nitric oxide (NO) production, and suppressed expression of inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-induced RAW264.7 macrophages.     

Methyl-triclosan and triclosan impact embryonic development of <Emphasis Type="Italic">Danio rerio</Emphasis> and <Emphasis Type="Italic">Paracentrotus lividus</Emphasis>

The presence of emerging pollutants in the environment is of major concern not only because of the potential negative impact in human health, but also due to the potential toxicity to non-target organisms. Within the personal and care products (PCPs), the disinfectant Triclosan (TCS) is one of the most concerning compounds. Once in the wastewater treatment plants (WWTPs), a small part of TCS can be biotransformed into a more persistent by-product: methyl-triclosan (M-TCS). Although several studies have focused on the occurrence of this compound in the water systems, the information on its toxicity to aquatic organisms is very limited. Here, we used embryo bioassays with two aquatic model animals to improve risk assessment of M-TCS; zebrafish (Danio rerio) embryo bioassays run up to 144?h post fertilization (hpf) and sea urchin (Paracentrotus lividus) up to 48?hpf, following established protocols. M-TCS and TCS exhibited similar toxicity to zebrafish with a NOEC of 160?µg/L. In contrast, M-TCS induced a delay in the development of the sea urchin larvae at all tested concentrations (1–1000?µg/L), whereas NOEC of TCS for P. lividus embryos was 40?µg/L. Overall, given the reported effects of M-TCS in the close range of environmentally relevant concentrations, and considering the low degradation rate and tendency to bioaccumulation (logKow: 5.2), further studies are warrant to better characterize the risk of this TCS metabolite to aquatic organisms.     

Combinatorial anti-<Emphasis Type="Italic">Trichophyton</Emphasis> effects of <Emphasis Type="Italic">Ligusticum chuanxiong</Emphasis> essential oil components with antibiotics

The antifungal activities of ligustilide and butylidene phthalide, which are major oil components comprising the essential oil of Ligusticum chuanxiong, in combination with antifungal drugs were evaluated. Checkerboard microtiter and microdilution tests were used to measure combined effects against Trichophyton species, T. erinacei, T. mentagrophytes, T. rubrum, T. schoenleinii, T. tonsurans and T. soudanense. Susceptibility of these Trichophyton species to L. chuanxiong essential oil differed distinctly. The fractional inhibitory concentrations (FICIs) against Trichophyton species ranged between 0.27 and 0.56 for ketoconazole combined with ligustilde or butylidene phthalide, indicating synergism or additive effects between the antibiotic and essential oil compounds. Testing by itraconazole instead of ketoconazole, similar combination effects were observed with FICIs from 0.31 to 0.63 against the tested strains of T. mentagrophytes, T. rubrum, T. schoenleinii, and T. soudanense. Thus, data reported here showed that Trichophyton susceptibility to ketoconazole and itraconazole could be notably improved by ligustilde and butylidene phthalide.     

A new <Emphasis Type="Italic">Erythrina</Emphasis> alkaloid from <Emphasis Type="Italic">Erythrina herbacea</Emphasis>

A new Erythrina alkaloid, 10-hydroxy-11-oxoerysotrine (1), has been isolated from the flowers of Erythrina herbacea together with five known compounds: erytharbine (2), 10,11-dioxoerysotrine (3), erythrartine (4), erysotramidine (5) and erysotrine-N-oxide (6). The structure of the new compound was elucidated on the basis of its spectral data, including 2-D NMR and mass (MS) spectra. The new compound is a rare C-10 oxygenated Erythrina alkaloid. The antioxidant activities of the isolated compounds 1–6 were evaluated by scavenging with peroxynitrite.     

Embryotoxic effects of nonylphenol and octylphenol in sea urchin <Emphasis Type="Italic">Arbacia lixula</Emphasis>

Nonylphenol (NP) and octylphenol (OP), both of which are biodegradation products of alkylphenols, are widely used in industrial applications and in some domestic products. These chemicals are found widely in surface water and aquatic sediments. We have carried out a comparative embryotoxicity analysis of the effects of increasing concentrations of NP (seven concentrations ranging from 0.937 to 18.74 μg/l) and OP (six concentrations ranging from 5 to 160 μg/l) on embryos of the sea urchin Arbacia lixula. The indicators evaluated were larval malformations, developmental arrest and embryonic/larval mortality. The results revealed that low concentrations of these chemicals (NP, OP) generally caused malformations in the skeletal system. High concentrations (18.74 μg NP/l, 160 μg OP/l) were found to inhibit the growth of embryos in the early life stages by preventing mitosis. We conclude that NP and OP present a major risk to the normal development of A. lixula at the low concentrations that have been recorded in the environment. These chemicals are therefore most likely to represent an ecological hazard at the population level given the cumulative effects of other environmental pollutants.     

Impact of a perfluorinated organic compound PFOS on the terrestrial pollinator <Emphasis Type="Italic">Bombus</Emphasis><Emphasis Type="Italic">terrestris</Emphasis> (Insecta,Hymenoptera)

Perfluorinated organic chemicals like perfluorooctane sulfonic acid (PFOS) are persistent environmental pollutants that have been measured in a great diversity of wildlife worldwide, especially in the aquatic compartment. However, little information is available on the presence and effects of PFOS in the terrestrial compartment. Therefore, we investigated in this project the risks for effects, bioaccumulation and potential mechanisms of activity of PFOS in the bumblebee Bombus terrestris L. (Hymenoptera: Apidae) that is an important worldwide pollinator in the terrestrial compartment of wildflowers and cultivated crops. The exposure to PFOS occurred orally via the drinking of treated sugar water in a wide range from 1 μg/l up to 10 mg/l, containing environmentally relevant as well as high concentrations, and this was done with use of microcolonies of B. terrestris in the laboratory. A chronic toxicity assay demonstrated high bumblebee worker mortality (up to 100%) with an LC₅₀ of 1.01 mg/l (R ² = 0.98). In addition, PFOS posed strong detrimental reproductive effects, and these concerted with a dramatic reduction in ovarian size. HPLC–MS demonstrated a bioaccumulation factor of 27.9 for PFOS in bumblebee workers fed with sugar water containing 100 μg/l PFOS during 5 weeks (2184 ± 365 ng/g BW). Finally, potential mechanisms of activity were investigated to explain the significant impact of PFOS on survival and reproduction capacity of B. terrestris. Exposure of bumblebee workers to PFOS resulted in a significant decrease in mitochondrial electron transport activity (p = 0.035) and lipid amounts (p = 0.019), while the respective p-values were 0.58 and 0.12 for protein and glucose amounts. Hence, addition of PFOS to ecdysteroid responsive Drosophila melanogaster S2 cells resulted in a strong antagonistic action on the EcR-b.act.luc reporter construct, demonstrating that PFOS may exert its effects partially through an endocrine disrupting action via the insect molting hormone or ecdysteroid receptor.     

Comparison of the Effect of Different pH Buffering Techniques on the Toxicity of Copper and Zinc to <Emphasis Type="Italic">Daphnia Magna</Emphasis> and <Emphasis Type="Italic">Pseudokirchneriella Subcapitata</Emphasis>

During the time-course of ecotoxicity tests with algae and chronic (reproductive) toxicity tests with daphnids, in which algae are present as a food source, pH can dramatically increase due to photosynthetic activity. As pH changes can significantly affect metal speciation and thus its bioavailability, it may be necessary to buffer the pH of the exposure medium. One class of buffers (Goods N-subtituted aminosulfonic acids) are increasingly being used in biological and chemical applications, including ecotoxicity testing. However, the potential effect of these buffers on metal toxicity has, so far, scarcely been examined. In this study we investigated if MOPS (3-N morpholino propane sulfonic acid) affected the toxicity of copper and zinc to two standard test organisms: the cladoceran Daphnia magna and the green alga Pseudokirchneriella subcapitata. First, we demonstrate that up to a concentration of 750 mg l^–1 (which proved to be sufficient for pH buffering) MOPS did not affect 21-day net reproduction of D. magna or the 72-h population growth of P. subcapitata. Second, we conducted bioassays in copper and zinc spiked standard media for the pH range 6 – 8. For D. magna the possible effect of 750 mg l^–1 MOPS on acute copper and zinc toxicity was investigated by performing parallel 48-h toxicity tests in NaHCO₃ and MOPS buffered test media. Seventy-two hour growth inhibition assays with P. subcapitata were performed in parallel in MOPS and NaHCO₃ buffered test media and in test media with daily manual pH adjustment with HCl. For daphnids no significant differences in copper and zinc toxicity were observed between MOPS or NaHCO₃ buffered test media. For algae no significant differences in metal toxicity were observed between MOPS and HCl buffered media, but in test media buffered with NaHCO₃ an increased copper and zinc toxicity was observed as a consequence of pH increases during the test. Clearly, the results of this study demonstrate the importance of pH buffering in metal toxicity testing and the suitability of the MOPS buffer for that purpose.     

<Emphasis Type="Italic">ent</Emphasis>-Abietane diterpenoids from <Emphasis Type="Italic">Isodon xerophilus</Emphasis>

Three new ent-abietanoids, named xerophilusins XIV–XVI, and four known analogues, as well as four known chemical constituents were isolated from the leaves of Isodon xerophilus. Their structures were elucidated by extensive spectroscopic studies, and comparison with literature data. In addition, the cytotoxic activity of the ent-abietanoids against chronic myelogenous leukemia (K562), stomach adenocarcinoma (MKN45), and hepatocellular carcinoma (HepG2) human cell lines was investigated and no activities were observed.