Biological activity of Xanthium strumarium seed extracts on different cancer cell lines and Aedes caspius,Culex pipiens (Diptera: Culicidae)

Effects of methanol extracts of Xanthium strumarium on different cancer cell lines and on the mortality rates of Aedes caspius, Culex pipiens (Diptera: Culicidae) were investigated. Among the cell lines tested, the Jurkat cell line was the most sensitive to the methanol extract and ethyl acetate fraction, with reported LC₅₀ values of 50.18 and 48.73 μg/ml respectively. Conversely, methanol extracts were not that toxic to the A549 cell line though the toxicity increased on further purification. The percentage of growth inhibition was dose dependent for the methanol extract and ethyl acetate fraction. The ethyl acetate fraction showed higher toxicity to all cell lines tested when compared to the methanol extract. The results showed that methanol extracts of plant seeds caused 100% mortality of mosquito larvae at a concentration of 1000 μg/ml after 24 h of treatment. The LC₅₀ and LC₉₀ values of X. strumarium were found to be 531.07 and 905.95 μg/ml against Ae. caspius and 502.32 and 867.63 μg/ml against Cx. Pipiens, respectively. From the investigations, it was concluded that the crude extract of X. strumarium showed a weak potential for controlling the larval instars of Ae. caspius and Cx. pipiens. However, on further purification the extract lost the larvicidal activity. The ethyl acetate fraction showed higher toxicity to all cell lines tested when compared to the methanol extract. The ethyl acetate fraction investigated in this study appears to have a weak larvicidal activity but a promising cytotoxic activity. Future studies will include purification and investigation in further detail of the action of X. strumarium on Cancer Cell Lines and mosquitoes.     

Isolation of antioxidant constituents from Combretum apiculatum subsp. apiculatum

Species of the family Combretaceae are used extensively in traditional medicine against inflammation and infections, and although antibacterial activity has been reported in non-polar extracts, further rationale for the widespread use of the Combretaceae is expected to exist. Methanol extracts of leaves of ten different Combretum species were evaluated for antioxidant activity by spraying TLC chromatograms of each leaf extract with 2,2-diphenyl-1-picrylhydrazyl (DPPH). Compounds with antioxidant activity were detected by bleaching of the purple DPPH colour. Leaf extracts of Combretum apiculatum subsp. apiculatum had the most antioxidant compounds. This species was consequently selected for phytochemical investigation. A DPPH assay-directed fractionation of the leaf extracts of C. apiculatum led to the isolation of four antioxidant compounds from the ethyl acetate and butanol soluble fractions. The structures of the compounds were determined by spectroscopic analyses (¹H-NMR, ¹³C-NMR and MS) and identified as: cardamonin (1), pinocembrin (2), quercetrin (3) and kaempferol (4). In a quantitative antioxidant assay, the more polar fractions (ethyl acetate and butanol) obtained by solvent–solvent fractionation had the highest antioxidant activity among the solvent fractions obtained from C. apiculatum, with EC₅₀ values of 3.91 ± 0.02 and 2.44 ± 0.02 μg/ml respectively. Of the four isolated compounds, quercetrin (4) and kaempferol (3) had the strongest antioxidant activity, with EC₅₀ values of 11.81 ± 85 and 47.36 ± 0.03 μM respectively. Cardamonin (1) and pinocembrin (2) did not demonstrate strong activity. L-ascorbic acid was used as standard antioxidant agent (EC₅₀ = 13.37 ± 0.20 μM or 2.35 μg/ml). The cytotoxicity of cardamonin and pinocembrin was evaluated on Vero kidney cells using the MTT (3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium bromide) assay with berberine as positive control. At concentrations higher than 50 μg/ml of cardamonin or pinocembrin, the cells were not viable. Cardamonin was more toxic (LC₅₀ = 1.97 μg/ml) than pinocembrin (LC₅₀ = 29.47 μg/ml) and even the positive control, berberine (LC₅₀ = 12.35 μg/ml).     

Evaluation of insecticidal activity of the essential oil of Allium chinense G. Don and its major constituents against Liposcelis bostrychophila Badonnel

Water-distilled essential oil from the dried bulbs of Allium chinense (Liliaceae) was analyzed by gas chromatography–mass spectrometry (GC–MS). Eighteen compounds, accounting for 98.4% of the total oil, were identified and the main components of the essential oil of A. chinense were methyl allyl trisulfide (30.7%), dimethyl trisulfide (24.1%), methyl propyl disulfide (12.8%) and dimethyl disulfide (9.6%) followed by methyl allyl disulfide (3.4%) and methyl propyl trisulfide (3.6%). The essential oil exhibited contact toxicity against the booklice (Liposcelis bostrychophila) with an LC₅₀ value of 441.8 μg/cm² while the two major constituents, dimethyl trisulfide and methyl propyl disulfide had LC₅₀ values of 153.0 μg/cm² and 738.0 μg/cm² against the booklice, respectively. The essential oil of A. chinense possessed strong fumigant toxicity against the booklice with an LC₅₀ value of 186.5 μg/l while methyl allyl trisulfide (LC₅₀ = 90.4 μg/l) and dimethyl trisulfide (LC₅₀ = 114.2 μg/l) exhibited stronger fumigant toxicity than methyl propyl disulfide (LC₅₀ = 243.4 μg/l) and dimethyl disulfide (LC₅₀ = 340.8 μg/l) against the booklice. The results indicated that the essential oil and its major constituents have potential for development into natural insecticides or fumigants for control of insects in stored grains.     

Toxicity of basil and orange essential oils and their components against two coleopteran stored products insect pests

Two commercialized essential oils and their constituent compounds were investigated for fumigant and contact activities against two grain storage insects, adults of the maize weevil (Sitophilus zeamais) and the red flour beetle (Tribolium castaneum). The two commercialized basil and orange oils showed strong fumigant and contact activities against S. zeamais and T. castaneum. The constituents of the basil oil were linalool (21.83%), estragole (74.29%), and α-humulene (2.17%), and those of the orange oil were α-pinene (0.54%), sabinene (0.38%), β-myrcene (1.98%), limonene (96.5%), and linalool (0.6%). As a toxic fumigant, the basil oil was more effective (24-h LC₅₀ = 0.014 and 0.020 mg cm^− 3) than the orange oil (24-h LC₅₀ = 0.106 and 0.130 mg cm^− 3) against S. zeamais and T. castaneum adults, respectively. Among the constituents of the two essential oils, the toxicity of estragole was the highest (0.004 and 0.013), followed by linalool (0.016 and 0.023), limonene (0.122 and 0.171), α-pinene (0.264 and 0.273), and β-myrcene (0.274 and 0.275) based on 24-h LC₅₀ values (mg cm^− 3). Similar results were obtained in a contact toxicity test. The contact activity of basil oil was more toxic than orange oil, and estragole and linalool showed pronounced contact toxicity against S. zeamais and T. castaneum adults. Alpha-humulene had no activity as a fumigant at the tested doses, but it did have an effect as a contact poison, having 24-h LD₅₀ values of 0.040 and 0.045 mg adult^− 1 to S. zeamais and T. castaneum, respectively. Although basil oil, orange oil, and their components displayed both contact and fumigant toxicities, their effects were mainly exerted by fumigant action via the vapor phase. Thus, basil oil, orange oil, and their components could be potential candidates as new fumigants for the control of S. zeamais and T. castaneum adults.     

Evaluación de la toxicidad de Psilocybe cubensis (Agaricales,Basidiomycota) sobre Artemia franciscana (Crustacea,Anostraca)

BackgroundPsilocybe cubensis is a species with psychodysleptic action that grows on cattle dung in pastures in the tropics and subtropics. This fungus has been widely used in Mexico since ancient times both for ceremonies and rituals, as well as for healing or medicinal purposes. Artemia franciscana is a crustacean frequently used as a model organism for toxicity testing.AimsWith the objective of determining the toxicity of P. cubensis, the results of a study with the extract of P. cubensis on nauplii and adults of the brine shrimp A. franciscana are presented.MethodsSpecimens were collected at Bahía de Banderas, Jalisco, Mexico, and were dried and homogenized in artificial sea water. Bioassays were carried out on crystal vials filled with different concentrations of the extract of P. cubensis (EAP), and with potassium dichromate as reference toxic compound. The median lethal concentration (LC₅₀) in nauplii and adults and the inhibition of cysts hatching in A. franciscana were calculated.ResultsNauplii showed a LC₅₀ = 135 μg/ml, while adults a LC₅₀ = 172 μg/ml. Cysts’ hatching was inhibited by the EAP at all tested concentrations.ConclusionsUnder the conditions of this study, the extract of P. cubensis was toxic for nauplii and adults of A. franciscana.     

Insecticidal and developmental inhibitory properties of monoterpenes on Culex pipiens L. (Diptera: Culicidae)

Twelve monoterpenes were evaluated for larvicidal and adulticidal activities towards Culex pipiens. Geraniol and cuminaldehyde were the most toxic monoterpenes to larvae, with LC₅₀ values of 38.6 and 38.9 mg/l after 24 h of treatment, respectively, whereas cuminaldehyde was the most potent compound after 48 h of treatment, followed by geraniol and thymol. In fumigant toxicity experiments, (R)-carvone and geraniol were the most toxic monoterpenes against the adults at all three tested concentrations and after both 24 and 48 h. When tested at sublethal concentrations (0.5 LC₅₀), (R)-carvone, (S)-limonene and cuminaldehyde decreased hatchability, pupation and adult emergence and induced high larval mortality. Our results suggest that geraniol, cuminaldehyde and (R)-carvone are promising toxicants against Culex pipiens and could be useful in the search for new natural insecticides.     

Acaricidal activity of Aloe vera L. leaf extracts against Tetranychus cinnabarinus (Boisduval) (Acarina: Tetranychidae)

Four different extracts of Aloe vera L. leaves were evaluated for acaricidal activity against female adults of carmine spider mite, Tetranychus cinnabarinus (Boisduval), by slide-dip bioassay. At 72 h after treatment, the acetone extract showed the strongest acaricidal activity with LC₅₀ value of 90 ppm. The LC₅₀ values for ethyl acetate, water, and ethanol extracts were 113, 340, and 391 ppm, respectively. The acetone extract was fractionated using a silica gel column. Among the twenty-two fractions obtained the fifth, tenth, eleventh, twelfth, fifteenth, and seventeenth fractions showed strong acaricidal activity, causing 80.39 to 92.16% mortality at 72 h after treatment. The tenth and eleventh fractions had the strong activity, with LC₅₀ values of 44 ppm and 33 ppm, respectively. The results suggested that A. vera has a great potential for development as a botanical acaricide for T. cinnabarinus control.     

Acetylcholinesterase inhibitory activity and mutagenic effects of Croton penduliflorus leaf extract constituents

Croton penduliflorus is a medicinal plant widely employed in the management of inflammatory conditions, infections and oxidative stress related diseases. The activities demonstrated by leaf extracts indicate that they possess the ability to reduce oxidative damage to cells. Repeated column fractionation of the ethyl acetate fraction of a 20% aqueous methanol leaf extract of C. penduliflorus on Sephadex LH-20 afforded four phenolic compounds: quercetin-3-O-rhamnoside (1), kaempferol-3-O-rhamnoside (2), protocatechualdehyde (3A) and its solvent derived dimer (3B) along with p-hydroxybenzoic acid (4). Compound 3B is described for the first time and its significance in bioassay is briefly outlined. Structure elucidation of the isolated compounds was carried out using spectroscopic techniques. The inhibitory properties of the four compounds against acetylcholinesterase were determined using the microplate assay. The IC₅₀ values of the isolated compounds ranged from 87.9 to 1231.9 μM, with compound 2 having the best inhibitory activity (IC₅₀ = 87.9 μM). The four isolated compounds showed no mutagenic effects against Salmonella typhimurium tester strains TA98 and TA100. The moderate activity demonstrated by these compounds suggests that they could be helpful in the management of neurodegenerative disorders.     

Toxicity of Acalypha indica (Euphorbiaceae) and Achyranthes aspera (Amaranthaceae) leaf extracts to Aedes aegypti (Diptera: Culicidae)

Alternative control strategies for the dengue vector Aedes aegypti L. (Diptera: Culicidae) include botanical insecticides. They are believed to pose little threat to the environment or to human health and may provide practical substitutes for synthetic insecticides. In this study, we determined the biological activities of methanol extracts of Acalypha indica L. (Euphorbiaceae) and Achyranthes aspera L (Amaranthaceae) leaves individually and in combination as botanical insecticides against Ae. aegypti. Based on LC₅₀ values for 4th instar Ae. aegypti, the combined extracts showed the strongest larvicidal activity (277 ppm). A. aspera and A. indica extracts individually gave similar results (409 and 420 ppm, respectively). Respective LC₅₀ values for pupae were 326 ppm, 456 ppm, and 467 ppm. In studies of smoke toxicity, 64% of females exposed to negative control smoke (no extract) blood fed on chicken, whereas 17% blood fed when exposed to smoke containing A. aspera extract and to positive control smoke (0.2% d-allethrin). In the field, treatment of water storage tanks (≈ 0.5 m³) with combined plant extract reduced larval and pupal populations by 97% and 81%, respectively, after 5 days. Given the results of this study, further evaluation of the combined (A. indica + A. aspera) extract as a mosquito larvicide is warranted. Mosquito coils with A. aspera extract also show promise as a practical and potentially economical means for mitigating mosquito blood feeding.     

The toxicity and enzyme activity of a chlorine and sulfate containing aeruginosin isolated from a non-microcystin-producing Planktothrix strain

The toxicity of six different Planktothrix strains was examined in acute toxicity assays with the crustacean Thamnocephalus platyurus. The presence of toxicity in two strains could be explained by the occurrence of microcystins. The other four Planktothrix strains were not able to produce microcystins due to different mutations in the microcystin synthetase (mcy) gene cluster. In these strains, toxicity was attributed to the presence of chlorine and sulfate containing compounds. The main representative, called aeruginosin 828A, of such a compound in the Planktothrix strain 91/1 was isolated, and structure elucidation by 2D NMR and MS methods revealed the presence of phenyllactic acid (Pla), chloroleucine (Cleu), 2-carboxy-6-(4′-sulfo-xylosyl)-octahydroindole (Choi), and 3-aminoethyl-1-N-amidino-Δ-3-pyrroline (Aeap) residues. Aeruginosin 828A was found to be toxic for T. platyurus with a LC₅₀ value of 22.4 μM, which is only slightly higher than the toxicity found for microcystins. Additionally, very potent inhibition values for thrombin (IC₅₀ = 21.8 nM) and for trypsin (IC₅₀ = 112 nM) have been determined for aeruginosin 828A. These data support the hypothesis that aeruginosins containing chlorine and sulfate groups, which were found in microcystin-deficient Planktothrix strains, can be considered as another class of toxins.     

Acetylenic 2-phenylethylamides and new isobutylamides from Acmella oleracea (L.) R. K. Jansen,a Brazilian spice with larvicidal activity on Aedes aegypti

Ethanol extract obtained from dried leaves of Acmella oleracea afforded after a liquid/liquid partition procedure a larvicidal hexane fraction (LC₅₀ = 145.6 ppm) and a non larvicidal dichloromethane one. From the inactive fraction, three amides were identified, two new structures, named deca-6,9-dihydroxy-(2E,7E)-dienoic acid isobutylamide (1), deca-8,9-dihydroxy-(2E,6Z)-dienoic acid isobutylamide (2) and the known nona-2,3-dihydroxy-6,8-diynoic acid 2-phenylethylamide (3). Bioassay-guided chromatographic fractionation of the hexane partition led to the identification of an amide mixture, nona-(2Z)-en-6,8-diynoic acid 2-phenylethylamide (4) and deca-(2Z)-en-6,8-diynoic acid 2-phenylethlylamide (5). This mixture was active against Aedes aegypti larvae at LC₅₀ = 7.6 ppm. Low toxicity of crude extracts and derived fractions on Artemia salina nauplies showed the possibility of using them to control the A. aegypti mosquito larvae. This is the first report on larvicidal activity of acetylenic 2-phenylethylamides and their identification in A. oleracea leaves.     

Monitoring of acaricide resistance of Tetranychus urticae (Acari: Tetranychidae) from Korean apple orchards

Tetranychus urticae populations were collected from ten commercial apple orchards and their susceptibilities to 12 acaricides were tested using a leaf disc bioassay. The resistance of each T. urticae population was reported as the LC₅₀ value, the resistance ratio (RR) and the slope of the probit–concentration regression. Cross resistances of T. urticae populations were estimated using the Spearman's rank correlation coefficient. Most local populations showed low resistance levels (RR ≤ 10). Development of resistance to METI and pyrethroid acaricides differed among local populations. The highest RR value (154.6) was found in the Uiseong population to tebufenpyrad. The Geochang population was highly resistant, especially to METI and pyrethroid acaricides. T. urticae populations collected from Suwon, Chungju, Yeongju and Geochang showed moderate resistance (10 < RR ≤ 40) to more than two acaricides. Resistance ratios to abamectin, chlorfenapyr, fenbutatin-oxide and milbemectin were low (RR ≤ 10) in all populations. The LC₅₀ values of abamectin, chlorfenapyr, fenbutatin-oxide and milbemectin ranged from 0.06 to 0.2 mg/l, from 0.67 to 3.38 mg/l, from 10.12 to 40.85 mg/l and from 0.47 to 3.01 mg/l, respectively. We discuss possible cross-resistance to acaricides using Spearman's rank correlation coefficient.     

Cloning and characterization of a novel cry8Ab1 gene from Bacillus thuringiensis strain B-JJX with specific toxicity to scarabaeid (Coleoptera: Scarabaeidae) larvae

Isolation of Bacillus thuringiensis (Bt) strain or its cry gene encoding insecticidal crystal protein (ICP) with specific toxicity is of great importance to biological control of insect pests. In this study, by screening 66 strains of Bt isolated from soil samples collected in Shandong Province, China, a new cry8-type gene from Bt strain B-JJX was identified via PCR-RFLP method. This novel gene, cry8Ab1, was cloned from the Bt strain B-JJX and expressed in an acrystalliferous mutant strain HD-73^?. The open reading frame of the cry8Ab1 gene consists of 3543 bp with a G + C content of 37.99% and encodes a protein of 1180 amino acids with a putative MW of 133.3 kDa which was confirmed by SDS-PAGE analysis. The Cry8Ab1 protein was expressed and released as spherical parasporal crystals from Bt acrystalliferous mutant strain HD-73^? along with the presence of spores. In bioassays, this protein was toxic to 3-day-old larvae of the scarabaeid pests, Holotrichia oblita and H. parallela, with an LC₅₀ of 5.72 and 2.00 μg toxin g^?1 soil, respectively. The results are in accordance with the insecticidal activities of the original Bt strain B-JJX, which had an LC₅₀ of 1.72 and 0.96 μg toxin g^?1 soil against H. oblita and H. parallela, respectively.     

Directional selection by termites at a branching node created by a ballpoint pen

Subterranean termites excavate complex underground tunnels for foraging. Most tunnels comprise primary and secondary tunnels. Tunnels originating from the nest are called primary and those branching from the primary tunnels are named secondary tunnels; tertiary and quaternary tunnels are rarely observed. During foraging, termites may thus encounter a considerable number of tunnel-branching nodes. Directional selection at such a node is likely correlated to tunnel-growth activity because tunnels containing more termites have a higher probability of growth. In this study, we investigated how termites select the direction of movement at an artificially-designed branching node, by making chemical trails on filter paper, drawing lines using a ballpoint pen which contained the chemical substance that induces the termite to follow trails. The trails consisted of two lines: straight and branching. The branching line was drawn from the center of the straight line at an angle θ (10°, 20°,…, 90°). We then calculated the ratio of the directional selection as r = N_s/N_b, where N_s and N_b represent the number of straight and branching tunnels selected, respectively. The values of r were statistically classified into three groups based on the angle of the branching trail, as follows: 10° ≤ θ ≤ 20°, 30° ≤ θ ≤ 60°, and 70° ≤ θ ≤ 90°. Our paper briefly discusses the underlying mechanisms of the experimental results.     

Stability of the intra- and extracellular toxins of Prymnesium parvum using a microalgal bioassay

Prymnesium parvum produces a variety of toxic compounds, which affect other algae, grazers and organisms at higher trophic levels. Here we provide the method for development of a sensitive algal bioassay using a microalgal target, Teleaulax acuta, to measure strain variability in P. parvum toxicity, as well as the temporal stability of both the intracellular and the extracellular lytic compounds of P. parvum. We show high strain variation in toxicities after 3 h incubation with LC₅₀s ranging from 24 to 223 × 10³ cells ml⁻¹. Most importantly we prove the necessity of testing physico-chemical properties of P. parvum toxins before attempting to isolate and characterize them. The extracellular toxin in the supernatant is highly unstable, and it loses significant lytic effects after 3 days despite storage at −20 °C and after only 24 h stored at 4 °C. However, when stored at −80 °C, lytic activity is more easily maintained. Reducing oxidation by storing the supernatant with no headspace in the vials significantly slowed loss of activity when stored at 4 °C. We show that the lytic activity of the intracellular toxins, when released by sonication, is not as high as the extracellular toxins, however the stability of the intracellular toxins when kept as a cell pellet at −20 °C is excellent, which proves this is a sufficient storage method for less than 3 months. Our results provide an ecologically appropriate algal bioassay to quantify lytic activity of P. parvum toxins and we have advanced our knowledge of how to handle and store the toxins from P. parvum so as to maintain biologically relevant toxicity.     

Synthesis and anti-Trypanosoma cruzi activity of naphthoquinone-containing triazoles: Electrochemical studies on the effects of the quinoidal moiety

In our continued search for novel trypanocidal compounds, twenty-six derivatives of para- and ortho-naphthoquinones coupled to 1,2,3-triazoles were synthesized. These compounds were evaluated against the infective bloodstream form of Trypanosoma cruzi, the etiological agent of Chagas disease. Compounds 17–24, 28–30 and 36–38 are described herein for the first time. Three of these novel compounds (28–30) were found to be more potent than the standard drug benznidazole, with IC₅₀/24 h values between 6.8 and 80.8 μM. Analysis of the toxicity to heart muscle cells led to LC₅₀/24 h of <125, 63.1 and 281.6 μM for 28, 29 and 30, respectively. Displaying a selectivity index of 34.3, compound 30 will be further evaluated in vivo. The electrochemical properties of selected compounds were evaluated in an attempt to find correlations with trypanocidal activity, and it was observed that more electrophilic quinones were generally more potent.     

Small molecule tolfenamic acid and dietary spice curcumin treatment enhances antiproliferative effect in pancreatic cancer cells via suppressing Sp1, disrupting NF-kB translocation to nucleus and cell cycle phase distribution

Combination of dietary/herbal spice curcumin (Cur) and COX inhibitors has been tested for improving therapeutic efficacy in pancreatic cancer (PC). The objective of this study was to identify agent with low toxicity and COX-independent mechanism to induce PC cell growth inhibition when used along with Cur. Anticancer NSAID, tolfenamic acid (TA) and Cur combination were evaluated using PC cell lines. L3.6pl and MIA PaCa-2 cells were treated with Cur (5–25 μM) or TA (25–100 μM) or combination of Cur (7.5 μM) and TA (50 μM). Cell viability was measured at 24–72 h posttreatment using CellTiter-Glo kit. While both agents showed a steady/consistent effect, Cur + TA caused higher growth inhibition. Antiproliferative effect was compared with COX inhibitors, Ibuprofen and Celebrex. Cardiotoxicity was assessed using cordiomyocytes (H9C2). The expression of Sp proteins, survivin and apoptotic markers (western blot), caspase 3/7 (caspase-Glo kit), Annexin-V staining (flow cytometry), reactive oxygen species (ROS) and cell cycle phase distribution (flow cytometry) was measured. Cells were treated with TNF-α, and NF-kB translocation from cytoplasm to nucleus was evaluated (immunofluorescence). When compared to individual agents, combination of Cur + TA caused significant increase in apoptotic markers, ROS levels and inhibited NF-kB translocation to nucleus. TA caused cell cycle arrest in G₀/G₁, and the combination treatment showed mostly DNA synthesis phase arrest. These results suggest that combination of Cur + TA is less toxic and effectively enhance the therapeutic efficacy in PC cells via COX-independent mechanisms.     

Esculentin-2CHa: A host-defense peptide with differential cytotoxicity against bacteria,erythrocytes and tumor cells

The host-defense peptide, esculentin-2CHa (GFSSIFRGVA¹⁰KFASKGLGK D²⁰LAKLGVDLVA³⁰ CKISKQC) shows potent (MIC ≤ 6 μM) growth inhibitory activity against clinical isolates of multidrug-resistant strains of Staphylococcus aureus, Acinetobacter baumannii, and Stenotrophomonas maltophilia and differential cytotoxic activity against human erythrocytes (LC₅₀ = 150 μM) and human non-small cell lung adenocarcinoma A549 cells (LC₅₀ = 10 μM). Esculentin-2CHa significantly (P < 0.01) stimulates the release of the anti-inflammatory cytokine IL-10 by mouse lymphoid cells and elevates its production after stimulation with concanavalin A and significantly (P < 0.05) stimulates TNF-α production by peritoneal macrophages. Effects on IL-6 and IL-1β production were not significant. Removal of the hydrophobic N-terminal hexapeptide (GFSSIF) from esculentin-2CHa results in abolition of growth inhibitory activity against S. aureus and cytotoxic activity against erythrocytes and A549 cells as well as a marked (≥16-fold) reduction in potency against A. baumannii and S. maltophilia. The primary structure of esculentin-2 has been poorly conserved between frog species but evolutionary pressure has acted to maintain the hydrophobic character of this N-terminal hexapeptide sequence. Removal of the cyclic C-terminal domain (CKISKQC) and replacement of the Cys³¹ and Cys³⁷ residues by serine resulted in appreciable decreases in cytotoxicity against all microorganisms and against mammalian cells. The more cationic [D20K, D27K] analog showed a modest increase in potency against all microorganisms (up to 4-fold) but a marked increase in cytotoxicity against erythrocytes (LC₅₀ = 11 μM) and A549 cells (LC₅₀ = 3 μM).     

Antifouling activity exhibited by secondary metabolites of the marine sponge,Haliclona exigua (Kirkpatrick)

Bioassay guided purification of the acetone extract of the marine sponge, Haliclona exigua, (Gulf of Mannar, India) yielded a fraction rich in bis-1-oxaquinolizidine alkaloids, active against seven strains of fouling bacteria as well as cyprids of the cosmopolitan barnacle, Balanus amphitrite. The major alkaloids in the mixture have been tentatively identified as nor-araguspongine C (33.76%), araguspongine C (6.49%), dihydroxy araguspongine (36.36%), methyl and dimethyl derivatives of the latter (12.98 and 10.38%, respectively) from HRMS studies. The lower EC₅₀ (6.6 μg/ml as against the US Navy standard of 25 μg/ml for NPAs) and low toxicity (LC₅₀ 18 μg/ml as compared to 0.00001 μg/ml for TBT) values, coupled with its favourable therapeutic ratio (2.7 as against the requirement of >1) makes these compounds ideal NPAs in environmentally compatible antifouling coatings.     

Chemical composition and larvicidal activity of leaf essential oil from Clausena dentata (Willd) M. Roam. (Rutaceae) against the chikungunya vector,Aedes aegypti Linn. (Diptera: Culicidae)

Larvicidal activity of essential oil and isolated compounds from Clausena dentata leaves were tested against early fourth instar Aedes aegypti larvae. GC–MS analysis of essential oil revealed the presence of fourteen compounds of which the major compounds were sabinene (21.27%), biofloratriene (19.61%), borneol (18.34%) and β-bisabolol (17.68%). The essential oil of C. dentata exhibited significant larvicidal activity, with 24 h LC₅₀ and LC₉₀ values of 140.2 and 341.6 mg/l, respectively. Larvicidal activities of the four major compounds of essential oil were also tested. The LC₅₀ values of sabinene, biofloratriene, borneol and β-bisabolol were 27.3, 47.4, 43.5 and 33.2 mg/l, respectively. Results of this study show that the leaf essential oil of C. dentata and its four major compounds may be a potent source of natural larvicides.