Bioprospection and secondary metabolites profiling of marine Streptomyces levis strain KS46

The quest for novel broad spectrum bioactive compounds is needed continuously because of the rapid advent of pathogenic multi drug resistant organisms. Actinomycetes, isolated from unexplored habitats can be a solution of this problem. The motive of this research work was isolation of actinomycetes having potential antimicrobial activities from unexplored regions of Devbag and Tilmati beach. The isolated actinomycetes were screened against pathogenic microbes for antimicrobial activities through cross streak method. Enzyme production activity was checked for these actinomycetes for amylase, protease, cellulase and lipase enzymes. Further antimicrobial activity of ethyl acetate extract of the potent strain KS46 was performed. The strain KS46 was identified with 16S rRNA gene sequencing and secondary structure was analysed. Gas chromatography–Mass spectrometry (GC–MS) profiling was conducted to ascertain the presence of bioactive metabolites in the ethyl acetate extract. The collected samples were pre-treated and 70 actinomycetes were isolated. The Streptomyces sp. strain KS46 showed the best antimicrobial activity in primary screening. Ethyl acetate extract of the strain KS46 revealed antimicrobial activity against S. aureus, B. subtilis, B. cereus, E. faecalis, K. pneumoniae, E. coli, S. flexneri, C. albicans and C. glabrata. The 16S rRNA gene sequencing identified the strain KS46 as Streptomyces levis strain KS46. The GC–MS metabolite profiling of the ethyl acetate extract revealed the availability of 42 compounds including fatty acid esters, fatty acid anhydrides, alkanes, steroids, esters, alcohols, carboxylic ester, etc. having antibacterial, antifungal, antiproliferative, antioxidant activities. This study indicated that Devbag and Tilmati beaches being untapped habitats have enormous diversity of promising antimicrobial metabolite producing actinomycetes. Therefore, further exploration should be carried out to characterize the potential actinomycetes, which can be optimistic candidates for generation of novel antimicrobial drugs.     

Dodecyl sorbitan ethers as antimicrobials against Gram-positive bacteria

A range of amphiphilic sorbitan ethers has been synthesized in two steps from sorbitan following an acetalization/hydrogenolysis sequence. These sorbitan ethers and the acetal intermediates have been evaluated as antimicrobials against Gram-negative and Gram-positive bacteria. No antimicrobial activity was observed for Gram-negative bacteria. However, the compounds bearing a linear dodecyl chain exhibit antimicrobial activity (MIC as low as 8 μg/mL) against Gram-positive bacteria such as Listeria monocytogenes, Enterococcus faecalis and Staphylococcus aureus. Encouraged by these preliminary results, dodecyl sorbitan was tested against a range of resistant strains and was found to be active against vancomycin-, methicillin- and daptomycin-resistant strains (MIC = 32–64 μg/mL).     

Effect of Ottoman Viper (Montivipera xanthina (Gray, 1849)) Venom on Various Cancer Cells and on Microorganisms

Cytotoxic and antimicrobial effects of Montivipera xanthina venom against LNCaP, MCF-7, HT-29, Saos-2, Hep3B, Vero cells and antimicrobial activity against selected bacterial and fungal species: Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, E. coli O157H7, Enterococcus faecalis 29212, Enterococcus faecium DSM 13590, Staphylococcus epidermidis ATCC 12228, S. typhimirium CCM 5445, Proteus vulgaris ATCC 6957 and Candida albicans ATCC 10239 were studied for evaluating the potential medical benefit of this snake venom. Cytotoxicity of venom was determined using MTT assay. Snake venom cytotoxicity was expressed as the venom dose that killed 50 % of the cells (IC₅₀). The antimicrobial activity of venom was studied by minimal inhibitory concentration (MIC) and disc diffusion assay. MIC was determined using broth dilution method. The estimated IC₅₀ values of venom varied from 3.8 to 12.7 or from 1.9 to 7.2 μg/ml after treatment with crude venom for 24 or 48 h for LNCaP, MCF-7, HT-29 and Saos-2 cells. There was no observable cytotoxic effect on Hep3B and Vero cells. Venom exhibited the most potent activity against C. albicans (MIC, 7.8 μg/ml and minimal fungicidal concentration, 62.5 μg/ml) and S. aureus (MIC, 31.25 μg/ml). This study is the first report showing the potential of M. xanthina venom as an alternative therapeutic approach due to its cytotoxic and antimicrobial effects.     

Isolation and biological activities of an endophytic Mortierella alpina strain from the Antarctic moss Schistidium antarctici

The Antarctic endophytic fungus (strain ITA1-CCMA 952) was isolated from the moss Schistidium antarctici found in Admiralty Bay, King George Island, Antarctica. Strain ITA1-CCMA 952 was assigned to the specie Mortierella alpina by phylogenetic analysis based on 18S rRNA gene sequences. This strain produces high levels of polyunsaturated fatty acids (PUFAs), including y-(gamma) linolenic acid and arachidonic acid, which when combined represents 48.3 % of the total fatty acid content. Fungal extracts demonstrated strong antioxidant activity with the EC₅₀ value of 48.7 μg mL^?1 and also a strong antibacterial activity, mainly against the following bacteria: Escherichia coli, with a MIC of 26.9 μg mL^?1 and Pseudomonas aeruginosa and Enterococcus faecalis, both with a MIC of 107 μg mL^?1. A GC–MS analysis of the chloroform fraction obtained from the crude extract revealed the presence of potential antimicrobials (Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) and Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(phenylmethyl)) as the major compounds. Therefore, the M. alpina strain ITA1-CCMA 952 is a promising fungus for the biotechnological production of antibiotics, antioxidant substances and PUFAs. This study highlights the need for more research in extreme environments, such as Antarctica.     

Agrobacterium tumefaciens-mediated transgenic plant and somaclone production through direct and indirect regeneration from leaves in Stevia rebaudiana with their glycoside profile

Agrobacterium tumefaciens (EHA-105 harboring pCAMBIA 1304)-mediated transgenic plant production via direct regeneration from leaf and elite somaclones generation through indirect regeneration in Stevia rebaudiana is reported. Optimum direct regeneration frequency along with highest transformation frequency was found on MS?+?1 mg/l BAP?+?1 mg/l NAA, while indirect regeneration from callus was obtained on MS?+?1 mg/l BAP?+?2 mg/l NAA. Successful transfer of GUS-positive (GUS assay and PCR-based confirmation) transgenic as well as four somaclones up to glasshouse acclimatization has been achieved. Inter-simple sequence repeat (ISSR) profiling of transgenic and somaclonal plants showed a total of 113 bands, out of which 49 were monomorphic (43.36 %) and 64 were polymorphic (56.64 %). Transgenic plant was found to be closer to mother plant, while on the basis of steviol, stevioside, and rebaudioside A profile, somaclone S2 was found to be the best and showed maximum variability in ISSR profiling.     

Hylaranins: prototypes of a new class of amphibian antimicrobial peptide from the skin secretion of the oriental broad-folded frog,Hylarana latouchii

Amphibian skin secretions contain a broad spectrum of biologically active compounds, particularly antimicrobial peptides, which are considered to constitute a first line of defence against bacterial infection. Here we describe the identification of two prototype peptides representing a novel structural class of antimicrobial peptide from the skin secretion of the oriental broad-folded frog, Hylarana latouchii. Named hylaranin-L1 (GVLSAFKNALPGIMKIIVamide) and hylaranin-L2 (GVLSVIKNALPGIMRFIAamide), both peptides consist of 18 amino acid residues, are C-terminally amidated and are of unique primary structures. Their primary structures were initially deduced by MS/MS fragmentation sequencing from reverse-phase HPLC fractions of skin secretion that demonstrated antimicrobial activity. Subsequently, their precursor-encoding cDNAs were cloned from a skin secretion-derived cDNA library and their primary structures were confirmed unequivocally. Synthetic replicates of both peptides exhibited broad-spectrum antimicrobial activity with mean inhibitory concentrations (MICs) of 34 μM against Gram-negative Escherichia coli, 4.3 μM against Gram-positive Staphylococcus aureus and 4–9 μM against the yeast, Candida albicans. Both peptides exhibited little haemolytic activity (<6 %) at the MICs for S. aureus and C. albicans. Amphibian skin secretions thus continue to provide novel antimicrobial peptide structures that may prove to be lead compounds in the design of new classes of anti-infection therapeutics.     

Micropropagation,antioxidant properties and phytochemical assessment of Swertia corymbosa (Griseb.) Wight ex C. B. Clarke: a medicinal plant

Swertia corymbosa (Griseb.) Wight ex C. B. Clarke, a valuable medicinal plant, has been investigated for its regeneration potential using nodal explants. Out of a range of concentrations of cytokinins [6-benzyl adenine (BA), 6-furfurylaminopurine (Kn), 2-isopentenyl adenine (2iP), thidiazuron (TDZ), and zeatin (Z)] used as supplements with MS, BA at 4.40 μM concentration proved best for multiple shoot induction yielding 26.50 ± 0.26 shoots after 12 weeks of culture. Addition of low concentration of NAA (1.3 μM) in MS medium supplemented with the cytokinin BA (4.40 μM) favoured shoot multiplication. A mean number of 35.78 ± 0.81 shoots were produced per explant. Additive effect of BA (4.40 μM) in combination with Kn (4.64 μM) produced highest number of shoots (83.20 ± 4.29). Addition of GA₃ (1.4 μM) to the above medium not only favored shoot elongation but also enhanced the number of shoots (113.98 ± 3.80). The microshoots were rooted successfully on half-strength MS medium supplemented with 9.8 μM of IBA. The plantlets were successfully transferred to hardening medium containing vermiculite with 87 % survival rate. Screening of the antibacterial, antioxidant activity and estimation of total phenolic and flavonoid content of methanolic extracts of micropropagated plants were also carried out and compared with that of the wild-grown plants. In all the tests, methanolic extract from wild-grown plants showed higher antioxidant, antimicrobial activity, total phenolic and flavonoid content than in vitro propagated plants. The content of secondary metabolites in wild-grown plants and in vitro propagated plants was determined by HPLC coupled with ESI-MS and the presence of loganic acid, swertiamarin, sweroside, gentiopicroside, isovitexin, amoroswertin, amarogentin, gentiacaulein, decussatin, and swertianin in the samples were confirmed. Gentiopicroside (40.726 mg/g) and swertianin (29.598 mg/g) were found to be the major compounds which may be responsible for the antimicrobial and antioxidant activities. The results of the present study confirmed the therapeutic potency of S. corymbosa used in the traditional medicine; in addition, the protocol for in vitro production developed in the present study could be applied for mass multiplication and for the conservation of germplasm.     

KR-12-a5 is a non-cytotoxic agent with potent antimicrobial effects against oral pathogens

This study evaluated the cytotoxicity and antimicrobial activity of analogs of cationic peptides against microorganisms associated with endodontic infections. L-929 fibroblasts were exposed to LL-37, KR-12-a5 and hBD-3–1C^V and chlorhexidine (CHX, control), and cell metabolism was evaluated with MTT. The minimal inhibitory concentration (MIC) and the minimal bactericidal/fungicidal concentration (MBC/MFC) of the peptides and CHX were determined against oral pathogens associated with endodontic infections. Enterococcus faecalis and Streptococcus mutans biofilms were cultivated in bovine dentin blocks, exposed to different concentrations of the most efficient antimicrobial peptide and analyzed by confocal laser scanning microscopy. CHX and peptides affected the metabolism of L-929 at concentrations > 31.25 and 500 μg ml^?1, respectively. Among the peptides, KR-12-a5 inhibited growth of both the microorganisms tested with the lowest MIC/MBC/MFC values. In addition, KR-12-a5 significantly reduced E. faecalis and S. mutans biofilms inside dentin tubules. In conclusion, KR-12-a5 is a non-cytotoxic agent with potent antimicrobial and anti-biofilm activity against oral pathogens associated with endodontic infections.     

Antimicrobial and antiviral activity-guided fractionation from Scutia buxifolia Reissek extracts

Antimicrobial and antiviral activities of the fractions from Scutia buxifolia stem bark and leaves were evaluated. Best antimicrobial results occurred with the ethyl acetate (EA) and n-butanolic (NB) fractions from the leaves against Micrococcus sp. (minimal inhibitory concentration—MIC = 62.5 μg/ml), and NB fraction from stem bark and leaves against Klebsiella pneumoniae and Enterococcus faecalis (MIC = 62.5 μg/ml). The most active fractions were selected and fractioned into silica column to perform an in vitro antibiofilm assay, which evidenced subfractions EA2 and EA3 as the more active against Candida albicans (biofilm inhibitory concentration—BIC = 582 ± 0.01 μg/ml) and Staphylococcus aureus (BIC = 360 ± 0.007 μg/ml), respectively. The NB (selectivity index—SI = 25.78) and the EA (SI = 15.97) fractions from the stem bark, and the EA (SI = 14.13) fraction from the leaves exhibited a potential antiviral activity towards Herpes Simplex Virus type 1 whereas EA2 and EA3 subfractions from leaves (SI = 12.59 and 10.06, respectively), and NB2 subfraction from stem bark (SI = 12.34) maintained this good activity. Phenolic acids and flavonoids (gallic acid, chlorogenic acid, caffeic acid, rutin, isoquercitrin, quercitrin and quercetin) were identified by HPLC and may be partially responsible for the antimicrobial and antiherpes activities observed. The results obtained in this study showed that Scutia buxifolia has antibiofilm and anti-herpetic activities and that these properties are reported for the first time for this species.     

Senegalin: a novel antimicrobial/myotropic hexadecapeptide from the skin secretion of the African running frog, Kassina senegalensis

Amphibian skin is a rich and unique source of novel bioactive peptides most of which are endowed with either antimicrobial or pharmacological properties. Here, we report the identification and structural characterization of a novel peptide, named senegalin, which possesses both activities. Senegalin is a hexadecapeptide amide (FLPFLIPALTSLISSL-NH₂) of unique primary structure found in the skin secretion of the African running frog, Kassina senegalensis. The structure of the biosynthetic precursor of senegalin, deduced from cloned skin cDNA, consists of 76 amino acid residues and displays the typical domain organization of an amphibian skin peptide precursor. Both natural senegalin and its synthetic replicate displayed antimicrobial and myotropic activities. Senegalin was active against Staphylococcus aureus (MIC 50 μM) and Candida albicans (MIC 150 μM) but was non-haemolytic at concentrations up to and including 150 μM. In contrast, senegalin induced a dose-dependent contraction of rat urinary bladder smooth muscle (EC₅₀ 2.9 nM) and a dose-dependent relaxation of rat tail artery smooth muscle (EC₅₀ 37.7 nM). Senegalin thus represents a prototype biologically active amphibian skin peptide and illustrates the fact that amphibian skin secretion peptidomes continue to be unique sources of such molecules.     

<Emphasis Type="Italic">Streptomyces albulus</Emphasis> yields ε-poly-<Emphasis Type="SmallCaps">l</Emphasis>-lysine and other products from salt-contaminated glycerol waste

Actinomycetes are the most important microorganisms for the industrial production of secondary metabolites with antimicrobial and anticancer properties. However, they have not been implicated in biorefineries. Here, we study the ability of the ε-poly-l-lysine producing Streptomyces albulus BCRC 11814 to utilize biodiesel-derived crude glycerol. S. albulus was cultured in a mineral medium supplemented with up to 10% w/v sodium chloride or potassium chloride, and with crude glycerol as the sole carbohydrate source. Under these conditions, the strain produced 0.1 g ε-poly-l-lysine per 1 g of biomass. RNA sequencing revealed upregulation of the ectoine biosynthetic pathway of S. albulus, which provides proof of halotolerance. S. albulus has several silent secondary metabolite biosynthetic clusters predicted within the genome. Based on the results, we conclude that S. albulus BCRC 11814 is a halotolerant microorganism capable of utilizing biodiesel-derived crude glycerol better than other actinomycetes included in the present study. S. albulus has the potential to be established as microbial platform production host for a range of high-value biological products.     

Temporal characterization of serum metabolite signatures in lung cancer patients undergoing treatment

Lung cancer causes more deaths in men and women than any other cancer related disease. Currently, few effective strategies exist to predict how patients will respond to treatment. We evaluated the serum metabolomic profiles of 25 lung cancer patients undergoing chemotherapy ± radiation to evaluate the feasibility of metabolites as temporal biomarkers of clinical outcomes. Serial serum specimens collected prospectively from lung cancer patients were analyzed using both nuclear magnetic resonance (¹H-NMR) spectroscopy and gas chromatography mass spectrometry (GC–MS). Multivariate statistical analysis consisted of unsupervised principal component analysis or orthogonal partial least squares discriminant analysis with significance assessed using a cross-validated ANOVA. The metabolite profiles were reflective of the temporal distinction between patient samples before during and after receiving therapy (¹H-NMR, p < 0.001: and GC–MS p < 0.01). Disease progression and survival were strongly correlative with the GC–MS metabolite data whereas stage and cancer type were associated with ¹H-NMR data. Metabolites such as hydroxylamine, tridecan-1-ol, octadecan-1-ol, were indicative of survival (GC–MS p < 0.05) and metabolites such as tagatose, hydroxylamine, glucopyranose, and threonine that were reflective of progression (GC–MS p < 0.05). Metabolite profiles have the potential to act as prognostic markers of clinical outcomes for lung cancer patients. Serial ¹H-NMR measurements appear to detect metabolites diagnostic of tumor pathology, while GC–MS provided data better related to prognostic clinical outcomes, possibility due to physiochemical bias related to specific biochemical pathways. These results warrant further study in a larger cohort and with various treatment options.     

Effect of agricultural production systems on the potato metabolome

Potato (Solanum tuberosum L.) cv. Santé was grown over 2 years under both conventional and organic fertiliser and crop protection regimes. The tuber metabolome was analysed using mass-spectrometry (MS) based approaches, principally liquid chromatography (LC)–MS and gas chromatography (GC)–MS. Data were analysed using Principal Components Analysis (PCA) and Analysis of Variance (ANOVA) to assess any differences between production practices. GC–MS analysis of non-polar metabolites did not detect any statistically significant differences, but GC–MS analysis of polar compounds identified 83 metabolites showing significant differences in the metabolome between the fertiliser treatments. Of the 62 metabolites that were less abundant in tuber samples from organic compared with conventionally fertilised crops, consistent year on year differences were dominated by free amino acids. The effect on free amino acids is associated with the lower nitrogen (N) content of the organically grown potatoes in this instance (50 % lower than for conventional production). LC–MS provided indications that levels of certain glycoalkaloids may be lower under the organic fertiliser regime in one growing season. Differences associated with the crop protection measures used were much less consistent, and relatively small, compared with the fertiliser effects found.     

A non-cyclic baboon θ-defensin derivative exhibiting antimicrobial activity against the phytopathogen Verticillium dahliae

θ-Defensins are the only natural cyclic proteins found in primates. They have strong antimicrobial activity related to their trisulfide ladders and macrocyclic conformation. A non-cyclic baboon θ-defensin (BTD) was synthesized by substituting valine with phenylalanine at position 17, at the C-terminal end of the BTD; this was termed “BTD-S.” The antimicrobial activities of this synthetic peptide were investigated against Escherichia coli and two cotton phytopathogens: Verticillium dahliae and Fusarium oxysporum. The minimum inhibitory concentration (MIC) of BTD-S for E. coli was 10 μg/mL and for V. dahliae was 5 μg/mL, significantly lower than that for F. oxysporum (40.0 μg/mL). A time course analysis of fungal cultures indicated that the growth of V. dahliae was completely inhibited after 96 h of BTD-S treatment. Furthermore, hemolysis assays revealed that BTD-S was not toxic to mammalian cells as it could not induce lysis of sheep red blood cells even at ten times the MIC (50 μg/mL). Scanning electron microscopy and double-stained (calcofluor white and propidium iodide binding) fluorescence microscopy showed that exposure of spores of V. dahliae to BTD-S either disabled normal germination or disintegrated the spores. The size of cells exposed to BTD-S was significantly reduced compared with controls, and their number increased in a dose-dependent curve when measured by flow cytometry. These findings suggest that BTD-S has great potential to inhibit the growth of V. dahliae and can be utilized as an effective remedy to control economic losses caused by Verticillium wilt in the development of wilt-resistant cotton.     

Endophytic actinomycetes isolated from Aquilaria crassna Pierre ex Lec and screening of plant growth promoters production

A total of 10 endophytic actinomycete strains were successfully isolated from healthy shoots and roots of Aquilaria crassna Pierre ex Lec (eaglewood). Analysis of 16S rDNA sequencing of those isolates showed that they belong to members of the genera Streptomyces (2 isolates), Nonomuraea (1 isolate), Actinomadura (1 isolate), Pseudonocardia (1 isolate) and Nocardia (3 isolates). The remaining 2 isolates were unidentified. All of isolates produced the amount of indole-3-acetic acid (IAA) and ammonia ranging between 9.85 ± 0.31 to 15.14 ± 0.22 μg ml^?1 and 2 to 60 mg ml^?1, respectively. Among 10 isolates tested, the amount of hydroxamate-type siderophore produced by 2 isolates was undetectable. While the remaining 8 isolates produced the amount of hydroxamate-type ranging between 3.21 ± 0.12 and 39.30 ± 0.40 μg ml^?1. Also, catechols-type siderophore produced by 9 isolates was undetectable. Actinomadura glauciflava is only one isolate that produced catechols-type 4.12 ± 0.90 μg ml^?1. In addition, 10 endophytic actinomycetes showed protease activity ranging from undetectable to 8.16 ± 0.15 unit ml^?1. Genetic relatedness amongst these isolates was determined base on Random amplified polymorphic DNA (RAPD) and Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC PCR). Both methodologies generated specific patterns corresponding to particular genotypes. RAPD fingerprinting proved to be slightly more discriminatory than ERIC PCR. This study is the first published report that actinomycetes can be isolated as endophytes within this plant. It is also the first published report that endophytic actinomycetes are capable of producing IAA and siderophores.     

Development of a Polygonum minus cell suspension culture system and analysis of secondary metabolites enhanced by elicitation

Polygonum minus has been reported to contain valuable metabolites and to date, there is no report on using cell culture technique for metabolite production in P. minus. Naphthalene acetic acid (NAA) concentrations in the range of 2–6 mg L^?1 were used in a matrix of combinations with dichlorophenoxyacetic acid (2,4-D) concentrations in the range of 2–10 mg L^?1 as plant growth regulators (PGRs) to induce callus cultures. Media that were supplemented with 2 mg L^?1 2,4-D + 4 mg L^?1 NAA, 2 mg L^?1 2,4-D + 6 mg L^?1 NAA and 6 mg L^?1 2,4-D + 8 mg L^?1 NAA were effective for callus induction (93.3 % of the explants produced callus). To establish cell culture, the best growth was obtained from medium that was supplemented with 1 mg L^?1 2,4-D + 2 mg L^?1 NAA. From a 1-g inoculum size, the fresh weight increases exponentially after 5–10 days of culture, and a 26.71 g maximum fresh weight was obtained after 25 days of culture. The cell culture medium was then analyzed using gas chromatography–mass spectrometry (GC–MS). Jasmonic acid (100, 50, 25 and 5 μM), salicylic acid (100, 50, 25 and 5 μM), yeast extract (500, 250 and 100 mg L^?1) and glass beads were used in this research as elicitors. The cell cultures were then incubated with the different elicitors for 1, 2, 3 and 4 days. Several compounds with high peak area percentages were detected, including 2-furancarboxaldehyde, 5-hydroxymethyl, furfural, and 2-cyclopenten-1-one, 2-hydroxy. These results show the diversity of metabolites released by P. minus cell into the culture medium under control conditions.     

Antimicrobial volatile glucosinolate autolysis products from Hornungia petraea (L.) Rchb. (Brassicaceae)

Plant samples of Hornungia petraea were analyzed for glucosinolate (GLS) autolysis metabolites for the first time. GC–MS analysis of the autolysate and the synthesis of a series (12 compounds) of possible glucosinolate breakdown products revealed/corroborated the presence of glucoaubrietin, glucolimnanthin, glucolepigramin and glucotropaeolin in this species as the most likely “mustard oil” precursors. GLS degradation products identified in the autolysate of H. petraea, benzyl isothiocyanate, 3- and 4-methoxybenzyl isothiocyanate, along with several other structurally related compounds were evaluated for antimicrobial activity in order to possibly pinpoint the role of the latter secondary metabolites in the plant tissues. The assays showed a very high antibacterial activity of the tested isothiocyanates against Sarcina lutea and an antifungal effect against Aspergillus fumigatus and Candida albicans with MIC values in the order of 1 μg/ml value.     

Biological effects of active fraction isolated from Hydnocarpus pentandra (Bunch. –Ham.) Oken seeds against Helicoverpa armigera (Hub.) (Lepidoptera: Noctuidae)

Hexane, chloroform, ethyl acetate and methanol extracts of Hydnocarpus pentandra (Flacourtiaceae) seeds were tested for antifeedant, larvicidal, pupal mortality and adult deformations activities against Helicoverpa armigera. Crude extracts were screened at 0.5, 1.0, 1.5 and 2.0% concentrations. Bioassay-guided fractionation method was followed to isolate the active fraction from the crude extract. Active fraction was analysed by FT-IR, ¹H NMR, ¹³C NMR and GC-MS. Hexane extract presented the highest antifeedant (87.89%), pupal mortality (41.67%) and adult malformation activities at 2% concentration. Seven different fractions were isolated from hexane extract, among which fraction-2 showed the highest antifeedant (81.43%) activity and recorded the lowest LC₅₀ of 792.07 ppm. The fraction-2 contained two cyclopentenyl carboxylic acids, such as hydnocarpic acid (1) and chaulmoogric acid (2) in the ratio of 2:1. These compounds were major constituents in the active fraction of hexane extract of H. pentandra seeds. Fraction-2 can be used for agricultural pest management.     

Antifouling potential of the marine microalga Dunaliella salina

Marine organisms have usually been viewed as sources of environmentally friendly compounds with antifouling activity. We performed a series of operations to investigate the antifouling potential of the marine microalga Dunaliella salina. For the ethyl acetate crude extract, the antialgal activity was significant, and the EC₅₀ value against Skeletonema costatum was 58.9 μg ml^?1. The isolated purified extract was tested for antifouling activity, the EC ₅₀ value against S. costatum was 21.2 μg ml^?1, and the LC₅₀ against Balanus amphitrite larvae was 18.8 μg ml^?1. Subsequently, both UHR–TOF–MS and GC–MS were used for the structural elucidation of the compounds, and a series of unsaturated and saturated 16- and 18-carbon fatty acids were detected. The data suggested that the fatty acid extracts from D. salina possess high antifouling activity, and could be used as substitutes for potent, toxic antifouling compounds.     

A novel combinatorial biocatalytic approach for producing antibacterial compounds effective against Mycobacterium tuberculosis (TB)

Two bacterial hosts expressing cloned aromatic oxygenases were used to catalyze the oxidation and polymerization of indole and related substrates, creating mixtures of indigoid compounds comprised of novel dimers and trimers. Crude extracts and purified compounds were tested for their ability to inhibit the growth of Gram-positive organisms, in general, and Mycobacterium tuberculosis (TB), in particular. Of the 74 compounds tested against M. tuberculosis, ~66 % had minimum inhibitory concentrations (MIC) of 5 μg/ml or less. The most effective antibiotic found was designated SAB-P1, a heterodimer of indole and anthranil, which had a MIC of 0.16 μg/ml, and did not inhibit kidney cells (IC⁵⁰) at concentrations of >8 μg/ml. Combinatorial biocatalysis was used to create a series of halogenated derivatives of SAB-P1 with a wider therapeutic window. None of the derivatives had MIC values that were superior to SAB-P1, but some had a wider therapeutic window because of decreased kidney cell toxicity. Generally, the indigoid dimers that were effective against TB appeared to be specific for TB. Some of the trimers generated, however, had a broader spectrum of activity inhibiting not only TB (MIC?=?1.1 μg/ml) but also the growth of Mycobacterium smegmatis MC2 155, Bacillus cereus, Enterococcus faecalis, Staphylococcus epidermidis, Bacillus subtilis 168, and Clostridium acetobutylicum. The structure of two of the novel dimers (SAB-C4 and SAB-P1) and a trimer (SAB-R1) were solved using X-ray crystallography.