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1,2-unsaturated pyrrolizidine alkaloids are found naturally in Symphytum officinale, well known as comfrey, which has a longstanding use for the topical treatment of painful muscle and joint complaints. Pyrrolizidine alkaloids (PA) are a relevant concern for the safety assessment due to their liver genotoxicity profile, and close attention is paid during manufacturing to minimizing their levels. Current regulatory risk assessment approaches include setting limits that derive from toxicity data coming from the oral route of exposure. This study investigated to what extent pyrrolizidine alkaloids are bioavailable following topical exposure, assessing penetration of retronecine-type PAs in an in vitro human skin model. A single comfrey root formulation was spiked with 3 different congeners (a 7R-monoester, an open-chained 7R-diester, and a cyclic diester) and percutaneous absorption measured per OECD guidelines and good laboratory practices. The measured penetration for all 3 PAs was low and compared favourably with existing in vitro data. Although consideration of different regulatory guidance influences the determination of dermally absorbed dose, these data facilitate the understanding of absorption differences following topical exposure, which in turn can be taken into account in the risk assessment.

The structures of five linear lipopeptides, thaxteramides A1, A2, B1, B2, and C isolated from the myxobacterium Jahnella thaxteri, were elucidated. They have a C-terminal common tetrapeptidic Tyr-Gly-β-Ala-Tyr core but differ in the stereochemistry of the tyrosine units, methylations, the remaining amino acids, and the N-terminal polyketide. In silico analysis of the genome sequence complemented with feeding experiments revealed two distinct hybrid PKS/NRPS gene clusters. Three semisynthesized cyclic analogues were found to inhibit the growth of Gram-positive bacteria.

Preparations of comfrey (Symphytum officinale L.) roots are used topically to reduce inflammation. Comfrey anti-inflammatory and analgesic properties have been proven in clinical studies. However, the bioactive compounds associated with these therapeutic activities are yet to be identified. An LC&ndash, ESI&ndash, Orbitrap&ndash, MSn metabolite profile of a hydroalcoholic extract of comfrey root guided the identification of 20 compounds, including a new arylnaphthalene lignan bearing a rare &delta, lactone ring, named comfreyn A. Its structure was determined using extensive 2D NMR and ESI&ndash, MS experiments. Additionally, the occurrence of malaxinic acid, caffeic acid ethyl ester, along with the lignans ternifoliuslignan D, 3-carboxy-6,7-dihydroxy-1-(3&prime, 4&prime, dihydroxyphenyl) -naphthalene, globoidnan A and B, and rabdosiin was reported in S. officinale for the first time. These results helped to redefine the metabolite profile of this medicinal plant. Finally, caffeic acid ethyl ester and comfreyn A were found to significantly inhibit E-selectin expression in IL-1&beta, stimulated human umbilical vein endothelial cells (HUVEC), with EC values of 64 and 50 &micro, M, respectively.

Cloning and engineering of natural product biosynthetic pathways followed by heterologous expression in a tractable host is a widely used approach for expression and genetic modification of microbial secondary metabolites. Herein, we employed ccdB counterselection combined with oligonucleotide-mediated recombineering to efficiently create point mutations in a complex nonribosomal peptide synthetase (NRPS) from Photorabdus luminescens directing the biosynthesis of luminmides. After in depth analysis of the luminmide production profile from the native NRPS, single and double point mutations were rationally constructed within the adenylation (A) domain from NRPS module 3 which turned out to have a broad substrate tolerance. Expression of mutated versions of the 15.6 kb NRPS gene plu3263 in E. coli led to alterations in luminmide production profiles and allowed to direct the biosynthesis towards certain derivatives. These results demonstrate the suitability of counterselection recombineering for site-directed mutagenesis of complex expression constructs, e.g., genes encoding NRPS biosynthetic pathways in multi-copy plasmids.

Colibactin represents a structurally undefined class of bacterial genotoxin inducing DNA damage and genomic instability in mammalian cells, thus promoting tumour development and exacerbating lymphopenia in animal models. The colibactin biosynthetic gene cluster (clb) has been known for ten years and it encodes a hybrid nonribosomal peptide synthetase (NRPS)/polyketide synthase (PKS) assembly line. Nevertheless, the final chemical product(s) remain unknown. Previously, we and others reported several colibactin pathway-related metabolites including N-myristoyl-D-asparagine (1) as part of a prodrug precursor that is cleaved from the putative precolibactin to form active colibactin by the peptidase ClbP. Herein, we report two new colibactin pathway-related metabolites (2 and 3) isolated from a clbP mutant of the probiotic E. coli Nissle 1917 strain. Their structures were established by HRMS and NMR. Compound 2 shows an additional 4-aminopenatanoic acid moiety with respect to 1, while 3 is characterized by the presence of an unusual 7-methyl-4-azaspiro[2.4]hept-6-en-5-one residue. Moreover, we propose the biosynthetic pathway towards both intermediates on the basis of extensive gene inactivation and feeding experiments. The identification of 2 and 3 provides further insight into colibactin biosynthesis including the involvement and formation of a rare 1-aminocyclopropanecarboxylic acid unit. Thus, our work establishes additional steps of the pathway forming the bacterial genotoxin colibactin.

Cystomanamides A-D were isolated as novel natural product scaffolds from Cystobacter fuscus MCy9118, and their structures were established by spectroscopic techniques including 2D NMR, LC-SPE-NMR/-MS, and HR-MS. The cystomanamides contain β-hydroxy amino acids along with 3-amino-9-methyldecanoic acid that is N-glycosylated in cystomanamide C and D. The gene cluster for cystomanamide biosynthesis was identified by gene disruption as PKS/NRPS hybrid incorporating an iso-fatty acid as starter unit and including a reductive amination step at the interface of the PKS and NRPS modules.

The present work deals with the optimization of an inhibitor of PqsD, an enzyme essential for Pseudomonas aeruginosa quorum sensing apparatus. Molecular docking studies, supported by biophysical methods (surface plasmon resonance, isothermal titration calorimetry, saturation transfer difference NMR), were used to illuminate the binding mode of the 5-aryl-ureidothiophene-2-carboxylic acids. Enabled to make profound predictions, structure-based optimization led to increased inhibitory potency. Finally a covalent inhibitor was obtained. Binding to the active site was confirmed by LC-ESI-MS and MALDI-TOF-MS experiments. Following this rational approach, potent PqsD inhibitors were efficiently developed within a short period of time. This example shows that a combination and careful application of in silico and biophysical methods represents a powerful complement to cocrystallography.

Seven new halogenated peptides termed svetamycins A-G (1-7) have been isolated from laboratory cultures of a Streptomyces sp. Svetamycins A-D, F, and G are cyclic depsipeptides, whereas svetamycin E is a linear analogue of svetamycin C. Their structures were determined using extensive spectroscopic analysis, and their stereochemical configuration was established by a combination of NMR data, quantum mechanical calculations, and chemical derivatizations. Svetamycins are characterized by the presence of a hydroxyl acetic acid and five amino acids including a rare 4,5-dihydroxy-2,3,4,5-tetrahydropyridazine-3-carboxylic acid, a g-halogenated piperazic acid, and a novel d-methylated piperazic acid in svetamycins B-C, E, and G. Moreover, isotope-labeled substrate feeding experiments demonstrated ornithine as the precursor of piperazic acid and that methylation at the d position of the piperazyl scaffold is S-adenosyl-l-methionine (SAM)-dependent. Svetamycin G, the most potent antimicrobial of this suite of compounds, inhibited the growth of Mycobacterium smegmatis with an MIC80 value of 2 mg/mL.

A new linear polyketide, juniperolide A (1), was produced by the terrestrial actinomycete (Lv1-48) isolated from the rhizosphere of the plant Juniperus excelsa. The juniperolide A (1) structure contains a THP unit and a 3-amino-2,3,6-trideoxyhexose as the glycosidic moiety. Mosher's analysis was used for absolute stereochemistry determinations at C-2, C-8, C-20, and C-4', while the relative stereochemistry assignments of the remaining stereocenters were based on ROESY correlations and J-based coupling.

Three new anabaenopeptin-like peptides, named paltolides A-C, were isolated from a deep-water specimen of the marine sponge Theonella swinhoei from Palau. Paltolides belong to a rare subgroup of sponge-derived anabaenopeptins that have in common a C-terminal tryptophan residue linked to the epsilon-amine of a lysine bearing a d configuration. The structures of paltolides A-C were determined by NMR and tandem MS techniques. Paltolide A is the first anabaenopeptin structure where a non-N-methylated amino acid precedes the C-terminal residue.

A new highly unsaturated macrolide lactam, termed mirabilin ( 1), was isolated from the aqueous extract of the marine sponge Siliquariaspongia mirabilis. Mirabilin is characterized by the presence of a 35-membered macrolide lactam ring bearing a pentadiene conjugated system and a tetrasubstituted tetrahydropyran ring. A linear polyketide moiety is attached to the macrocyclic ring through an amide linkage. The structure of mirabilin was determined using extensive 2D NMR and ESIMS and tandem MS techniques. Mirabilin inhibits the growth of the tumor cell line HCT-116 with an IC 50 value of 0.27 +/- 0.09 microM and is noncytotoxic to several other cell lines.

Seven new chromone-containing polyketides, termed cystochromones A-G, were isolated from the myxobacterial strain Cystobacter sp. MCy9104. Their structures were elucidated using comprehensive NMR spectroscopy and HR-MS/MS. Cystochromones bear a pentadecyl moiety unusually attached at C-5 of the chromone ring. Moreover, isotope-labeled substrate feeding experiments and NMR analysis suggested a hybrid iso-fatty acid and polyketide synthase biosynthetic pathway for these secondary metabolites.

Seven new 15-keto pregnane glycosides, namely Stemmosides E--K, were isolated from Solenostemma argel. Stemmosides E--J are characterized by the occurrence of an uncommon 14 beta proton configuration while stemmosides E and F possess in addition a rare enolic function in C-16. On the other hand, stemmosides G-J display an unusual C-17 alpha side chain. Their structures were established by ESI-MS and NMR experiments. Moreover, the effect of these compounds on the VEGF-induced in Kaposi's sarcoma cell proliferation was tested. Results indicated that all the compounds reduced the cell proliferation in a dose dependent manner.

Two new dammarane saponins identified as jujubogenin 3-O-alpha-l-arabinofuranosyl(1-->2)-[beta-d-glucopyranosyl(1-->6) beta-d-glucopyranosyl(1-->3)]-alpha-l-arabinopyranoside (2) and jujubogenin 3-O-alpha-l-arabinofuranosyl(1-->2)-[6-O-[3-hydroxy-3-methylglutaryl]-beta-d-glucopyranosyl(1-->3)]-alpha-l-arabinopyranoside (3) and a new lupane saponin, 3beta-hydroxylup-20(29)-en-27,28-dioic acid 28-O-beta-d-glucopyranosyl(1-->2)-[beta-d-xylopyranosyl(1-->3)]-beta-d-xylopyranosyl(1-->2)-beta-d-glucopyranoside ester (5), along with the known jujubogenin 3-O-alpha-l-arabinofuranosyl(1-->2)-[beta-d-glucopyranosyl(1-->3)]-alpha-l-arabinopyranoside (1) and 3beta-hydroxylup-20(29)-ene-27,28-dioic acid (4), were isolated from the methanol extract of the stems of Anomospermum grandifolium. The structures of the new compounds were established by spectral analysis. Antimicrobial activity screening of compounds 1-3 revealed antifungal properties against C. albicans ATCC 3153 for compounds 2 and 3. The antibacterial and antifungal activities of the petroleum ether, chloroform, and methanol extracts of A. grandifolium stems were also evaluated.

We assessed in vivo the anti-inflammatory activity of two Cat's claw bark extracts, by comparing a spray-dried hydroalcoholic extract against an aqueous freeze-dried extract, to determine which extract was more effective. We used the carrageenan-induced paw edema model in mice. In addition, to assess the molecular mechanism of action, we determined the inhibition of NF-kappa B through the Electrophoretic Mobility Shift Assay (EMSA) and the effects on cycloxygenase-1 and -2. Results showed that the anti-inflammatory activity was significantly higher using the hydroalcoholic compared with the aqueous extract (P

Bacterial RNA polymerase (RNAP) represents a validated target for the development of broad-spectrum antibiotics. However, the medical value of RNAP inhibitors in clinical use is limited by the prevalence of resistant strains. To overcome this problem, we focused on the exploration of alternative target sites within the RNAP. Previously, we described the discovery of a novel RNAP inhibitor class containing an ureidothiophene-2-carboxylic acid core structure. Herein, we demonstrate that these compounds are potent against a set of methicillin-resistant Staphylococcus aureus (MRSA) strains (MIC 2-16 μg mL(-1)) and rifampicin-resistant Escherichia coli TolC strains (MIC 12.5-50 μg mL(-1)). Additionally, an abortive transcription assay revealed that these compounds inhibit the bacterial transcription process during the initiation phase. Furthermore, the binding mode of the ureidothiophene-2-carboxylic acids was characterized by mutagenesis studies and ligand-based NMR spectroscopy. Competition saturation transfer difference (STD) NMR experiments with the described RNAP inhibitor myxopyronin A (Myx) suggest that the ureidothiophene-2-carboxylic acids compete with Myx for the same binding site in the RNAP switch region. INPHARMA (interligand NOE for pharmacophore mapping) experiments and molecular docking simulations provided a binding model in which the ureidothiophene-2-carboxylic acids occupy the region of the Myx western chain binding site and slightly occlude that of the eastern chain. These results demonstrate that the ureidothiophene-2-carboxylic acids are a highly attractive new class of RNAP inhibitors that can avoid the problem of resistance.

Two new cyclic peptides, termed jahnellamides A and B, were isolated from the myxobacterium Jahnella sp. Their structures were solved by NMR, ESIMS, and chemical derivatizations. Jahnellamides are a new class of α-ketoamide-containing peptides comprised of nonproteinogenic amino acids, including α-keto-β-methionine and 4-hydroxyglutamic acid. Moreover, in silico analysis of the genome sequence along with feeding experiments allowed us to identify and annotate a candidate nonribosomal peptide synthetase biosynthetic gene cluster containing a polyketide synthase module involved in the formation of the α-ketoamide moiety.

The 18 kb "silent" luminmycin biosynthetic pathway from Photorhabdus luminescens was cloned into a vector by using the newly established linear-linear homologous recombination and successfully expressed in Escherichia coli. Luminmycins A-C (1-3) were isolated from the heterologous host, and their structures were elucidated using 2D NMR spectroscopy and HRESIMS. Luminmycin A is a deoxy derivative of the previously reported glidobactin A, while luminmycins B and C most likely represent its acyclic biosynthetic intermediates. Compound 1 showed cytotoxicity against the human colon carcinoma HCT-116 cell line with an IC(50) value of 91.8 nM, while acyclic 2 was inactive at concentrations as high as 100 μg/mL.

Drug-resistant Staphylococcus aureus is a continuing public health concern, both in the hospital and community settings. Antibacterial compounds that possess novel structural scaffolds and are effective against multiple S. aureus strains, including current drug-resistant ones, are needed. Previously, we have described the chrysophaentins, a family of bisdiarylbutene macrocycles from the chrysophyte alga Chrysophaeum taylori that inhibit the growth of S. aureus and methicillin-resistant S. aureus (MRSA). In this study we have analyzed the geographic variability of chrysophaentin production in C. taylori located at different sites on the island of St. John, U.S. Virgin Islands, and identified two new linear chrysophaentin analogs, E2 and E3. In addition, we have expanded the structure activity relationship through synthesis of fragments comprising conserved portions of the chrysophaentins, and determined the antimicrobial activity of natural chrysophaentins and their synthetic analogs against five diverse S. aureus strains. We find that the chrysophaentins show similar activity against all S. aureus strains, regardless of their drug sensitivity profiles. The synthetic chrysophaentin fragments indeed mimic the natural compounds in their spectrum of antibacterial activity, and therefore represent logical starting points for future medicinal chemistry studies of the natural products and their analogs.

The discovery, structure elucidation, and solid-phase synthesis of namalide, a marine natural product, are described. Namalide is a cyclic tetrapeptide; its macrocycle is formed by only three amino acids, with an exocyclic ureido phenylalanine moiety at its C-terminus. The absolute configuration of namalide was established, and analogs were generated through Fmoc-based solid phase peptide synthesis. We found that only natural namalide and not its analogs containing l-Lys or l-allo-Ile inhibited carboxypeptidase A at submicromolar concentrations. In parallel, an inverse virtual screening approach aimed at identifying protein targets of namalide selected carboxypeptidase A as the third highest scoring hit. Namalide represents a new anabaenopeptin-type scaffold, and its protease inhibitory activity demonstrates that the 13-membered macrolactam can exhibit similar activity as the more common hexapeptides.

Functional genomics requires facile methods to recover sequences of interest. Fu et al. show that the phage proteins RecE and RecT mediate recombination between linear DNA fragments and can facilitate natural product discovery. Functional analysis of genome sequences requires methods for cloning DNA of interest. However, existing methods, such as library cloning and screening, are too demanding or inefficient for high-throughput application to the wealth of genomic data being delivered by massively parallel sequencing. Here we describe direct DNA cloning based on the discovery that the full-length Rac prophage protein RecE and its partner RecT mediate highly efficient linear-linear homologous recombination mechanistically distinct from conventional recombineering mediated by Redαβ from lambda phage or truncated versions of RecET. We directly cloned all ten megasynthetase gene clusters (each 10–52 kb in length) from Photorhabdus luminescens into expression vectors and expressed two of them in a heterologous host to identify the metabolites luminmycin A and luminmide A/B. We also directly cloned cDNAs and exactly defined segments from bacterial artificial chromosomes. Direct cloning with full-length RecE expands the DNA engineering toolbox and will facilitate bioprospecting for natural products.

Biological, biochemical, and structural studies presented in this paper show Chrysophaentin A (Ia) is the most potent of the isolated antibiotics, inhibited the growth of clinically relevant Gram-positive bacteria including methicillin-resistant Staphylococcus aureus, multidrug-resistant S.

Eight new antimicrobial natural products named chrysophaentins A-H belonging to a new structural class have been isolated from the marine chrysophyte alga Chrysophaeum taylori. Their structures were determined by extensive 2D NMR and MS techniques and are characterized by the presence of two polyhalogenated, polyoxygenated omega,omega'-diarylbutene units connected by two ether bonds to form the suite of macrocyclic natural products. Chrysophaentin A, the most potent of these antibiotics, inhibited the growth of clinically relevant Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MIC(50) 1.5 +/- 0.7 microg/mL), multidrug-resistant S. aureus (1.3 +/- 0.4 microg/mL), and vancomycin-resistant Enterococcus faecium (MIC(50) 2.9 +/- 0.8 microg/mL). In vitro enzyme assays and transmission electron microscopy showed chrysophaentin A to inhibit the GTPase activity of the bacterial cytoskeletal protein FtsZ with an IC(50) value of 6.7 +/- 1.7 microg/mL, as well as GTP-induced formation of FtsZ protofilaments. Saturation Transfer Difference (STD) NMR experiments further confirmed chrysophaentin A binds to FtsZ, and NMR competition experiments with GTPgammaS showed chrysophaentin A and GTP to bind competitively to FtsZ. Last, molecular docking simulations provided a low energy model in which chrysophaentin A binds in and occludes a large portion of the GTP binding site of FtsZ in a manner that is consistent with the binding epitope determined by STD NMR.

Seven new antibacterials, motualevic acids A−F (1−6) and (4E)-(R)-antazirine (7), have been isolated from the marine sponge Siliquariaspongia sp. and their structures elucidated by spectroscopic methods. Motualevic acids A−D are the first glycyl conjugates of the ω-brominated lipid (E)-14,14-dibromotetradeca-2,13-dienoic acid, and motualevic acid F is the first long-chain 2H-azirine 2-carboxylic acid to be found in nature. Carboxylic acid-containing compounds 1 and 6 inhibit the growth of Staphylococcus aureus and methicillin-resistant S. aureus at 1.2−10.9 μg/mL.

Six new depsipeptides belonging to two different structural classes, termed celebesides A-C and theopapuamides B-D, have been isolated from the marine sponge Siliquariaspongia mirabilis. Their structures were determined using extensive 2D NMR and ESI-MS/MS techniques. Celebesides are unusual cyclic depsipeptides that comprise a polyketide moiety and five amino acid residues, including an uncommon 3-carbamoyl threonine, and a phosphoserine residue in celebesides A and B. Theopapuamides B-D are undecapeptides with an N-terminal fatty acid moiety containing two previously unreported amino acids, 3-acetamido-2-aminopropanoic acid and 4-amino-2,3-dihydroxy-5-methylhexanoic acid. The relative configuration of the polyketide moiety in celebesides was resolved by J-based analysis and quantum mechanical calculations, the results of which were self consistent. Celebeside A neutralized HIV-1 in a single round infectivity assay with an IC50 value of 1.9 ± 0.4 μg/mL while the non-phosphorylated analog celebeside C was inactive at concentrations as high as 50 μg/mL. Theopapuamides A-C showed cytotoxicity against human colon carcinoma (HCT-116) cells with IC50 values between 2.1 and 4.0 μg/mL, and exhibited strong antifungal activity against wildtype and amphotericin B-resistant strains of Candida albicans at loads of 1-5 μg/disk.

Seven new antibacterials, motualevic acids A-F (1-6) and (4E)-(R)-antazirine (7), have been isolated from the marine sponge Siliquariaspongia sp. and their structures elucidated by spectroscopic methods. Motualevic acids A-D are the first glycyl conjugates of the omega-brominated lipid (E)-14,14-dibromotetradeca-2,13-dienoic acid, and motualevic acid F is the first long-chain 2H-azirine 2-carboxylic acid to be found in nature. Carboxylic acid-containing compounds 1 and 6 inhibit the growth of Staphylococcus aureus and methicillin-resistant S. aureus at 1.2-10.9 microg/mL.

Six new depsipeptides belonging to two different structural classes, termed celebesides A-C and theopapuamides B-D, have been isolated from the marine sponge Siliquariaspongia mirabilis. Their structures were determined using extensive 2D NMR and ESI-MS/MS techniques. Celebesides are unusual cyclic depsipeptides that comprise a polyketide moiety and five amino acid residues, including an uncommon 3-carbamoyl threonine, and a phosphoserine residue in celebesides A and B. Theopapuamides B-D are undecapeptides with an N-terminal fatty acid moiety containing two previously unreported amino acids, 3-acetamido-2-aminopropanoic acid and 4-amino-2,3-dihydroxy-5-methylhexanoic acid. The relative configuration of the polyketide moiety in celebesides was resolved by J-based analysis and quantum mechanical calculations, the results of which were self-consistent. Celebeside A neutralized HIV-1 in a single-round infectivity assay with an IC(50) value of 1.9 +/- 0.4 microg/mL while the nonphosphorylated analog celebeside C was inactive at concentrations as high as 50 microg/mL. Theopapuamides A-C showed cytotoxicity against human colon carcinoma (HCT-116) cells with IC(50) values between 2.1 and 4.0 microg/mL and exhibited strong antifungal activity against wildtype and amphotericin B-resistant strains of Candida albicans at loads of 1-5 microg/disk.

Four new cyclic depsipeptides termed mirabamides A-D (1-4) have been isolated from the marine sponge Siliquariaspongia mirabilis and shown to potently inhibit HIV-1 fusion. Their structures were elucidated by NMR and ESIMS, and absolute stereochemistry of the amino acids was determined using advanced Marfey's methods and NMR. Mirabamides contain two new entities, including 4-chlorohomoproline in 1-3 and an unusual glycosylated amino acid, beta-methoxytyrosine 4'-O-alpha-L-rhamnopyranoside (in 1, 2, and 4), along with a rare N-terminal aliphatic hydroxy acid. These elements proved to be useful for anti-HIV structure-activity relationship studies. Mirabamide A inhibited HIV-1 in neutralization and fusion assays with IC50 values between 40 and 140 nM, as did mirabamides C and D (IC50 values between 140 nM and 1.3 microM for 3 and 190 nM and 3.9 microM for 4), indicating that these peptides can act at the early stages of HIV-1 entry. The potent activity of depsipeptides containing the glycosylated beta-OMe Tyr unit demonstrates that beta-OMe Tyr itself is not critical for activity. Mirabamides A-C inhibited the growth of B. subtilis and C. albicans at 1-5 microg/disk in disk diffusion assays.

Continuing our investigations on plants belonging to the Asclepiadaceae family, three new cardenolide glycosides, 3'-O-beta-D-glucopyranosylcalactin (1), 12-dehydroxyghalakinoside (2), and 6'-dehydroxyghalakinoside (3), along with the known ghalakinoside (4) and calactin (5), were isolated from the roots of Pergularia tomentosa. The structures of these compounds were elucidated by extensive spectroscopic methods including 1D- and 2D-NMR experiments as well as ESIMS analysis. The isolated cardenolides caused apoptotic cell death of Kaposi's sarcoma cells.

Two new and one known furostanol saponins were isolated from the rhizomes of Yucca gloriosa. The structures of the isolated compounds were established by detailed spectroscopic analysis (1D-, 2D NMR, ESI-MS, HR-MALDI-MS). The glycosidic profile of Y. gloriosa in comparison to that of Yucca schidigera, the well known commercial source of saponins, is briefly discussed. The similarity between the two species regarding the high steroidal content suggests that it might be possible to use Y. gloriosa for the same applications as Y. schidigera.

Two new furostanol saponins, (25R)-26-O-beta-D-glucopyranosyl-5alpha-furostan-2alpha,3beta,22alpha,26-tetraol 3-O-{beta-D-galactopyranosyl-(1-->2)-O-[beta-D-xylopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->4)-beta-D-galactopyranoside} (1) and (25R)-26-O-beta-D-glucopyranosyl-5alpha-furostan-3beta,22alpha,26-triol 3-O-{beta-D-galactopyranosyl-(1-->2)-O-[beta-D-xylopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->4)-beta-D-galactopyranoside} (2), and their O-methyl derivatives (3 and 4), and a new megastigmane glucoside, (6S,7E,9xi)-6,9,10-trihydroxy-4,7-megastigmadien-3-one 10-O-beta-D-glucopyranoside (6), along with one known spirostanol saponin, gitonin (5), and four known megastigmane glucosides were isolated from the aerial parts of Tribulus parvispinus. Their structures were established by detailed spectroscopic analysis. The cytotoxic activities of 1-6 against U937, MCF7, and HepG2 cells were evaluated. Compounds 2 (IC(50) 0.5 microM) and 5 (IC(50) 0.1 microM) showed the highest activity against U937 cells.

Lepidium meyenii (Maca) is traditionally employed in the Andean region for its supposed properties in improving fertility. The aim of this study was to determine the effect of subacute oral administration of hexanic, methanolic and chloroformic extracts of Maca root on sexual performance in inexperienced male rats. The following sexual performance parameters were evaluated: 1st mount, 1st intromission, ejaculation and post-ejaculatory latencies, intercopulatory interval and copulatory efficacy. All the tested fractions significantly decreased intromission latency and intercopulatory interval and increased intromission frequency and copulatory efficacy (P < 0.05) as compared to controls. Hexanic and methanolic extracts were able to increase mount frequency (MF), while only hexanic fraction significantly improved mount latency (ML) (P=0.038). Globally, only the hexanic fraction significantly improved the majority of the sexual parameters measured. Sub-acute oral administration of hexanic Maca extract improved sexual performance parameters in sexually inexperienced male rats most effectively.

Seven new depsipeptides, termed largamides A-G (1-7), and one new cyclic peptide, largamide H (8), have been isolated from the marine cyanobacterium Oscillatoria sp. Their structures were determined by NMR and ESI-MS techniques. The absolute configurations were assigned using LC-MS, chiral HPLC, and combined analysis of homonuclear and heteronuclear (2,3)J couplings, along with ROE data. Largamides, isolated from a single homogeneous cyanobacterial collection, represent three different structural classes of peptides. Largamides A-C (1-3) are characterized by the unusual occurrence of a senecioic acid unit, while largamides B (2) and C (3) possess in addition the rare 2-amino-5-(4'-hydroxyphenyl)pentanoic acid (Ahppa) and the novel 2-amino-6-(4'-hydroxyphenyl)hexanoic acid (Ahpha), respectively. Largamides D-G (4-7) are the first 3-amino-6-hydroxy-2-piperidone acid (Ahp)-containing depsipeptides reported with the rare Ahppa unit. Largamide H (8) is a unique cyclic peptide displaying a new 2,5-dihydroxylated beta-amino acid moiety, a methoxylated derivative of Ahppa, and two residues of the nonstandard 2,3-dehydro-2-aminobutanoic acid (Dab). Largamides D-G (4-7) inhibited chymotrypsin with IC(50) values ranging between 4 and 25 microM.