Three new analogues of dolastatin 13, termed lyngbyastatins 5-7 ( 1- 3), were isolated from two different collections of marine cyanobacteria, Lyngbya spp., from South Florida. Their planar structures were deduced by a combination of NMR techniques, and the absolute configurations were established by modified Marfey's analysis of the acid hydrolyzates. The related cyclodepsipeptide somamide B ( 4), previously reported from a Fijian cyanobacterium, has also been found in one of the extracts, and its absolute stereochemistry was unambiguously assigned for the first time. Compounds 1- 4 were found to selectively inhibit elastase over several other serine proteases, with IC50 values for porcine pancreatic elastase ranging from 3 to 10 nM.

As part of our ongoing investigation of filamentous fungi for anticancer leads, an active fungal extract was identified from the Mycosynthetix library (MSX 63935; related to Phoma sp.). The initial extract exhibited cytotoxic activity against the H460 (human non-small cell lung carcinoma) and SF268 (human astrocytoma) cell lines and was selected for further study. Bioactivity-directed fractionation yielded resorcylic acid lactones (RALs) 1 (a new natural product) and 3 (a new compound) and the known RALs zeaenol (2), 5E-7-oxozeaenol (4), 5Z-7-oxozeaenol (5) and LL-Z1640-1 (6). Reduction of 5E-7-oxozeaenol (4) with sodium borohydride produced 3, which allowed assignment of the absolute configuration of 3. Other known resorcylic acid lactones (7–12) were purchased and assayed in parallel for cytotoxicity with isolated 1–6 to investigate structure-activity relationships in the series. Moreover, the isolated compounds (1–6) were examined for activity in a suite of biological assays, including antibacterial, mitochondria transmembrane potential, and NF-κB. In the latter assay, compounds 1 and 5 displayed sub-micromolar activities that were on par with the positive control, and as such, these compounds may serve as a lead scaffold for future medicinal chemistry studies.

Collections of the marine cyanobacterium Lyngbya bouillonii from shallow patch reefs in Apra Harbor, Guam, afforded three hitherto undescribed analogues of the glycosidic macrolide lyngbyaloside, namely 2-epi-lyngbyaloside (1) and the regioisomeric 18E-and 18Z-lyngbyalosides C (2 and 3). Concurrently we discovered two new analogues of the cytoskeletal actin-disrupting lyngbyabellins, 27-deoxylyngbyabellin A (4) and lyngbyabellin J (5), a novel macrolide of the laingolide family, laingolide B (6), and a linear modified peptide, lyngbyapeptin D (7), along with known lyngbyabellins A and B, lyngbyapeptin A, and lyngbyaloside. The structures of 1-7 were elucidated by a combination of NMR spectroscopic and mass spectrometric analysis. Compounds 1-6 were either brominated (1-3) or chlorinated (4-6), consistent with halogenation being a hallmark of many marine natural products. All extracts derived from these L. bouillonii collections were highly cytotoxic due to the presence of apratoxin A or also apratoxin C. Compounds 1-5 showed weak to moderate cytotoxicity to HT29 colorectal adenocarcinoma and HeLa cervical carcinoma cells.Marine cyanobacteria have been attracting increasing attention for probe and drug discovery due to the high incidence of structurally novel bioactive secondary metabolites that complement those known from terrestrial sources. These natural products are predominantly modified peptides and depsipeptides, polyketides and peptide-polyketide hybrids, many of which are cyclic and oftentimes halogenated.1 One intriguing characteristic of marine cyanobacteria is that a single organism commonly produces several distinct classes of natural products so that up to 10% of the genome may be dedicated to secondary metabolism. One example of such a "superproducer" is Lyngbya bouillonii.2 , 3 Various collections carried out over the past two decades have consistently yielded apratoxin A,4 lyngbyabellin A,5 lyngbyapeptin A6 and, with variable reproducibility, also lyngbyastatin 2,7 , 8 lyngbyabellin B,6 apratoxin B9 and apramides A-G.10 Recently we found that the secondary metabolite content of L. bouillonii may be depth-dependent, because at the same site (Finger's Reef, Guam) but at greater depth (14 m instead of 2 m) apratoxin E rather than apratoxin A was the major apratoxin produced by a morphologically identical * To whom correspondence should be addressed. Tel.: (352) Fax: (352) 273-7741, luesch@cop.ufl.edu. ‡ Contributed equally.Supporting Information Available: NMR spectra for compounds 1-7. This material is available free of charge via the Internet at http://pubs.acs.org. NIH Public AccessAuthor Manuscript J Nat Prod. Author manuscript; available in PMC 2011 September 24. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript cyanobacterium.8 The latter, however, lacked the usually co-existing snapping shrimp Alpheus frontalis that is known to use L. bouillonii as food and tubular shelter.11 -13Previous investigations of L. bouillonii from Finger's Reef in Apra Harbor we...

The main factor influencing the sex determination of an embryo is the genetic sex determined by the presence or absence of the Y chromosome. However, some individuals carry a Y chromosome but are phenotypically female (46,XY females) or have a female karyotype but are phenotypically male (46,XX males). 46,XX maleness is a rare sex reversal syndrome affecting 1 in 20,000 newborn males. Molecular analysis of sex-reversed patients led to the discovery of the SRY gene (sex-determining region on Y). The presence of SRY causes the bipotential gonad to develop into a testis. The majority of 46, SRY-positive XX males have normal genitalia; in contrast SRY-negative XX males usually have genital ambiguity. A small number of SRY-positive XX males also present with ambiguous genitalia. Phenotypic variability observed in 46,XX sex reversed patients cannot be explained only by the presence or absence of SRY despite the fact that SRY is considered to be the major regulatory factor for testis determination. There must be some other genes either in the Y or other autosomal chromosomes involved in the definition of phenotype. In this article, we evaluate four patients with 46,XX male syndrome with various phenotypes. Two of these cases are among the first reported to be diagnosed prenatally.

A new caged xanthone (1), a new prenylxanthone (2), seven known xanthones, and a known sterol glucoside were isolated from the stems of Cratoxylum cochinchinense, collected in Vietnam. Compounds 1 and 2 were determined structurally by analysis of their spectroscopic data. In addition, five new (10 and 16–19) and eight known prenylated xanthone derivatives were synthesized from the known compounds, α-mangostin (3) and cochinchinone A (6). Several of these substances were found to be cytotoxic towards HT-29 human colon cancer cells, with the most potent being 3,6-di-O-acetyl-α-mangostin (8, ED50, 1.0 μM), which was tested further in an in vivo hollow fiber assay, but found to be inactive at the highest dose used (20 mg/kg; ip). Of the substances evaluated in a NF-κB p65 inhibition assay, 1,3,7-trihydroxy-2,4-diisoprenylxanthone (5) exhibited the most potent activity (IC50, 2.9 μM). In a mitochondrial transmembrane potential (MTP) assay, two new compounds, 1 (IC50, 3.3 μM) and 10 (IC50, 1.4 μM), and two known compounds, 3 (α-mangostin, IC50, 0.2 μM) and 11 (3,6-di-O-methyl-α-mangostin, IC50, 0.9 μM), were active. A preliminary analogue development study showed that 3,6-di-acetylation and 6-benzoylation both slightly increased the cytotoxicity of α-mangostin (3), whereas methylation reduced such activity. In contrast, neither acetylation, benzoylation, nor methylation enhanced the cytotoxicity of cochinchinone A (6).

Lyngbyastatin 4 (1), a new depsipeptide containing the unusual amino acid homotyrosine and a 3-amino-6-hydroxy-2-piperidone (Ahp) residue, was isolated from a collection of the marine cyanobacterium Lyngbya conferVoides off the Florida Atlantic coast. Its gross structure was determined by NMR spectroscopy, and the configurations of asymmetric centers were assigned after chiral HPLC analysis of hydrolysis products. Lyngbyastatin 4 (1) is an analogue of the sea hare isolate dolastatin 13 and several marine cyanobacterial metabolites, further supporting the notion that many of the dolastatins are of cyanobacterial origin. Lyngbyastatin 4 (1) selectively inhibits elastase and chymotrypsin in Vitro over other serine proteases with IC 50 values of 0.03 and 0.30 µM, respectively.Marine cyanobacteria produce a wide array of secondary metabolites, in particular peptides and depsipeptides. 1 Several of these compounds resemble dolastatins, which were originally isolated from the sea hare Dolabella auricularia, suggesting that many of the dolastatins are actually derived from the cyanobacterial diet. 2 Cyanobacterial metabolites commonly contain modified or unusual amino acid units, which presumably confer resistance to proteolytic degradation and thus contribute to bioactivity. Concomitantly, these structural features may also allow them to interact with proteases in a substrate-like manner or unconventional ways, leading to protease inhibition, as previously shown. 3,4 In our quest for novel bioactive compounds, including novel protease inhibitors with biomedical utility, 5 we have initiated chemical investigations of cyanobacteria in Florida waters. Here we report the structural elucidation and biological evaluation of a new protease inhibitor we term lyngbyastatin 4 (1), due to its structural analogy to dolastatin 13. 6 Lyngbyastatin 4 (1) is also closely related to the marine cyanobacterial metabolites symplostatin 2 and somamides A and B (Figure 1). 7,8 A sample of the marine cyanobacterium Lyngbya conferVoides was collected from reef habitats off Fort Lauderdale, Florida, during a cyanobacterial bloom 9 and extracted with organic solvents. The crude extract was fractionated by HP-20 chromatography, where 1 coeluted with several other compounds in a polar fraction (50% aqueous acetone). Subsequent crude fractionation over C 18 cartridges followed by reversed-phase HPLC afforded lyngbyastatin 4 (1) as a colorless, amorphous solid. NMR data combined with a [M

Tubulin-targeted chemotherapy has proven to be a successful and wide spectrum strategy against solid and liquid malignancies. Therefore, new ways to modulate this essential protein could lead to new antitumoral pharmacological approaches. Currently known tubulin agents bind to six distinct sites at α/β-tubulin either promoting microtubule stabilization or depolymerization. We have discovered a seventh binding site at the tubulin intradimer interface where a novel microtubule-destabilizing cyclodepsipeptide, termed gatorbulin-1 (GB1), binds. GB1 has a unique chemotype produced by a marine cyanobacterium. We have elucidated this dual, chemical and mechanistic, novelty through multidimensional characterization, starting with bioactivity-guided natural product isolation and multinuclei NMR-based structure determination, revealing the modified pentapeptide with a functionally critical hydroxamate group; and validation by total synthesis. We have investigated the pharmacology using isogenic cancer cell screening, cellular profiling, and complementary phenotypic assays, and unveiled the underlying molecular mechanism by in vitro biochemical studies and high-resolution structural determination of the α/β-tubulin−GB1 complex.

The cyanobacterial genus Lyngbya includes free-living, benthic, filamentous cyanobacteria that form periodic nuisance blooms in lagoons, reefs, and estuaries. Lyngbya spp. are prolific producers of biologically active compounds that deter grazers and help blooms persist in the marine environment. Here, our investigations reveal the presence of three distinct Lyngbya species on nearshore reefs in Broward County, FL, sampled in 2006 and 2007. With a combination of morphological measurements, molecular biology techniques, and natural products chemistry, we associated these three Lyngbya species with three distinct Lyngbya chemotypes. One species, identified as Lyngbya cf. confervoides via morphological measurements and 16S rRNA gene sequencing, produces a diverse array of bioactive peptides and depsipeptides. Our results indicate that the other two Lyngbya species produce either microcolins A and B or curacin D and dragonamides C and D. Results from screening for the biosynthetic capacity for curacin production among the three Lyngbya chemotypes in this study correlated that capacity with the presence of curacin D. Our work on these bloom-forming Lyngbya species emphasizes the significant phylogenetic and chemical diversity of the marine cyanobacteria on southern Florida reefs and identifies some of the genetic components of those differences.Marine harmful algal blooms are increasing in frequency and severity as a result of eutrophication in the marine environment, changes in global climate patterns, and increased monitoring and use of marine habitats (22,23,60). The genus Lyngbya consists of filamentous cyanobacteria that cause periodic, but in some cases long-lasting, blooms in shallow (usually Ͻ30 m) tropical and subtropical marine and estuarine environments (42,43). Lyngbya species are prolific producers of secondary metabolites, primarily lipopeptides, cyclic peptides, and depsipeptides. To date, over