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Bacterial biofilms are responsible for many persistent infections by many clinically relevant pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa. Biofilms are muchmore resistant to conventional antibiotics than their planktonic counterparts. Quorum sensing, an intercellular communication system, controls pathogenesis and biofilm formation in most bacterial species. Quorum sensing provides an important pharmacological target since its inhibition does not provide a selective pressure for resistance. In this study, we investigated the quorum sensing and biofilm inhibitory activities of 126 plant extracts from 71 species collected from neotropical rainforests in Costa Rica. Quorum sensing and biofilm interferencewere assessed using a modified disc diffusion bioassay with Chromobacterium violaceum ATCC 12472 and a spectrophotometric bioassay with Pseudomonas aeruginosa PA14, respectively. Species with significant anti-quorum sensing and/or anti-biofilm activities belonged to the Meliaceae, Melastomataceae, Lepidobotryaceae, Sapindaceae, and Simaroubaceae families. IC50 values ranged from 45 to 266 μg/mL. Extracts of these active species could lead to future development of botanical treatments for biofilm-associated infections. [ABSTRACT FROM AUTHOR]

Bioassay-guided fractionation of a crude extract (80% EtOH in H2O) of stem bark of Sorbus decoraled the isolation of three new pentacycle triterpenes (compounds 1−3). The structures of 1−3were established on the basis of spectroscopic methods (IR, HREIMS, 1D and 2D NMR) as 23,28-dihydroxyursan-12-ene-3β-caffeate, 23,28-dihydroxylupan-20(29)-ene-3β-caffeate, and 3β,23,28-trihydroxy-12-ursene, respectively. Compound 2significantly enhanced glucose uptake in C2C12 cells, but compounds 1and 3did not. In addition, triterpenoids 4−8, catechin, and epicatechin were also isolated. This is the first comprehensive report of the phytochemical constituents of S. decorasince the initial study by Narashmachari and von Rudloff (1962) and includes evaluation of their antidiabetic activity.

Six new triterpenoids named spirocarcolitones (G−L), which belong to a novel class of CD-spiro triterpenoids, were isolated from the dichloromethane-soluble fraction of the bark of Ruptiliocarpon caracolito.The structures of these natural products were established using mainly 1D and 2D NMR spectroscopy. One known CD-spiro triterpenoid and canophyllol were also isolated from the same source.

Two novel steroids, 3-hydroxypregnane-2,16-dione [ 1] and 2-hydroxyandrosta-1,4-diene-3,16 dione [ 2], were isolated from ethanolic extracts of the wood and bark of Trichilia hirta. The structure of 1was rigorously determined from 2D-INADEQUATE NMR data that was: 1) acquired with a new higher-sensitivity 13C probe called a Nano·nmr probe, and; 2) processed with a new NMR-analysis program called FRED, which automatically generated the complete carbon structure (as shown). In this first known application of both a Nanoprobe and FRED software to an unknown compound, the complete carbon skeleton was easily determined using only 11 mg (30 μmoles) of sample.

γ-Epoxy sulfones in which the epoxide function is terminal yield cyclopropylmethanol derivatives on reaction with methyllithium or lithium diisopropylamide. In contrast, treatment of these epoxides with two equivalents of CH3MgI gives only cis-3-phenylsulfonylcyclobutanols. The cis-relationship between the OH and sulfonyl groups was proven in one instance by an X-ray structure determination. Internal γ-epoxy sulfones yield cyclopropylmethanols with all bases studied. All δ-epoxy sulfones studied furnished cis-3-phenylsulfonylcyclopentanols upon reaction with the Grignard reagent. These same epoxides gave either cyclopentanols or noncyclic products upon reaction with LDA; no cyclobutane ring containing products were obtained contrary to the expectations based on Stork's results with the corresponding epoxy nitriles (ref. 2). The mechanism of the Grignard-mediated reaction involves epoxide opening by iodide ion, α-sulfonyl Grignard formation, and, finally, cyclization. When LDA or CH3Li is used the products are formed by an intramolecular SN2 opening of the epoxide by an α-lithio sulfone.

The preparation of 1-carboalkoxy-1,3-dihydrobenzo[b]thiophene 2,2-dioxides via rhodium acetate or rhodium trifiuoro-acetate catalyzed decomposition of α-diazo-β-arylmethanesulfonyl esters is described. The reaction has been extended to yield 1,3-dihydrothiophene 2,2-dioxides fused to the 2,3 position of thiophene and indole, but not of furans. In the latter case products derived from the opening of the furan ring were obtained. Keywords: synthesis, 1-carboalkoxy-1,3-dihydrobenzo[b]thiophene 2,2-dioxides, intramolecular carbenoid insertions, rhodium acetate catalysis.

The azomethine imine group of isoquinolinium Narylimides 2is partially incorporated into an aromatic ring. The nucleophilicelectrophilic 1,3dipoles 2undergo cycloadditions to ethylene derivatives bearing either electronwithdrawing or electronreleasing substituents. The regiochemistry is bidirectional; electronattracting substituents appear at the 1position of the tricyclic adducts. Various enamines, however, adopt an orientation such that the amino function appears at the 2position. The tricyclic adducts undergo an acidcatalyzed hyrazo rearrangement.

A general route leading to 5- to 8-membered cyclic sulfinate esters (sultines) is described. The method is based on the reaction of tert-butyl hydroxyalkyl sulfoxides with SO2Cl2in an inert solvent.

4,5-Benzo-3,6-dihydro-1,2-oxathiin-2-oxides (benz-fused δ-sultines) 1, were prepared by reaction of 1-hydroxy-1,3-dihydrobenzo[c]thiophen-2,2-dioxides 6with NaBH4. Derivatives of 1bearing alkyl substituents at position 6 are accessible from 1upon reaction of 6with 2RLi. 3-Aryl substituted derivatives were prepared by converting 2-benzylbenzylalcohols into their O, C dianion followed by quenching with SO2and acidification. Benz-fused δ-sultines such as 15–17were also prepared via the dianion route.

Hydroxylation of the enolates of several 3-alkylideneazetidin-2-ones with MoOPH leads to the formation of 3-hydroxy-3-alkenylazetidin-2-ones in fair to good yields. The products were formed with transstereochemistry in the alkenyl moiety and a presumed transrelationship between the hydroxyl substituent and a 4-substituent. Hydrogenation leads to 3-alkyl-3-hydroxy-azetidin-2-ones. The prerequisite 3-alkylideneazetidin-2-ones were formed from 3-trimethylsilylazetidin-2-ones and aldehydes via a Peterson olefin synthesis.