Novel calcium ionophores: Supramolecular complexation by the hydroxylated-bistetrahydrofuran skeleton of potent antitumor Annonaceous acetogenins

Steric and Stereochemical Modulation in Pyridyl- and Quinolyl-Containing Ligands

Nitrogen-containing pyridine and quinoline are outstanding platforms on which excellent ionophores and sensors for metal ions can be built. Steric and stereochemical effects can be used to modulate the affinity and selectivity of such ligands toward different metal ions on the coordination chemistry front. On the signal transduction front, such effects can also be used to modulate optical responses of these ligands in metal sensing systems. In this review, steric modulation of achiral ligands and stereochemical modulation in chiral ligands, especially ionophores and sensors for zinc, copper, silver, and mercury, are examined using published structural and spectral data. Although it might be more challenging to construct chiral ligands than achiral ones, isotropic and anisotropic absorption signals from a single chiroptical fluorescent sensor provide not only detection but also differentiation of multiple analytes with high selectivity.

Acetogenins from Annonaceae

In recent decades, annonaceous acetogenins have become highly studied plant secondary metabolites in terms of their isolation, structure elucidation, synthesis, biological evaluation, mechanism of action, and toxicity. The aim of the present contribution is to summarize chemical and biological reports published since 1997 on annonaceous acetogenins and synthetic acetogenin mimics. The compounds are considered biologically in terms of their cytotoxicity for cancer cell lines, neurotoxicity, pesticidal effects, and miscellaneous activities.

Mono-tetrahydrofuran annonaceous acetogenins from Annona squamosa as cytotoxic agents and calcium ion chelators

Eight new mono-tetrahydrofuran (THF)-type annonaceous acetogenins, squafosacins B, C, F, and G (1-4), squadiolins A-C (5-7), and cis-annotemoyin-1 (8), as well as eight known annonaceous acetogenins, glabranin, annotemoyins-1 and -2, bullatencin, cis-bullatencin, and uvariamicins-I, -II, and -III, were isolated from the seeds of Annona squamosa by HPLC. The structures of all new isolates were elucidated by using spectroscopic and chemical methods. Squadiolins A (5) and B (6) showed ng/mL potency against human Hep G2 hepatoma cells and significant cytotoxic activity against human MDA-MB-231 breast cancer cells. Squafosacin B (1) also exhibited significant cytotoxic activity against human Hep G2 and 3B hepatoma and MCF-7 breast cancer cells. In addition, the chelation of mono-THF acetogenins with calcium ions was investigated using isothermal titration calorimetry.

Novel class of DNA binding motifs based on bistetrahydrofuran and bisfuran skeleton with long alkyl chains

Small molecules with DNA-binding affinity within the minor groove have become of great interest. In this paper, new DNA binding molecules; diamino-bistetrahydrofuran (bisTHF) and diamino-bisfuran are reported. The bisTHF ligand with RR configuration at the amino groups and C8 alkyl chains (RR8) stabilized GC-rich duplex. In contrast, bisfuran compounds stabilized AT-rich duplex. The binding affinity of RR8 with 12 mer duplex DNA was determined by isothermal titration calorimetry to be 3.3 x 10(8) M-1.

Diastereoselective two-directional synthesis and cation transport ability of the central tristetrahydrofuranyl unit of meso polyether glabrescol as naturally occurring podand

The diastereoselective synthesis of the central 2,5-linked tristetrahydrofuran (trisTHF) 6 of naturally occurring meso polyether, glabrescol (5), has been achieved in a two-directional manner by the vanadium(V)-catalyzed anti oxidative cyclizations of diol 14. The trisTHF podand 6 and its stereoisomeric analogs 7 and 8 exhibited outstanding cation transport abilities for physiologically important Na+ and K+.

New bioactive adjacent bis-THF annonaceous acetogenins from Annona bullata

Five new adjacent bis-THF annonaceous acetogenins, 32-hydroxybullatacin, 31-hydroxybullatacin, 30-hydroxybullatacin, and (2,4-cis and trans)-28-hydroxybullatacinones, were isolated from the ethanolic extract of the bark of Annona bullata Rich. (Annonaceae). The absolute configurations of the above five compounds, as well as those of (2,4-cis and trans)-32-, 31-, and 30-hydroxybullatacinones and (2,4-cis and trans)-bulladecinones, previously isolated from the same extract, were defined by the application of the advanced Mosher ester [methoxy(trifluoromethyl)phenyl acetate or MTPA] methodology. The determination of the absolute configuration of C-20 of (2,4-cis and trans)-bulladecinones to be S supports our hypothesis that the cyclization of the THF rings of (2,4-cis and trans)-bulladecinones starts from C-12 (the right side). The first five compounds listed above showed potent bioactivities in the brine shrimp lethality test (BST) and among six human solid tumour cell lines.