Microtubule stabilizing agents, such as paclitaxel, docetaxel, and cabazitaxel have been among the most used chemotherapeutic agents in the last decades for the treatment of a wide range of cancers in the clinic. One of the concerns that limit their use in clinical practice is their intrinsic and acquired drug resistance, which is common to most anti-cancer chemotherapeutics. Taccalonolides are a new class of microtubule stabilizers isolated from the roots of a few species in the genus of Tacca. In early studies, taccalonolides demonstrated different effects on interphase and mitotic microtubules from those of paclitaxel and laulimalide suggesting a unique mechanism of action. This prompts the exploration of new taccalonolides with various functionalities through the identification of minor constituents of natural origin and semi-synthesis. The experiments on the new highly potent taccalonolides indicated that taccalonolides possessed a unique mechanism of covalently binding to the microtubule. An X-ray diffraction analysis of a crystal of taccalonolides AJ binding to tubulin indicated that the covalent binding site is at β-tubulin D226. Taccalonolides circumvent all three mechanisms of taxane drug resistance both in vitro and in vivo. To improve the activity, the structure modification through semi-synthesis was conducted and the structure-activity relationships (SARs) was analyzed based on natural and semi-synthetical taccalonolides. The C22–C23 epoxide can significantly increase the antiproliferation potency of taccalonolides due to the covalent link of C22 and the carboxylic group of D226. Great progress has been seen in the last few years in the understanding of the mechanism of this class of microtube-stabilizing agents. This review summarizes the structure diversity, structure-activity relationships (SARs), mechanism of action, and in vivo activities of taccalonolides.

The microwave synthesis of twenty quaternary ammonium salts is described. The syntheses feature comparable yields to conventional synthetic methods reported in the current literature with reduced reaction times and the absence of solvent or minimal solvent.

The microwave synthesis of several quaternary ammonium salts is described. The synthesis provides comparable or better yields than published methods with reduced reaction times and in the absence of solvent.

The title compound, (E)-3′,6′-bis(diethylamine)-2-[(2-methoxynaphthalen-1-yl)methyleneamino]spiro[isoindoline-1,9′-xanthen]-3-one, was synthesized in 92% isolated yield using microwave-assisted organic synthesis. This new rhodamine derivative was fully characterized by ¹H-NMR, ¹³C-NMR, FTIR and high resolution MS.

Cyanine dyes are an interesting class of near infrared (NIR) dyes that have captured the interest of the scientific community. The NIR cyanine dye of interest, heptamethine cyanine dye NIR-1, exhibits characteristics that satisfy the qualifications as an acceptor in a Fluorescence Resonance Energy Transfer (FRET) biosensor [Wher, 1976]. Applications of FRET systems include structure determination and conformation of proteins [Hammer et al., 2002], receptor/ligand interactions [Hammer et al., 2002], and the cellular exposure to environmental toxins [Schwartz and Ulfelder, 1992]. This research stems from an interdepartmental collaboration to develop a NIR FRET biosensor, with significant advantages over the existing systems. A critical component of this endeavor is the development of an efficient environmentally conscious synthesis of novel NIR cyanine dyes utilizing microwave technology. Herein, we report the microwave synthesis of NIR-1. 2,3,3-Trimethyl-1-ethyl-3H-indolium iodide (I) synthesis is advantageous over the reported synthesis due to the significantly reduced reaction time of450 s from 15 h and a decrease in the amount of iodoethane from 5 eq. to 3 eq. The condensation of heterocyclic salt I and bisaldehyde II has been accomplished in 220 s in 85% yield in the microwave oven; benzene has been eliminated from the condensation reaction procedure. Spectral characteristics of NIR-1 were determined and compared to commercially available NIR-1. A significant absence of asymmetry at the broad peak associated with the maximum absorbance wavelength, a slight increase in quantum yield (+—.02) and the blue shift of the maximum absorbance wavelength (—5 nm) was observed.