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A number of 5‐acyl rhodanines and thiorhodanines with bulky acyl groups (pivaloyl and adamantoyl), not previously available, have been synthesized. The compounds are shown to exist in the enol form. Structures have been calculated using both the MP2 approach and the B3LYP‐GD3BJ functional and the 6‐311++G(d,p) basis set. Hydrogen bond energies are estimated by subtracting energies of a structure with the OH group turned 180° from those of the intramolecularly hydrogen‐bonded one. Properties such as OH chemical shifts, two‐bond isotope effects on 13C chemical shifts, electron densities at the bond critical point from atoms in molecules analysis, and the hydrogen bond energies show that the sterically hindered compounds have stronger hydrogen bonds than methyl or isopropyl derivatives. The combination of oxygen and sulfur derivatives enables a detailed analysis of hydrogen bond energies. [ABSTRACT FROM AUTHOR]

Intake of fruit and vegetables is well known to reduce the risk of cancer. Some of the compounds responsible for this effect are indoles, which occur naturally in vegetables of the Cruciferae family (e.g., broccoli and cabbage). Recent studies in our laboratory showed that indole-3-carbinol (I3C) and N-methoxyindole-3-carbinol (NI3C) inhibit the growth of human cancer cell lines DLD-1 and HCT-116. NI3C was shown to be a more potent inhibitor of cell proliferation than I3C, and both indoles inhibit cell proliferation by different mechanisms. The aim of this study was to show the combined inhibitory effects of NI3C and I3C on cell proliferation and to determine the chemical stability of I3C and NI3C in an acidic solution. Our experiments clearly showed that I3C and NI3C synergistically inhibit cell proliferation. Furthermore, human colon cells treated with both compounds simultaneously showed a significant increase in the accumulation of cells in [G.sub.0]/[G.sub.1] phase compared with cells treated with I3C or NI3C alone. When cells were treated with NI3C alone, a small amount of the cells arrested in S phase. These data showed for the first time that NI3C and I3C work synergistically, which explains why lower doses of the indoles have the same chemopreventive effect as the higher dose required for either indole alone. It is assumed that the acid-catalyzed conversion of I3C is compulsory for the biological effect in vivo and that the conversion primarily occurs in the acidic environment of the stomach. Whether this conversion occurs in cell culture is unclear. We presume that NI3C is more stable than I3C because of the methoxy group, and this difference in stability may explain the difference in their biological activity. Some preliminary results on the acid stability of NI3C will be presented.

The sulfinylation reaction of aromatic and hetero-aromatic compounds with sulfinic esters as electrophiles has been investigated in different ionic liquids and by means of different Lewis acid salts in order to get moderate to good yields of asymmetrical sulfoxides. Mixtures of 1-butyl-3-methylimidazolium chloride and aluminum chloride were found to be the most efficient and recyclable reaction framework. Ultrasound sonication appeared to be the most useful and green activation method to afford the sulfoxides in yields better than or equivalent to those obtained under the longer-lasting conventional stirring conditions. [ABSTRACT FROM AUTHOR]

The essential oils from peels and leaves of Citrus clementine Hort. ex Tan. were extracted via two methods: conventional hydrodistillation (CHD) and microwave-assisted hydrodistillation (MAHD). Their physicochemical properties were investigated. Their chemical compositions of the oils were determined by GC/FID and GC/MS. A total of forty-one and seventy-seven compounds of the total essential oil composition of the peels and leaves respectively were identified. The peel oils were dominated by monoterpene hydrocarbons in which limonene was the main component (95.48% [CHD], and 95.03% [MAHD]). The leaf oils were also dominated by sesquiterpene hydrocarbons with sabinene (26.02% [CHD], and 19.52% [MAHD]), β-elemene (10.50% [CHD], and 18.04% [MAHD]), linalool (9.88% [CHD], and 7.51% [MAHD]), (E)-β-ocimene (5.87% [CHD], and 5.00% [MAHD]), β-caryophyllene (4.04% [CHD], and 7.49% [MAHD]), and δ-selinene (4.76% [CHD], and 8.02% [MAHD]) as major components. The oil contents of peels were obtained with 5.31% and 5.67% by CHD method and MAHD method, respectively. The oil contents of the leaves were obtained with 0.33% and 0.20% by CHD method and MAHD method, respectively. The antimicrobial activity (disc diffusion antibiotic sensitivity assay) of the oils was investigated against six reference test organisms including two Gram (+) bacteria (Bacillus subtilis, Staphylococcus aureus), three Gram (-) bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella flexneri), and one fungus (Candida albicans). [ABSTRACT FROM AUTHOR]