David Liang

Analysis of Substituent Effects on C-13 NMR Parameters of Substituted Arylacetylene Derivatives. Linear Free Energy Relationships and PM3 Semiempirical Calculations

Abstract The substituent-induced chemical shifts (SCS) of C(α,β) on the 13C NMR spectra of arylalkynes (i.e. containing H, CH3, Cl and Br) were studied. The correlation between SCS and Hammett constants shows that the tendency of the effect by the substituents on the phenyl ring is Br (ρ=8.15)>Cl (ρ=7.27)>CH3 (ρ=6.79)>H (ρ=5.78). This order can be rationalized as due to the ability of the group on the alkyne to stabilize the partial positive charge on C(β) resulting from polarization with π electron transfer from C(β) to the phenyl ring. The SCS values are also well correlated with the electron densities obtained from PM3 calculations. The solvent effect on the 13C chemical shifts of phenylalkynyl bromide demonstrates a strong dependence on the relative permittivity as well as the shielding character of the solvents.

Quality, antioxidative ability, and cell proliferation-enhancing activity of fermented black soybean broths with various supplemental culture medium.

UNLABELLED The fermented soybean-based foods have played an important role in traditional diets around the world for many centuries, and Bacillus subtilis is typically used in the fermentation of soybean-based foods. The fermentation process may improve not only the flavor but also the nutritional value of food, and substances produced in this fermented broth were affected by many factors including culture medium and the selected soybeans. In this study, we use 3 potential culture mediums in the fermentation of black soybean and the fermented black soybean broths were used for the examination of amino acid composition, total phenolics content, flavonoids and anthocyanins contents, the antioxidant properties, and cytotoxicity. Our results indicated that the fermented black soybean broth, fermentation III, have the most abundant essential amino acid (79.77 mg/g), phenolics (19.33 mg/g), flavonoids (46.01 mg/g), and anthocyanins (1.06 mg/g). Besides, all of the fermented black soybean broths exhibited the significant antioxidative abilities with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effect, reducing power and ferrous ion chelating effect. In addition, the fermented black soybean broths demonstrated the cell proliferation-enhancing activity in Detroit 551 cells. The cells were augmented up to the maximum value of 183.6% (compared with control) at 10 mg/mL of the fermentation I. Therefore, the different supplemental culture medium fermented black soybean broths may be used as a functional ingredient in the products of nutritional drinks and health foods. PRACTICAL APPLICATION The present study illustrated the potential of various supplemental culture medium fermented black soybean broths in the application of functional ingredient for nutritional drinks and health foods.

Preparation of [2.2]-para-, meta-, and ortho-cyclophanes containing a 1,3-cyclohexano group

[2.2]-para-, meta-, and ortho-Cyclophanes containing a 1,3-cyclohexane ring bridged with two carbons were prepared through a coupling reaction to form dithiacyclophane, followed by oxidation to yield the sulfone and then pyrolysis.

Degradative and synthetic approaches to the polyhydric array of polyene macrolides

Procedures for obtaining the polyhydric array of polyene macrolides by degradation of pimaricin (natamycin) and by synthetic elaboration of a hemiacetal chiron are described.

An optically active synthon for the ubiquitous hemiacetal moiety of polyene macrolides

A stereocontrolled synthesis of (2), a synthon for the hemiacetal moiety of amphotericin B (and, presumably, many other polyene macrolides) has been carried out in 16 steps (20% overall yield) from ‘diacetone glucose’.