Capsaicinoids exist in chili peppers, whereas capsinoids are present in some sweet peppers. The present study investigated the effects of capsaicinoids and capsinoids on plasma lipids, relaxation of the aorta, atherosclerotic plaque development, and fecal sterol excretion in hamsters fed a high-cholesterol diet. Five groups of male hamsters were given the control diet or one of the four experimental diets containing 1.3 mmol of capsaicinoids (NL), 2.6 mmol of capsaicinoids (NH), 1.3 mmol of capsinoids (OL), or 2.6 mmol of capsinoids (OH), respectively. Results showed capsaicinoids but not capsinoids could decrease plasma total cholesterol (TC), reduce the formation of atherosclerotic plaque, and relax the aortic artery. This was accompanied by a 28-175% increase in fecal excretion of acidic sterols in hamsters fed the diets containing capsaicinoids. Similarly, capsaicinoids but not capsinoids could decrease the pad weights of epididymal and prerenal adipose tissues. It was concluded that capsaicinoids but not capsinoids could favorably modulate plasma lipids and possess beneficial vascular activity.

Nucleophilic reactions of a 14-vertex closo-carborane are reported. 2,3-(CH(2))(3)-2,3-C(2)B(12)H(12) (1) reacts with MeOH at 70 degrees C to give closo-CB(11) anions [1,2-(CH(2))(3)CH(OMe)-1-CB(11)H(10)](-) ([2a](-)), [1,2-(CH(2))(2)CH(OMe)CH(2)-1-CB(11)H(10)](-) ([2b](-)), and [1,2-(CH(2))(2)CH horizontal lineCH-1-CB(11)H(10)](-) ([2c](-)). It is suggested that [2c](-) is an intermediate for the isomerization from [2a](-) to [2b](-). Treatment of 1 with MeOH/Me(3)N, (t)BuOK or LiNMe(2) affords nido-C(2)B(12) species [8,9-(CH(2))(3)-mu-11,12-(Nu)BH-8,9-C(2)B(11)H(11)](-) (Nu = MeO ([3a](-)), (t)BuO ([3b](-)), and Me(2)N ([3c](-))). In the presence of acid such as HCl, anions [3](-) are converted to 1. However, [3](-) undergo deboration reaction, in the presence of bases, to generate a nido-C(2)B(11) anion [8,9-(CH(2))(3)-8,9-C(2)B(11)H(12)](-) ([4](-)) that can also be formed directly from the reaction of 1 with excess CsF or piperidine. Mechanistic studies show that [3a](-) is the first intermediate in the reaction of 1 with MeOH and [4](-) is unlikely an intermediate.

Several monoanions of 13-vertex carboranes were prepared in high yields from the reactions of C,C'-linked 13-vertex carboranes with tBuOK or NaH in dry THF at room temperature. These monoanions were characterized by various spectroscopic methods, elemental analysis, and single-crystal X-ray diffraction. The results showed substantial double-bond character between the cage-carbon atom and the exo vicinal carbon atom, thus leading to charge delocalization into the cage. As a result, the atom-atom distances within the cage were elongated, with one broken C-B bond. However, the cage geometry of the monoanions remained very similar to that of their corresponding neutral 13-vertex closo-carboranes. These monoanions represent the first examples of 13-vertex carboranes with exo-π bonding to hypercarbon atoms.

Several nido-carborane-carbene 1 : 1 adducts were prepared in very high yields from the reaction of o-carboranes with 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene in dry THF at room temperature. Single-crystal X-ray analyses reveal that they are zwitterionic salts consisting of a nido carborane cage and imidazolium moiety that are linked by a five-coordinate boron atom. They are inert toward carbenes, but sensitive toward moisture and water, leading to the formation of deboration products, nido-C(2)B(9) ions. These results shed light on the deboration reaction mechanism of o-carboranes.