Cardenolides from the leaves of Nerium oleander.

Six new cardenolides (1-6), including three 14-hydroxylated cardenolides and three 14-carbonylated cardenolides were isolated from the dried aerial parts of Nerium oleander Linn in addition to twenty-seven known compounds (7-33). Their structures were elucidated on the basis of extensive spectroscopic evidences and single-crystal X-ray diffraction analysis. Compounds 1, 4, 7-10 and 13 exhibited significant cytotoxicity against four colon cancer cell lines (HCT116, HT29, SW620, RKO), one gastric cancer cell line (GT) and one cervical cancer cell line (HeLa) in vitro.

Detection of nitric oxide in plants by electron spin resonance.

ABSTRACT Three methods to detect nitric oxide (NO()) are reported here. The first method was determining NO() in extracted plant tissue. NO() was trapped by spin trapping reagent containing diethyldithiocarbamate (DETC) and FeSO(4), extracted by ethyl acetate, and determined with an electron spin resonance (ESR) spectrometer. The second method was indirectly determining NO() in live wheat leaves. Seedlings were cultured in a medium containing FeSO(4), and the leaves were brushed by DETC. Then, the leaves were ground and the complex of (DETC)(2)-Fe(2+)-NO was extracted and determined with an ESR spectrometer. The third method was directly determining NO* in live wheat leaves. After treating plant materials as in the second method, part of the water in leaves was transpired, and the leaf disks were inserted directly into quartz tubes to determine NO() with an ESR spectrometer. The NO() scavenger 2-phenyl-4,4,5,5,-tetramethylimidazoline- 1-oxyl 3-oxide (PTIO) decreased NO() signal detected either by an indirect or a direct method. This result indicates that both methods could detect NO() in the live plant. Using the first methods, we detected NO() change in wheat infected by Puccinia striiformis race CY22-2 pathogen (incompatible interaction) at different inoculation times, and it was found that the NO() content dramatically increased at 24 h postinoculation, quickly decreased at 48 h, and increased again at 96 h.

Developmental expression and activity variation of nitric oxide synthase in the brain of golden hamster.

Nitric oxide (NO) is the downstream effector after the activation of N-methyl-D-aspartate (NMDA) receptors. It is involved in various physiological processes, such as synapse reconstruction and plasticity, neurotoxity and neuronal death. It also participates in the development and maturation of cortical neurons. The expression of nitric oxide synthase (NOS) during the postnatal development of the visual cortex was investigated by both electron spin resonance (ESR) and Western blot methods. A typical spectrum of (DETC)(2)-Fe(II)-NO complex was found in the visual cortex of different age golden hamsters by ESR method. The signal intensity increased after birth, peaked at postnatal day 14 (PD14) and then gradually decreased. An analysis of variance (ANOVA) implied that the NO synthase expression significantly correlated with the developmental processes (p < 0.05). Results of Western blot further confirmed (one-way ANOVA, p < 0.05) the developmental relating expression pattern of NO synthase shown by ESR technique.