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91.
92.
Scavenging of reactive oxygen species by a novel glucurinated flavonoid antioxidant isolated and purified from spinach 总被引:4,自引:0,他引:4
NAO is a natural water soluble antioxidant that was isolated and purified from spinach leaves. Using HPLC, NMR, and CMR spectroscopy, the main components were identified as flavonoids and p-coumaric acid derivatives. The NAO was found to be a very effective antioxidant in several in vivo and in vitro biological systems. In the present study, the antioxidant activity of the novel antioxidant glucurinated flavonoid (GF) isolated and characterized from NAO, is compared to well-known antioxidants. In addition, the direct free radical scavenging properties of the purified component GF were studied using the electron spin resonance (ESR) technique. GF and NAO were found to be superior to EGCG and NAC and to the Vitamin E homologue Trolox in inhibiting reactive oxygen species (ROS) formation in the autooxidation system of linoleic acid and in fibroblasts exposed to metal oxidation. GF and NAO were found to inhibit the ESR signal intensity of DMPO-O(2) radical formation during the riboflavin photodynamic reaction. 10 mM GF caused approximately 90% inhibition in the intensity of the ESR signal, while NAO at a concentration of 60 microg/ml caused an inhibition of about 50%. Using the Fenton reaction, GF and NAO were found to inhibit DMPO-OH radical formation. A concentration of 2 mM GF caused a 70% inhibition in the intensity of the DMPO-OH radical ESR signal, while propyl gallate at the same concentration caused only 50% inhibition. Furthermore, both GF and NAO also inhibited the (1)O(2) dependent TEMPO radical generated in the photoradiation TPPS4 system. About 80% inhibition was obtained by 4 mM GF. The results obtained indicate that the natural antioxidants derived from spinach may directly affect the scavenging of ROS and, as a consequence, may be considered as effective sources for combating oxidative damage. 相似文献
93.
Grossman AR 《Photosynthesis research》2003,76(1-3):207-215
Photosynthetic activity and the composition of the photosynthetic apparatus are strongly regulated by environmental conditions.
Some visually dramatic changes in pigmentation of cyanobacterial cells that occur during changing nutrient and light conditions
reflect marked alterations in components of the major light-harvesting complex in these organisms, the phycobilisome. As noted
well over 100 years ago, the pigment composition of some cyanobacteria is very sensitive to ambient wavelengths of light;
this sensitivity reflects molecular changes in polypeptide constituents of the phycobilisome. The levels of different pigmented
polypeptides or phycobiliproteins that become associated with the phycobilisome are adjusted to optimize absorption of excitation
energy present in the environment. This process, called complementary chromatic adaptation, is controlled by a bilin-binding
photoreceptor related to phytochrome of vascular plants; however, many other regulatory elements also play a role in chromatic
adaptation. My perspectives and biases on the history and significance of this process are presented in this essay.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
94.
Florell SR Schmidt SJ Porter-Gill P Albertine KH Murphy KJ McKinney CB Boucher KM Grossman D Biddle DL Clayton F Layfield LJ Leachman SA 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》2003,16(6):662-669
Confirming melanocytic lineage and purity is important for experiments using cultured human melanocytes. The objective of this study was to develop a simple, reliable method to evaluate and archive cultured melanocytic cells. Melanocytes were isolated from adult skin biopsies or from neonatal foreskins using standard culturing methods. Fibrin cell blocks (FCBs) were prepared from cultured cells at passages two and six. Fibrin blocks were paraffin-embedded and sectioned for immunohistochemical (CD68, Melan-A, and HMB-45) and H & E staining. Flow cytometry was performed (Melan-A) at passage six. A mixing experiment with cultured melanocytes and fibroblasts was performed and cell population purity was determined by manual counts of positively staining cells in the FCBs and by flow cytometry. The FCB method of evaluating population purity was validated experimentally and by correlation with flow cytometry results. Preparation of a FCB followed by immunohistochemical staining is an easy and inexpensive way to confirm melanocytic lineage, estimate population purity, and provide a permanent archive of cultured cells. 相似文献
95.
96.
97.
Marques BG Hausman DB Latimer AM Kras KM Grossman BM Martin RJ 《American journal of physiology. Regulatory, integrative and comparative physiology》2000,278(3):R654-R662
To determine if high-fat (HF) diet-induced changes in adipose tissue cellularity are associated with the presence of paracrine growth factor(s) that alter preadipocyte proliferation, Osborne-Mendel rats were fed either a HF (76% energy) or a low-fat (LF, 12% energy) diet for 85 days. HF-fed rats had greater (P < 0.05) fat pad size, total fat cell number, number of small (30-70 microm) and large (80-140 microm) adipocytes, and percentage of 100- to 140-microm adipocytes compared with LF-fed rats. Preadipocytes in primary cell culture treated with inguinal adipose tissue conditioned medium (ATCM) prepared from HF-fed rats had greater (P < 0.05) proliferation compared with cultures treated with ATCM from LF-fed rats. Proliferative capacity of ATCM prepared from HF-fed rats was attenuated after the stripping of the medium of insulin-like growth factor I using an immunomagnetic bead separation system. These data are consistent with the concept that insulin-like growth factor I is involved in the paracrine regulation of adipogenesis. 相似文献
98.
Grossman AJ 《Plastic and reconstructive surgery》2000,106(4):960-961
99.
We have isolated and examined the gene for the heart isoform of cytochromecoxidase subunit VIIa (COX VIIa-H) in mouse, an isoform gene previously thought to be lacking in rodents. Interspecies amino acid comparisons indicate that mouse COX VIIa-H protein displays 82.5 and 70.9% identity with the bovine and human heart isoforms of COX VIIa, but only 53.7% identity with the paralogous mouse liver isoform (COX VIIa-L). Expression in adult mouse tissues is limited to heart and skeletal muscle, as found in other species. In the early mouse embryo,Cox7alwas the exclusive isoform expressed andCox7ahmRNA was not detectable until day 17postcoitum.That the mouseCox7ahgene characterized in this study is orthologous to the humanCOX7AHgene was also suggested by its mapping to mouse chromosome 7, to a conserved region syntenic with the human chromosome location ofCOX7AH,19q13.1. As a result, all three COX heart isoform genes in mouse group to chromosome 7. Interestingly, mapping of the mouseCox7alto chromosome 9 suggests a new syntenic region between the mouse and the human genomes. 相似文献
100.
1-Thio-beta-D-galactofuranosides: synthesis and evaluation as beta-D- galactofuranosidase inhibitors
Marino C; Marino K; Miletti L; Manso Alves MJ; Colli W; de Lederkremer RM 《Glycobiology》1998,8(9):901-904
Beta-D-galactofuranosidase is a good chemotherapeutic target for the design
of inhibitors, since beta-D-galactofuranose is a constituent of important
parasite glycoconjugates but is not present in the host mammals. With this
aim, we have synthesized for the first time alkyl, benzyl and aryl
1-thio-beta-D-galactofuranosides by condensation of
penta-O-benzoyl-alpha,beta-D-galactofuranose with the corresponding thiols,
in the presence of SnCl4as catalyst. The complete chemical and
spectroscopical characterization of these compounds showed that the
reaction was stereoselective. Debenzoylation with sodium methoxide afforded
the beta-S-galactofuranosides in high yield. The thioglycosides were tested
as inhibitors of the beta-D- galactofuranosidase of Penicillium fellutanum,
using for the first time 4-nitrophenyl-beta-D-galactofuranoside as
chromogenic substrate. The 4- aminophenyl-1-thio-beta-D-galactofuranoside,
obtained by catalytic hydrogenation of the nitrophenyl derivative, was the
best inhibitor being then an adequate ligand for the preparation of an
affinity phase aimed at the isolation of beta-d-galactofuranosidases from
different sources. Also the inhibitory activity of d-galactono-1, 4-lactone
was shown.
相似文献