A carotenoid biosynthesis gene cluster mediating the production of 2-hydroxyastaxanthin was isolated from the marine bacterium Brevundimonas sp. strain SD212 by using a common crtI sequence as the probe DNA. A sequence analysis revealed this cluster to contain 12 open reading frames (ORFs), including the 7 known genes, crtW, crtY, crtI, crtB, crtE, idi, and crtZ. The individual ORFs were functionally analyzed by complementation studies using Escherichia coli that accumulated various carotenoid precursors due to the presence of other bacterial crt genes. In addition to functionally identifying the known crt genes, we found that one (ORF11, named crtG) coded for a novel enzyme, carotenoid 2,2--hydroxylase, which showed intriguingly partial homology with animal sterol-C5-desaturase. When this crtG gene was introduced into E. coli accumulating zeaxanthin and canthaxanthin, the resulting transformants produced their 2-hydroxylated and 2,2-dihydroxylated products which were structurally novel or rare xanthophylls, as determined by their nuclear magnetic resonance and high-performance liquid chromatography/photodiode array detector/atmospheric pressure chemical ionization mass spectrometry spectral data. The new carotenoid produced was suggested to have a strong inhibitory effect on lipid peroxidation.Carotenoid pigments, which are included in a majority of vegetables, a variety of fruits, and a certain part of edible fish and shellfish, have attracted strong attention due to their beneficial effects on human health, e.g., their very likely prevention of chronic diseases such as cancer, cardiovascular ailments, and age-related macular degeneration (7,12,27,36). A number of studies on carotenoids in relation to their health benefits, ranging from basic studies using experimental animals to clinical and epidemiological studies, have revealed that each carotenoid has characteristic individuality. For example, recent epidemiological studies have shown that -cryptoxanthin (3-hydroxy--carotene), among dietary carotenoids, is associated with a reduced risk of lung cancer (24, 56), whereas supplemental -carotene has been observed to have either no effect or even a harmful effect on lung cancer risk (2, 24). Epidemiological and clinical studies have also shown that only lycopene, among dietary carotenoids, was inversely associated with prostate cancer risk (16, 51). Supplemental lutein and zeaxanthin are thought to protect against the development or progression of age-related macular degeneration and other eye diseases from the results of many studies (28,45). Astaxanthin has been shown to inhibit the oxidation of low-density lipoprotein (20).Xanthophylls are modified carotenes with various oxygencontaining functional groups, which constitute a major part of structurally and functionally diverse carotenoid pigments.More than 700 carotenoids have now been isolated from natural sources (8), and evaluating the pharmaceutical potential of various carotenoids with different structures could be an exciting field for medical resea...
COMMUNICATIONSt o refine independently. A t o t d of 101 parameters were refined and cower-and C were already available,[5] the synthesis of fragment B and reactions used for the fragment B construction address a previously unsolved problem in this methodology: the stereoselective coupling of chiral fragments through the aldol reaction. ["] gcncc. b a s reached at R, = 0.042 ( R = 0.058) by using o ( F o ) -2 welghts. Further d c t u k of the crystal structure investigatlon are available on rcquect from the Dii-ector of the Cambridge Crystallographic Data Centre. 11 Union Road.
Atherosclerosis is a vascular disorder involving inflammation, a narrowed vascular lumen in the entire tunica intima, and reduced elasticity of the arterial wall. It has been found that Hsp60 from Chlamydia pneumoniae, an obligate bacterial pathogen associated with atheroma lesions, mimics human Hsp60, thereby causing attacks by immune cells on stressed endothelial cells expressing endogenous Hsp60 on their surface. Furthermore, Hsp60 from C. pneumoniae has been shown to promote the growth of vascular smooth muscle cells (VSMCs). To explore probes that can be used for studying signal transduction elicited by the chlamydial Hsp60, we have tested several natural products for their inhibitory actions on the Hsp60-induced proliferation of rat arterial smooth muscle cells. Sesamol, vanillyl alcohol, and trans-ferulic acid exhibited moderate inhibitory actions on the Hsp60-induced cell proliferation; zerumbone, humulene, and caryophylene effectively inhibited it at low concentrations with IC(50) values of 529, 122, and 110 nM, respectively. The results indicated that the 11-membered alicyclic ring is favorable for interactions with receptors involved in the Hsp60-induced VSMC proliferation.
A new carotenoid glycosyl ester, neurosporaxanthin beta-D-glucopyranoside (2), together with neurosporaxanthin (1), beta-carotene, gamma-carotene, and torulene were isolated from cultured cells of a marine microorganism, strain T-1, which was identified as Fusarium sp. Their structures were determined by chemical and spectral data.
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