Stereochemical diversity in lignan biosynthesis of Arctium lappa L. (1/19)

The stereochemistry of lignan biosynthesis in Arctium lappa L. is regulated organ-specifically. (+)-Secoisolariciresinol [81% enantiomeric excess (e.e.)] was isolated from A. lappa petioles. In sharp contrast, lignans whose predominant enantiomers have the opposite absolute configuration to that of (+)-secoisolariciresinol [i.e., (-)-matairesinol (>99% e.e.), (-)-arctigenin (>99% e.e.), and (-)-secoisolariciresinol (65% e.e.)] were isolated from seeds of the species. The stereochemical diversity of secoisolariciresinol was demonstrated with enzyme preparations from A. lappa petioles and seeds. Thus, a petiole enzyme preparation catalyzed the formation of (+)-pinoresinol (33% e.e.), (+)-lariciresinol (30% e.e.), and (+)-secoisolariciresinol (20% e.e.) from achiral coniferyl alcohol in the presence of NADPH and H202, whereas that from ripening seeds catalyzed the formation of (-)-pinoresinol (22% e.e.), (-)-lariciresinol (>99% e.e.), and (-)-secoisolariciresinol (38% e.e.) under the same conditions. In addition, the ripening seed enzyme preparation mediated the selective formation of the optically pure (>99% e.e.) (-)-enantiomer of matairesinol from racemic (+/-)-secoisolariciresinols in the presence of NADP. These results indicate that the stereochemical mechanism for lignan biosynthesis in A. lappa varies with organs, suggesting that multiple lignan-synthesizing isozymes are involved in the stereochemical control of lignan formation in A. lappa.  (+info)

Antimicrobial activity of Arctium lappa constituents against microorganisms commonly found in endodontic infections. (2/19)

This study evaluated in vitro the antimicrobial activity of rough extracts from leaves of Arctium lappa and their phases. The following microorganisms, commonly found in the oral cavity, specifically in endodontic infections, were used: Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. The agar-diffusion method allowed detection of the hexanic phase as an inhibitor of microbial growth. Bioautographic assays identified antimicrobial substances in the extract. The results showed the existence, in the rough hexanic phase and in its fractions, of constituents that have retention factors (Rf) in three distinct zones, thereby suggesting the presence of active constituents with chemical structures of different polarities that exhibited specificity against the target microorganisms. It may be concluded that the Arctium lappa constituents exhibited a great microbial inhibition potential against the tested endodontic pathogens.  (+info)

An experimental research into the anti-aging effects of Radix Arctii Lappae. (3/19)

PURPOSE: To delve into the anti-aging effects and mechanism of Niubanggen (Radix Arctii Lappae). METHOD: The activity of SOD and the content of MDA and lipofuscin in the tissues of the liver, brain and blood serum of the lab rats were observed 30 days after they had been fed with the Niubanggen decoction. RESULT: The activity of SOD in the liver tissue and blood serum of the decoction-fed lab rats was improved dramatically (P<0.05 or P<0.01), the content of MDA in the brain tissue and blood serum lowered obviously (P<0.05 or P<0.01), and the content of lipofuscin dropped distinctly (P<0.01). CONCLUSION: The mechanism of the anti-aging effects of the Niubanggen is mainly obtained by raising the activity of SOD and reducing the contents of MDA and lipofuscin.  (+info)

Identification of arctigenin as an antitumor agent having the ability to eliminate the tolerance of cancer cells to nutrient starvation. (4/19)

Tumor cells generally proliferate rapidly and the demand for essential nutrients as well as oxygen always exceeds the supply due to the unregulated growth and the insufficient and inappropriate vascular supply. However, cancer cells show an inherent ability to tolerate extreme conditions, such as that characterized by low nutrient and oxygen supply, by modulating their energy metabolism. Thus, targeting nutrient-deprived cancer cells may be a novel strategy in anticancer drug development. Based on that, we established a novel screening method to discover anticancer agents that preferentially inhibit cancer cell viability under the nutrient-deprived condition. After screening 500 medicinal plant extracts used in Japanese Kampo medicine, we found that a CH(2)Cl(2)-soluble extract of Arctium lappa exhibited 100% preferential cytotoxicity under the nutrient-deprived condition at a concentration of 50 microg/mL with virtually no cytotoxicity under nutrient-rich condition. Further bioassay-guided fractionation and isolation led to the isolation of arctigenin as the primary compound responsible for such preferential cytotoxicity; the compound exhibited 100% preferential cytotoxicity against nutrient-deprived cells at a concentration of 0.01 microg/mL. Furthermore, arctigenin was also found to strongly suppress the PANC-1 tumor growth in nude mice, as well as the growth of several of the tested pancreatic cancer cell lines, suggesting the feasibility of this novel antiausterity approach in cancer therapy. Further investigation of the mechanism of action of arctigenin revealed that the compound blocked the activation of Akt induced by glucose starvation, which is a key process in the tolerance exhibited by cancer cells to glucose starvation.  (+info)

Arctigenin from Fructus Arctii is a novel suppressor of heat shock response in mammalian cells. (5/19)

Because heat shock proteins (Hsps) are involved in protecting cells and in the pathophysiology of diseases such as inflammation, cancer, and neurodegenerative disorders, the use of regulators of the expression of Hsps in mammalian cells seems to be useful as a potential therapeutic modality. To identify compounds that modulate the response to heat shock, we analyzed several natural products using a mammalian cell line containing an hsp promoterregulated reporter gene. In this study, we found that an extract from Fructus Arctii markedly suppressed the expression of Hsp induced by heat shock. A component of the extract arctigenin, but not the component arctiin, suppressed the response at the level of the activation of heat shock transcription factor, the induction of mRNA, and the synthesis and accumulation of Hsp. Furthermore, arctigenin inhibited the acquisition of thermotolerance in mammalian cells, including cancer cells. Thus, arctigenin seemed to be a new suppressive regulator of heat shock response in mammalian cells, and may be useful for hyperthermia cancer therapy.  (+info)

Decreased hardness of dietary fiber-rich foods by the enzyme-infusion method. (6/19)

A novel technique is reported for softening plant tissues while retaining their shape by impregnating them with macerating enzymes under reduced pressure after defrosting the frozen plants. Samples were removed immediately from the enzyme solution after the freeze-infusion treatment, and the hardness was measured. Six enzymes and three enzymes were respectively chosen from 18 commercial enzymes for softening burdock roots and bamboo shoots. The tissue degradation due to impregnation of the tissues with the enzymes and the reaction time were investigated. Burdock roots and bamboo shoots were progressively softened during the reaction: the hardness reached 1.0 x 10(4) N/m(2) or less. The water-soluble dietary fiber contents increased as a result of the freeze-infusion treatment. This softening technique, which retained the food shape, could enhance the production of food products for elderly persons and those under nursing care. Foods produced by this method can replace current minced and liquid dietary components.  (+info)

Lignans from Arctium lappa and their inhibition of LPS-induced nitric oxide production. (7/19)

A new butyrolactone sesquilignan, isolappaol C (1), together with four known lignans, lappaol C (2), lappaol D (3), lappaol F (4), and diarctigenin (5), were isolated from the methanolic extract of the seeds from the Arctium lappa plant. The structure of isolappaol C (1) was determined by spectral analysis including 1D- and 2D-NMR. All the isolates were evaluated for their inhibitory effects on the LPS-induced nitric oxide production using murine macrophage RAW264.7 cells. Lappaol F (4) and diarctigenin (5) strongly inhibited NO production in the LPS-stimulated RAW264.7 cells with IC(50) values of 9.5 and 9.6 microM, respectively.  (+info)

Diarctigenin, a lignan constituent from Arctium lappa, down-regulated zymosan-induced transcription of inflammatory genes through suppression of DNA binding ability of nuclear factor-kappaB in macrophages. (8/19)

 (+info)

• 1
• 2
• 3