Organ-specific analysis of mahonia using gel-free/label-free proteomic technique.

Mahonia is an important medicinal plant used for the treatment of human diseases. To explore the molecular mechanisms underlying the different pharmacological functions of Mahonia, organ-specific proteomics was performed. Protein profiles of leaves, stems, and roots from 2-year-old Mahonia plants were determined using gel-free/label-free proteomic technique, and totals of 304, 314, and 182 proteins were identified, respectively, and included 36 common proteins. In leaves, the most abundant proteins related to photosynthesis. Furthermore, polyethylene glycol fractionation was used to identify low-abundance proteins in leaves. With this approach, oxidative pentose phosphate-related proteins were identified in leaves. In stems, the main functional categories of proteins were protein synthesis and redox ascorbate/glutathione metabolism. In roots, proteins were mainly related to protein synthesis, stress, and amino acid metabolism. Of the proteins identified, the abundance of calreticulin was markedly higher in roots than that detected in stems and leaves. Many roots-specific proteins, including S-adenosylmethionine synthetase and (S)-tetrahydroprotoberberine oxidase, involved in the biosynthesis of alkaloids, were identified. Consistent with this finding, levels of the alkaloids, which were columbamine, jatrorrhizine, palmatine, tetrandrine, and berberine, were markedly higher in roots compared to those detected in stems and leaves. Taken together, these results suggest that alkaloid biosynthesis is an important function in Mahonia roots.

Absorption characteristics of the total alkaloids from Mahonia bealei in an in situ single-pass intestinal perfusion assay.

AIM: To investigate the absorption characteristics of the total alkaloids from Mahoniae Caulis (TAMC) through the administration of monterpene absorption enhancers or protein inhibitors. METHOD: The absorption behavior was investigated in an in situ single-pass intestinal perfusion (SPIP) assay in rats. RESULTS: The intestinal absorption of TAMC was much more than that of a single compound or a mixture of compounds (jatrorrhizine, palmatine, and berberine). Promotion of absorption by the bicyclic monoterpenoids (borneol or camphor) was higher than by the monocyclic monoterpenes (menthol or menthone), and promotion by compounds with a hydroxyl group (borneol or menthol) was higher than those with a carbonyl group (camphor or menthone). The apparent permeability coefficient (Papp) of TAMC was increased to 1.8-fold by verapamil, while it was reduced to one half by thiamine. The absorption rate constant (Ka) and Papp of TAMC were unchanged by probenecid and pantoprazole. CONCLUSION: The intestinal absorption characteristics of TAMC might be passive transport, and the intestinum tenue was the best absorptive site. In addition, TAMC might be likely a substrate of P-glycoprotein (P-gp) and organic cation transporters (OCT), rather than multidrug resistance protein (MRP) and breast cancer resistance protein (BCRP). Compared with a single compound and a mixture of compounds, TAMC was able to be absorbed in the blood circulation effectively.

Measurement of carbon flux through the MEP pathway for isoprenoid synthesis by (31)P-NMR spectroscopy after specific inhibition of 2-C-methyl-d-erythritol 2,4-cyclodiphosphate reductase. Effect of light and temperature.

The methylerythritol 4-phosphate (MEP) and the mevalonate pathways are the unique synthesis routes for the precursors of all isoprenoids. An original mean to measure the carbon flux through the MEP pathway in plants is proposed by using cadmium as a total short-term inhibitor of 2-C-methyl-d-erythritol 2,4-cyclodiphosphate (MEcDP) reductase (GcpE) and measuring the accumulation rate of its substrate MEcDP by (31) P-NMR spectroscopy. The MEP pathway metabolic flux was determined in spinach (Spinacia oleracea), pea (Pisum sativum), Oregon grape (Mahonia aquifolium) and boxwood (Buxus sempervirens) leaves. In spinach, flux values were compared with the synthesis rate of major isoprenoids. The flux increases with light intensity (fourfold in the 200-1200 µmol m(-2) s(-1) PPFR range) and temperature (sevenfold in the 25-37 °C range). The relationship with the light and the temperature dependency of isoprenoid production downstream of the MEP pathway is discussed.