Andrew J. Burt

Dehydrodimers of Ferulic Acid in Maize Grain Pericarp and Aleurone: Resistance Factors to Fusarium graminearum.

ABSTRACT The relationship between the primary cell wall phenolic acids, dehydrodimers of ferulic acid, and maize grain resistance to Fusarium graminearum, the causal agent of gibberella ear rot, was investigated. Concentrations of dehydrodimers of ferulic acid were determined in the pericarp and aleurone tissues of five inbreds and two hybrids of varying susceptibility and in a segregating population from a cross between a resistant and susceptible inbred. Significant negative correlations were found between disease severity and diferulic acid content. Even stronger correlations were observed between diferulic acid and the fungal steroid ergosterol, which is an indicator of fungal biomass in infected plant tissue. These results were consistent over two consecutive field seasons, which differed significantly for temperature and rainfall during pollination, the most susceptible stage of ear development. No correlation was found between the levels of these phenolics and deoxynivalenol levels. This is the first report of in vivo evidence that the dehydrodimers of ferulic acid content in pericarp and aleurone tissues may play a role in genotypic resistance of maize to gibberella ear rot.

Antidiabetic Activity of Nigella sativa. Seed Extract in Cultured Pancreatic β-cells, Skeletal Muscle Cells, and Adipocytes

Abstract The seeds of Nigella sativa. L. (NS), a plant of the Runanculaceae family, are used in traditional medicine in North Africa and the Middle East for the treatment of diabetes. Despite widespread use and a number of scientific studies, the target tissues and cellular mechanisms of action of this plant product are not well understood. This study evaluated the effects of NS seed crude ethanol extract on insulin secretion in INS832/13 and β TC-tet lines of pancreatic β-cells and on glucose disposal by C2C12 skeletal muscle cells and 3T3-L1 adipocytes. An 18-h treatment with NS amplified glucose-stimulated insulin secretion by more than 35% without affecting sensitivity to glucose. NS treatment also accelerated β-cell proliferation. An 18-h treatment with NS increased basal glucose uptake by 55% (equivalent to approximately two-fold the effect of 100 nM insulin) in muscle cells and approximately by 400% (equal to the effect of 100 nM insulin) in adipocytes; this effect was perfectly additive to that of insulin in adipocytes. Finally, NS treatment of pre-adipocytes undergoing differentiation accelerated triglyceride accumulation comparably with treatment with 10 μ M rosiglitazone. It is concluded that the well-documented in vivo. antihyperglycemic effects of NS seed extract are attributable to a combination of therapeutically relevant insulinotropic and insulin-like properties.

The Inhibition of Human Cytochrome P450 by Ethanol Extracts of North American Botanicals

Abstract High-throughput enzyme inhibition screening assays were used to quantify the effect of ethanol extracts of 2 accessions of 10 North American (NA) botanicals against the activity of the human cytochrome P450s: CYP3A4, CYP19, and CYP2C19. In addition, phytochemical biomarkers within each extract were identified and quantified using HPLC-MS or GC. Extracts containing uncharacterized phytochemicals were identified taxonomically. The overall objective was to describe the relationship between types and quantities of phytochemicals in ethanol extracts and their ability to inhibit CYP activity. The top three inhibitors of CYP3A4 were Gaultheria procumbens. L. leaf > Rhodiola rosea. L. root > Arctostaphylos uva-ursi. L. Spreng leaf; of CYP19 were R. rosea. root > Rhododendron groenlandicum. (Oeder) Kron & Judd leaf > A. uva-ursi. leaf; and of CYP2C19 were Achillea millefolium. L. leaf and flower > Vaccinium. sp. L. leaf > Polygala senega. L. root. Equisetum arvense. L. leaf, Arctium lappa. L. root, and P. senega. root had the least effect on CYP3A4 and CYP19 activity. These results suggest that North American botanicals have the potential to inhibit the metabolism of drug-specific CYPs in vivo., causing a direct shift in the availability of drugs and their pharmacokinetics in the body. Furthermore, the concentration of certain phytochemical markers varied significantly between accessions (i.e., rosarin and essential oils), suggesting that the extent of metabolic inhibition is directly dependent upon the concentration of bioactive constituents in an extract.