Vascular effects, angiotensin I-converting enzyme (ACE)-inhibitory activity, and antihypertensive properties of peptides derived from egg white

In this study, we have identified novel antihypertensive peptides derived from egg-white proteins. The sequences YRGGLEPINF and ESIINF produced an acute blood-pressure-lowering effect in spontaneously hypertensive rats upon a single oral administration. Our results suggest that the antihypertensive action could be attributed to a vascular-relaxing mechanism that would occur in vivo independently of angiotensin I-converting enzyme (ACE) inhibition, because neither these peptides nor their main digestion fragments, except for the dipeptide YR, acted as ACE inhibitors in vitro. The vasodilator and antihypertensive activity of the sequences ESI and NF would explain the blood-pressure-lowering effect of ESIINF. With regard to YRGGLEPINF, in addition to NF, YR appeared as the main fragment responsible for its activity. The dipeptide YR, named kyotorphin and previously identified as an endogenous analgesic neuropeptide in the central nervous system, showed strong vasodilator and antihypertensive properties. The structure-activity features of the vasodilator peptides are discussed.     

High-pressure effects on Maillard reaction between glucose and lysine

Glucose-lysine model systems prepared over a range of pH values (5-10) in unbuffered and buffered media were incubated at 60 degrees C either under atmospheric pressure or at 400 MPa. The results obtained showed that high pressure affected in different ways the different stages of the Maillard reaction and that such effects were strongly influenced by pressure-induced changes in the pH of the systems. In unbuffered media, at an initial pH < or =8.0, the formation of Amadori rearrangement products (ARP) was not considerably affected by pressure, whereas the intermediate and advanced stages of the Maillard reaction were suppressed, suggesting a retardation of the degradation of the ARP. In buffered media, at pH values < or =8.0, pressure slowed the Maillard reaction from the initial stages. These effects are attributed to the pH drop caused by the pressure-induced dissociation of the acid groups. In unbuffered and buffered media at initial pH = 10.2, high pressure accelerated the formation and subsequent degradation of ARP, leading to increased levels of intermediate and advanced reaction products.     

Ralstonia solanacearum Biovar 2/Rasse 3 (Erreger der Schleimkrankheit der Kartoffel) in Oberflächengewässern und Solanum dulcamara – Ergebnisse eines mehrjährigen Monitorings in Bayern

The potato brown rot, caused by the bacterium Ralstonia solanacearum biovar 2/race 3 (potato race) was classified as quarantine pathogen by the European Union (EU) due to the risks it would pose for the cultivation of potatoes and tomatoes. Quarantine regulations stipulate control surveys and tests on potatoes used as seed, for food as well as industrial purposes and in surface water to check for contamination with R. solanacearum. Toward this end, the Institute for Plant Protection of the Bavarian State Research Center for Agriculture has been conducting an intensive survey for the presence of the potato brown rot pathogen in Bavarian rivers since 1997. An important component of this monitoring is the testing of potential weed hosts growing near river banks. Every year, from June to September, water- and plant samples have been collected from rivers in potato cultivation areas and near potato processing plants. Since the start of the survey, a total of 70 rivers has been tested. The presence of the pathogen was checked by immunofluorescence antibody staining (IFAS) and polymerase chain reaction (PCR). Positive IFAS or PCR tests were checked again by biotests and pathogenicity tests on eggplant (Solanum melongena). So far R. solanacearum could be found in nine Bavarian rivers. Concerning wild plants growing near the river banks the bacterium could be isolated only from roots of the bittersweet nightshade (Solanum dulcamara). However, from stinging nettle (Urtica dioica), nodding beggartick (Bidens cernua), black nightshade (Solanum nigrum), great yellowcress (Rorippa amphibia) and gipsywort (Lycopus europaeus) R. solanacearum could not be isolated. In contaminated rivers, with S. dulcamara growing on the river banks, R. solanacearum could be detected repetitively for several years. In 1997 it was found that rivers can be contaminated by the pathogen, if insufficiently treated sewage from potato processing plants is released into waterways. Potato cultivation is threatened by surface water only, if contaminated water is used to irrigate potato fields. Consequently, surface water should never be used for irrigation of potato fields or application of plant protection products.