In vitro antioxidant and antimicrobial assays of acetone extracts from Nepeta meyeri Bentham.

UNLABELLED: BACKGROUND AND OBJECTIVIES: Nepeta species are used as diuretic, diaphoretic, antitussive, antispasmodic, antiasthmatic, febrifuge, emmenagogue, sedative agents, insecticidal, acaricidal, antiviral, anti-inflammatory and antioxidant. Acetone extract of Nepeta meyeri (Labiatae) was screened for antioxidant and antimicrobial activities. MATERIALS AND METHODS: The antioxidant prop erties of the extract were investigated by using various methods established in vitro systems such as 1,1-diphenyl-2-picrylhydrazyl (DPPH)/nitric oxide (NO) radical scavenging activity. Reducing power and total phenolic substance analysis and also antimicrobial activity of acetone extract of Nepeta meyeri were tested against six gram negative, seven gram positive bacteria and the yeast strain using the disc diffusion method. RESULTS AND DISCUSSION: Acetone extract of the plant examined exhibited a significant concentration-dependent inhibition of DPPH and NO* radical. Furthermore, Nepeta meyeri showed very high reducing power. In DPPH radical and NO* scavenging assays the IC50 value of extract was 672.2 microg/ml and 165.32 microg/ml, respectively. The amounts of total phenolic compounds were also determined and 12.86 microg pyrocatechol equivalents of phenols were detected in the extract. The data obtained from these in vitro models clearly demonstrated antioxidant potential of acetone extract of Nepeta meyeri. The extract revealed antibacterial activity against all gram positive bacteria but not was active against gram negative bacteria.

Mutational analysis of Turnip crinkle virus movement protein p8.

Summary Turnip crinkle virus encodes two proteins, p8 and p9, that are both required for cell-to-cell movement. The p8 movement protein has been demonstrated to bind RNA in a cooperative manner, although, similar to many other plant virus movement proteins, it contains no canonical RNA binding domain(s). However, three positively charged regions of p8 may potentially form ionic interactions with the RNA backbone. To identify functional regions of p8, a series of alanine and deletion scanning mutations were produced. The effects of these mutations were analysed using both in vitro RNA binding assays and in vivo infections of susceptible (Di-3) and resistant (Di-17) Arabidopsis thaliana plants. Several mutants that have reduced RNA binding ability were also demonstrated to be movement deficient and replication competent. Based on these results, there appear to be two regions, located between amino acids 18 and 31, and 50 and 72, that are required for RNA binding. Furthermore, additional regions (amino acids 12-15, and 34-37) appear to play a role in vivo unrelated to in vitro RNA binding activity.

A single amino acid change in turnip crinkle virus movement protein p8 affects RNA binding and virulence on Arabidopsis thaliana.

Comparison of the symptoms caused by turnip crinkle virus strain M (TCV-M) and TCV-B infection of a resistant Arabidopsis thaliana line termed Di-17 demonstrates that TCV-B has a greater ability to spread in planta. This ability is due to a single amino acid change in the viral movement protein p8 and inversely correlates with p8 RNA binding affinity.

Chernobyl radioactivity on the Black Sea coast of Turkey.

After the Chernobyl reactor accident, Eastern Black Sea coast was one of the heavily contaminated regions of Turkey. Clouds loaded with radioactive isotopes arrived the region on May 1986 and emptied their contents with the heavy rains that are frequently seen in the region. In order to asses the current level of contamination, several different samples, moss, lichen, litter, surface soil and soil cores were collected on August 1994. Samples were brought to the laboratory and their moisture, pH and organic matter contents were determined. Gamma-ray spectra of the samples were collected with a HpGe detector. (137)Cs was the major isotope observed. Activity of most litter samples were below 1000 Bq/kg, while most of the moss samples had activities below 5000 Bq/kg, there were a few with higher (137)Cs activities. Surface soil samples generally had activities less than 2000 Bq/kg and depth profiles of cesium activities in the soil cores showed regional variations.