Characterization of two O-methyltransferases involved in the biosynthesis of O-methylated catechins in tea plant.

Tea is known for having a high catechin content, with the main component being (-)-epigallocatechin gallate (EGCG), which has significant bioactivities, including potential anti-cancer and anti-inflammatory activity. The poor intestinal stability and permeability of EGCG, however, undermine these health-improving benefits. O-methylated EGCG derivatives, found in a few tea cultivars in low levels, have attracted considerable interest due to their increased bioavailability. Here, we identify two O-methyltransferases from tea plant: CsFAOMT1 that has a specific O-methyltransferase activity on the 3''-position of EGCG to generate EGCG3''Me, and CsFAOMT2 that predominantly catalyzes the formation of EGCG4″Me. In different tea tissues and germplasms, the transcript levels of CsFAOMT1 and CsFAOMT2 are strongly correlated with the amounts of EGCG3''Me and EGCG4''Me, respectively. Furthermore, the crystal structures of CsFAOMT1 and CsFAOMT2 reveal the key residues necessary for 3''- and 4''-O-methylation. These findings may provide guidance for the future development of tea cultivars with high O-methylated catechin content.

[Surveys on the conditions of Keshan disease and selenium levels of 15 counties in Shandong Province in 2008].

OBJECTIVE: To investigate the conditions of Keshan disease and the selenium nutritional status of residents in Keshan disease endemic area in Shandong Province. METHODS: One site from each of 15 Keshan disease endemic counties in Shandong Province was selected for the survey and 700 subjects in each site were randomly selected for the investigation. Physical examination, electrocardiogram and X-ray radiography of the subjects and the selenium contents of hair, wheat, corn and dried sweet potato were surveyed. RESULTS: A total of 10679 people were investigated in 15 counties and 315 patients were found, including 287 cases of latent type and 28 cases of chronic type, but no acute or subacute type patients were found. There were 1776 cases of abnormal electrocardiogram. Among the 461 cases checked up by radiography, the heart of 195 cases was enlarged. The selenium content of hair, wheat, corn and dried sweet potato were (0.5191 +/- 0.5538), (0.0268 +/- 0.0045), (0.0194 +/- 0.0052) and (0.0193 +/- 0.0039) mg/kg respectively. CONCLUSION: The occurrence of Keshan disease is in a stable status in Shandong Province at present. Hair selenium of residents in Keshan disease endemic area has reached an appropriate level. The selenium nutritional status of residents has improved, and the prevalence of Keshan disease is expected to be decreased in these areas.

[Observation on conditions and related factors of Keshan disease in Shandong province, 1990-2007].

OBJECTIVE: To observe the serial changes of condition and related factors of Keshan disease (KSD) and provide the scientific basis for disease control and further research. METHODS: The villages in KSD epidemic area of Juxian, Yishui, Pingyi, Zoucheng counties were selected. Since 1990, every five-year was counted as a stage. For the first to third stage, 3-14 year-old residents and over 14 year-old suspicious patients were selected as surveillance subjects. And in the fourth stage, all residents were selected as surveillance subjects. The same group of surveillance subjects in each stage were observed consecutively for 5 years. Surveillance contents included physical checkup, electrocardiogram (ECG) and Xray. At the same time, the selenium (Se) concentration in hair, wheat, corn and sweet potato was measured. The economic income and grain availability were also investigated. RESULTS: Totally, 14,510 cases were visited during 18 years. The incidence of KSD was 3.02% in the first stage, 2.31% in the second stage, 3.57% in the third stages and 3.65% in the fourth stage. Totally, 14,510 cases were examined by ECG, 809 cases showed the abnormal ECG and the total incidence of abnormal ECG was 5.49%. The incidence of abnormal ECG was 3.52% -5.24% from 1990 to 2004 but was 10.97%-10.91% from 2005 to 2007. 732 of hair samples, 701 of wheat samples, 615 of corn samples and 643 of sweet potato samples were collected and the Se concentration was determined by the fluorescent method. Se levels in hair samples had increased (P < 0.05) year by year but Se levels in food have not changed significantly. The economic income and grain availability had increased gradually from 535.8 yuan and 254.6 kg per person in 1990 to 2968.0 yuan and 602.0 kg per person in 2007. CONCLUSION: The condition of KSD was in a stable situation in Shandong Province. Related factors improvement should be an important environmental condition.