Mimicking DNA Periodic Docking Grooves for Adaptive Identification of l-/d-Tryptophan in a Biological Metal-Organic Framework.

Bioinspired metal-organic frameworks (MOFs) serve as suitable crystalline models for recognition and sensing of biomolecules mimicking natural processes, providing new ideas and concepts for cutting-edge biomedical applications. Here, we have successfully prepared a robust biological metal-organic framework with periodic docking grooves resembling the major and minor grooves in the DNA double helix structure, which can be used as unique recognition sites for selectively identifying l-/d-tryptophan (l-/d-Trp). Notably, successful encapsulation of Trp could be observed by single-crystal X-ray diffraction for the first time. Trp has matched size and shape to fit snugly into the major groove. Combined with isothermal titration calorimetry, it was found that ZnBTCHx could spontaneously capture l-/d-Trp through two different thermodynamic pathways: enthalpy-driven for encapsulating l-Trp and entropy-driven for uptaking d-Trp. Furthermore, molecular dynamics and density functional theory verified the role of hydrogen bonding and π-π/C-H···π interactions in the host-guest interface. This work provides unique insight for the construction of bionic models to mimic the natural binding properties, which is of great significance for the fields of pharmaceutical chemistry and biomedical science.

Construction of a Luminescent Cadmium-Based Metal-Organic Framework for Highly Selective Discrimination of Ferric Ions.

Fluorescent metal-organic frameworks (MOFs) are ideal materials for sensors because of their adjustable pore size and functional groups, which provide them with favorable metal ion selective recognition. In this paper, a new cadmium-based MOF was synthesized using Cd(NO3)2·4H2O and 3,3',5,5'-biphenyltetracarboxylic acid by solvothermal method. CdBPTC owned three types of channels with dimensions of approximately 8.4 × 8.3 Å, 6.0 × 5.2 Å, 9.7 × 8.4 Å along a, b, and c axis, respectively. This MOF has high selectivity to ferric ions and shows excellent anti-inference ability toward many other cations. The results indicate that the fluorescence quenching efficiency of CdBPTC is close to 100% when the concentration of Fe3+ reaches 1.0 × 10-3 mol·L-1. Moreover, the luminescent intensity at 427 nm presents a linear relationship at a concentration range of 2.0 × 10-4~7.0 × 10-4 mol·L-1, which can be quantitatively expressed by the linear Stern-Volmer equation I0/I = 8489 [Fe3+] - 0.1400, which is comparable to the previously reported better-performing materials. Competitive energy absorption and ion exchange may be responsible for the variation in fluorescence intensity of CdBPTC in different Fe3+ concentrations.

Trichodermatides E and F from fungus Trichoderma applanatum.

Two new polyketide derivatives, trichodermatides E (1) and F (2), are unprecedented examples of a polyketide with 6/6/6/6 tetracyclic skeleton, together with five known analogs koninginin B (3), koninginin D (4), 7-O-methylkoninginin D (5), koninginins E and F (6-7), were isolated from the plant endophytic fungus Trichoderma applanatum. The structures of these two compounds were determined by NMR data and HR-ESI-MS analysis. The putative biosynthesis of compounds 1-7 was presented.

Cladosins F and G, two new hybrid polyketides from the deep-sea-derived Cladosporium sphaerospermum 2005-01-E3.

Two new fungal hybrid polyketides, cladosins F (1) and G (2), with rare 6(3)-enamino-8,10-dihydroxy-tetraketide system were discovered from the deep-sea-derived fungus Cladosporium sphaerospermum 2005-01-E3 guided by OSMAC approach. Their structures were elucidated on the basis of comprehensive spectroscopic analyses, and cytotoxicity, antitubercular, anti-influenza A H1N1 virus, and NF-κB inhibitory activities were evaluated.

Microbial transformations of diosgenin by the white-rot basidiomycete Coriolus versicolor.

Microbial transformation of diosgenin (3ß-hydroxy-5-spirostene) using white-rot fungus Coriolus versicolor afforded four previously unreported polyhydroxylated steroids, 25(R)-spirost-5-en-3ß,7α,15α,21-tetraol (5), 25(R)-spirost-5-en-3ß,7ß,12ß,21-tetrol (6), (25R)-spirost-5-en-3ß,7α,12ß,21-tetraol (7), and (25R)-spirost-5-en-3ß,7ß,11α,21-tetraol (8), along with three known congeners, 25(R)-spirost-5-en-3ß,7ß-diol (2), 25(R)-spirost-5-en-3ß,7ß,21-triol (3), and 25(R)-spirost-5-en-3ß,7ß,12ß-triol (4). These structures were elucidated by 1D and 2D NMR as well as HR-ESIMS analysis. In addition, we provide evidence for two new microbial hydroxylations of diosgenin: C-21 primary carbon hydroxylation and C-15 hydroxylation. The 3ß-hydroxyl group and double bond in the B-ring of diosgenin were found to be important structural determinants for their activity.

[Study on spectral detection of green plant target].

Weeds grow scatteredly in fields, where many insentient objects exist, for example, withered grasses, dry twig and barriers. In order to improve the precision level of spraying, it is important to study green plant detecting technology. The present paper discussed detecting method of green plant by using spectral recognizing technology, because of the real-time feature of spectral recognition. By analyzing the reflectivity difference between each of the two sides of the "red edge" of the spectrum from plants and surrounding environment, green plant discriminat index (GPDI) is defined as the value which equals the reflectivity ratio at the wavelength of 850 nm divided by the reflectivity ratio at the wavelength of 650 nm. The original spectral data of green plants and the background were measured by using the handhold FieldSpec 3 Spectroradiometer manufactured by ASD Inc. in USA. The spectral data were processed to get the reflectivity of each measured objects and to work out the GPDI thereof as well. The classification model of green plant and its background was built up using decision tree method in order to obtain the threshold of GPDI to distinguish green plants and the background. The threshold of GPDI was chosen as 5.54. The detected object was recognized as green plant when it is GPDI>GPDITH, and vice versa. Through another test, the accuracy rate was verified which was 100% by using the threshold. The authors designed and developed the green plant detector based on single chip microcomputer (SCM) "AT89S51" and photodiode "OPT101" to realize detecting green plants from the background. After passing through two optical filters, the center wavelengths of which are 650 and 850 nm respectively, the reflected light from measured targets was detected by two photodiodes and converted into electrical signals. These analog signals were then converted to digital signals via an analog-to-digital converter (ADS7813) after being amplified by a signal amplifier (OP400). The converted digital signal of reflected light was eventually sent to the SCM (AT89S51) and was calculated and processed there. The processing results and the control signals were given out to actuate executive device to open or close the solenoid valve. The test results show that the level of detectivity of the designed detector was affected by the species, size, and density of weeds. The detectivity of broad-leaf species is higher than that of narrow-leaf species. Broad-leaf species are more easily detected than those narrow-leaf ones; the bigger the plants and the denser the leaves are, the higher the level of detectivity is.

[Cox regression analysis on influencing factors of coronary heart disease among people over 40 years of age].

OBJECTIVE: To explore the affecting factors on coronary heart disease among people over 40 years of age in Guangxi area, China. METHODS: Baseline data was gathered through the Third National Blood Pressure Survey in 1991 in China. A total number of 11 818 adults over 40 years old had been studied in Guangxi province. Data of morbidity and mortality of coronary heart disease was obtained. RESULTS: Cardiovascular events were related to systolic blood pressure, diastolic blood pressure, pulse pressure, smoking, BMI regardless of their myocardial infarct (MI) history. Cox regression analysis showed that the relative risk for cardiovascular events increased by 21 [95% confidence interval (CI): 9.06-48.44] times for those people having MI history. When pulse pressure, systolic blood pressure, diastolic blood pressure increased by every 10 mm Hg, the relative risk for cardiovascular events increased by 1.29 (95% CI: 1.11-1.49), 1.18 (95% CI: 1.02-1.22), 1.13 (95% CI: 1.05-1.28) respectively. There was 1.23 (95% Cl: 1.05-1.45) times higher in smoker than non-smoker on relative risk for cardiovascular events. When BMI increasing 1, the relative risk for cardiovascular events would increase 1.03 (95% CI: 1.01-1 .05) times. CONCLUSION: Hypertension, smoking, increase of BMI were the risk factors of coronary heart disease among people who were over 40 years of age.