Modulating the organic photovoltaic properties of non-fullerene acceptors by molecular modification based on Y6: a theoretical study.

Developing non-fullerene acceptors (NFAs) by modifying the backbone, side chains and end groups is the most important strategy to improve the power conversion efficiency of organic solar cells (OSCs). Among numerous developed NFAs, Y6 and its derivatives are famous NFAs in the OSC field due to their good performance. Herein, in order to understand the mechanism of tuning the photovoltaic performance by modifying the Y6's center backbone, π-spacer and side-chains, we selected the PM6:Y6 OSC as a reference and systematically studied PM6:AQx-2, PM6:Y6-T, PM6:Y6-2T, PM6:Y6-O, PM6:Y6-1O and PM6:Y6-2O OSC systems based on extensive quantum chemistry calculations. The results indicate that introducing quinoxaline to substitute thiadiazole in the backbone induces a blue-shift of absorption spectra, reduces the charge transfer (CT) distance (Δd) and average electrostatic potential (ESP), and increases the singlet-triplet energy gap (ΔEST), CT excitation energy and the number of CT states in low-lying excitations. Inserting thienyl and dithiophenyl as π spacers generates a red-shift of absorption spectra, enlarges Δd and average ESP, and reduces ΔEST and the number of CT states. Introducing furo[3,2-b]furan for substituting one thieno[3,2-b]thiophene unit in the Y6's backbone causes a red-shift of absorption spectra and increases ΔEST, Δd and average ESP as well as CT excitation energy. Introducing alkoxyl as a side chain results in a blue-shift of absorption spectra, and increases ΔEST, Δd, average ESP, CT excitation energy and the number of CT states. The rate constants calculated using Marcus theory suggest that all the molecular modifications of Y6 reduce the exciton dissociation and charge recombination rates at the heterojunction interface, while introducing furo[3,2-b]furan and alkoxyl enlarges CT rates.

[Explore antioxidant quality markers of Hippophae tibetana based on "dry-method + wet-method" technology].

The cross combination of dry-method(network pharmacology analysis) and wet-method(high-resolution mass spectro-metry with antioxidation experiment) was used to predict antioxidant quality markers(Q-markers) of Hippophae tibetana. Ultra-high performance liquid chromatography coupled with hybrid quadrupole-orbitrap mass spectrometry(UPLC-Q-Exactive Orbitrap-MS) was developed to rapidly separate and identify the chemical constituents in H. tibetana. Then in DPPH free radicals and superoxide anion scavenging experiment, the antioxidant activity of the four different polar parts with extracts of petroleumether, ethyl acetate, n-butanol and water was evaluated. Network pharmacology method was used for functional enrichment and pathway analysis to screen antioxidant-related components and preliminarily explain the mechanism of action. On this basis, multi-source information was integrated to predict the antioxidant Q-markers. The results showed that 51 components in H. tibetana were identified, including 18 flavonoids, 14 terpenoids, 6 alkaloids, 4 coumarins and phenylpropanoids, 3 volatile components and 2 polyphenols. The antioxidant capacity of different fractions: ethyl acetate > n-butanol > water > petroleum ether. The medicine mainly acted on PI3 K-Akt and FoxO signaling pathways to perform antioxidant effects through flavonoids such as quercetin, luteolin and kaempferol. According to the results of dry-method and wet-method, quercetin, luteolin and kaempferol, the representatives of poly-hydroxy flavone, may be the antioxidant Q-markers of H. tibetana. In this study, with the antioxidant Q-markers of H. tibetana as an example, an investigation model of predicting Q-marker was discussed based on the ternary system of composition, function and informatics, providing a scientific basis for the establishment of quality evaluation standards for H. tibetana.

Inhibition of DNA demethylation enhances plant tolerance to cadmium toxicity by improving iron nutrition.

Although the alteration of DNA methylation due to abiotic stresses, such as exposure to the toxic metal cadmium (Cd), has been often observed in plants, little is known about whether such epigenetic changes are linked to the ability of plants to adapt to stress. Herein, we report a close linkage between DNA methylation and the adaptational responses in Arabidopsis plants under Cd stress. Exposure to Cd significantly inhibited the expression of three DNA demethylase genes ROS1/DML2/DML3 (RDD) and elevated DNA methylation at the genome-wide level in Col-0 roots. Furthermore, the profile of DNA methylation in Cd-exposed Col-0 roots was similar to that in the roots of rdd triple mutants, which lack RDD, indicating that Cd-induced DNA methylation is associated with the inhibition of RDD. Interestingly, the elevation in DNA methylation in rdd conferred a higher tolerance against Cd stress and improved cellular Fe nutrition in the root tissues. In addition, lowering the Fe supply abolished improved Cd tolerance due to the lack of RDD in rdd. Together, these data suggest that the inhibition of RDD-mediated DNA demethylation in the roots by Cd would in turn enhance plant tolerance to Cd stress by improving Fe nutrition through a feedback mechanism.

Fusing Thienyl with N-Annulated Perylene Dyes and Photovoltaic Parameters for Dye-Sensitized Solar Cells.

Due to the role of dyes in dye-sensitized solar cells (DSSCs), designing novel dye sensitizers is an effective strategy to improve the power conversion efficiency. To this end, the fundamental issue is understanding the sensitizer's trilateral relationship among its molecular structure, optoelectronic properties, and photovoltaic performance. Considering the good performance of N-annulated perlyene dye sensitizers, the geometries, electronic structures, and excitations of the selected representative organic dye sensitizers C276, C277, and C278 as well as dyes adsorbed on TiO2 clusters were calculated in order to investigate the relationship between molecular structures and properties. It was found that fusing thienyl to N-annulated perlyene can elevate the highest occupied molecular orbital (HOMO) energy, reduce the orbital energy gap, increase the density of states, expand the HOMO to the benzothiadiazole moiety, enhance the charge transfer excitation, elongate the fluorescence lifetime, amplify the light harvesting efficiency, and induce a red-shift of the absorption spectra. The transition configurations and molecular orbitals of the dye-adsorbed systems support that the electron injection in DSSCs based on these dyes is a fast mode. Based on extensive analysis of the electronic structures and excitation properties of these dye sensitizers and the dye-adsorbed systems, we present new quantities as open-circuit voltage and short-circuit current density descriptors that celebrate the quantitative bridge between the photovoltaic parameters and the electronic structure-related properties in order to expose the relationship between properties and performance. The results of this work are critical for the design of novel dye sensitizers for solar cells.

Nitrate transporter 1.1 alleviates lead toxicity in Arabidopsis by preventing rhizosphere acidification.

Identification of the mechanisms that control lead (Pb) concentration in plants is a prerequisite for minimizing dietary uptake of Pb from contaminated crops. This study examines how nitrate uptake by roots affects Pb uptake and reveals a new resistance strategy for plants to cope with Pb contamination. We investigated the interaction between nitrate transporter (NRT)-mediated NO3- uptake and exposure to Pb in Arabidopsis using NRT-related mutants. Exposure to Pb specifically stimulated NRT1.1-mediated nitrate uptake. Loss of function of NRT1.1 in nrt1.1-knockout mutants resulted in greater Pb toxicity and higher Pb accumulation in nitrate-sufficient growth medium, whereas no difference was seen between wild-type plants and null-mutants for NRT1.2, NRT2.1, NRT2.2, NRT2.4, and NRT2.5. These results indicate that only NRT1.1-mediated NO3- uptake alleviated Pb toxicity in the plants. Further examination indicated that rhizosphere acidification, which favors Pb entry to roots by increasing its availability, is prevented when NRT1.1 is functional and both NO3- and NH4+ are present in the medium.

Donor Halogenation Effects on Electronic Structures and Electron Process Rates of Donor/C60 Heterojunction Interface: A Theoretical Study on F nZnPc ( n = 0, 4, 8, 16) and Cl nSubPc ( n = 0, 6).

Molecular engineering is significantly important for developing electron donor and acceptor materials of active layers in organic photovoltaics (OPVs). The OPVs based on halogenated donors frequently produced high power conversion efficiencies. Here, based upon density functional theory calculations with optimally tuned range separation parameters and solid polarization effects, we studied the effects of donor halogenation on molecular geometries, electronic structures, excitation, and spectroscopic properties for F nZnPc ( n = 0, 4, 8, 16) and Cl nSubPc ( n = 0, 6) monomers and the complexes with C60 as well as the photoinduced direct charge transfer (CT), exciton dissociation (ED), and charge recombination (CR) processes that were described by rate constants calculated using Marcus theory. The tiny differences of the molecular orbital energy gap, excitation, and spectroscopic properties of F nZnPc ( n = 0, 4, 8, 16) and Cl nSubPc ( n = 0, 6) monomers suggest that halogenation cannot effectively tune the electronic and optical gap but the significant decrease of molecular orbital energies support the idea that halogenation has a remarkable influence on the energy level alignment at heterojunction interfaces. The halogenation also enhances intermolecular binding energies between C60 and donors and increases the CT excitation energies of donor/C60 complexes, which are favorable for improving open circuit voltage. Furthermore, for F nZnPc/C60 ( n = 0, 4, 8, 16) and SubPc/C60 ( n = 0, 6) complexes, the CR rates dramatically decrease (several orders) with increasing number of halogen atoms (except for F16ZnPc/C60), meaning suppression of CR processes by halogenation. As for the special case of F16ZnPc/C60, it underlines the importance of fluorination degree in molecular design of donor materials. This study provides a theoretical understanding of the halogenation effects of donors in OPVs and may be helpful in molecular design for electron donor materials.

Assessment of Ab Initio and Density Functional Theory Methods for the Excitations of Donor-Acceptor Complexes: The Case of the Benzene-Tetracyanoethylene Model.

The understanding of the excited-state properties of electron donors, acceptors and their interfaces in organic optoelectronic devices is a fundamental issue for their performance optimization. In order to obtain a balanced description of the different excitation types for electron-donor-acceptor systems, including the singlet charge transfer (CT), local excitations, and triplet excited states, several ab initio and density functional theory (DFT) methods for excited-state calculations were evaluated based upon the selected model system of benzene-tetracyanoethylene (B-TCNE) complexes. On the basis of benchmark calculations of the equation-of-motion coupled-cluster with single and double excitations method, the arithmetic mean of the absolute errors and standard errors of the electronic excitation energies for the different computational methods suggest that the M11 functional in DFT is superior to the other tested DFT functionals, and time-dependent DFT (TDDFT) with the Tamm-Dancoff approximation improves the accuracy of the calculated excitation energies relative to that of the full TDDFT. The performance of the M11 functional underlines the importance of kinetic energy density, spin-density gradient, and range separation in the development of novel DFT functionals. According to the TDDFT results, the performances of the different TDDFT methods on the CT properties of the B-TCNE complexes were also analyzed.

Molecular Docking toward Panchromatic Dye Sensitizers for Solar Cells Based upon Tetraazulenylporphyrin and Tetraanthracenylporphyrin.

Novel dye sensitizers are highly expected in the development of dye-sensitized solar cells (DSSCs) because dye sensitizers can significantly affect the power conversion efficiency (PCE). Here, the molecular docking strategy is applied to design panchromatic dye sensitizers for DSSCs to improve light-harvesting efficiency covering the full solar spectrum. Considering the broad absorption bands of tetraanthracenylporphyrins (TAnPs) and tetraazuleneporphyrins (TAzPs), based upon porphyrin dye sensitizer YD2-o-C8, the panchromatic dye sensitizers coded as H2(TAnP)-α, H2(TAzP)-γ, H2(TAzP)-ε, and H2(TAzP)-δ are designed by the substitution of the porphyrin-ring in YD2-o-C8 with TAnPs and TAzPs moieties at different positions. The geometries, electronic structures, and excitation properties of the designed dye sensitizers are investigated using density functional theory (DFT) and time-dependent DFT methods. The analysis of geometries, conjugation lengths, electronic structures, absorption spectra, transition configurations, exciton binding energies, and free energy variations for electron injection and dye regeneration supports that the designed molecules are effective to be applied as potential candidates of dye sensitizers for DSSCs. Among the designed dye sensitizers, H2(TAzP)-γ and H2(TAnP)-α must have the better performance in DSSCs.

Therapeutic effects of growth hormone combined with low-dose stanozolol on growth velocity and final height of girls with Turner syndrome.

OBJECTIVE: Turner syndrome (TS), which is characterized by short stature and gonadal dysfunction, is managed by pharmacotherapy. This study aimed to investigate the therapeutic effects of recombinant human growth hormone (rhGH) combined with low-dose stanozolol on the growth and final adult height (FAH) of girls with Turner syndrome (TS). DESIGN: Prospective study. PATIENTS: A total of 44 girls with TS were treated with rhGH (47·6-52·4 µg/kg/day) and low-dose stanozolol (20-35 µg/kg/day), starting at a mean age of 12·65 ± 1·99 year. The control group consisted of 22 girls with TS, who did not receive treatment. MEASUREMENTS: Subjects' growth velocity (GV) was investigated. Height standard deviation score (HtSDS) was calculated relative to healthy Chinese girls (HtSDSN or ) as well as untreated Chinese girls with TS (HtSDSTS ). Post-treatment follow-up was performed until the subjects achieved FAH or near FAH. RESULTS: FAH was significantly higher in subjects receiving treatment compared to the untreated controls (151·42 vs 137·75 cm, P < 0·001). GV was significantly higher in the first to fourth years of treatment compared to baseline values (P < 0·001); it was significantly lower in the second to fourth years of treatment compared to the first year (P < 0·001). CONCLUSIONS: In girls with TS, 9-12 years of age, rhGH combined with low-dose stanozolol may effectively increase growth. At least a 2-year course of this treatment may effectively improve FAH with proper delay of oestrogen-induced development.

The Role of Porphyrin-Free-Base in the Electronic Structures and Related Properties of N-Fused Carbazole-Zinc Porphyrin Dye Sensitizers.

Dye sensitizers can significantly affect power conversion efficiency of dye-sensitized solar cells (DSSCs). Porphyrin-based dyes are promising sensitizers due to their performances in DSSCs. Here, based upon a N-fused carbazole-zinc porphyrin-free-base porphyrin triad containing an ethynyl-linkage (coded as DTBC), the novel porphyrin dyes named DTBC-MP and DTBC-TP were designed by varying the porphyrin-free-base units in the π conjugation of DTBC in order to study the effect of porphyrin-free-base in the modification of electronic structures and related properties. The calculated results indicate that, the extension of the conjugate bridge with the porphyrin-free-base unit results in elevation of the highest occupied molecular orbital (HOMO) energies, decrease of the lowest unoccupied molecular orbital (LUMO) energies, reduction of the HOMO-LUMO gap, red-shift of the absorption bands, and enhancement of the absorbance. The free energy changes demonstrate that introducing more porphyrin-free-base units in the conjugate bridge induces a faster rate of electron injection. The transition properties and molecular orbital characters suggest that the different transition properties might lead to a different electron injection mechanism. In terms of electronic structure, absorption spectra, light harvesting capability, and free energy changes, the designed DTBC-TP is a promising candidate dye sensitizer for DSSCs.

The adsorption of α-cyanoacrylic acid on anatase TiO2 (101) and (001) surfaces: a density functional theory study.

The adsorption of α-cyanoacrylic acid (CAA) on anatase TiO2 (101) and (001) surfaces, including adsorption energies, structures, and electronic properties, have been studied by means of density functional theory calculations in connection with ultrasoft pseudopotential and generalized gradient approximation based upon slab models. The most stable structure of CAA on anatase TiO2 (101) surface is the dissociated bidentate configuration where the cyano N and carbonyl O bond with two adjacent surface Ti atoms along [010] direction and the dissociated H binds to the surface bridging O which connects the surface Ti bonded with carbonyl O. While for the adsorption of CAA on (001) surface, the most stable structure is the bidentate configuration through the dissociation of hydroxyl in carboxyl moiety. The O atoms of carboxyl bond with two neighbor surface Ti along [100] direction, and the H from dissociated hydroxyl interacts with surface bridging O, generating OH species. The adsorption energies are estimated to be 1.02 and 3.25 eV for (101) and (001) surfaces, respectively. The analysis of density of states not only suggests the bonds between CAA and TiO2 surfaces are formed but also indicates that CAA adsorptions on TiO2 (101) and (001) surfaces provide feasible mode for photo-induced electron injection through the interface between TiO2 and CAA. This is resulted from that, compared with the contribution of CAA orbitals in valence bands, the conduction bands which are mainly composed of Ti 3d orbitals have remarkable reduction of the component of CAA orbitals.

The role of the conjugate bridge in electronic structures and related properties of tetrahydroquinoline for dye sensitized solar cells.

To understand the role of the conjugate bridge in modifying the properties of organic dye sensitizers in solar cells, the computations of the geometries and electronic structures for 10 kinds of tetrahydroquinoline dyes were performed using density functional theory (DFT), and the electronic absorption and fluorescence properties were investigated via time dependent DFT. The population analysis, molecular orbital energies, radiative lifetimes, exciton binding energies (EBE), and light harvesting efficiencies (LHE), as well as the free energy changes of electron injection ( ) and dye regeneration ( ) were also addressed. The correlation of charge populations and experimental open-circuit voltage (Voc) indicates that more charges populated in acceptor groups correspond to larger Voc. The elongating of conjugate bridge by thiophene units generates the larger oscillator strength, higher LHE, larger absolute value of , and longer relative radiative lifetime, but it induces the decreasing of EBE and . So the extending of conjugate bridge with thiopene units in organic dye is an effective way to increase the harvest of solar light, and it is also favorable for electron injection due to their larger . While the inversely correlated relationship between EBE and LHE implies that the dyes with lower EBE produce more efficient light harvesting.

Association between height and weight catch-up growth with insulin resistance in pre-pubertal Chinese children born small for gestational age at two different ages.

This study was performed to test whether children born small for gestational age (SGA) with catch-up growth (CUG) could be associated with the early development of insulin resistance and the ß-cell dysfunction and to explore the impacts of height CUG and weight CUG on the insulin resistance in a Chinese population. A total of 30 children born SGA with CUG, 37 non-CUG (NCUG), and 42 born appropriate for gestational age (AGA) with normal height were recruited. Their fasting serum insulin, fasting glucose, insulin-like growth factor-1 (IGF-1) concentrations, and the homeostasis assessment model for insulin resistance (HOMA-IR) and ß-cell function (HOMA%) were evaluated. The values of HOMA-IR in CUG SGA were significantly higher than that in NCUG SGA (P = 0.002) and AGA children (P = 0.036), respectively. Correlation analysis revealed that the concentrations of fasting serum insulin were positively correlated with IGF-1 (r = 0.443, P = 0.001) and Δheight standard deviation score (SDS; r = 0.500, P = 0.002) in ≤ 6-year-old SGA children, but only with Δweight SDS (r = 0.496, P = 0.030) in >6-year-old children. In conclusion, SGA children with CUG in height and a higher body mass index are prone to the development of insulin resistance. Higher levels of insulin were closely correlated with the postnatal height CUG in young SGA children and with the weight CUG in old children.

Clinical characteristics of adrenocortical tumors in children.

BACKGROUND: Adrenocortical tumors (ACTs) are rare in children. Because of the rarity and various manifestations of ACTs, patients of ACTs are not easily diagnosed. Some patients were misdiagnosed before surgery. OBJECTIVE: Identify the clinical, laboratorial, imaging and histopathological characteristics of adrenocortical tumors in children. Compare adrenalcortical adenoma with carcinoma. METHODS: A retrospective review of 34 identified patients who were younger than 15 years old with histologic confirmation of adrenocortical carcinoma (ACC) or adenomas from 1991 to 2010. RESULTS: In these 34 patients, 19 were adrenocortical adenoma (ACA) and 15 were ACC. The median age at diagnosis was 3.33 years (range, 0-16 years), and 70.6% of the patients were younger than five years. Girls slightly predominated over boys (1.4:1). For endocrine abnormality, 14 patients had isolated precocious puberty, five patients had isolated Cushing syndrome, 10 patients had precocious puberty plus Cushing syndrome, and five patients did not have any symptoms. The most frequent findings in laboratory tests were disturbance of the normal circadian rhythm of cortisol secretion (93.8%), followed by elevated serum level of testosterone (89.7%). Only 3.8% of ultrasound diagnosis and 12.1% of computed tomography (CT) diagnosis were consistent with pathologic diagnosis. CONCLUSION: Different from those in adult, the most frequent presentation in children with ACTs is peripheral precocious puberty with or without Cushing syndrome, and isolated Cushing syndrome. Few present with non-functional local mass. Laboratory tests usually reveal the discordantly elevated serum levels of sexual corticosteroid hormones, change of diurnal rhythm of cortisol or increase of morning cortisol. The differentiation of malignant from benign tumor cannot merely depend on imaging. Final diagnosis relies on comprehensive evaluation of clinical manifestations, laboratory data, imaging and pathology.

Two cases of Fanconi-Bickel syndrome: first report from China with novel mutations of SLC2A2 gene.

Fanconi-Bickel syndrome (FBS) is a rare inherited disease caused by mutations in the glucose transporter 2 gene, SLC2A2. We reported the first two Chinese cases of FBS. Both cases presented typical clinical features of hepatomegaly, hypophosphatemic rickets, severely stunted growth, fasting hypoglycemia along with postprandial hyperglycemia, and proximal renal tubular dysfunction with disproportionately severe glucosuria. Genetic analysis of SLC2A2 gene revealed novel compound heterozygous mutations in both patients. The characteristics of being born as small for gestational age and apparent liver dysfunction in our cases have been seldom discussed in the literature. It seems FBS patients in general have lower birth weight than normal, but further data collection is still needed. Symptomatic treatments were effective, but the serum transaminase of patient 2 remained moderately increased, and he patient needed further follow-up. The present study will supplement the up-to-date clinical characteristic spectrum for FBS.

Bioactive triterpenoids from Kadsura heteroclita.

A phytochemical study of Kadsura heteroclita led to the isolation of eight triterpenoids, including two new compounds, named kadheterilactone A (1) and kadheterilactone B (2), as well as six known compounds, longipedlactone H (3), longipedlactone A (4), longipedlactone F (5), kadsuranic acid A (6), nigranoic acid (7), and schisandronic acid (8). Their structures were elucidated on the basis of spectroscopic methods, including 2D NMR techniques. The cytotoxic activities of 1-8 were tested against several tumor cell lines by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium hydrobromide (MTT) assay in vitro. As a result, 4 and 5 turned out to be significantly cytotoxic against Hep-G2 and Bel-7402 tumor cell lines. All compounds were also tested for inhibition on HIV-1 protease (PR) and reverse transcriptase (RT). Compounds 6 and 7 showed strong inhibition on HIV-1 PR, while 8 exhibited moderate activity, others were only weakly active. No compounds were active against HIV-1 RT.

[Inhibition of the replication of HIV-1 by norcantharidin in vitro].

For obtaining new structural compounds with unique resistance profiles or novel mechanisms of action on HIV-1 from natural products, anti-HIV-1 drug screening models were used in vitro. Norcantharidin (NCTD), a derivative from cantharidin, was found to have inhibitory activities on HIV-1(IIIB) p24 antigen in lymphocyte lines MT-4, CEM and H9. It inhibited HIV-1 strain 018a (sensitive to zidovudine) from replicating with EC50 (50% effective concentration) of 14.9 micromol L(-1) and also inhibited HIV-1 strain 018c (resistant to zidovudine) from replicating with EC50 of 20.2 micromol L(-1) in primary lymphocytes peripheral blood mononuclear cells (PBMC). Norcantharidin showed synergistic activity with zidovudine on HIV-1(IIIB) in MT-4 cells, the combination index was less than 0.3. But, it was not active on HIV-1 integrase, reverse transcriptase or protease in vitro. As the structure of norcantharidin is unique and different from that of all clinic drugs approved, it would be possible to obtain new and effective compounds against HIV-1 with low toxicities after modification of norcantharidin.

[Effective components against HIV-1 replicative enzymes isolated from plants].

Plant active components characterized of many different structures and activities on multiple targets, have made them to be the important sources of inhibitors on HIV-1. For finding leading compounds with new structure against HIV-1, three key HIV-1 replicative enzymes (reverse transcriptase, protease and integrase) were used as screening models. The in vitro activities of 45 plant derived components isolated from Schisandraceae, Rutaceae and Ranunculaceae were reported. Within twelve triterpene components isolated, eight compounds were found to inhibit HIV-1 protease, in these eight active compounds, kadsuranic acid A (7) and nigranoic acid (8), inhibited both HIV-1 protease and integrase; Among fifteen lignans, meso-dihydroguaiaretic acid (15) and kadsurarin (16) were active on HIV-1 reverse transcriptase, and 4, 4-di(4-hydroxy-3-methoxyphenly)-2, 3-dimethylbutanol (13) active on HIV-1 integrase. All of the six alkaloids, seven flavones, and five others compounds were not active or only with low activities against HIV-1 replicative enzymes. Further studies of the triterpene components showing strong inhibitory activities on HIV-1 were warranted.

Optoelectronic properties of diathiafulvalene-functionalized diketopyrrolopyrrole-fullerene molecular dyad.

Single component molecular dyad donor-acceptor junction is an important type of organic solar cells. Understanding the optoelectronic properties of molecular dyad plays the critical role to develop active layer materials for such kind of solar cells. Here, diathiafulvalene-functionalized diketopyrrolopyrrole-fullerene (DFDPP-Ful) was selected as the representative system, and the geometries, electronic structures and excitation properties of DFDPP-Ful monomer and dimer were systematically investigated based on extensive quantum chemistry calculations. The transition configurations and molecular orbitals show that the effective electron donor and acceptor are DFDPP and fullerene moieties, respectively. It also found the light harvesting is dominated by local excitation in DFDPP moiety. Meanwhile, the hybridization and quasi-degeneration between charge transfer (CT) and local excitation exist. The dimer data suggest that the increased excited states contribute to the expanding of absorption spectra, and the excitations exhibit both the intermolecular and intra-molecular CTs. Also, the remarkable CT energy differences among the different dimer models for the lowest CT excited states support the strong interface and energy disorder in such system. Therefore, the suggestions for developing molecular dyad of single component organic solar cells would be the combination of increasing light absorption, enhancing CT and local excitation hybridization, as well as suppressing energy and interface disorder by the aid of molecular design.

Design, synthesis, and biological evaluation of ligustrazine - betulin amino-acid/dipeptide derivatives as anti-tumor agents.

The ligustrazine - betulin derivative (TB), TB amino acids derivatives (TB-01 - TB-09) and TB dipeptide derivatives (TB-10 - TB-18) were designed and synthesized. And their in vitro cytotoxic activities were evaluated against four cancer cell lines (Hela, HepG2, BGC-823 and HT-29) and normal cells MDCK by standard methylthiazol tetrazolium (MTT) assay. Most of them demonstrated better antitumor activity than the relevant material betulin. Among them, compound TB-01 showed the best anti-tumor effect on the cancer cells and the lowest toxicity on the normal cells. For example, the cytotoxicity of TB-01 against the cancer cells (mean IC50 = 4.86 ±â€¯1.16 µM) was 3-fold higher than that against the normal cells MDCK (IC50 = 16.11 ±â€¯2.29 µM). Moreover, TB-01 showed better cytotoxic than positive drug cisplatin (DDP) on tumor cells. Besides, the Zebrafish toxicity evaluation test showed that TB-01 demonstrated high biosafety. Subsequently, fluorescent staining, apoptosis detection and cell cycle analysis indicated that TB-01 induced early apoptosis in HepG2 cells and blocked the cell cycle in the G1 phase. In addition, the structure-activity relationships of these derivatives were briefly discussed.