Differential Photosynthetic Acclimation Pattern to Limiting Growth-Irradiance in Two Types of C4 Plants

Photosynthetic acclimation to reduced growth irradiances (650 and 200 µmol m^–2 s^–1) in Eleusine coracana (L.) Garten, a nicotinamide adenine dinucleotide-malic enzyme (NAD-ME) C₄ species and Gomphrena globosa L., a nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME) C₄ species were investigated. E. coracana plants acclimated in 4 and 8 d to 650 and 200 µmol m^–2 s^–1, respectively, whereas G. globosa plants took 8 and 10 d, respectively, to acclimate to the same irradiances. The acclimation to reduced irradiance was achieved in both species by greater partitioning of chlorophyll towards the light-harvesting antennae at the expense of functional components. However, magnitude of increase in the light-harvesting antenna was higher in E. coracana as compared to G. globosa. Superior photosynthetic acclimation to reduced irradiance in G. globosa was due to the smaller change in functions of the cytochrome b ₆/f complex, photosystem (PS) 1 and PS2 leading to the higher carbon fixation rates compared to E. coracana.     

Chemical synthesis and tyrosinase inhibitory activity of rhododendrol glycosides

The concise synthesis of rhododendrol glycosides 3–8, which are novel derivatives of (+)-epirhododendrin (1) and (−)-rhododendrin (2), has been achieved in six steps from benzaldehyde 9. The key reactions include aldol condensation and trichloroacetimidate glycosylation. From biological studies, it has been determined that synthetic derivatives of 1 and 2 possess potent tyrosinase inhibitory activity. Particularly, the inhibitory activity of cellobioside 8 (IC₅₀ = 1.51 μM) is six times higher than that of kojic acid. The R-epimers (4, 6, and 8) possessed more potent activity than the corresponding S-epimers (3, 5, and 7), indicating that tyrosinase inhibitory activity is significantly governed by stereochemistry of rhododendrol glycosides.     

Synthesis of a Glycosylated Peptide Thioester by the Boc Strategy and Its Application to Segment Condensation

The synthesis of a chitobiosylated peptide thioester by the t-butoxycarbonyl (Boc) strategy is demonstrated. Boc-Asn carrying benzyl-protected chitobiose was introduced during application of the Boc mode solid-phase method. HF treatment of the resulting protected peptide resin gave the desired chitobiosylated peptide thioester. This thioester was used to prepare the peptide sequence derived from extracellular matrix metalloproteinase inducers (emmprin) (34-94), (34-118) and (22-118) by the thioester segment condensation method. The conformation of these glycopeptides is characterized by circular dichroism (CD) spectral measurement.     

DNA-binding affinity and anticancer activity of β-carboline–chalcone conjugates as potential DNA intercalators: Molecular modelling and synthesis

A new series of DNA-interactive β-carboline–chalcone conjugates have been synthesized and evaluated for their in vitro cytotoxicity and DNA-binding affinity. It has been observed that most of these new hybrids have shown potent cytotoxic activities on A-549 (lung adenocarcinoma) cell lines with IC₅₀ values lower than 10 μM. The hybrid 7b is more effective against some of the selected cancer cell lines with IC₅₀ values less than 50 μM. In addition, compounds 7e, 7k, 7p–u has displayed significant elevation in ΔT_m of DNA in comparison to Adriamycin, suggesting significant interaction and remarkable DNA stabilization. The DNA intercalation of these new hybrids has been investigated by fluorescence titration, DNA viscosity measurements, molecular docking as well as molecular dynamics and the results are in agreement with the thermal denaturation studies.     

Impact of mitochondrial electric field on modal occupancy in the Fröhlich model of cellular electromagnetism

Fröhlich model describes emission of electromagnetic field in the interior of biological cells by oscillating polar units, now mostly identified with microtubule filaments. Central element of this theory is the system of rate equations for the quantum occupancy numbers n _i of collective oscillation modes. These equations describe both linear and nonlinear properties of the system; presence of the latter can lead to condensation of the incoming energy into the lowest frequency mode – a phenomenon deemed to be of major importance for cell's biochemistry, because the excited mode can engage in chemical reactions while the major part of the system remains near the equilibrium, not exposed to energetic stress. This paper explores, using a simple model, the influence of strong static electric field created by mitochondria flanking the microtubules on nonlinear interactions and, in turn, on occupancy numbers. The computed results show that simultaneous presence of both sufficient metabolic pumping and adequately elevated static electric field is necessary for the full unfolding of the hallmark properties of the Fröhlich model. It is suggested that cancer-related mitochondrial dysfunction leading to metabolic transformation has additional adverse effect mediated by diminution of static fields which in turn reduces the nonlinear processes in the Fröhlich systems, essential for energy condensation in the fundamental mode.     

Synthesis and Biological Assays of 9‐(Acylamino)homocamptothecins as DNA Topoisomerase I Inhibitors

In an effort to improve the stability of homocamptothecin and reduce the toxicity, novel homocamptothecin analogs with acylamino groups at C(9) were designed and synthesized. The cytotoxic activities of all the synthetic compounds against three cancer cell lines were evaluated by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐2H‐tetrazolium bromide (MTT) assay, and irinotecan was used as reference compound. Compound 7c with a piperidinylacetamido group and 10a with phenylacetamido group at C(9) showed potent activities both in vitro and in vivo. In addition, they also revealed remarkable topoisomerase I inhibitions which were exhibited with well‐established bonds with amino acid residues Arg364 and Asp533 in the active pocket. On the basis of the biological activities, 7c and 10a would be potential candidates for further studies.     

Modular and scalable biocatalytic tools for practical safety,health and environmental improvements in the production of speciality chemicals

Biocatalytic tools for both end-of-the-pipe solutions and direct reaction methodology have been developed for the improvement of practical oxidations. The identification of bottlenecks and limitations in biocatalytic Baeyer-Villiger oxidations, and the comparison of scalable process designs to overcome these limitations, have shown the direction for improvements. The first kilogram-scale asymmetric microbial Baeyer-Villiger oxidation with optimized productivity has been realized by the combination of a resin-based in-situ SFPR strategy together with micro-bubble aeration. Regioselective asymmetric dihydroxylation of aromatic nitriles has been achieved by recombinant chlorobenzenedioxygenase. The introduction of novel biocatalytic tools for key catalytic asymmetric transformations will change chemical manufacturing in the 21st century.     

Concentration of Virus from Water by Electro-Osmosis and Forced-Flow Electrophoresis

A Canalco Model CF-3 Electrophoretic Filter/Concentrator (modified ter Bier) was used to concentrate Type 1 polio virus from water using ectro-osmotic and forced-flow electrophoretic principles. Using2 ectro-osmosis water can be removed at a rate of up to 0.8 ral/hr/cm membrane area. Under conditions of 12–14 V/cm (5–6 amps) and adjusted mping rates, 20 fold concentration, without virus loss, can be achieved. ring forced-flow electrophoresis, the virus, which is negatively charged an alkaline buffer, moves toward the positive pole. At 20 V/cm and th adjusted pumping rates, the best that could be achieved was a 3 fold ncentration of virus and a 10 fold dehydration. Virus spill-over at e cathode and/or virus adsorption at the anode accounted for the poor suits, but theoretically this can be overcome by adjustment of the V/cm upled with adjustment of the pumping rates. Voltage (30 V/cm) and rrent (6 amps) have no detrimental effects on viral stability. These chniques appear to be more rapid and gentle than other methods for ncentration of virus and could be scaled up for practical use.     

Regulation of biomolecular condensate dynamics by signaling

Biomolecular condensates are mesoscopic biomolecular assemblies devoid of long range order that contribute to important cellular functions. They form reversibly, are stabilized by numerous but relatively weak intermolecular interactions, and their formation can be regulated by various cellular signals including changes in local concentration, post-translational modifications, energy-consuming processes, and biomolecular interactions. Condensates formed by liquid–liquid phase separation are initially liquid but are metastable relative to hydrogels or irreversible solids that have been associated with protein aggregation diseases and are stabilized by stronger, more permanent interactions. As a consequence of this, a series of cellular mechanisms are available to regulate not only biomolecular condensation but also the physical properties of the condensates.