Quantum-optical analogies of dimer structures

By using the concepts of canonical two-level systems, microwave-addressable photonic molecule enables on-demand photon storage and retrieval based on coupled lithium niobate microring resonators, which simultaneously achieve large electrical bandwidth, strong modulation efficiency, and long photon lifetime.

Design, synthesis and anti-proliferative effects in tumor cells of new combretastatin A-4 analogs

A total of 11 novel combretastatin A-4（CA-4） analogs were designed, synthesized, and evaluated for the anti-proliferative effects in tumor cells. The compounds represent four structural classes：（i）hydrogenated derivatives,（ii） ethoxyl derivatives,（iii） amino derivatives and（iv） pro-drugs. Biological evaluations demonstrate that multiple structural features control the biological potency. Three of the compounds, sit-1, sit-2 and sit-3, have potent anti-proliferative activity against multiple cancer cell lines. Their pro-drugs were synthesized to increase water solubility. Structure–activity relationship study and Surflex-Docking were studied in this paper. These results will be useful for the design of new CA-4 analogs that are structurally related to the SAR study.

Design and synthesis of novel coumarin analogs and their nematicidal activity against five phytonematodes

The presence of hydroxyl groups at the C4 and C7 positions in coumarin backbone has been proposed as a potential modification site for providing excellent bioactivity according to previous studies. A series of novel coumarin derivatives were rationally designed and synthesized by use of a complex catalytic system for a targeted modification at the above sites. These derivatives were assayed for nematicidal activity. As predicted, the derivatization enhanced the activity of the coumarins against five nematodes.Compounds 7b, 9a, 10 c and 11 c showed significant strong nematicidal broad spectrum activity against all tested nematodes. Compound 10 c was the most effective with the lowest LC50 values against Meloidogyne incognita（5.1 mmol/L）, Ditylenchus destructor（3.7 mmol/L）, Bursaphelenchus mucronatus（6.4 mmol/L）, Bursaphelenchus B. xylophilus（2.5 mmol/L） and Aphelenchoides besseyi（3.1 mmol/L）,respectively. A brief investigation on the structure–activity relationships（SAR） revealed that the targeted modification by a C7 hydroxyl was optimum compared with that of a C4 hydroxyl and that the coupling chain length was crucial for the nematicidal activity.

Construction of a mutant of Actinoplanes sp. N902-109 that produces a new rapamycin analog

In the present study, we introduced point mutations into Ac_rap A which encodes a polyketide synthase responsible for rapamycin biosynthesis in Actinoplanes sp. N902-109, in order to construct a mutant with an inactivated enoylreductase(ER) domain, which was able to synthesize a new rapamycin analog. Based on the homologous recombination induced by double-strand breaks in chromosome mediated by endonuclease I-SceI, the site-directed mutation in the first ER domain of Ac_rapA was introduced using non-replicating plasmid pL YERIA combined with an I-SceI expression plasmid. Three amino acid residues of the active center, Ala-Gly-Gly, were converted to Ala-Ser-Pro. The broth of the mutant strain SIPI-027 was analyzed by HPLC and a new peak with the similar UV spectrum to that of rapamycin was found. The sample of the new peak was prepared by solvent extraction, column chromatography, and crystallization methods. The structure of new compound, named as SIPI-rapxin, was elucidated by determining and analyzing its MS and NMR spectra and its biological activity was assessed using mixed lymphocyte reaction(MLR). An ER domain–deficient mutant of Actinoplanes sp. N902-109, named as SIPI-027, was constructed, which produced a novel rapamycin analog SIPI-rapxin and its structure was elucidated to be 35, 36-didehydro-27-O-demethylrapamycin. The biological activity of SIPI-rapxin was better than that of rapamycin. In conclusion, inactivation of the first ER domain of rap A, one of the modular polyketide synthase responsible for macro-lactone synthesis of rapamycin, gave rise to a mutant capable of producing a novel rapamycin analog, 35, 36-didehydro-27-O-demethylrapamycin, demonstrating that the enoylreductase domain was responsible for the reduction of the double bond between C-35 and C-36 during rapamycin synthesis.