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5-Aminolaevulinic acid (ALA) and its derivatives have been widely used in photodynamic therapy (PDT) as precursors of the photosensitizer, protoporphyrin IX (PpIX) in dermatology and urology. However, ALA-PDT is limited by the low bioavailability of ALA due to the fact that ALA is poorly absorbed by cells by virtue of its zwitterionic nature at physiological pH. In order to improve the therapeutic effect and induce higher levels of PpIX, a series of ALA prodrugs were synthesized by the conjugation of ALA to 3-hydroxypyridin-4-one (HPO) iron chelator using an amino acid linkage via amide bonds. Pharmacokinetic studies indicated that one ALA–HPO conjugate significantly enhanced PpIX production in a range of tumor cell lines over ALA alone or the co-administration of ALA and CP94 (1,2-diethyl-3-hydroxypyridin-4-one). The intracellular porphyrin fluorescence levels showed good correlation with cellular photo-toxicity following light exposure, suggesting the potential application of the ALA–HPO conjugates in photodynamic therapy.

Polyacrylonitrile(PAN) microspheres were synthesized by soapless emulsion polymerization of acrylonitrile(AN) in water. The effects of monomer and initiator concentration on the conversion of AN and the diameter of microspheres were investigated. The results showed that when the concentration of monomer increases, the conversion of AN decreases while the diameter of PAN microspheres increases. When the concentration of initiator increases, the conversion of AN and the diameter of PAN microspheres both increase. For this method of PAN microspheres synthesis, the highest conversion of AN is about 60% and the diameter can be controlled in need ranging from approximately 140 to 500nm.

A new method for the separation of naringin from pomelo peels was investigated by using ultrasonic-assisted extraction and macroporous resin purification technology. The ultrasonic extraction efficiency was dependent on agent's concentration, ratio of sample and solvent and ultrasonic time. Several parameters of macroporous resin-purified process, including resin selection, initial concentration, concentration of eluted agent and pH, were optimized. The experimental results showed that the naringin content in the mature pomelo peels was 2.20% and purification rate of naringin was 77.26% under optimum conditions of purification. The structure of synthetic naringin dihydrochalcone was determined by a series of spectroscopic methods, such as UV, NMR and MS.

Kojic acid derivatives have been prepared in excellent yield by the condensation of two molecules of kojic acid and one molecule of an aldehyde using sodium carbonate as a base under microwave irradiation.

SAMHD1 is the only known eukaryotic deoxynucleoside triphosphate triphosphohydrolase (dNTPase) and is a major regulator of intracellular dNTP pools. It has been reported to be a potent inhibitor of retroviruses such as HIV-1 and endogenous retrotransposons. Previous crystal structures have revealed that SAMHD1 is activated by dGTP-dependent tetramer formation. However, recent data have indicated that the primary activator of SAMHD1 is GTP, not dGTP. Therefore, how its dNTPase activity is regulated needs to be further clarified. Here, five crystal structures of the catalytic core of SAMHD1 in complex with different combinations of GTP and dNTPs are reported, including a GTP-bound dimer and four GTP/dNTP-bound tetramers. The data show that human SAMHD1 contains two unique activator-binding sites in the allosteric pocket. The primary activator GTP binds to one site and the substrate dNTP (dATP, dCTP, dUTP or dTTP) occupies the other. Consequently, both GTP and dNTP are required for tetramer activation of the enzyme. In the absence of substrate binding, SAMHD1 adopts an inactive dimer conformation even when complexed with GTP. Furthermore, SAMHD1 activation is regulated by the concentration of dNTP. Thus, the level of dNTP pools is elegantly regulated by the self-sensing ability of SAMHD1 through a novel activation mechanism.