Total Biosynthesis of Mutaxanthene Unveils a Flavoprotein Monooxygenase Catalyzing Xanthene Ring Formation.

Flavoprotein monooxygenases (FPMOs) play important roles in generating structural complexity and diversity in natural products biosynthesized by type II polyketide synthases (PKSs). In this study, we used genome mining to discover novel mutaxanthene analogues and investigated the biosynthesis of these aromatic polyketides and their unusual xanthene framework. We determined the complete biosynthetic pathway of mutaxathene through in vivo gene deletion and in vitro biochemical experiments. We show that a multifunctional FPMO, MtxO4, catalyzes ring rearrangement and generates the required xanthene ring through a multistep transformation. In addition, we successfully obtained all necessary enzymes for in vitro reconstitution and completed the total biosynthesis of mutaxanthene in a stepwise manner. Our results revealed the formation of a rare xanthene ring in type II polyketide biosynthesis, and demonstrate the potential of using total biosynthesis for the discovery of natural products synthesized by type II PKSs.

New Antibacterial Phenone Derivatives Asperphenone A-C from Mangrove-Derived Fungus Aspergillus sp. YHZ-1.

Marine fungi are a promising source of novel bioactive natural products with diverse structure. In our search for new bioactive natural products from marine fungi, three new phenone derivatives, asperphenone A-C (1-3), have been isolated from the ethyl acetate extract of the fermentation broth of the mangrove-derived fungus, Aspergillus sp. YHZ-1. The chemical structures of these natural products were elucidated on the basis of mass spectrometry, one- and two-dimensional NMR spectroscopic analysis and asperphenone A and B were confirmed by single-crystal X-ray crystallography. Compounds 1 and 2 exhibited weak antibacterial activity against four Gram-positive bacteria, Staphylococcus aureus CMCC(B) 26003, Streptococcus pyogenes ATCC19615, Bacillus subtilis CICC 10283 and Micrococcus luteus, with the MIC values higher than 32.0 µM.

AvmM catalyses macrocyclization through dehydration/Michael-type addition in alchivemycin A biosynthesis.

Macrocyclization is an important process that affords morphed scaffold in biosynthesis of bioactive natural products. Nature has adapted diverse biosynthetic strategies to form macrocycles. In this work, we report the identification and characterization of a small enzyme AvmM that can catalyze the construction of a 16-membered macrocyclic ring in the biosynthesis of alchivemycin A (1). We show through in vivo gene deletion, in vitro biochemical assay and isotope labelling experiments that AvmM catalyzes tandem dehydration and Michael-type addition to generate the core scaffold of 1. Mechanistic studies by crystallography, DFT calculations and MD simulations of AvmM reveal that the reactions are achieved with assistance from the special tenuazonic acid like moiety of substrate. Our results thus uncover an uncharacterized macrocyclization strategy in natural product biosynthesis.

Clinical observation of infantile herpetic angina treated with acupuncture:a randomized controlled trial / 中国针灸

<p><b>OBJECTIVE</b>To observe the difference in the therapeutic effects on infantile herpetic angina among the treatments with western medication, acupuncture and the combined therapy of acupuncture and western medication.</p><p><b>METHODS</b>One hundred and twenty children of herpetic angina were randomized into a western medication group, an acupuncture group and a combined therapy group, 40 cases in each one. Besides the basic treatment with symptomatic support, in the western medication group, ribavirin granules were prescribed for oral administration, 10 mg/kga day, three times a day, for 3 days. In the acupuncture group, acupuncture was applied at Fengchi (GB 20), Hegu (LI 4), Quchi (LI 11), Xiaguan (ST 7), Jiache (ST 6), Dicang (ST 4), Shaoshang (LU 11) and Shangyang (LI 1), once a day, for 3 days. In the combined therapy group, the treatments as the western medication group and the acupuncture group were used, in which, the oral administration with ribavirin granules and acupuncture were adopted for 3 days. The clinical therapeutic effects were compared after treatment and the follow-up visit was conducted since the 4th day at the end of treatment to compare the antifebrile time, herpes relieving time and the use frequency of ibuprofen oral liquid in the children among the three groups.</p><p><b>RESULTS</b>After treatment, the total effective rate was 95.0% (39/40) in the combined therapy group, was 62.5% (25/40) in the western medication group and was 80.0% (32/40) in the acupuncture group. The result in the combined therapy group was better than those in the acupuncture group and the western medication group, indicating the significant differences (both<0.05). The antifebrile time and the herpetic relief time in the combined therapy group were earlier than those in the acupuncture group and the western medication group, indicating the significant differences (both<0.05). The use frequency of ibuprofen oral liquid in the combined therapy group was lower than those in the acupuncture group and the western medication group, indicating the significant difference (both<0.05).</p><p><b>CONCLUSIONS</b>The combined therapy with acupuncture and western medication relieve fever and herpes much more quickly and reduces the use frequency of ibuprofen oral liquid as compared with the simple use of acupuncture or western medication in the treatment of infantile herpetic angina, which achieve the much better therapeutic effects.</p>

Bone marrow mesenchymal stem cell transplantation for skin wound healing / 中国组织工程研究

BACKGROUND:At present,most of the experiments on the treatment of skin wound by mesenchymal stem cells have been performed in rats,mice and rabbits,while the research on skin wound treatment by canine bone marrow mesenchymal stem calls is less reported.OBJECTIVE:To observe the effect of canine bone marrow mesenchymal stem calls on skin wound healing.METHODS:A 3 cmx3 cm wound was made on the both sides of the scapula and buttocks of the dog,with the right side as experimental group and the left side as control group.After the wound was made,allogeneic canine bone marrow mesenchymal stem calls suspension was injected subcutaneously around the wound in the experimental group on the 1st and 3rd days.The control group was injected subcutaneously around the wound with mesenchymal stem call culture medium on the 1st and 3rd days after the wound was made.Wound healing was observed dynamically in both groups.RESULTS AND CONCLUSION:In the 1st week,there were pale yellow inflammatory substances in the wound of two groups indicating obvious inflammations.Compared with the control group,the inflammatory substances were fewer and the growth rate of the granulation tissue was faster in the experimental group.From the 2nd week until the wound healing,epithelialization on the wound became obvious following the formation of the granulation tissue,which was mainly displayed by the formation of fresh epithelial tissues from the surrounding to the wound center.The epithelialization time of the experimental group was earlier than that of the control group,and the wound area of the experimental group was smaller than that of the control group.In the 3rd week,the wound in the experimental group healed completely,and became smoother than that in the control group.The wound area of the experimental group was slightly smaller than that of the control group on the 8th and 12th days after cell transplantation,and the healing speed of the experimental group was slightly faster than that of the control group,but there was no significant difference between the two groups.Our findings indicate that the transplantation of canine bone marrow mesenchymal stem cells has the possibility or trend to promote skin wound healing.