Synthesis of acridone derivatives via heterologous expression of a plant type III polyketide synthase in Escherichia coli.

BACKGROUND: Acridone alkaloids are heterocyclic compounds that exhibit a broad-range of pharmaceutical and chemotherapeutic activities, including anticancer, antiviral, anti-inflammatory, antimalarial, and antimicrobial effects. Certain plant species such as Citrus microcarpa, Ruta graveolens, and Toddaliopsis bremekampii synthesize acridone alkaloids from anthranilate and malonyl-CoA. RESULTS: We synthesized two acridones in Escherichia coli. Acridone synthase (ACS) and anthraniloyl-CoA ligase genes were transformed into E. coli, and the synthesis of acridone was examined. To increase the levels of endogenous anthranilate, we tested several constructs expressing proteins involved in the shikimate pathway and selected the best construct. To boost the supply of malonyl-CoA, genes coding for acetyl-coenzyme A carboxylase (ACC) from Photorhabdus luminescens were overexpressed in E. coli. For the synthesis of 1,3-dihydroxy-10-methylacridone, we utilized an N-methyltransferase gene (NMT) to supply N-methylanthranilate and a new N-methylanthraniloyl-CoA ligase. After selecting the best combination of genes, approximately 17.3 mg/L of 1,3-dihydroxy-9(10H)-acridone (DHA) and 26.0 mg/L of 1,3-dihydroxy-10-methylacridone (NMA) were synthesized. CONCLUSIONS: Two bioactive acridone derivatives were synthesized by expressing type III plant polyketide synthases and other genes in E. coli, which increased the supplement of substrates. This study showed that is possible to synthesize diverse polyketides in E. coli using plant polyketide synthases.

Effects of high-frequency repetitive transcranial magnetic stimulation on reducing hemiplegic shoulder pain in patients with chronic stoke: a randomized controlled trial.

OBJECTIVE: To examine whether high-frequency (10 Hz) repetitive transcranial magnetic stimulation (rTMS), applied over the primary motor cortex of the affected hemisphere, could be used to manage hemiplegic shoulder pain (HSP). METHODS: Twenty-four chronic stroke patients with chronic HSP, randomly assigned into the rTMS group (10 sessions of high-frequency stimulation) or the sham group (sham stimulation), were performed. The Numeric Rating Scale (NRS) was used to evaluate the intensity of pain at pretreatment, and at 1 day, and 1, 2 and 4 weeks after treatment. Changes in upper-limb motor function were evaluated using the Motricity Index (MI-UL) and modified Brunnstrom Classification (MBC). RESULTS: When compared to pretreatment, the rTMS group showed a significant decrease in the NRS score at 1 day, and 1, 2 and 4 weeks after finishing rTMS sessions, with no significant change in the sham group. The NRS score after the rTMS sessions reduced by 30.1% at 1 day, 29.3% at 1 week, 28.0% at 2 weeks and 25.3% at 4 weeks. Passive shoulder range of motion, MI-UL, and MBC, however, did not significantly change in either group. CONCLUSIONS: High-frequency rTMS could be used as a safe, beneficial therapeutic tool to manage HSP. We think it can be used as an adjuvant therapeutic modality to enhance the therapeutic outcome of HSP.