Utilization of carbon catabolite repression for efficiently biotransformation of anthraquinone O-glucuronides by Streptomyces coeruleorubidus DM.

Carbon catabolite repression (CCR) is a highly conserved mechanism that regulates carbon source utilization in Streptomyces. CCR has a negative impact on secondary metabolite fermentation, both in industrial and research settings. In this study, CCR was observed in the daunorubicin (DNR)-producing strain Streptomyces coeruleorubidus DM, which was cultivated in high concentration of carbohydrates. Unexpectedly, DM exhibited a high ability for anthraquinone glucuronidation biotransformation under CCR conditions with a maximum bioconversion rate of 95% achieved at pH 6, 30°C for 24 h. The co-utilization of glucose and sucrose resulted in the highest biotransformation rate compared to other carbon source combinations. Three novel anthraquinone glucuronides were obtained, with purpurin-O-glucuronide showing significantly improved water solubility, antioxidant activity, and antibacterial bioactivity. Comparative transcript analysis revealed that glucose and sucrose utilization were significantly upregulated as DM cultivated under CCR condition, which strongly enhance the biosynthetic pathway of the precursors Uridine diphosphate glucuronic acid (UDPGA). Meanwhile, the carbon metabolic flux has significantly enhanced the fatty acid biosynthesis, the exhaust of acetyl coenzyme A may lead to the complete repression of the biosynthesis of DNR, Additionally, the efflux transporter genes were simultaneously downregulated, which may contribute to the anthraquinones intracellular glucuronidation. Overall, our findings demonstrate that utilizing CCR can be a valuable strategy for enhancing the biotransformation efficiency of anthraquinone O-glucuronides by DM. This approach has the potential to improve the bioavailability and therapeutic potential of these compounds, opening up new possibilities for their pharmaceutical applications.

Photothermal-responsive Prussian blue nanocages loaded with thrombin for tumor starvation therapy and photothermal therapy.

The goal of inhibiting tumor growth can be achieved by cutting off the supply of nutrients in the blood vessels of a tumor site, but finding ways to effectively, accurately and safely deliver drugs that can induce vascular embolism remains a challenge. Phase change materials (PCM) can undergo solid-liquid transformation at the phase change temperature. This study reports on a near-infrared ray (NIR)-responsive nano-drug delivery platform based on Prussian blue (PB) nanoparticles. The PCM (lauric acid) can encapsulate thrombin (Thr) in the Prussian blue nanocage (PB Cage), and effectively avoid the pre-leakage of Thr during blood circulation. When the (Thr/PCM)@PB Cage is accumulated at the tumor site and irradiated with NIR, the thermal effect induced by the PB Cage causes the PCM to undergo a solid-liquid state transition, rapidly releasing the encapsulated Thr and inducing coagulation in the tumor blood vessels. Based on the safe delivery and precisely controlled release of Thr, the proliferation of tumor cells can be inhibited without damaging other tissues and organs. In addition, PB Cage-induced photothermal therapy can also ablate tumor cells. Thr-induced "starvation therapy" based on PB Cage loading provides a good reference for precise controlled-release drug delivery systems.

Crosstalk between traditional Chinese medicine-derived polysaccharides and the gut microbiota: A new perspective to understand traditional Chinese medicine.

Polysaccharide is a kind of macromolecule polymer composed of monosaccharides connected by glycosidic bonds. Traditional Chinese medicine (TCM), composed of various bioactive ingredients, is usually rich in polysaccharides. In recent years, extensive research on TCM polysaccharides has demonstrated their pharmacological effects. Polysaccharides can hardly be catabolized by enzymes encoded by the human genome but can be degraded to absorbable metabolites by bacteria inhabiting the colon. Hence, the gut microbiota plays a vital role in degrading TCM polysaccharides into short-chain fatty acids (SCFAs) which exert physiological functions locally and systemically. Besides, TCM polysaccharides can also modulate the composition and activities of the gut microbiota by promoting the growth of beneficial bacteria and inhibiting the colonization of pathogenic bacteria, ultimately restoring gut homeostasis and improving human health. In this review, we discuss the extraction and pharmacological effects of TCM polysaccharides, various functions of the gut microbiota, and the interactions between TCM polysaccharides and the gut microbiota, illuminating the mechanisms of TCM polysaccharides modulating host physiology via the gut microbiota. To firmly establish the clinical efficacy of TCM polysaccharides, further high-quality studies especially clinical trials are needed. Generally, discussion on the interplay between TCM polysaccharides and the gut microbiota is expected to elucidate their application prospects and inspire new thoughts in the development of TCM.