Fujian Institute of Microbiology

In this study, we explore a novel application of conventional hydrazone analogs SA and LG series as a new class of photocages, which are successfully developed by coupling various phenylhydrazines with two aldehydes of coumarin and triphenylamine (TPA) via one-step reaction.Under 450 nm irradiation, these compounds exhibit significant photolysis behavior, achieving impressive conversion rate of up to 99.0 %.Notably, this ultrahigh photolysis efficiency may represent the highest conversion rate reported to date.Meanwhile, we propose the photolysis mechanism identified as a photooxidation process based on the identification of key intermediates and final products.In cellular studies, the uncaging process is real-time visualized in MCF-7 cancer cells, as evidenced by fluorescence intensity increase over irradiation time, demonstrating these hydrazone-based photocage spotential for bioimaging applications.Moreover, by conjugating one of the LG photocage with a staurosporine analog, we develop a photo-controlled drug delivery system (DDS), LG-STS, which also demonstrate efficient photolysis.The staurosporine analog can be released and visualized via a progressive fluorescence enhancement and a 25-fold increase in anticancer activity at cellular level.Overall, our study highlights the significant potential of hydrazone-based photocages for applications in fluorescent bioimaging and photo-controlled drug release, providing a promising platform for advanced DDS development.

Simultaneous monitoring of multiple mech. stimuli is a widespread requirement in practical applications.However, decoupling the photoluminescence (PL) response to mech. stimuli remains elusive for organic emitters.Here, we achieved the decoupled response to grinding and compression in 5-methoxy-1-indanone modified tetraphenylethylene (TPE) derivatives (IT) by employing the hydrogen bonding cooperativity effect (HBCE).The synthesized IT crystals exhibit a significant red-shifted emission from 480 nm to 550 nm under compression and an increased PL quantum yield from 1.87% to 22.2% upon grinding.Detailed exptl. anal. shows that the strengthened C-H···O interactions between indanone units facilitate denser intermol. π-π stacking, while the weak C-H···π interactions between TPE units regulate intramol. orbital coupling.The synergy of these two effects enables the decoupling of responses to shear and normal forces during the grinding and compression processes.This HBCE-empowered decoupled responsiveness in the organic emitter opens avenues for the development of multistimuli-response smart materials.

Rakicidin J (1) and rakicidin K (2), two new cyclic depsipeptides, were isolated from culture broth of Micromonospora chalcea FIM-R150103. Their structures were elucidated by extensive analysis of NMR, HR-ESI-MS, and electronic circular dichroism (ECD) data. The two compounds showed strong cytotoxic activity against human colon carcinoma HCT-8 and human pancreatic cancer PANC-1 cells under normoxic and hypoxic conditions in the range of IC₅₀ values from 0.024 to 0.79 μg/mL. Moreover, compounds 1 and 2 also showed moderate antibacterial activity against ten Gram-positive bacterial strains with MIC values ranging from 4 to more than 32 μg/mL. Structure-activity relationship of these two compounds with a close analogue, rakicidin B1, is also discussed.