A novel flavonoid and other constituents from Rubus rosifolius S.Vidal (Rosaceae).

Various reports revealed that chemical constituents from many species of Rubus exhibit diverse biological activities. In this study, a novel flavonoid with a 2-(phenanthren-9-yl)-4H-chromen-4-one structure (1), a 5-phenylthiophene-2-carbaldehyde derivative (5) first isolated from a natural source, together with five known compounds including three polyketides (2-4) and two sesquiterpenoids (6-7) were isolated from a traditional Chinese medicine Rubus rosifolius S.Vidal (Rosaceae). The structures of new compounds were elucidated by detailed spectroscopic analysis including NMR and X-ray single-crystal diffraction. The bioassays results indicated that, compound 1 displayed significant cytotoxicity against human colon cancer cell line HCT116 with IC50 value of 8.6 ± 1.9 µM, and compound 5 exhibited moderate cytotoxicity against human breast cancer cell line MDA-MB-435 with IC50 value of 24.1 ± 0.8 µM.

Fabrication of a pH-responsive core-shell nanosystem with a low-temperature photothermal therapy effect for treating bacterial biofilm infection.

Recently, photothermal therapy (PTT) has been recognized as a viable alternative strategy against bacterial biofilm infection. However, the hyperthermia required for PTT to ablate a biofilm usually induces damage in normal tissues/organs nearby. Herein, we developed zeolite-based imidazole framework (ZIF-8)-coated mesoporous polydopamine (MPDA) core-shell nanoparticles and then loaded Pifithrin-µ (PES), a natural inhibitor of heat-shock protein (HSP) that plays an essential role in bacteria resisting heating-induced damage. The ZIF-8 shell of the MPDA@ZIF-8/PES nanoplatform enabled a rapid degradation in response to the acidic environment in bacterial biofilm infection, which triggered the controlled release of PES and Zn ions. As a result, HSP was remarkably suppressed for enhancing PTT efficacy upon mild near-infrared light irradiation. In addition, the release of Zn2+ also had an antibacterial/antibiofilm effect. Thus, the fabricated nanosystem was able to induce the effective elimination of the bacterial biofilm, realizing low-temperature PTT (∼45 °C) with excellent antibacterial efficacy. This work presented here not only provides a facile approach to fabricate the MPDA@ZIF-8/PES nanosystem with the responsiveness of the bacterial infection environment, but also proposes a promising low-temperature PTT strategy to treat bacterial biofilm-infection effectively.