Photocontrolled Release of Carbendazim from Photocaged Molecule

Carbendazim (MBC) is a high-efficient and broad-spectrum fungicide, but excessive residues caused by its improper use have caused health toxicity and environmental pollution. It is an irresistible trend to find green, safe, accurate and controllable release technology of MBC. To achieve the purpose of safe and efficient use of MBC, photolabile protecting group was used to realize the controllable release. This study aimed to covalently link MBC and 6-nitropiperonyl alcohol (NP) to synthesize photocaged molecule NP-MBC. The photodegradation test showed that NP-MBC could effectively release MBC under ultraviolet light. The antifungal activity of NP-MBC showed significant difference against Rhizoctonia solani, Sclerotinia sclerotiorum and Fusarium graminearum before and after irradiation, and the effects on mycelial morphology are different. The hyphae morphology of R. solani and F. graminearum changed significantly, and mycelia were severely damaged. The hyphae surface of former was swollen and broken, and the latter was collapsed and shriveled after NP-MBC light treatment. NP-MBC could realize the light-controlled release of MBC, and the antifungal activity before and after irradiation was significantly different, which provides an effective way to release MBC.

2,9-Dimethyl-4H-oxazolo[5’,4’:4,5]pyrano[3,2-f]quinolin-4-one

The new 2,9-dimethyl-4H-oxazolo[5’,4’:4,5]pyrano[3,2-f]quinolin-4-one was successfully prepared through the three-component iodine-catalyzed reaction of n-butyl vinyl ether with the new 8-amino-2-methyl-4H-chromeno[3,4-d]oxazol-4-one. The latter was prepared by the reduction of 2-methyl-8-nitro-4H-chromeno[3,4-d]oxazol-4-one with Pd/C in a hydrogen atmosphere. The above nitro compound was synthesized by the condensation of N-(4-hydroxy-6-nitro-2-oxo-2H-chromen-3-yl)acetamide with P2O5 under microwave irradiation. The above acetamide derivative was prepared during the nitration of 2-methyl-4H-chromeno[3,4-d]oxazol-4-one with H2SO4 and KNO3. The structure of the newly synthesized compounds was confirmed by FT-IR, LC-MS, 1H-NMR, and 13C-NMR analyses. Preliminary biological tests show significant anti-lipid peroxidation activity for the title compound and the other synthesized new intermediates, as well as interesting soybean lipoxygenase inhibition for acetamide 2 (IC50 55 μM) and nitro-compound 3 (IC50 27 μM).

4-Amino-2-(p-tolyl)-7H-chromeno[5,6-d]oxazol-7-one

The new 4-amino-2-(p-tolyl)-7H-chromeno[5,6-d]oxazol-7-one was successfully prepared through the Au/TiO2-catalyzed NaBH4 activation and chemoselective reduction of the new 4-nitro-2-(p-tolyl)-7H-chromeno[5,6-d]oxazol-7-one. The latter was synthesized by the one-pot tandem reactions of 6-hydroxy-5,7-dinitrocoumarin with p-tolylmethanol under Au/TiO2 catalysis. The dinitrocoumarin was obtained by the nitration of 6-hydroxycoumarin with cerium ammonium nitrate (CAN). The structure of the synthesized compounds was confirmed by FT-IR, HR-MS, 1H-NMR and 13C-NMR analysis. Preliminary biological tests show low anti-lipid peroxidation activity for the title compound.

Visible-to-NIR-Light Activated Release: From Small Molecules to Nanomaterials

Photoactivatable (alternatively, photoremovable, photoreleasable, or photocleavable) protecting groups (PPGs), also known as caged or photocaged compounds, are used to enable non-invasive spatiotemporal photochemical control over the release of species of interest. Recent years have seen the development of PPGs activatable by biologically and chemically benign visible and near-infrared (NIR) light. These long-wavelength-absorbing moieties expand the applicability of this powerful method and its accessibility to non-specialist users. This review comprehensively covers organic and transition metal-containing photoactivatable compounds (complexes) that absorb in the visible- and NIR-range to release various leaving groups and gasotransmitters (carbon monoxide, nitric oxide, and hydrogen sulfide). The text also covers visible- and NIR-light-induced photosensitized release using molecular sensitizers, quantum dots, and upconversion and second-harmonic nanoparticles, as well as release via photodynamic (photooxygenation by singlet oxygen) and photothermal effects. Release from photoactivatable polymers, micelles, vesicles, and photoswitches, along with the related emerging field of photopharmacology, is discussed at the end of the review.

Chemical approaches for the enhancement of 5-aminolevulinic acid-based photodynamic therapy and photodiagnosis

The development of photodynamic therapy and photodiagnosis with 5-aminolevulinic acid presents a number of challenges that can be addressed by applying chemical insight and a range of novel prodrug strategies.