Role of sulphur-heterocycles in medicinal chemistry: An update

Acting by producing reactive oxygen species (ROS) in situ, nanozymes are promising as antimicrobials. ROS’ intrinsic inability to distinguish bacteria from mammalian cells, however, deprives nanozymes of the selectivity necessary for an ideal antimicrobial. Here we report that nanozymes that generate surface-bound ROS selectively kill bacteria over mammalian cells. This result is robust across three distinct nanozymes that universally generate surface-bound ROS, with an oxidase-like silver-palladium bimetallic alloy nanocage, AgPd0.38, being the lead model. The selectivity is attributable to both the surface-bound nature of ROS these nanozymes generate and an unexpected antidote role of endocytosis. Though surface-bound, the ROS on AgPd0.38 efficiently eliminated antibiotic-resistant bacteria and effectively delayed the onset of bacterial resistance emergence. When used as coating additives, AgPd0.38 enabled an inert substrate to inhibit biofilm formation and suppress infection-related immune responses in mouse models. This work opens an avenue toward biocompatible nanozymes and may have implication in our fight against antimicrobial resistance. Nanozymes have been used for antibacterial applications but have potential toxicity to mammalian cells. Here the authors suggest that nanozymes that generate surface bound reactive oxygen species disrupt bacterial cell walls but not mammalian cells walls due to the different particle uptake mechanisms.

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Surface-bound reactive oxygen species generating nanozymes for selective antibacterial action

Fluorinated alcohols have been widely used in the synthetic organic chemistry over the past decades. The unique properties such as the strong hydrogen-bonding donor ability and low nucleophilicity allow them to promote organic reactions in the absence of any catalyst. These approaches have distinct advantages in terms of operational simplicity, practicability and environmental friendliness. Reactions promoted by fluorinated alcohols, including nucleophilic substitution reactions, annulation reactions, electrophilic reactions, dearomatization reactions, functionalization of multiple bond, epoxidation reactions and miscellaneous reactions have been summarized in this account.

Fluorinated Alcohols: Magic Reaction Medium and Promoters for Organic Synthesis.

The photoactivity of natural products - An overlooked potential of phytomedicines?

Foodborne microbial diseases are still considered a growing public health problem worldwide despite the global continuous efforts to ensure food safety. The traditional chemical and thermal-based procedures applied for microbial growth control in the food industry can change the food matrix and lead to antimicrobial resistance. Moreover, currently applied disinfectants have limited efficiency against biofilms. Therefore, antimicrobial photodynamic therapy (aPDT) has become a novel alternative for controlling foodborne pathogenic bacteria in both planktonic and sessile states. The use of aPDT in the food sector is attractive as it is less likely to cause antimicrobial resistance and it does not promote undesirable nutritional and sensory changes in the food matrix. In this review, aspects on the antimicrobial photodynamic technology applied against foodborne pathogenic bacteria and studied in recent years are presented. The application of photodynamic inactivation as an antibiofilm strategy is also reviewed.

Photodynamic inactivation as an emergent strategy against foodborne pathogenic bacteria in planktonic and sessile states.

Phytoalexins phenalenones (PNs) are phytochemicals biosynthesized inside the plant in responsive to exterior threat. PNs are excellent type-II photosensitizers, which efficiently produce singlet oxygen upon light irradiation. Based on the core functional structure of PNs, novel PN derivatives were synthesized here and their singlet oxygen generating abilities and their phototoxicity were evaluated. At the presence of light, these PNs have photoinduced toxicity towards Aedes albopictus larvae and nematode Meloidogyne incognita, while the activity lost in the dark. The obvious tissue damage was observed on the treated mosquito larvae and nematode due to the generation of singlet oxygen. Our results revealed the potential of phenalenones as photoactivated agents for mosquito and root-knot nematode management together with light.

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Phytoalexin Phenalenone Derivatives Inactivate Mosquito Larvae and Root-knot Nematode as Type-II Photosensitizer.

2,2,2-Trifluoroethanol activated one-pot Mannich-like reaction of β-nitroenamines, secondary amines, and aromatic aldehydes

A method for preparation of 1,4,2-dithiazolidine or 1,3-thiazetidine heterocycles was developed by reactions of phenylthioureas with 1,1-dichloro-2-nitroethene. The solvent has a significant influence on the type of product formation. 1,4,2-Dithiazolidines were formed in the aprotic solvent chloroform, while in the protic solvent ethanol, 1,3-thiazetidines were the main products.

Formation of 1,4,2-Dithiazolidines or 1,3-Thiazetidines from 1,1-Dichloro-2-nitroethene and Phenylthiourea Derivatives.

Synthesis and insecticidal evaluation of phytoalexin phenalenones derivatives

A unique and efficient 2,2,2-trifluoroethanol-activated one-pot reaction of β-nitroenamines, secondary amines and aromatic aldehydes was developed under mild and convenient conditions. In the presence of 2,2,2-trifluoroethanol (TFEA), aromatic aldehydes were activated by hydrogen bonding with TFEA. The newly-developed reaction could afford the desired Mannich-like products in moderate to excellent yields with wide substrate scopes.

Yian Feng

Papers

Phytoalexin Phenalenone Derivatives Inactivate Mosquito Larvae and Root-knot Nematode as Type-II Photosensitizer.

2,2,2-Trifluoroethanol activated one-pot Mannich-like reaction of β-nitroenamines, secondary amines, and aromatic aldehydes

Formation of 1,4,2-Dithiazolidines or 1,3-Thiazetidines from 1,1-Dichloro-2-nitroethene and Phenylthiourea Derivatives.

Synthesis and insecticidal evaluation of phytoalexin phenalenones derivatives

2,2,2-Trifluoroethanol Activated One-Pot Mannich-Like Reaction of β-Nitroenamines, Secondary Amines, and Aromatic Aldehydes.