Synthesis and structure-activity relationship of berkeleylactone A-derived antibiotics.

Berkeleylactone A is a potent 16-membered macrolactone antibiotic, recently isolated from a coculture of Berkeley Pit Lake fungi. Although its antimicrobial activity has already been investigated, little is known about the structure-activity relationship. Based on our previous synthetic studies, a series of berkeleylactone A derivatives were synthesized and evaluated for their antimicrobial activities against methicillin-sensitive and methicillin-resistant (MRSA) strains.

New total synthesis and structure confirmation of putative (+)-hyacinthacine C and (+)-5--hyacinthacine C.

A unique synthesis of polyhydroxylated pyrrolizidine alkaloids, namely (+)-hyacinthacine C and (+)-5--hyacinthacine C is presented. The strategy relies on a 1,3-dipolar cycloaddition of an l-mannose derived nitrone, which owing to its great -stereoselectivity builds up the majority of the required stereocenters. The following key steps include Wittig olefination and iodine-mediated aminocyclisation, that provide two epimeric pyrrolizidines with the appropriate configuration.

Chemiluminescence Detection of Hydrogen Sulfide Release by β-Lactamase-Catalyzed β-Lactam Biodegradation: Unprecedented Pathway for Monitoring β-Lactam Antibiotic Bacterial Resistance.

β-Lactamase positive bacteria represent a growing threat to human health because of their resistance to commonly used antibiotics. Therefore, development of new diagnostic methods for identification of β-lactamase positive bacteria is of high importance for monitoring the spread of antibiotic-resistant bacteria. Here, we report the discovery of a new biodegradation metabolite (HS), generated through β-lactamase-catalyzed hydrolysis of β-lactam antibiotics.