Nonenzymatic formation of advanced glycation end products (AGEs) is accelerated under hyperglycemic conditions characteristic of type 2 diabetes mellitus and contributes to the development of vascular complications. As such, inhibition of AGE formation represents a potential therapeutic target for the prevention and treatment of diabetic complications. In the present study, ethanolic extracts of 17 medicinal plants were assessed for inhibitory effects on in vitro AGE formation through fluorometric and immunochemical detection of fluorescent AGEs and N(ε)-(carboxymethyl)lysine adducts of albumin (CML-BSA), respectively. Most extracts inhibited fluorescent AGE formation with IC (50) values ranging from 0.4 to 38.6 µg/mL and all extracts reduced CML-BSA formation but to differing degrees. Results obtained through both methods were highly correlated. Antiglycation activities were positively correlated with total phenolic content, free radical scavenging activity and reduction in malonyldiadehyde levels following oxidation of low-density lipoprotein, but negatively correlated with lag time to formation of conjugated dienes. Together, these results provide evidence that antioxidant phenolic metabolites mediate the antiglycation activity of our medicinal plant collection, a relationship that likely extends to other medicinal and food plants.

Diabetic hyperglycaemia promotes the production of advanced glycation end-products (AGEs), which play a significant role in the development of complications associated with type 2 diabetes mellitus. Vaccinium angustifolium, a medicinal plant used for the treatment of diabetes, produces a variety of phenolic metabolites with putative anti-diabetic activities. To assess optimal cultivation time, seasonal changes in the concentration of six phenolic compounds in leaves and twelve compounds in stems were examined using HPLC-DAD and examined in relation to seasonal changes in AGE inhibition activity, assessed with a fluorescence-based assay. A seasonal decline occurred in the concentration of chlorogenic acid, rutin, and quercetin 3-arabinoside in leaves and chlorogenic acid in stems. The concentration of (+)-catechin, and (-)-epicatechin in stems declined within two weeks before rising and fluctuating insignificantly. AGE inhibition activity of leaves was significantly greater at the final compared to the initial collection date whereas the activity of stems did not change significantly. Relative to the leaf extract, the stem was a more potent inhibitor of AGE formation, which could be a result of the unique phytochemistry of stems. Together, these results revealed significant seasonal variation in the phenolic profile and anti-glycation effects of V. angustifolium extracts and indicated late summer as the collection time yielding optimal activity.

Highly enantio- and diastereoenriched monofluorocyclopropanes were accessed via the Simmons-Smith fluorocyclopropanation of allylic alcohols using difluoroiodomethane and ethylzinc iodide as the substituted carbenoid precursors. The scrambling of halogens at the zinc carbenoid led to the formation of the fluorocyclopropanating agent (fluoroiodomethyl)zinc(II) fluoride. This strategy circumvented the ongoing limitation in Simmons-Smith fluorocyclopropanations relying on the use of the relatively inaccessible and expensive carbenoid precursor fluorodiiodomethane.

Highly strained biarylazacyclooctynone (BARAC) and analogous bioconjugation reagents were shown to undergo novel rearrangement and addition reactions leading to tetracyclic products. This may limit their practical applicability as bioorthogonal reporters for imaging biomolecules within living systems.