The Polarity of Fullerene C60 Derivatives for Enhanced Photodynamic Inactivation.

In this article, four novel fulleropyrrolidines derivatives were synthesized to study how the effect of polarity and positive charge distribution can influence the efficacy of photodynamic inactivation treatments to kill bacteria. The design of the photosensitizers was based on DFT calculations that allowed us to estimate the dipolar moment of the molecules. Neutral compounds bearing N-methyl bis-acetoxy-ethyl (1) and bis-hydroxyethyl (2) amine were the starting material to obtain the dicationic analogs N,N-dimethyl bis-methoxyethyl (3), and bis-acetoxy-ethyl) (4) methylammonio. As expected from fullerene C60 derivatives, compounds 1-4 absorb in the UV region, with a peak at 430 nm, a broader range of absorption up to 710 nm, and exhibit weak fluorescence emission in toluene and reverse micelles. In the biomimetic AOT micellar system, the highest singlet oxygen photosensitization was found for compounds 1, followed by 3, 2, and 4. Whereas 4 was the most effective reducing nitro blue tetrazolium in the presence of ß-NADH. The influence of type I and type II mechanism on the photodynamic activity of compounds 3 and 4 was further examined in the presence of L-tryptophan and two reactive oxygen species scavengers. In vitro experiments indicated that the compounds with the highest dipolar moments, 3 (37.19 D) and 4 (38.46 D), inactivated methicillin-resistant Staphylococcus aureus and Escherichia coli bacteria using an energy dose <2.4 J cm-2 . No inactivation was observed for the neutral analogs with the lowest dipolar moments. These findings help to optimize sensitizer structures to improve photodynamic inactivation.

Synthesis of New Steroidal Carbamates with Plant-Growth-Promoting Activity: Theoretical and Experimental Evidence.

A priority of modern agriculture is to use novel and environmentally friendly plant-growth promoter compounds to increase crop yields and avoid the indiscriminate use of synthetic fertilizers. Brassinosteroids are directly involved in the growth and development of plants and are considered attractive candidates to solve this problem. Obtaining these metabolites from their natural sources is expensive and cumbersome since they occur in extremely low concentrations in plants. For this reason, much effort has been dedicated in the last decades to synthesize brassinosteroids analogs. In this manuscript, we present the synthesis and characterization of seven steroidal carbamates starting from stigmasterol, ß-sitosterol, diosgenin and several oxygenated derivatives of it. The synthesis route for functionalization of diosgenin included epoxidation and epoxy opening reactions, reduction of carbonyl groups, selective oxidation of hydroxyl groups, among others. All the obtained compounds were characterized by 1H and 13C NMR, HRMS, and their melting points are also reported. Rice lamina inclination test performed at different concentrations established that all reported steroidal carbamates show plant-growth-promoting activity. A molecular docking study evaluated the affinity of the synthesized compounds towards the BRI1-BAK1 receptor from Arabidopsis thaliana and three of the docked compounds displayed a binding energy lower than brassinolide.