Thermal tool to evaluate essential oil composition of different Eucalyptus genotypes in relation to Glycaspis brimblecombei susceptibility (Hemiptera: Aphalaridae)

Journal of Thermal Analysis and Calorimetry - Eucalyptus spp. (Myrtaceae) is economically important worldwide and is native from Australia. Glycaspis brimblecombei (Hemiptera: Aphalaridae) is an...     

Tripeptide Self-Assembly into Bioactive Hydrogels: Effects of Terminus Modification on Biocatalysis

Bioactive hydrogels based on the self-assembly of tripeptides have attracted great interest in recent years. In particular, the search is active for sequences that are able to mimic enzymes when they are self-organized in a nanostructured hydrogel, so as to provide a smart catalytic (bio)material whose activity can be switched on/off with assembly/disassembly. Within the diverse enzymes that have been targeted for mimicry, hydrolases find wide application in biomaterials, ranging from their use to convert prodrugs into active compounds to their ability to work in reverse and catalyze a plethora of reactions. We recently reported the minimalistic l-His–d-Phe–d-Phe for its ability to self-organize into thermoreversible and biocatalytic hydrogels for esterase mimicry. In this work, we analyze the effects of terminus modifications that mimic the inclusion of the tripeptide in a longer sequence. Therefore, three analogues, i.e., N-acetylated, C-amidated, or both, were synthesized, purified, characterized by several techniques, and probed for self-assembly, hydrogelation, and esterase-like biocatalysis. This work provides useful insights into how chemical modifications at the termini affect self-assembly into biocatalytic hydrogels, and these data may become useful for the future design of supramolecular catalysts for enhanced performance.     

A pimpinellin monomer and dimer isolated from the roots of Esenbeckia grandiflora

X‐ray diffraction studies carried out on single crystals of the monomeric, viz. 5,6‐di­methoxy‐2H‐furo­[2,3‐h][1]benzo­pyran‐2‐one, C₁₃H₁₀O₅, and dimeric, viz. 5,5′,6,6′‐tetra­methoxy‐3,3′,4,4′‐tetra­hydro‐2H,2′H‐3,3′:4,4′‐bi­(furo­[2,3‐h][1]benzo­pyran)‐2,2′‐dione, C₂₆H₂₀O₁₀, forms of pimpinellin have revealed that, following cyclo­dimerization, the carbonyl groups are head‐to‐head with respect to one another. In the monomer, the heterocyclic ring is planar, but it exhibits a twisted‐boat conformation in the dimer. Both the monomer and the dimer interact through C—H⋯O interactions.