The Methionine 549 and Leucine 552 Residues of Friedelin Synthase from Are Important for Substrate Binding Specificity.

Friedelin, a pentacyclic triterpene found in the leaves of the Celastraceae species, demonstrates numerous biological activities and is a precursor of quinonemethide triterpenes, which are promising antitumoral agents. Friedelin is biosynthesized from the cyclization of 2,3-oxidosqualene, involving a series of rearrangements to form a ketone by deprotonation of the hydroxylated intermediate, without the aid of an oxidoreductase enzyme. Mutagenesis studies among oxidosqualene cyclases (OSCs) have demonstrated the influence of amino acid residues on rearrangements during substrate cyclization: loss of catalytic activity, stabilization, rearrangement control or specificity changing.

H NMR determination of adulteration of anabolic steroids in seized drugs.

Counterfeiting and adulteration of pharmaceuticals is a prevalent problem worldwide and represents a major health risk to the population, with anabolic steroids being one of the main classes of drugs consumed and obtained from dubious sources. In this work, we propose the use of the H NMR technique to evaluate formulations containing anabolic steroids, with analysis of 40 samples of anabolic drugs that are used in injectable and capsule forms. The samples analyzed presented the following active ingredients: testosterone propionate, testosterone phenylpropionate, testosterone isocaproate, testosterone decanoate, testosterone cypionate, testosterone undecanoate, stanozolol, drostanolone propionate, trenbolone acetate, oxymetholone, and methandrostenolone.

Crude leaf extracts of Piperaceae species downmodulate inflammatory responses by human monocytes.

In this study, we aimed to evaluate the immunomodulatory effects of crude leaf extracts from Piper gaudichaudianum Kunth, P. arboreum Aub., P.

Friedelin Synthase from Maytenus ilicifolia: Leucine 482 Plays an Essential Role in the Production of the Most Rearranged Pentacyclic Triterpene.

Among the biologically active triterpenes, friedelin has the most-rearranged structure produced by the oxidosqualene cyclases and is the only one containing a cetonic group. In this study, we cloned and functionally characterized friedelin synthase and one cycloartenol synthase from Maytenus ilicifolia (Celastraceae). The complete coding sequences of these 2 genes were cloned from leaf mRNA, and their functions were characterized by heterologous expression in yeast.

VCD to determine absolute configuration of natural product molecules: secolignans from Peperomia blanda.

The absolute configuration and solution-state conformers of three peperomin-type secolignans isolated from Peperomia blanda (Piperaceae) are unambiguously determined by using vibrational circular dichroism (VCD) spectroscopy associated with density functional theory (DFT) calculations. Advantages of VCD over the electronic form of CD for the analysis of diastereomers are also discussed. This work extends our growing knowledge about secondary metabolites within the Piperaceae family species while providing a definitive and straightforward method to assess the absolute stereochemistry of secolignans.

Trypanocidal tetrahydrofuran lignans from Peperomia blanda.

Five tetrahydrofuran lignans and two known flavones were isolated from the aerial parts of Peperomia blanda. The structures of the isolated lignans were elucidated by interpretation of their spectroscopic data, including by gHMQC and gHMBC. The relative and absolute configurations of the isolates were determined from NOESY interactions and optical properties, respectively.