Yellow Twig (Nauclea orientalis) from Thailand: Strictosamide as the Key Alkaloid of This Plant Species

Abstract

Comprehensive phytochemical examination from different perspectives using preparative and analytical chromatographic techniques combined with spectroscopic/spectrometric methods of the so-called “yellow twig” Nauclea orientalis (L.) L. (Rubiaceae) led to the identification of 13 tryptamine-derived (=monoterpene-indole) alkaloids. The identified alkaloids comprise strictosamide and four of its glucosidic derivatives, three oxindole derivatives, and five yellow-colored angustine-type aglycones. Qualitative and quantitative HPLC analyses showed the enrichment of strictosamide in all studied organs. Based on these results, we performed metabolomic analyses of monoterpene-indole alkaloids and made a 1H NMR in vitro monitoring of enzymatic deglucosylation of strictosamide. A comparison of the stability of strictosamide and its enantiomer vincoside lactam by theoretical calculations was also performed revealing a slightly higher stability of vincoside lactam. Additionally, we conducted two different anti-feedant assays of strictosamide using larvae of the polyphageous moth Spodoptera littoralis Boisduval. The obtained results indicate that generally two different biosynthetic pathways are most likely responsible for the overall alkaloid composition in this plant. Strictosamide is the key compound in the broader pathway and most likely the source of the identified angustine-type aglycones, which may contribute significantly to the yellow color of the wood. Its cross-organ accumulation makes it likely that strictosamide is not only important as a reservoir for the further biosynthesis, but also acts in the plants’ defense strategy.

Flavan-Benzofurans from Artocarpus lacucha: Their Intracellular Antioxidant Activity and Molecular Docking to Glutathione Reductase

“…27 The structure of GR was energetically minimized using the steepest descent and subsequently refined through the conjugate gradient method until the root-mean-square (RMS) of the energy gradient reached below 0.05 (kcal/mol/Å). For compound ligands, the compound molecule structures were optimized using the B3LYP hybrid functional and a double-ζ polarized basis set with six d-type Cartesian Gaussian polarization functions (6-31G(d,p)), 28 as provided by the Gaussian 09 software package. The ANTECHAMBER 29 was used to perform compatible AMBER force field parameters for specific modification molecules.…”

Recent Updates on the Antimicrobial Compounds from Marine‐Derived Penicillium fungi

“…Alkaloids are produced by a variety of organisms, including bacteria, fungi, plants, and animals. [67,68,69,70] Most have complex ring structures and have significant biological activity. [71,72,73,74] The antimicrobial activities of alkaloids from marine Penicillium sp.…”