Structure and Antimicrobial Activity of Phloroglucinol Derivatives from Achyrocline satureioides

Abstract

The new prenylated phloroglucinol α-pyrones 1-3 and the new dibenzofuran 4, together with the known 23-methyl-6-O-demethylauricepyrone (5), achyrofuran (6), and 5,7-dihydroxy-3,8-dimethoxyflavone (gnaphaliin A), were isolated from the aerial parts of Achyrocline satureioides. Their structures were determined by 1D and 2D NMR spectroscopic studies, while the absolute configuration of the sole stereogenic center of 1 was established by vibrational circular dichroism measurements in comparison to density functional theory calculated data. The same (S) absolute configuration of the α-methylbutyryl chain attached to the phloroglucinol nucleus was assumed for compounds 2-6 based on biogenetic considerations. Derivatives 7-16 were prepared from 1 and 5, and the antimicrobial activities of the isolated metabolites and some of the semisynthetic derivatives against a selected panel of Gram-positive and Gram-negative bacteria, as well as a set of yeast molds, were determined.

Antimicrobial hydrogels: promising materials for medical application

“…210 Achyrocline satureioides is a medicinal plant widely used in South America, which exhibits a welldocumented antioxidant activity against Gram-positive and Gram-negative bacteria, as well as a set of yeast molds. 211 Curcumin is non-toxic and bioactive agent with multifunction; it is found in turmeric and has been applied for centuries as a remedy to various ailments. 212 However, low aqueous solubility and poor bioavailability limit the application of curcumin, and thus curcumin nanoparticles and hydrogels were developed.…”

Difficulties to Determine the Absolute Configuration of Guaiaretic Acid

“…The difficulties we experienced for the AC determination of guaiaretic acid diacetate (1b) are in line with other difficult VCD studied molecules in which a stereogenic center is found on a carbon atoms chain. A good deal of difficulty occurred during the determination of the AC of the sole stereogenic center of a phloroglucinol derivative [20] possessing an α-methylbutyryl chain, which was isolated from Achyrocline satureioides. The molecule is relatively complex, C 25 H 30 O 7 , containing 236 electrons, and 180 vibrational frequency modes that are active in the VCD and IR spectra.…”

Optimization of the Number of Considered Conformers for the Absolute Configuration Determination of Catechin and Epicatechin Peracetates by VCD

“…A literature search shows that VCD has been used only for a few molecules having high conformational freedom [24][25][26][27][28][29]. Thus, with the aim of reducing the large time invested in molecular modeling calculations, truncated models have been used [24,25].…”