Kavalactones are a diverse class of pharmacologically active compounds that are generated as secondary metabolites in the leaf and root portions of the plant kava-kava. This plant has been used to prepare medicinal and ceremonial teas by cultures of the islands of the South Pacific for hundreds, if not thousands of years. The therapeutic values of kava-kava have come under scrutiny due to the apparent hepatotoxicity of solvent extracts rich in certain kavalactones including kavain, yangonin, methysticin, and other related compounds. We have recently reported protocols and methods for identifying diverse molecular extracts for their particular kavalactone content based on soxhlet extraction in combination with GC-MS and HPLC. Here we describe a novel combination approach to identifying the pharmacologically active kavalactones that exploit the unique chiral optical properties of the known therapeutic and toxic components. Experimental absorbance and circular dichroism spectra of isolated kavalactone stereoisomers were compared to calculated spectral parameters. Specifically, kavalactone structures of defined absolute configuration are treated at the density functional theory and coupled cluster levels for the purpose of computing excitation energies, rotational strengths, and oscillator strengths. Combined, these computed parameters allow the prediction of absorption and circular dichroism spectra. Results from these studies are discussed in the context of the distribution of kavalactones obtained from kava-kava by various methods of extraction and separation.

Chiral optical properties of kavalactones from root extracts of kava-kava assessed by combined experimental and computational methods

255th National Meeting (2018)

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