UHPLC-HRMS profile and accumulation of argentatins in stems of 27 accessions of guayule (Parthenium argentatum A. Gray) and its hybrids along the growth cycle

Abstract

The argentatins are the most abundant compounds in guayule resin with promising potential for the biopharmaceutical industry. However, their accumulation along the vegetative cycle of the plant and their quantification in different guayule accessions has not been assessed. The present study established the profile of 16 known compounds of the argentatin family in 27 guayule and guayule interspecific accessions using UHPLC-Q-Orbitrap-HRMS. In addition, the structure of five unreported argentatins was tentatively identified. All compounds were present in all accessions (27) and samples (135) analyzed, although in varying amounts. Those compounds found in the highest proportion were argentatins A, B, C, G, isoargentatin A, 16-dehydroargentatin C and quisquagenin. The mass spectra of the compounds were more complex than expected, revealing the lability of the compounds and a high probability to partially degrade during analysis, even at the mildest ionization energies. Based on available standards, argentatins A and B and isoargentatins A and B were quantified in 27 accessions and five samplings along the growing season. The total abundance of the four compounds was 13.4–39.6% of the guayule resin in stems depending on the accession. The profiles of accumulation were related to the genetic origin, with the summer and spring periods producing the greatest yield of argentatins. Pure guayule accessions generally produced more argentatins than hybrids, although the most productive for argentatins and isoargentatins A and B was the non-mariola hybrid AZ-3. • Twenty-one argentatins and related compounds were found in 27 guayule accessions. • Major compounds were argentatins A, B, C, G, isoargentatin A and 16-dehydroargentatin C. • The argentatins profile of accumulation was related to the genetic origin. • Pure guayule accessions produced more argentatins than hybrids. • Four compounds’ account for 13.4–39.6% of the resin depending on the accession.