Chemical diversity of kānuka: Inter- and intraspecific variation of foliage terpenes and flavanones of Kunzea (Myrtaceae) in Aotearoa/New Zealand. (April 2022)

• Record Type: Journal Article
• Authors: Fuller, Ioan D.; de Lange, Peter J.; Burgess, Elaine J.; Sansom, Catherine E.; van Klink, John W.; Perry, Nigel B.
• Is Part Of: Phytochemistry. Volume 196(2022)
• Publication Date: 2022-04
• Subjects: Kunzea -- Myrtaceae -- Kānuka -- Chemotaxonomy -- 1H NMR spectroscopy -- GC-MS -- Monoterpene -- Sesquiterpene -- Flavonoid -- 5, 7-dihydroxy-6, 8-dimethyl flavanone; Botanical chemistry -- Periodicals; Biochemistry -- Periodicals; Botany -- Periodicals; Chimie végétale -- Périodiques; 572.2
• DOI: 10.1016/j.phytochem.2022.113098
• Languages: English
• ISSNs: 0031-9422

Abstract

Abstract: Kunzea (Myrtaceae) trees and shrubs, generally called kānuka, grow across most of Aotearoa/New Zealand (NZ). With the exception of K. sinclairii, an offshore island endemic, kānuka had been treated as an Australasian species K. ericoides . However, a 2014 taxonomic revision recognized ten species, all endemic to NZ. Kānuka chemistry is less studied than that of its closest relative in NZ, mānuka ( Leptospermum scoparium ), which shows very distinct regional foliage chemotypes. We have used a miniaturized method with GC and 1 H NMR to analyze foliage chemistry of voucher specimens from across the geographic ranges of the ten NZ Kunzea species. We found common mono- and sesquiterpenes, with α-pinene dominant in all samples, but only traces of antimicrobial triketones. Two unusual flavanones, with unsubstituted B-rings and known bioactivity against Phytophthora, did distinguish some of the samples. 5, 7-Dihydroxy-6, 8-dimethyl flavanone was only found at high concentrations in the three K. sinclairii samples in this study's sample set, but this compound has separately been reported in K. robusta samples from a nearby region. Therefore none of the NZ Kunzea species was distinguished by the chemistry analyzed in this study, but there is a possibility of regional flavonoid chemotypes cutting across the species boundaries. Graphical abstract: Image 1 Highlights: Kunzea (Myrtaceae) trees and shrubs, kānuka, grow across most of Aotearoa/New Zealand (NZ). Foliage chemistry of voucher specimens of ten species was analyzed by GC and 1 H NMR. Two rare bioactive flavanones were found in some of the samples. None of the NZ Kunzea species was distinguished by the chemistry analyzed in this study. There may be regional flavonoid chemotypes cutting across the species boundaries.