Kunzea sinclairii marker

Fuller, Ioan D., de Lange, Peter J., Burgess, Elaine J., Sansom, Catherine E., van Klink, John W. & Perry, Nigel B., 2022, Chemical diversity of k ¯ anuka: Inter- and intraspecific variation of foliage terpenes and flavanones of Kunzea (Myrtaceae) in Aotearoa / New Zealand, Phytochemistry (113098) 196, pp. 1-8 : 7

4.5. Isolation and identification of Kunzea sinclairii marker compound 10

A Dunedin Botanic Garden K. robusta × K. sinclairii sample (Table S1) also showed the GC and 1 H NMR peaks distinctive for K. sinclairii . Dried foliage (5.7 g) was ground (Breville coffee grinder), then shaken (150 rpm) with HPLC grade CHCl 3 (57 ml) overnight at room temperature. Filtering and solvent removal gave the extract (green gum, 0.76 g). This was coated onto silica (silica gel 60, 200–400 mesh, 40–63 μm, 1.52 g) by rotary evaporation from CHCl 3, which was then added dry to a bench column of silica (10 g). This was eluted with one column volume (25 ml) of petroleum ether (PE), then two column volumes each of 5% EtOAc in PE, 10%, 15%, 20%, 50% and 100% EtOAc. Compound elution was tracked using TLC (Merck silica gel 60 F 254), developed with 20% EtOAc in PE and visualized by UV light. Fractions eluted with 20% EtOAc, which showed the same TLC spot at RF 0.4, were combined and rotary evaporated to give a yellow-green gum (22 mg, 85% one compound by GC-FID, RI 2594 on DB-5). This main compound was identified as 5,7- dihydroxy-6,8-dimethyl flavanone 10 (Registry No. 56297-79-1 or 27,593-80-2, absolute stereochemistry not determined) by: EI-MS m/z 284.1 [M +, 95%], 207.1 [M + -C 6 H 5, 55], 180.1 [M + -C 8 H 8, 75], 152.1 [M + -C 9 H 8 O, 100]; 1 H and 13 C NMR spectra matching ( Mustafa et al., 2005) and ( Lawrence et al., 2019), including 5-OH at δ 12.26 (s, 1H) (CDCl 3).