Analysis of the flavonoid component of bioactive New Zealand mānuka (Leptospermum scoparium) honey and the isolation, characterisation and synthesis of an unusual pyrrole

• Published in: Food chemistry 2013-12, Vol.141 (3), p.1772-1781
• Main Authors: Chan, Ching W., Deadman, Benjamin J., Manley-Harris, Merilyn, Wilkins, Alistair L., Alber, Dagmar G., Harry, Elizabeth
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - chemical synthesis; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Antibacterial activity; Antibacterial agents; Antibiotics. Antiinfectious agents. Antiparasitic agents; Biological and medical sciences; Flavonoids; Flavonoids - chemistry; Flavonoids - isolation & purification; Flavonoids - pharmacology; Honey - analysis; Leptospermum - chemistry; Medical sciences; Microbial Sensitivity Tests; Mānuka honey; Pharmacology. Drug treatments; Pyrrole; Pyrroles - chemical synthesis; Pyrroles - chemistry; Pyrroles - isolation & purification; Pyrroles - pharmacology; Staphylococcus aureus - drug effects
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2013.04.092

•31 New Zealand mānuka honeys of varying UMF were analysed for flavonoid content.•Pinobanksin, pinocembrin, luteolin and chrysin were 61% of the flavonoid content.•2-formyl-5-(2-methoxyphenyl)-pyrrole, (1), was isolated and characterised.•1 was weakly correlated with non-peroxide antibacterial activity as was luteolin.•1 and luteolin do not have an individual or synergic contribution to bioactivity. The flavonoid components of New Zealand mānuka (Leptospermum scoparium) honey have been quantified in a series of 31 honeys of varying non-peroxide antibacterial activity to clarify discrepancies between previous studies reported in the literature. Total flavonoid content was 1.16mg/100g honey. The principal flavonoids present were pinobanksin, pinocembrin, luteolin and chrysin and together these represented 61% of the total flavonoid content. 1, 2-formyl-5-(2-methoxyphenyl)-pyrrole, which was weakly correlated with the non-peroxide antibacterial activity, was isolated from the flavonoid fraction and separately synthesised. 1 did not display inhibitory activity against Staphylococcus aureus in vitro and thus the origin of the correlation, which is still unknown, is not a direct contribution.