Phytochemical composition and biological activity of native Australian ginger (Alpinia caerulea)

The edible, endemic Australian species Alpinia caerulea belongs to the same family as ginger and turmeric. The rhizome and fruit have a mild ginger-like flavour, but there is very little information on its chemical composition or potential biological activities. This study found low levels of ascorbic acid in the fruit and fruit capsule (2.3–3.4 mg/100 g fresh weight), as well as detecting six polyphenols (rutin, quercetin-3-glucoside, quercetin, vanillic acid, kaempferol and chlorogenic acid) across all of the plant parts. The volatile profile of the rhizome was also explored for the first time. The volatiles were dominated (91.7%) by (E)-8(17),12-labdadiene-15,16-dial, but included 20 other minor constituents; mainly monoterpenes and sesquiterpenes. Extracts showed no inhibitory activity against tyrosinase or cyclooxygenase-2 (COX-2), but moderate anti-acetylcholinesterase was found for the rhizome and stem extracts. Further investigation into A. caerulea and other species from this genus will help to elucidate their full nutritional and bioactive potential.