Gnetum gnemon is a gymnosperm species of Gnetum. Its native area spans from Mizoram and Assam in India down south through Malay Peninsula, Malay Archipelago and the Philippines in southeast Asia to the western Pacific islands. Common names include gnetum, joint fir, two leaf, melinjo/belinjo (Indonesian), bago/lumbay (Filipino), hanthu (Karbi) and tulip (Tok Pisin).
Description
thumb|upright|left|Melinjo (G. gnemon) branch with fruit
This species can be easily confused for an angiosperm due to the fruit-like female strobili, broad leaves and male strobili looking like flowers due to convergent evolution.
Tree
It is a small to medium-size tree (unlike most other Gnetum species, which are lianas), growing to 15–22 metres tall and with a trunk diameter of up to 40 cm (16 in). In addition to the tree form, there are also varieties that includes shrub forms (brunonianum, griffithii, and tenerum).
Melinjo resveratrol, having antibacterial and antioxidative activity, works as a food preservative, off flavour inhibitor and taste enhancer. This species may have applications in food industries which do not use any synthetic chemicals in their processes.
Four new stilbene oligomers, gnemonol G, H, I and J, were isolated from acetone extract of the root of Gnetum gnemon along with five known stilbenoids, ampelopsin E, cis-ampelopsin E, gnetin C, D and E.
The extraction of dried leaf of Gnetum gnemon with acetone water (1:1) gave C-glycosylflavones (isovitexin, vicenin II, isoswertisin, swertisin, swertiajaponin, isoswertiajaponin).
The separation of a 50% ethanol extract of the dried endosperms yielded gnetin C, gnetin L (new stilbenoid), gnemonosides A, C and D, and resveratrol which were tested for DPPH radical scavenging action, antimicrobial activity and inhibition of lipase and α-amylase from porcine pancreas. Gnetin C showed the best effect among these stilbenoids.
Oral administration of the 50% ethanol extract of melinjo fruit at 100 mg/kg/day significantly enhanced the production of the Th1 cytokines IL-2 and IFN-γ irrespective of concanavalin-A stimulation, whereas the production of the Th2 cytokines IL-4 and IL-5 was not affected. New stilbene glucosides gnemonoside L and gnemonoside M, and known stilbenoids resveratrol, isorhapontigenin, gnemonoside D, gnetins C and E were isolated from the extract. Gnemonoside M strongly enhanced Th1 cytokine production in cultured Peyer's patch cells from mice at 10 mg/kg/day.