Gnetum gnemon is a species of Gnetum native to southeast Asia and the western Pacific Ocean islands, from Mizoram and Assam in India, south and east through Indonesia and Malaysia to the Philippines and Fiji. Common names include gnemon, melinjo, belinjo, kuliat/culiat, padi oats or paddy oats.
It is a small to medium-size tree (unlike most other Gnetum species, which are lianas), growing to 15–20 m tall. The leaves are evergreen, opposite, 8–20 cm long and 3–10 cm broad, entire, emerging bronze-coloured, maturing glossy dark green. The fruit-like female strobilus consist of little but skin and a large nut-like seed 2–4 cm long inside. Male strobili are small, arranged in long stalks, and are often mistaken for flowers.
Fleshy strobili weigh about 5.5 g, the seed alone 3.8 g. Strobili mature mainly from June to September in NE Philippines. The red (ripe) strobili are eaten by birds, mammals and reptiles.
Melinjo is native to Indonesia and widely used in Indonesian cuisine. The seeds are used for sayur asem (sour vegetables soup) and also, made into raw chips that later need to be deep-fried as crackers (emping, a type of krupuk). The crackers have a slightly bitter taste and are frequently served as a snack or accompaniment to Indonesian dishes. The leaves are also commonly used for vegetables dishes in Indonesia and southern Thailand.
This plant is commonly cultivated throughout the Aceh region and is regarded as a vegetable of high status. Its male strobili, young leaves and female strobilus are used as ingredients in traditional vegetable curry called kuah pliek. This dish is served on all important traditional occasions, such as khanduri and keureudja. In the Pidie district, the women pick the ripe fruit (its skin color is red) and make keureupuk muling from it. In Java, the young leaves and unpeeled seeds are used for ingredients in a dish called sayur asem.
At the present, Melinjo Extract is produced and supervised under cooperation between Indonesian Agricultural Association (NOFA (id:KTNA) ; Ikamaja's Mother Organization) and JASMELINDO (Japanese Non-Profit Organization), to protect certain profit for Indonesian farmers.
Recently, it has been discovered that melinjo strobili are rich in a stilbenoid composed of resveratrol and identified as a dimer. This result was published in XXIII International Conference on Polyphenols, Canada, in 2006.
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.