Java-apple
StarSyzygium samarangense
Synonyms: Jambosa timorensis, Eugenia alba, Jambosa samarangensis var. obtusissima, Jambosa timorensis var. laxiflora, Eugenia mindanaensis, Eugenia samarangensis, Eugenia javanica var. roxburghiana, Eugenia javanica var. parviflora, Myrtus timorensis, Jambosa obtusissima, Jambosa alba, Myrtus obtusissima, Syzygium samarangense var. parviflorum, Jambosa ambigua, Jambosa suzukii, Jambosa samarangensis, Myrtus samarangensis, Jambosa samarangensis var. microcarpa, Eugenia suzukii
Western Herbalism Properties
Traditional Uses
In Southeast Asian traditional medicine, various parts of Syzygium samarangense are employed: the leaves and bark are used to treat bronchitis, asthma, fever, diarrhoea and dysentery, while the roots act as a diuretic and astringent and are taken to relieve dehydration in hot weather (Sandhiya & Amudha, 2025). Modern pharmacological studies support several of these uses, showing that leaf extracts exert gastroprotective and anti-inflammatory effects via the NF-kB pathway in rats, alongside antinociceptive (analgesic), antidiabetic and antimicrobial activities (Sobeh et al., 2021).
Gallery
Botanical Description
Syzygium samarangense, the wax apple, Java apple or bell fruit, is an evergreen tree of the myrtle family (Myrtaceae) native to the Malay Archipelago and the Andaman and Nicobar Islands, now widely cultivated throughout tropical Southeast Asia. It grows up to about 12 metres tall with a short trunk and a dense, spreading crown. The opposite leaves are large, oblong to elliptic, leathery and aromatic when crushed. Showy flowers are borne in clusters and have four small petals and a prominent brush of numerous long, creamy-white to yellowish stamens. The fruit is a glossy, waxy, bell- or pear-shaped berry, ranging from white and green to pink and deep red, with crisp, watery, mildly sweet flesh and few or no seeds. Grown chiefly for its refreshing edible fruit, the tree is also planted for shade and ornament across the humid tropics.
Active Constituents
2',4'-Dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC)
C-methylated chalcone (flavonoid)Concentration: Characteristic major flavonoid of the leaves
DMC is the signature bioactive of Java-apple leaves, with documented antioxidant, anti-inflammatory, spasmolytic and anticancer activity. It activates AMPK and suppresses the alarmin HMGB1, mechanisms linked to its metabolic and anticancer effects.
7-Hydroxy-5-methoxy-6,8-dimethylflavanone
C-methylated flavanone (flavonoid)Concentration: One of several rare C-methylated flavonoids isolated from the leaves
This flavanone was isolated together with DMC as a spasmolytic flavonoid, relaxing gastrointestinal smooth muscle and contributing to the plant's traditional use for cramps and digestive complaints.
Myricetin and other flavonols
Flavonols (flavonoids)Concentration: Present in leaves and fruit
Flavonols contribute to the antioxidant, anti-glycation and anti-hyperglycaemic activity reported for the fruit and leaf extracts.
Ellagitannins and gallic acid derivatives
Hydrolysable tannins / phenolic acidsConcentration: Notable in bark and leaves
These phenolics provide astringent, antimicrobial and antiulcer activity and are part of the total phenolic pool responsible for the plant's antioxidant capacity.
Anthocyanins
Flavonoid pigmentsConcentration: Concentrated in the coloured fruit peel; increase with peel colour and ripeness
Peel anthocyanins account for much of the fruit's antioxidant activity, with content correlating positively with peel colour and total soluble solids.
Vitamin C (ascorbic acid)
Water-soluble vitaminConcentration: Present in the fresh fruit
Ascorbic acid adds to the antioxidant value and nutritional role of the fruit.
Triterpenoids (e.g. betulinic acid, friedelin type)
TerpenoidsConcentration: Reported in bark and non-fruit tissues
Triterpenoids contribute anti-inflammatory and cytotoxic activity documented in bark and leaf extracts.
⚠ Drug Interactions
Antidiabetic drugs (insulin, sulfonylureas, metformin)
Leaf and fruit extracts lower serum glucose and raise insulin in streptozotocin-diabetic rats and interact in silico with PPARγ and GLP-1 targets, so combined use with glucose-lowering drugs could have an additive effect.
Clinical note: Monitor blood glucose if concentrated leaf/fruit extracts are used alongside antidiabetic medication; watch for hypoglycaemia.
Antihypertensive drugs
Extracts produce endothelium-dependent vasorelaxation via the NO/cGMP pathway in isolated rat aorta, which could add to the effect of antihypertensive agents.
Clinical note: Use caution when combining large medicinal doses with blood-pressure medication.
Preparation Methods
Fresh fruit (food and folk remedy)
Parts: fruit
The crisp, watery fruit is eaten fresh as a cooling, thirst-quenching food and is used in folk practice as a mild diuretic and to relieve heat. It is well tolerated as a food.
Leaf or bark decoction (traditional)
Parts: leaves, bark
Leaves or bark are simmered in water to make a decoction used traditionally in Southeast Asia for fever, diarrhoea, coughs and inflammatory complaints. Medicinal decoctions should be used moderately; safety of concentrated long-term use has not been established in humans.
Clinical Studies
Syzygium samarangense leaf extract mitigates indomethacin-induced gastropathy via the NF-κB signaling pathway in rats
Pre-treatment with the leaf extract significantly reduced the gastric ulcer index, inflammatory-cell infiltration, inflammatory markers and lipid peroxidation (MDA) while raising endogenous antioxidants, mucus content and goblet-cell proliferation, indicating cytoprotective, antioxidant, anti-inflammatory and antiapoptotic gastroprotective activity mediated via NF-κB and prostaglandin EP3/EP4 signalling.
Syzygium samarangense leaf extract exhibits distinct antidiabetic activities: Evidences from in silico and in vivo studies
Molecular docking of 457 secondary metabolites against PPARγ and GLP-1 identified several compounds with better scores than reference ligands; in streptozotocin-induced diabetic rats the leaf extract lowered serum glucose and lipid peroxides and restored insulin levels, supporting an antidiabetic effect.
Historical Texts
Malay and Indonesian traditional medicine (jambu air / jambu semarang)
Long-standing traditional usePhilippine and Taiwanese folk medicine
TraditionalReferences
- Resurreccion-Magno MHC, Villaseñor IM, Harada N, Monde K. Antihyperglycaemic flavonoids from Syzygium samarangense (Blume) Merr. and Perry . Phytotherapy Research (2005) [DOI]
- Simirgiotis MJ, Adachi S, To S, et al.. Cytotoxic chalcones and antioxidants from the fruits of Syzygium samarangense (Wax Jambu) . Food Chemistry (2008) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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