Gen info
- Cratoxylum (Cratoxylon  Blume, an orthographic variant) is a genus of flower plants in the family Hypericaceae.
- Etymology: The genus name derives from Greek meaning "strong wood", referring to its timber quality.   The specific epithet is Latinized meaning "from Sumatra".

Botany
Guyong-guyong is a smooth, branched, small- to medium-sized tree, up to 20 meters high. Leaves are opposite, ovate, oblong or oblong-elliptic, 5 to 15 centimeters long, 3 to 7 centimeters wide, smaller at the apex, entire, pointed at the apex, blunt or rounded at the base. Petioles are very short. Flowers are red and small, borne on terminal or axillary panicles, 5 to 7 centimeters long. Fruit is smooth, dark reddish-brown, ellipsoid, about 1 centimeter long, subtended at the base by a persistent calyx, dehiscing apically into 3 parts, containing numerous small, thin, brown, winged seeds, each 5 millimeters long.

• A small to medium-sized, deciduous tree of up to 35 m tall, bole up to 40 cm in diameter, bark surface fissured, peeling off in thin, long strips, dark brown to rust brown, inner bark pink or red to orange-brown. Leaves elliptical to ovate-oblong, 4-18 cm × 2-7 cm, with a rounded to cuspidate apex, sometimes glaucous beneath. Inflorescence many-flowered, often a large, foliate panicle; flowers homostylous, petals dark red to brick or brownish-red. Seeds 3-10 per locule, unilaterally winged. (4)

Distribution
- Native to the Philippines.
- Common in thickets and secondary forests, at low and medium altitudes.
- Widespread in Luzon; Babuyan Islands, Catanduanes, Palawan, Masbate, Panay, Negros, Bohol, Leyte, Samar, Basilan, Mindanao.
- Also native to Borneo, Jawa, Lesser Sunda Is., Malaya, Sulawesi, Sumatra. (3)

Constituents
- Study of rot bark yielded isolated a new xanthone, sumatranaxanthone A. (1)
- Study of leaves, twigs and stem bark yielded six new xanthones, cratoxyarborenones A-F, along with known compound, vismione B, and two novel anthraquinobenzophenones, cratoxyarborequinones A and B, and known compounds, 2,4,6-trihydroxybenzophenone 4-O-geranyl ether and delta-tocotrienol. (2)

Properties
- Stems produce a whitish-yellowish latex.
- Considered galactagogue and abortifacient.
- Studies have suggested  amtioxidant, cytotoxic, antibacterial, antimalarial, anti-amoebic, aphrodisiac properties.

Parts used
Roots, leaves, bark.

Uses
Edibility
- In the ethnobotany, stems reported used as energy drink or aphrodisiac. (see study below)   (9)
Folkloric
- In the Philippines, a decoction of roots, leaves, and bark is given to women after childbirth as protective medicine.
- The Subanen tribe of Zamboanga del Sur apply young leaves on the forehead as anticonvulsant. (10)
- Crushed leaves placed on forehead and breast for colds.
- Internally, decoction of bark and leaves used as abortifacient.
- Decoction of bark used as galactagogue.
- Young leaves are chewed for relief of coughs.
- In Indonesia, used for infections, dysentery, cold and toothache. (1)
Others
- Wood: Wood used for interior construction, furniture, carving, and implements. 
- Fuel: Wood used for fuel; also makes a good charcoal.

Studies
• Sumatraxanthone / Antioxidant / Rot Bark: Study of rot bark isolated a new xanthone, sumatranaxanthone A. Preliminary study showed antioxidative activity with ascorbic acid as standard.   (1)
• Xanthones and Vismione B: Study of leaves, twigs, and stem bark yielded six new xanthones, cratoxyarborenones A-F, along with known compound, vismione B, active constituents by fractionation using KB human cancer cell line cytotoxicity assay. (2)
• Cytotoxic Prenylated Xanthones: Study isolated six new xanthones, cratoxyarborenones A-F from the leaves, twigs, and/or stem bark of C. sumatranum along with known compound, visimone B, active constituents by bioassay-directed fractionation using the KB human cancer cell line cytotoxicity assay. (see constituents above) (5)
• Antimalarial / Stem Bark: Study evaluated the antimalarial activities of C. sumatranum stem bark extracts and fractions. The extracts were tested against Plasmodium flaciparum 3D7 by lactate dehydrogenase (LDH) assay. The dichloromethane extract (BP14-SB-D) showed strongest inhibition of parasite growth with IC50 of 0.44 µg/mL and moderate cytotoxicity with CC50 of 29.09 µg/mL. LDH assay of 12 fractions showed F6 with strongest parasite growth inhibition (IC50 0.19 µg/ml). TLC showed BP14-SB-D contained xanthone. Results showed the DCM extract of stem bark and F6 have potential as antimalarial substance. (6)
• Benzophenones and Xanthone / Antibacterial / Antioxidant / Roots and Twigs: Study of roots and twigs isolated two new benzophenones (1 and 2) and four new xanthones (4-6 and 17) along with 24 known compounds (3, 7-16 and 18-30). Compounds 5 and 26 showed antibacterial activity against Micrococcus luteus and Staphylococcus epidermis with MICs ranging from 4 to 8 µg/mL, while compounds 7, 20, and 26 showed selective activities against S. aureus, S. typhimurium, and P. aeruginosa. Compounds 11 and 21 showed potent activity against DPPH with IC50 of 7.0 ± 1.0 and 6.0 ± 0.2 µM, respectively. (7)
• Anti-Amebic / Xanthones / Stem Bark: Study evaluated the anti-amoeba activity of C. sumatranum by an in vitro cell-based assay against Entamoeba histolytica and enzymatic assay on NAD kinase. Bioassay-guided analysis isolated two known compounds from cage xanthone groups, namely cochichinoxanthone (1) and cochinchinone D (2). Compound 1 showed higher level of anti-amebic activity in both cell-based and enzymatic assay, with IC50s of 4.57 and 12.17 µg/mL, respectively, compared to Compound 2 with IC50s of 5.19 and 12.60 µg/mL. Results showed potential for development as anti-amebic medicine against E. histolytica. (8)
• Aphrodisiac / Xanthones / Stems: Study evaluated the in vitro aphrodisiac activity of CS extract using isolated rat corpus cavernosum. The CSS ethanol extract induced a vasodilatory response on rat Corpus carvernosum blood vessels, which increased with increasing concentration. Results suggest the aphrodisiac activity is directly related to the vasodilation of blood vessels on rat cavernosum. (9)

Availability
Wild-crafted.

SOURCES

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