Sterculia setigera
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Sterculia setigera Common Names: Sterculia gum, African tragacanth,
karaya gum tree Scientific
Classification Kingdom: Plantae Clade: Tracheophytes Clade: Angiosperms Order: Malvales Family: Malvaceae Genus: Sterculia Species: S. setigera Binomial Name: Sterculia setigera Delile Synonyms: Sterculia tomentosa Guill. & Perr. Morphological Description Sterculia setigera, known as the African tragacanth or karaya gum tree, is a
deciduous tree typically growing to heights of 15–30 meters, with some specimens
reaching up to 40 meters in favorable conditions (Kew Science, 2024). The trunk
features a smooth, grayish-purple bark when young, which peels off in thin,
irregular scales with age, revealing a fibrous, brownish-red inner bark and
exuding a white gum (Tropical Plants Database, 2024). Leaves are large, simple,
and alternate, with 5–7 palmate lobes, measuring 10–25 cm in diameter, and
covered with stellate hairs on the underside, giving a tomentose texture
(Ahlidja et al., 2024). The unisexual flowers, 1–2 cm long, are borne in short
panicles, displaying a reddish-yellow to yellow-brown perianth with a velvety
appearance. The fruit is a woody, ovoid capsule, 5–10 cm long, splitting open
to release 5–10 black seeds, each 1–2 cm long, embedded in irritating hairs
(Burkill, 2000). Distribution and Habitat Native to tropical
Africa, Sterculia setigera is widespread across the Sahel-Sudan and Guinea savannah
zones, from Senegal eastward to Sudan, Ethiopia, and Somalia, and south to
Angola and East Africa (Kew Science, 2024). It thrives in seasonally dry
tropical biomes, favoring woodlands, savannas, and rocky hillsides at
elevations up to 1,500 meters (Tropical Plants Database, 2024). The tree
prefers shallow, gritty soils rich in gneiss or schist, with annual rainfall of
500–1,200 mm and temperatures of 20–35°C, showcasing its resilience in
semi-arid environments. Ethnopharmacology Sterculia setigera medicinal properties include anti-inflammatory, antimicrobial,
antioxidant, analgesic, antidiarrheal, and anti-ulcer activities. The gum
exudate (gum karaya) is particularly known for its demulcent, laxative, and
emollient properties, and is traditionally used to soothe respiratory tract
irritations, digestive problems, and constipation. The bark decoction is often
used in traditional African medicine to treat fevers, diarrhea, and skin
infections, while leaf extracts have shown activity against bacterial and
fungal infections in laboratory studies. Phytochemical studies have identified
compounds such as tannins, saponins, flavonoids, and mucilage, which contribute
to its pharmacological effects. While Sterculia setigera has a long-standing
role in folk medicine, scientific validation through clinical studies is still
limited, and caution is advised with its use, especially regarding dosage and
purity of the gum, as excessive intake may cause digestive irritation. · Skin Ailments and Infections: In Togo, stem bark decoctions treat wounds
and abscesses. · Fever and Antipyretic: In Senegal, leaf infusions manage fever. · Diarrhea and Gastrointestinal Issues: In Burkina Faso, bark is used for diarrhea. · Antioxidant and Anti-inflammatory: In Nigeria, leaf extracts treat
inflammation; phenolic content showed DPPH scavenging activity (IC50 34.64
gET/100gDM), reducing oxidative stress in diabetic rats (Ojo et al., 2021). These properties align
with its phytochemical profile, including galacturonic acid and rhamnose in gum
karaya, enhancing its therapeutic versatility (Ahlidja et al., 2024). ⚠ Toxicity Profile: A study assessing the methanol stem extract
reported an oral median lethal dose (LD₅₀) of ≥ 5111 mg/kg in animal models,
suggesting a relatively low acute toxicity . However, this finding pertains to
the stem bark, and extrapolation to the leaf extract should be approached with
caution (Ukwuani-Kwaja, et al., 2021). The irritating hairs on fruit capsules
can cause skin and respiratory irritation if mishandled (Burkill, 2000).
Traditional use appears safe when moderated. Additional Uses · Nutritional Value: Seeds, rich in oil (26%) and protein
(21.4%), are eaten roasted by nomadic groups in Northern Nigeria, providing
45.27% carbohydrates (Adelakun et al., 2014). · Gum Karaya Production: The tree yields gum karaya, a
water-soluble polysaccharide exported from Senegal, used as a thickener in
foods, a laxative, and a pharmaceutical binder · Ecological and Economic Role: It supports rural economies through gum
harvesting and provides shade and soil stabilization in savannah ecosystems References External Links More Pictures
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| Compounds of Sterculia setigera | |
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