Hinds' staff vine

Xạ đen is a woody climbing vine 3–10 m long; young stems are green, turning grey-brown when woody. Leaves are alternate, ovate, finely toothed, with about 7 pairs of lateral veins. Inflorescences arise in leaf axils with 3–5 small white, 5-merous flowers; the capsule is globose, about 8–12 mm across, splitting into 3 valves at maturity, seeds covered by a red aril. The plant prefers warm, humid climates and climbs over bushes and trees at forest edges, stream banks and low hills.

According to Plants of the World Online (Kew), the species is native to Indochina; in Vietnam it is recorded in Ninh Bình, Quảng Bình, Quảng Trị and Thừa Thiên Huế provinces, and it also occurs in China (Hainan). Xạ đen is cultivated and grows wild at forest fringes; stems and leaves are harvested year-round, dried and brewed as a daily drink.

Leaves and stems contain triterpenoids (α-amyrin, β-amyrin), rosmarinic acid, flavonoids and the characteristic diphenylpropanes hindsiipropanes A and B (Hu et al., 2014). Luo et al. (2018) isolated terpenoids with activity against respiratory syncytial virus (RSV); Viet et al. (2019) profiled constituents and antioxidant activity by GC-MS/ESI-MS; Viet et al. (2021) quantified α-/β-amyrin in the leaves.

In Vietnamese folk practice, xạ đen is decocted as a drink to support tumour care, detoxify the liver, relieve joint and muscle pain and treat boils and sores. Pham et al. (Biomed Res Int, 2020) reported that leaf flavonoids show antioxidant and in vitro antitumour activity; Ho et al. (Sci Rep, 2024) continued the biological evaluation of the extracts. Acute and semi-chronic toxicity studies in animals (Pham T. Loan et al., 2020) indicated good tolerance at the tested doses.

Xạ đen is widely marketed in Vietnam as herbal tea and dietary supplements; available evidence is mainly from preclinical studies, with no full clinical trials yet, so cancer patients should use it only as an adjunct to specialist treatment. The species has not been assessed by IUCN (Not Evaluated); heavy wild harvesting calls for cultivation and sustainable collection. Note: in some regions the name 'xạ đen' is also applied to other species (e.g. the genus Ehretia, Boraginaceae), so Celastrus hindsii should be properly identified when sourcing the raw material.