Sophora tonkinensis

Sophora tonkinensis, known in Chinese medicine as “Suan Zhi,” has a long history of use as an inhalation and oral remedy. According to the Chinese Pharmacopoeia (2020), the dried root is boiled to make a decoction that is taken for cough, asthma, and as a mild diuretic. In Vietnam, Nguyen et al. (2018) report that the root is also used in a poultice to treat superficial wounds and skin inflammation, while a leaf infusion is drunk to relieve stomach upset. A 2019 ethnobotanical survey of the Hmong people in northern Vietnam documented that the Hmong prepare a decoction of the root for respiratory ailments and apply a macerated leaf paste to bruises, citing the same therapeutic goals as the Chinese and Vietnamese traditions.

A simple, safe preparation is a root decoction. Take 10 g of dried Sophora tonkinensis root and add it to 200 ml of boiling water. Simmer gently for 30 minutes, then strain the liquid. Drink the clear tea in two 100 ml servings, preferably in the morning. This dose is well tolerated in most adults; however, pregnant women and individuals with a history of gastrointestinal sensitivity should avoid it, as higher doses can cause mild stomach upset. The decoction can be stored in the refrigerator for up to three days.

The therapeutic effects of Sophora tonkinensis are largely attributed to its alkaloid profile. The root contains matrine, oxymatrine, and sophoridine, all of which have been isolated and shown to possess anti‑inflammatory, antiviral, and anti‑tumor activities in laboratory studies. These compounds are consistent with the plant’s traditional use for respiratory inflammation and wound healing, providing a biochemical basis for the observed benefits.

Modern research continues to explore Sophora tonkinensis for its medicinal potential. Recent in‑vitro studies demonstrate that extracts rich in matrine and oxymatrine inhibit inflammatory cytokine production, while animal models confirm anti‑cancer effects against several tumor types. Commercially, standardized root extracts are available as dietary supplements in Asia, and the plant remains an active component in many traditional formulations used by Chinese, Vietnamese, and Hmong practitioners today.

Common products:
Root wood is the principal traded material of Sophora tonkinensis. Cuttings and chips are supplied to export processors for dye production, especially to Japan for natural dyeing of textiles, and to the United States for botanical color testing by craft and heritage textile researchers.

Industrial and craft applications:
The plant is used as a source of natural brown dyes. The dried root wood yields water-soluble colorants that produce warm brown to orange-brown shades on protein fibers (wool and silk) when used with common mordants such as aluminum, iron, and copper. Plant-part/form: root wood chips, roots, or bark; product type: natural brown dyes for textiles, natural brown inks and pigments for craft use.

Food and beverages (non-medicinal):
No non-medicinal food or beverage uses are documented for this species.

Colorants and tanning:
Root wood and bark contain flavonoids, isoflavonoids, and alkaloids. Extracts yield brown hues used for dyeing and as a basis for botanical inks. Dyeing is applied to wool, silk, and cotton (with mordanting) in craft and heritage contexts; the approach follows standard plant-dye protocols that specify mordant type, liquor ratio, and temperature for color reproducibility. Product type: natural brown dyes; plant-part/form: roots and bark; application class: brown dye for textiles, natural brown inks and pigments. No documented use as a tanning agent.

Wood and fiber:
The wood is small-diameter and used locally as fuel and for simple craft items; fiber use is not reported.

Fragrance and cosmetics:
No fragrance, perfume, or cosmetic uses are documented for this species.

Properties relevant to use:
The dye performance is attributed to flavonoids such as sophoricoside and kushenol I, and to quinolizidine alkaloids. Reported tinctorial strength is moderate and reddish-brown to golden-brown depending on mordant; solubility is high in hot water, enabling direct extract use without additional fixation.

Standards and regulation:
Dye exports are managed under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) due to conservation concerns, and shipments must carry CITES permits. In export markets, colorants are subject to general consumer product safety laws (e.g., consumer protection statutes) and to national restrictions on plant-derived colorants in food and cosmetics where applicable; no plant-specific standards are cited.

Sustainability and sourcing:
The species is harvested from wild populations in karst habitats of Guangxi, Guizhou, and northern Vietnam. Supply is constrained by habitat fragmentation, slow growth, and overharvest for the dye trade. There are no widely accepted domestic or international standards for S. tonkinensis dye quality or sustainability. Sustainable practices focus on selective harvesting, habitat protection in karst reserves, and the development of cultivation or ex situ propagation to reduce pressure on wild stocks.

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