An Xi Xiang
StarStyrax tonkinensis (Pierre) Craib ex Hart.
Traditionally used for
- Cough & breathing
- Digestion
☯ TCM Properties
Opens the Orifices and Revives Consciousness; Dispels Turbidity and Filth; Invigorates Blood and Moves Qi; Alleviates Pain
Traditional Chinese Uses
An Xi Xiang (benzoin resin) is a warm, aromatic substance used to revive consciousness and open the orifices in cases of sudden collapse, coma, or loss of consciousness from Phlegm obstruction or cold invasion. It also warms the Stomach and chest to relieve cold pain in the epigastric region and disperses Blood stasis from traumatic injury. It functions as an aromatic penetrant that restores the free flow of Qi and Blood in emergency situations.
Western Herbalism Properties
Relationships
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Botanical Description
Styrax tonkinensis is a small to medium evergreen tree in the family Styracaceae, native to montane forests of southern China (Yunnan, Guangxi), Laos, Vietnam, and northern Thailand, growing 10–20 m tall with a slender trunk, smooth grey bark, and alternate ovate-elliptic leaves 5–10 cm long with whitish stellate-tomentose undersurfaces. Pendulous panicles of small fragrant white five-lobed flowers appear in spring, followed by globose drupes about 1 cm across with stellate hairs. The medicinal substance, Siam benzoin, is the balsamic resin obtained by tapping the trunk: V-shaped or triangular incisions are made through the bark in the rainy season, and the milky exudate hardens on exposure to air into yellow-brown to reddish-brown irregular tears and lumps with a vanilla-like aroma. In traditional Chinese medicine An Xi Xiang is acrid, bitter, and neutral, opening the orifices and reviving the spirit in sudden loss of consciousness from cold-phlegm or stroke patterns, and invigorating the blood to relieve chest and abdominal pain from blood stasis.
Active Constituents
Coniferyl benzoate
Aromatic ester (phenylpropanoid benzoate)Concentration: the principal constituent of Siam benzoin, reported at roughly 60-80% of the resin
The dominant ester of Siam benzoin, the resin this record describes, and the chemical marker that separates it from Sumatra benzoin and from storax. It is also a recognised contact sensitiser and one of the cross-reacting substances in balsam of Peru allergy.
Benzoic acid
Aromatic carboxylic acidConcentration: roughly 10% of the resin, present free in addition to the esterified fraction
Free benzoic acid gives the resin its antiseptic and mildly antifungal character and contributes to the mucous-membrane irritancy of benzoin vapour. Siam benzoin is characterised by benzoic acid with essentially no cinnamic acid, the reverse of storax.
Siaresinolic acid (3-beta,19-alpha-dihydroxyolean-12-en-28-oic acid)
Oleanane triterpenoid acidConcentration: roughly 6% of the resin
The characteristic triterpene acid of Siam benzoin, used analytically to confirm Styrax tonkinensis origin. Related oxidised forms, 3-oxo-siaresinolic acid and the sumaresinolic acid pair, occur alongside it.
Stybenpropol A
Phenylpropane derivative (C24H20O5)Concentration: a minor isolate; no content figure established for commercial resin
A compound first described from benzoinum resin of this species. In human umbilical vein endothelial cells challenged with TNF-alpha it lowered sICAM-1, sVCAM-1, IL-8 and IL-1 beta, increased nitric oxide release and suppressed apoptosis via NF-kappaB and caspase-9 signalling. The work is entirely in vitro.
Vanillin
Phenolic aldehydeConcentration: traces
Present only in traces but responsible for much of the sweet vanilla note that identifies benzoin organoleptically.
Benzyl benzoate and benzyl cinnamate
Aromatic estersConcentration: minor esters within the more than twenty aromatic esters of the resin
Minor aromatic esters of the resin. Benzyl cinnamate in particular is one of the shared constituents behind cross-reactivity between benzoin, storax, balsam of Tolu and balsam of Peru in fragrance-allergic patients.
Coniferyl alcohol (lubanol)
Phenylpropanoid alcoholConcentration: small amounts, free in the resin
The free alcohol corresponding to the resin's principal ester, present in small quantity in Siam benzoin.
⚠ Drug Interactions
Topical and inhaled preparations in patients patch-test positive to balsam of Peru (Myroxylon pereirae) or fragrance mix
Benzoin shares coniferyl benzoate, benzyl cinnamate and related esters with balsam of Peru. In de Groot's review of patch-test data, patients reacting to balsam of Peru co-reacted to Siam benzoin in 80% of cases and to compound benzoin tincture in 90%, with Sumatra benzoin at 43%. Balsam of Peru itself is positive in about half of all fragrance-allergic patients. This is a genuine allergological cross-reaction, not a theoretical one.
Clinical note: Ask about fragrance and balsam of Peru allergy before prescribing An Xi Xiang topically, in a plaster, or as a steam inhalation. A documented balsam of Peru positive is a reason to avoid benzoin-containing external preparations, including compound benzoin tincture used as a dressing adhesive.
Benzoin resin from Styrax japonicus or contaminated with Aquilaria sinensis, Dimocarpus longan, Acronychia pedunculata, Glycine, Ageratum conyzoides or Musa acuminata
Feng and colleagues applied molecular diagnostics to commercial benzoin and found the trade split between Styrax tonkinensis (16 of 30 samples) and Styrax japonicus (14 of 30). About 29.6% of samples additionally carried plant tissue from unrelated genera, which the authors attributed to unstandardised harvesting and transport in North Sumatra. Benzoin is a semipetrified resin, so once it is in the pot there is nothing morphological left to check.
Clinical note: Treat botanical origin as a supplier question, not something the dispensary can verify by eye. Where the species matters clinically, ask for material with a molecular or chromatographic certificate of origin; the presence of Aquilaria debris in particular means an unrelated and much more expensive drug is in the mix.
Storax / Styrax liquidus (Su He Xiang, from Liquidambar orientalis)
This is a nomenclature hazard rather than a pharmacological one, and it is easy to fall into. The pharmacy names Styrax and Storax denote the liquid balsam of Liquidambar orientalis, which is Su He Xiang, whereas the botanical genus Styrax yields benzoin, which is An Xi Xiang. The two drugs are chemically distinguishable: benzoin from Styrax tonkinensis is a benzoic-acid resin dominated by coniferyl benzoate, while storax is a cinnamic-acid balsam dominated by cinnamyl cinnamate and 3-phenylpropyl cinnamate. Both sit in the orifice-opening category and both appear in aromatic resuscitation formulas, so a substitution can pass unnoticed at the counter.
Clinical note: Order by both pinyin and binomial. If a supplier's label reads only Styrax, establish whether the intended drug is the solid benzoin resin of Styrax tonkinensis or the viscid balsam of Liquidambar orientalis before dispensing.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction, or powder/pills | 0.6–1.5 g | Daily | — | — | 中国药典 2020 【用法与用量】0.6～1.5g，多入丸散用。 【性味与归经】辛、苦，平。归心、脾经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Both warm aromatic resins open the orifices and expel turbid filth, together reviving consciousness from cold-phlegm obstruction.
Core pair of a classical formula — Su He Xiang Wan, Tai Ping Hui Min He Ji Ju Fang
Evidence Tier
Limited evidence · 2 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
0
Randomized controlled trial
0
Other clinical trial
0
Observational / case report
0
In vitro / animal
2
0 verified · 2 unverified
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Anti-Inflammatory and Anti-Apoptotic Effects of Stybenpropol A on Human Umbilical Vein Endothelial Cells
Stybenpropol A, a phenylpropane derivative newly described from the benzoinum resin of Styrax tonkinensis, protected human umbilical vein endothelial cells against TNF-alpha injury. It reduced sICAM-1, sVCAM-1, IL-8 and IL-1 beta, raised nitric oxide release, and suppressed apoptosis through NF-kappaB and caspase-9 signalling. The authors propose it as a candidate for atherosclerosis, which at this stage is a cell-culture hypothesis only; there is no animal or human work behind it.
Successful identification of the species of the semipetrified amber medicinal resin benzoin using molecular diagnostic technology
Molecular diagnostics applied to commercial benzoin resin, which is semipetrified and therefore impossible to authenticate morphologically. Of thirty samples, sixteen were Styrax tonkinensis and fourteen Styrax japonicus, and about 29.6% carried plant tissue from unrelated genera including Aquilaria sinensis, Dimocarpus longan, Acronychia pedunculata, Glycine, Ageratum conyzoides and Musa acuminata. The authors trace the contamination to unstandardised harvesting and transport at source in North Sumatra.
Historical Texts
Xin Xiu Ben Cao (Newly Revised Materia Medica, Tang Ben Cao)
Tang dynasty, 659 CEReferences
- Pauline Burger, Alexandre Casale, Audrey Kerdudo, Thomas Michel, Rémi Laville, Francis Chagnaud. New insights in the chemical composition of benzoin balsams . Food Chemistry (2016) [DOI]
- Anton C. de Groot. Myroxylon pereirae resin (balsam of Peru) – A critical review of the literature and assessment of the significance of positive patch test reactions and the usefulness of restrictive diets . Contact Dermatitis (2019) [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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