Long Kui
StarSolanum nigrum L.
☯ TCM Properties
Clears Heat and Resolves Toxicity; Invigorates Blood and Reduces Swelling; Promotes Urination and Reduces Edema; Cools the Blood and Stops Bleeding; Dissipates Nodules and Softens Hardness
Traditional Chinese Uses
Long Kui (black nightshade herb) is a cold, bitter herb used in Chinese medicine to clear Heat toxin, promote Blood circulation, and reduce swelling. It is applied for carbuncles, boils, inflammatory skin conditions, and sore throat from Heat toxin, as well as for certain types of abdominal masses. Due to the presence of solanine alkaloids, it has mild toxicity and requires careful professional dosing. Topically it is used in poultices for inflammatory lesions.
Botanical Description
Solanum nigrum, the black nightshade, is a cosmopolitan annual or short-lived perennial herb in the Solanaceae, growing 30-90 cm tall in disturbed ground, gardens, and field margins worldwide. The much-branched stems are erect to ascending, slightly angled, green to purplish, sparsely hairy. Alternate leaves are ovate to ovate-lanceolate, 4-9 cm long, with entire to sinuate-toothed margins, dull green and softly hairy on both surfaces. Small white five-petalled star-shaped flowers about 5-8 mm across with prominent yellow anther cones are borne in small umbel-like extra-axillary cymes of 3-10 flowers. Fruits are small globose berries 6-10 mm across that ripen from green to dull black, containing many flat seeds. The dried whole flowering and fruiting aerial plant is the medicinal Long Kui; unripe parts are toxic due to solanine.
Active Constituents
Solasonine
Steroidal glycoalkaloidConcentration: A principal glycoalkaloid of the aerial parts and unripe berries
A cytotoxic steroidal glycoalkaloid that induces apoptosis and inhibits proliferation in tumour cell models; part of the toxic alkaloid fraction responsible for both anticancer activity and the plant's potential toxicity.
Solamargine
Steroidal glycoalkaloidConcentration: Co-major glycoalkaloid with solasonine
Pro-apoptotic and anti-proliferative glycoalkaloid shown to trigger tumour-cell apoptosis and suppress angiogenesis in laboratory studies; a key contributor to the herb's reputed anti-toxic, swelling-reducing actions.
Solanine / solamargine aglycone (solasodine)
Steroidal (glyco)alkaloidsConcentration: Variable; higher in unripe green berries and mature foliage
Cholinesterase-inhibiting steroidal alkaloids that account for the plant's toxicity in overdose (gastrointestinal and neurological symptoms). Their content underlies the strict dosing caution for this cold, toxin-resolving herb.
Solanigrosides / steroidal saponins
Steroidal saponinsConcentration: Present in the aerial parts
Saponin constituents contributing anti-inflammatory and cytotoxic activity reported in pharmacological studies of the herb.
Polysaccharides
PolysaccharidesConcentration: Water-extractable fraction of the aerial parts
Immunomodulatory and anti-tumour polysaccharides that have shown thymus-protective and tumour-growth-inhibitory effects in tumour-bearing mice.
Polyphenols (gallic acid, catechin, caffeic acid, rutin, epicatechin)
Phenolic acids and flavonoidsConcentration: Present in leaf/aerial extracts
Antioxidant phenolics contributing to the hepatoprotective, anti-inflammatory and free-radical-scavenging activity documented for the plant.
⚠ Drug Interactions
Cholinesterase inhibitors / anticholinergic drugs and neuromuscular blockers
The solanine-type glycoalkaloids in Solanum nigrum inhibit acetylcholinesterase and butyrylcholinesterase. Concurrent use with cholinesterase inhibitors, anticholinergics or drugs metabolised by plasma cholinesterase could theoretically alter their effect, and may prolong the action of ester-type agents. No controlled human data exist.
Clinical note: Because of variable glycoalkaloid content and inherent toxicity, avoid combining medicinal doses with cholinergic/anticholinergic drugs; inform anaesthetists of use.
CNS depressants and sedatives
Glycoalkaloid toxicity can produce drowsiness and neurological depression; large or toxic doses could theoretically add to the effects of CNS depressants. This reflects toxicity rather than a documented therapeutic-dose interaction.
Clinical note: Use only under professional guidance and within recommended dosing; overdose is toxic irrespective of concomitant drugs.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 6-15g | Daily | — | — | — |
Preparation Methods
Decoction (internal)
Parts: Dried aerial parts (Herba Solani Nigri)
The dried whole herb (commonly ~15–30 g) is decocted to clear heat, resolve toxicity, reduce swelling and promote urination. Dosing must be conservative because of the glycoalkaloid content; not for use in pregnancy or in the debilitated.
External poultice / wash
Parts: Fresh aerial parts / leaves
Crushed fresh herb is applied topically or as a strong decoction wash to reduce localized swelling, sores and toxic-heat skin lesions.
Fresh juice (traditional, cautious use)
Parts: Fresh aerial parts
Expressed juice of the fresh herb has been used traditionally for heat-toxin swellings; because glycoalkaloid content varies, this is a high-caution preparation used only in small, controlled amounts.
Historical Texts
Xinxiu Bencao (Tang Materia Medica / Newly Revised Materia Medica)
Tang dynasty, 659 CEBencao Gangmu (Compendium of Materia Medica), Li Shizhen
Ming dynasty, 1578References
- Zhao Z, et al.. Main chemical constituents and mechanism of anti-tumor action of Solanum nigrum L. . Cancer Medicine (2024) [DOI]
- Lin HM, Tseng HC, Wang CJ, et al.. Induction of Autophagy and Apoptosis by the Extract of Solanum nigrum Linn in HepG2 Cells . Journal of Agricultural and Food Chemistry (2007) [DOI]
- Son YO, Kim J, Lim JC, et al.. Solanum nigrum L. Extract Inhibits 2-Acetylaminofluorene-Induced Hepatocarcinogenesis through Overexpression of Glutathione S-Transferase and Antioxidant Enzymes . Journal of Agricultural and Food Chemistry (2009) [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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