Long Yan Rou
StarDimocarpus longan Lour.
Traditionally used for
- Sleep
- Mood & calm
- Heart & circulation
- Energy & fatigue
Cautions & contraindications
- Diabetes
☯ TCM Properties
Tonifies the Heart and Spleen; Nourishes Blood; Calms the Spirit; Tonifies Qi
Traditional Chinese Uses
Long Yan Rou (longan fruit) is a sweet, warm herb that nourishes Blood and calms the Spirit. It is used for patterns of Heart and Spleen Blood deficiency presenting with insomnia, anxious dreams, palpitations, forgetfulness, and chronic fatigue. Because it functions simultaneously as a food and a tonic medicine, it is one of the most approachable and accessible herbs in Chinese medicine for restoring Blood and settling the mind after prolonged stress or overwork.
Western Herbalism Properties
Used In Formulas (4)
Relationships
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Botanical Description
Dimocarpus longan is an evergreen tropical and subtropical tree in the family Sapindaceae, native to southern China, northern Indochina, and southern Asia, and now widely cultivated for its edible fruit throughout Southeast Asia, southern India, and Florida. Mature trees reach 10-20 m in height with a dense, broad, rounded crown and dark, rough, corky bark. The alternate, pinnately compound leaves have 4-10 elliptic to oblong-lanceolate leaflets 6-15 cm long, glossy dark green above and paler beneath. Small yellowish-white, fragrant, five-petalled flowers are borne in large terminal and axillary panicles in spring, attracting bees. The fruit is a globose drupe 1.5-2.5 cm across, with a thin, leathery, yellowish-brown shell that surrounds a single shiny black seed coated by a translucent, sweet, juicy, white edible aril, the longan. The dried, pulpy aril (Long Yan Rou) is the medicinal and culinary part used as a tonic.
Active Constituents
Longan pulp polysaccharides
Water-soluble heteropolysaccharideConcentration: not standardised for the crude drug; the isolated fraction characterised from pulp has a backbone of alternating alpha-D-glucopyranosyl and alpha-D-galactopyranosyluronic acid residues with polysaccharide side chains
The best-characterised bioactive fraction of the aril and the one carrying the immunological activity reported for this drug. In mice, a polysaccharide-protein complex from the pulp raised antibody production, concanavalin A-induced splenocyte proliferation, macrophage phagocytosis, natural killer cell cytotoxicity, and interferon-gamma and interleukin-2 secretion. All of this is animal and cell work; it does not establish an immune effect at a 9 to 15 g dose in a person.
Gallic acid
Phenolic acidConcentration: one of the three dominant phenolics of longan pulp alongside corilagin and ellagic acid; content varies widely with cultivar and drying method and is not standardised
Contributes most of the measurable antioxidant capacity of the aril in vitro. It is also the marker most affected by processing, so the phenolic profile of commercial dried Long Yan Rou differs from that of fresh fruit.
Corilagin
EllagitanninConcentration: reported as one of the major polyphenols of the pulp; not standardised in the crude drug
An ellagitannin, and a compound with well-documented anti-inflammatory activity in its own right in other plants. Its presence, together with ellagic acid, makes longan aril a tannin-containing sweet drug rather than a purely nutritive one.
Ellagic acid
Polyphenol (ellagitannin hydrolysis product)Concentration: one of the three major pulp phenolics reported by HPLC alongside gallic acid and corilagin
Arises partly from hydrolysis of corilagin and other ellagitannins. Together with gallic acid it accounts for most of the radical-scavenging activity attributed to the aril.
Sucrose, glucose and fructose
Mono- and disaccharidesConcentration: the overwhelming bulk of the dried aril by dry weight; the drug is a concentrated sugar matrix, which is why it is palatable enough to be eaten as a food
Clinically the most consequential constituents of this drug for most patients, and the reason the classical Spleen-and-Heart tonic indication should not be extended to poorly controlled diabetes without adjusting for carbohydrate load. The sugar content is also why sulfur fumigation and mould are recurring quality problems in dried longan.
Hypoglycin A
Non-proteinogenic amino acid (cyclopropyl amino acid)Concentration: measurable in 3 of 5 longan arils tested, at 1.08 to 2.45 micrograms per gram; methylenecyclopropylglycine (MCPG) was below the lower reporting limit in all five. Litchi arils in the same study ran far higher, 1.00 to 21.2 micrograms per gram of hypoglycin A and 1.35 to 9.73 micrograms per gram of MCPG
This matters because the drug in this record is the aril, the exact tissue in which hypoglycin A was first reported for longan. Hypoglycin A and MCPG are metabolised to acyl-CoA species that inhibit fatty acid beta-oxidation, and they are the agents of the hypoglycaemic encephalopathy outbreaks in undernourished children linked to unripe litchi. Longan's measured levels are one to two orders of magnitude below litchi's, so this is a compositional fact to be aware of rather than a hazard of ordinary dosing; the risk case is a fasting, undernourished child eating large quantities of fruit, not an adult taking a decoction.
⚠ Drug Interactions
Long Yan Hua (Flos Longanae, the longan flower)
Both drugs come from Dimocarpus longan Lour. and both carry the pinyin element Long Yan, but they are different organs of the plant: this record is the aril, the fleshy sarcotesta surrounding the seed (Arillus Longan), while Flos Longanae is the inflorescence. The aril is the sweet blood-and-Heart tonic of the classical literature and is the tissue in which the polysaccharide, phenolic and hypoglycin A data above were measured. None of that phytochemistry transfers to the flower, which has no comparable literature. Sharing a binomial is not sharing a drug.
Clinical note: Check the Latin pharmaceutical name, not the pinyin, when ordering. Arillus Longan is Long Yan Rou or Gui Yuan Rou; Flos Longanae is Long Yan Hua. Do not substitute one for the other or transfer dosing between them.
Insulin, sulfonylureas and other glucose-lowering drugs
Dried longan aril is predominantly sugar by dry weight, and the usual 9 to 15 g dose is a real carbohydrate quantity taken daily, often in sweetened decoction or as a snack. There is no pharmacokinetic interaction with any hypoglycaemic agent; the issue is purely that the drug is a concentrated sugar being added to a diet that the patient's insulin or sulfonylurea dose was titrated against. Separately, the aril contains trace hypoglycin A, whose metabolites inhibit fatty acid beta-oxidation and impair gluconeogenesis, but at 1 to 2 micrograms per gram this is not expected to be clinically relevant at any realistic dose in an adequately fed adult.
Clinical note: Count Long Yan Rou as carbohydrate when prescribing it to a patient on insulin or a sulfonylurea, and advise glucose monitoring when starting a course. Avoid using it as the sweetening element of a formula in poorly controlled diabetes.
Sulfur-fumigated Long Yan Rou (residual sulfur dioxide and sulfites)
Sulfur fumigation is routinely applied to sweet, moisture-retaining dried herbs and fruits to lighten colour and suppress mould, and dried longan is one of the commodities on which it is used. Fumigation leaves sulfur dioxide and sulfite residues and also chemically transforms constituents, so a fumigated lot is not the same material as an unfumigated one. Regional standards cap sulfur dioxide in most Chinese herbal commodities at around 150 ppm, with a higher limit for a small number of items. Sulfite-sensitive asthmatic patients are the group at practical risk.
Clinical note: Prefer sulfur-free (wu liu) certified lots, particularly for asthmatic patients and for children. An unnaturally pale, glossy aril with a faint acrid smell is the visual signal of fumigation. This is a supply-chain decision rather than a dose adjustment.
Immunosuppressants (ciclosporin, tacrolimus, azathioprine, mycophenolate)
Longan pulp polysaccharide and polysaccharide-protein complex are immunostimulant in mice, raising antibody titres, splenocyte proliferation, macrophage phagocytosis, natural killer activity and interferon-gamma and interleukin-2 secretion. Whether any of this survives oral dosing of the whole drug in a human is unknown, and polysaccharides of this size are poorly absorbed. The concern is raised on mechanism alone and applies to concentrated polysaccharide extracts far more than to the food-grade aril.
Clinical note: No restriction on culinary use. Exercise judgement before prescribing concentrated longan polysaccharide extracts to a transplant recipient or a patient on immunosuppression for autoimmune disease, and prefer the whole drug at food-level doses.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 9–15 g | Daily | — | — | 中国药典 2020 【用法与用量】9～15g。 【性味与归经】甘，温。归心、脾经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Evidence Tier
Moderate evidence · 4 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
3
2 verified · 1 unverified
Show 3 studies
- Immunomodulatory Activity of Polysaccharide-Protein Complex of Longan (Dimocarpus longan Lour.) Pulp
- Structure and Antitumor and Immunomodulatory Activities of a Water-Soluble Polysaccharide from Dimocarpus longan Pulp
- Longan (Dimocarpus longan Lour.) inhibits lipopolysaccharide-stimulated nitric oxide production in macrophages by suppressing NF-κB and AP-1 signaling pathways
Other / unclassified
1
0 verified · 1 unverified
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Immunomodulatory Activity of Polysaccharide-Protein Complex of Longan (Dimocarpus longan Lour.) Pulp
A polysaccharide-protein complex isolated from longan pulp was given to mice and raised antibody production, concanavalin A-induced splenocyte proliferation, macrophage phagocytosis, natural killer cell cytotoxicity, and interferon-gamma and interleukin-2 secretion. This is the primary source for the immunomodulatory claim attached to this drug, and it is a mouse study of an isolated fraction rather than of the aril as dispensed.
Structure and Antitumor and Immunomodulatory Activities of a Water-Soluble Polysaccharide from Dimocarpus longan Pulp
Structural characterisation of a water-soluble polysaccharide from longan pulp, giving a backbone of alternating alpha-D-glucopyranosyl and alpha-D-galactopyranosyluronic acid units with polysaccharide side chains, together with antitumor and immunomodulatory assays. It supplies the structural basis for the polysaccharide constituent entry above.
Longan (Dimocarpus longan Lour.) inhibits lipopolysaccharide-stimulated nitric oxide production in macrophages by suppressing NF-κB and AP-1 signaling pathways
Longan extract suppressed lipopolysaccharide-induced nitric oxide production in cultured macrophages, with the effect traced to inhibition of NF-kappaB and AP-1 signalling. Note that this is an anti-inflammatory readout in the same tissue that the polysaccharide studies report as immunostimulant; the two lines of evidence concern different fractions and are not directly reconcilable, which is a reason to be cautious about asserting any single immune direction for this drug.
Quantification of Toxins in Soapberry (Sapindaceae) Arils: Hypoglycin A and Methylenecyclopropylglycine
The first method to quantify hypoglycin A and methylenecyclopropylglycine simultaneously in soapberry fruit aril, and the first report of hypoglycin A in longan, litchi and mamoncillo arils. Three of five longan arils contained measurable hypoglycin A at 1.08 to 2.45 micrograms per gram and all five were below the reporting limit for MCPG, whereas litchi arils ran 1.00 to 21.2 micrograms per gram hypoglycin A and 1.35 to 9.73 micrograms per gram MCPG. Directly relevant because the drug in this record is the aril, and useful for putting the litchi encephalopathy literature in proportion rather than importing it wholesale to longan.
⚠ Safety & Contraindications
- Diabetes
Contraindications
Its use is prohibited in patients with exuberant dampness and abdominal flatulence, or fluid retention, phlegm and fire.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 361–364.
Historical Texts
Shen Nong Ben Cao Jing
Han dynastyReferences
- Zhang X; Guo S; Ho CT; Bai N. Phytochemical constituents and biological activities of longan (Dimocarpus longan Lour.) fruit: a review . Food Science and Human Wellness (2020) [DOI]
- Duan SM; Xu J; Bai YJ; Ding Y; Kong M; Liu HH; Li XY; Zhang QS; Chen HB; Liu LF; Li SL. Sulfur dioxide residue in sulfur-fumigated edible herbs: The fewer, the safer? . Food Chemistry (2016) [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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