Dimocarpus longan

Dimocarpus Longan (Dragon Eye or Euphoria) is a fruit with limited medicinal use. It does not appear to have a unique composition, but extracts appear quite neuroprotective and may boost cognition.

This page features 32 unique references to scientific papers.

Summary

All Essential Benefits/Effects/Facts & Information

Longan fruits (Dragon Eye and Euphoria Longan have both been used to refer to Longan fruits) have some traditional usage for alleviating cognitive losses and improving memory. Limited evidence so far suggests this may be true, as oral administration of the fruits to rats appears to exhibit potent neuroprotective effects and has twice been implicated in enhancing cognition.

However, the composition of Longan fruits currently is not remarkable. It is a great source of ellagic and gallic acids, which are potent anti-oxidants; these compounds are not inherently linked to improvements in cognition nor are the Procyanidins or catechins found in Longan. There actually does not appear to be a large amount of compounds known to be unique to Longan fruits, which may be discovered in the future. No bioactive is linked to the cognitive protective or memory enhancing properties.

Beyond that, the polysaccharides appear to be able to interact with the immune system and can act in an immunostimulatory manner. At least one study suggests that the potency is comparable to Ganoderic Acid (from Ganoderma lucidum) but this needs to be replicated; it is another promising avenue.

Other interactions of Longan such as interactions with fat mass, skin quality, or the colorectal cancer interactions are currently unremarkable. There is not enough evidence to suggest Longan fruit as a recommended option for anything although it might be a useful functional food to ingest for cognitive purposes.

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Editors' Thoughts on Dimocarpus longan

I have a feeling that there is a currently unknown bioactive in Longan that is a cognitive enhancer. The current main components (ellagic acid and gallic acid; procyanidins) do not inherently do this.

Loganolactone seems to have some structural similarity to the racetam class of molecules (such as Piracetam) and is worth further investigation.


Kurtis Frank

Scientific Research

Table of Contents:

  1. 1 Sources and Composition
    1. 1.1 Sources
    2. 1.2 Composition
  2. 2 Neurology
    1. 2.1 Neuroprotection
    2. 2.2 Memory
  3. 3 Inflammation and Immunology
    1. 3.1 Immunomodulatory
    2. 3.2 Macrophages
  4. 4 Interactions with Fat Mass
    1. 4.1 Mechanisms
  5. 5 Interactions with Physical Performance
    1. 5.1 Mechanisms
  6. 6 Interactions with Organ Systems
    1. 6.1 Kidneys
  7. 7 Interactions with Cancer Metabolism
    1. 7.1 Colorectal
  8. 8 Interactions with Aesthetics
    1. 8.1 Skin
  9. 9 Nutrient-Nutrient Interactions
    1. 9.1 Smilax
  10. 10 Safety and Toxicology

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1Sources and Composition

1.1. Sources

Dimocarpus longan (of the Sapindaceae family) is a tree bearings fruits known as Longan, which are sometimes referred to either Dragon Eyes (with the word Longan being translated into Dragon Eye), Euphoria Longan, or Lumyai (Thai)[3] with a more colloquiol name for Lognan fruits "the little brother of Lychee".[4]

Traditional usage includes as a tonic and for the treatment of forgetfulness, insomnia, or palpitations caused by fright.[5] The seeds and fruits tend to be used in traditional medicine, while the flowers tend to be sold in supermarkets for usage as an aromatic tea.[4]

Traditional usage of Longan fruits is to support memory and cognitive function

1.2. Composition

Some constituents of Longan include:

  • Polyphenolics (6.3-8.09% dry weight) consisting of ellagic acid (25.84g/kg, the range of 8.13-12.65g/kg also being reported in the fruits;[3] up to 156g/kg in the seeds[6]), corilagin (13.31g/kg in one study,[7] but ranging from undetectable to 50.64g/kg[3]), chebulagic acid (13.06g/kg), isomallotinic acid (8.56g/kg), ellagic acid 4-O-α-l-arabinofuranoside (9.93g/kg), geraniin (5.79g/kg), and gallic acid (9.18-23.04g/kg)[7][3][6]

  • Longanlactone (seeds[8])

  • An A type proanthocyanidin trimer (1.63g/kg),[7] an A2 dimer, and Procyanidin B2;[6] with procyanidins consisting of 112.5 +/-5.2mg/g of the flower water extract and 186.7 +/- 7.8mg/g of the ethanolic flower extract[4]

  • (-)-epicatechin (1.13g/kg whole seeds)[7]

  • Methyl brevifolin carboxylate (0.16g/kg)[7]

  • Paltmitic acid and Oleic acid, comprising 35% and 28% of the oils[7]

  • Adenosine and Adenine[9]

  • Uridine and 5-Methyluridine[9]

  • Chlorogenic Acid, ferulic acid, vanillic acid, and gentisic acid[10]

  • Sinapic Acid, syringic acid, and p-coumaric acid[10]

  • Gallic Acid/Glucose combination structures (monogalloyl-glucose, digalloyl-glucose...heptagalloyl-glucose)[6]

  • Quercetin-3-O-Rhamnoside[6]

In regards to the non-caloric bioactives, there does not appear to really be anything unique in Longan that has yet been reported. Overall though, it appears to have a very large amount of antioxidant potential due to the large tannin and procyanidin content

Some polysaccharides (carbohydrate content) include:

  • Longan Pulp Polysaccharide LP3,[11] named subsequently after LP1 and LP2;[12][13] all nitrogen containing polysaccharides

  • Pericarp oligosaccharide rich in Galactose (71.5%), Glucose (24.6%), and Galacturonic acid (3.9%)[14]

Polysaccharides may be involved in the immune system and possibly cancer metabolism aspects

Polyphenolic compounds tend to be highest in the seeds (with higher levels in dry seeds on a weight basis, due to the loss of water), followed the fruits and then by the pulps and rinds which are negligible sources of polyphenolics.[15][3]

Extracts of the flowers can lead to remarkably high concentrations of phenolic compounds (47.7% of total weight of the ethanolic extract; 54.8% of the water extract) and flavonoids (15.6% of the total weight of the ethanolic extract; 13.9% of the water extract) with similar levels of condensed tannins as flavonoids.[4] The methanolic extract results in 50.9% phenolics by weight and 14.2% flavonoids (comparable to the previous two extracts), 11.1% tannins and 15.2% procyanidins; both the ethyl acetate and n-hexane extracts have poor phenolic and flavonoid content.[16]


2Neurology

2.1. Neuroprotection

The polysaccharides of Longan fruits, when intragastically administered to rats at 0.05-0.2g/kg for 14 days prior to cerebral ischemia (MCAO injury), the size of the subsequent infarct is reduced in a dose-dependent manner at 0.05g/kg (8%), 0.1g/kg (13%), and 0.2g/kg (29.5%) outperforming the active control of nimodipine at 0.02g/kg (14%).[17] The edema associated with brain injury was also dose-dependently reduced (almost normalized at the highest dose) and acted to normalize alterations in antioxidative enzymes and inflammatory cytokines, although the root cause of these protective effects was not noted.[17] Protective effects may also exist with the hot water extract of the flowers (125-500mg/kg), where administration of the Parkinson's neurotoxin MPP+- after a week of Longan extract had progressively less effects on dopaminergic neurons on the substantia nigra, with 500mg/kg abolishing the effects of the toxin (lipid peroxidation, dopamine content of cells, ED-1 induction).[18]

Remarkably, the hot water extract of the flowers was more potent than both Trolox (water soluble analogue of Vitamin E) and glutathione itself in preventing lipid peroxidation in vitro; lipid peroxidation protection was noted in brain slices of rats fed the powder, suggesting it is biologically relevant[18] although a suppression of microglia activation may also be an underlying cause.[18] This anti-oxidant capabilities of the flowers has been noted elsewhere, where Vitamin E and Vitamin C were outperformed and the water extract was comparable to isolated catechin.[16]

Some neuroprotective effects appear to exist with Dragon Eye fruits, which may be related to the anti-oxidant capabilities. These protective effects seem quite potent to be honest, but limited evidence on the subject matter

2.2. Memory

Mechanistically, Oral ingestion of 200mg/kg Longan fruit (water extract) appears to enhance Brain-Derived Neurotrophic Factor (BDNF) immunopositive regions in the hippocampal CA1 and DG regions with increased phosphorylated CREB and ERK in these regions, and this increased cell count is though to be due to preserving cell survival rather than inducing proliferation.[5]

The aqueous extraction of Longan fruits fed at 100-400mg/kg bodyweight to ICR mice over a period of 14 days is able to enhance memory performance on a step-down latency task, with all doses (100, 200, and 400mg/kg) being equally effective as 400mg/kg Piracetam used as active control.[5]

Two studies in rats suggesting improvements in memory possibly related to BNDF induction, but more studies are needed; looks promising


3Inflammation and Immunology

3.1. Immunomodulatory

Oral administration of LP3 polysaccharide from Longan (50-200mg/kg) to mice who were currently undergoing immunosuppression increased serum hemolysin production, macrophage phagocytosis, NK cell cytotoxicity, and splenic lymphocyte proliferation; all of which were most effective at 100mg/kg and on par with Ganoderan (50mg/kg; bioactive from Ganoderma lucidum).[11] These effects suggest protection from immunosuppression, and appear to extend to LP1 and LP2 as well.[12]

The polysaccharides of Longan fruit (100-400mg/kg), in response to DTH (research model of immunity due to T-cells mediating DTH being similar to those that are protective against intracellular infections[19]) immunity appeared to be enhanced with 400mg/kg being similar to an 0.02g/kg injection of lentinan (shiitake polysaccharide) and 100-200mg/kg outperforming; this was extended to macrophagocytosis, where 200mg/kg of Longan fruit polysaccharide increased phagocytosis to 514.3% of control levels, and to both splenocyte proliferation as well as tumor cytotoxicity via the immune system (S180 model; 82.64-83.22% inhibition at 100-200mg/kg with Lentinan at 33.14%).[20]

Appears to enhance proliferation of immune cells and exert an immunopotentiating effect, which can help alleviate immunosuppression

3.2. Macrophages

In vitro, water extracts of Lognan with a polyphenolic content (2.65% ellagic acid, 0.81% epicatechin) appear to inhibit LPS-induced NO release in macrophages with an IC50 of 179.8μg/mL; with isolated ellagic acid and gallic acid possessing IC50 values of 5.2uM and 18.8uM respectively.[21] Similar results have been noted elsewhere, where both water and ethanolic extracts weakly inhibited macrophage activation in response to LPS[4] and a twig extract from Longan (high polyphenolic concentration) also appeared to inhibit NO production from LPS-stimulated macrophages.[22]

A test using the water extract of Longan pericarp (100-400mg/kg) taken 2 hours prior to Carrageenan-induced inflammation in mice was able to exert anti-inflammatory effects, as evidenced by a reduction in edema up to 58% after 5 hours relative to control; when relative to the active control (10mg/kg Indomethacin), the reduction by Indomethacin to 39% was seen as statistically similar.[21]

Water extracts of Longan appear to exert antiinflammatory effects of moderate potency in vivo


4Interactions with Fat Mass

4.1. Mechanisms

In rats given either a normal or hypercaloric diet paired with 1.25-2.5% water extract of the flowers of Lognan, the higher dose was able to attenuate the rate of weight gain over 9 weeks (with 1.25% being ineffective), bringing the 36.65% weight increase seen in hypercaloric control to 30.71% (with normal fed control at 27.99%) without affecting food intake.[10] This study noted a polyphenolic intake of 112.01mg/kg daily in the high dose group, and also noted increased fecal triglyceride content (possible lipase inhibition) and noted normalized PPARα activity that was hindered with high caloric feeding.[10]

Possible anti-obese effects associated with Longan fruit, unknown practical relevance


5Interactions with Physical Performance

5.1. Mechanisms

A study using the polysaccharides from Longan seeds noted that 100-400mg/kg of the polysaccharides orally for 30 days to mice enhances hepatic glycogen content in a dose-dependent manner; improvements in swimming time and reductions in serum urea and lactate were both noted (and thought to be due to anti-fatigue effects) but were inconsistent with no dose response.[23]

Possible performance enhancing effects, but more studies are needed to confirm


6Interactions with Organ Systems

6.1. Kidneys

Components of Longan seeds appear to inhibit Xanthine Oxidase in a dose dependent manner in vitro, although oral ingestion of 80mg/kg failed to influence liver Xanthine Oxidase activity; regardless, serum uric acid levels were reduced through modulation of urate transporters in the kidneys (induction of GLUT9, suppression of GLUT1).[24]


7Interactions with Cancer Metabolism

7.1. Colorectal

One study[25] (duplicated in Medline[26]) using SW480 and Colo 320DM colorectal cell lines noted that the water extract of the flower was able to induce apoptosis in a concentration and time dependent manner with a potency comparable to EGCG (the main catechin of the four Green Tea Catechins), with cancer cells reaching under 20% viability with 400mcg/mL for 48 hours.[25] The mechanism of apoptosis was related to caspase-3 release and PARP cleavage from reductions in mitochondrial membrane potential,[25] and this has been replicated elsewhere where an antiproliferative effect was also noted with longan seeds.[27]

May induce apoptosis in cancer cells, but only one study has so far been conducted


8Interactions with Aesthetics

8.1. Skin

Longan appears to have anti-oxidative properties due mostly to the gallic acid and ellagic acid components, as in a DPPH assay both compounds are more effective in sequestering free radicals as the reference compound Vitamin C and dried seeds seem somewhat comparable to Camellia Sinensis (source of Green Tea Catechins).[3] These effects may underlie tyrosinase inhibitory potential, with IC50 values of 2.9 and 3.2mg/mL (fresh and dried seeds respectively) both of which are significantly weaker than the reference compound Kojic Acid (8.9ug/mL).[3]

Weak protective effects on the skin


9Nutrient-Nutrient Interactions

9.1. Smilax

Smilax is a phytonutrient combination therapy of Hordeum vulgare, Polygonatum multiflorum, Longan, Ligusticum sinense, Lilium brownii, Gynura pinnatifida, Coreopsis lanceolata, Juniperus communis, and Ginger in a 30:2:4:10:20:20:2:2:1 ratio.[1] After administration of liquid drops thrice a day for 6 weeks to obese persons (totalling a daily dose of 40mg dry weight of the combination) noted a decrease in body weight of 8.5% that, although exceeding placebo, was not statistically significant; relative to their own baseline, the Smilax group lost BMI, weight, and hip circumference while the placebo group did not.[1]

A later in vitro test noted that incubation of human adipocytes with Smilax resulted in less lipid accumulation and increased glycerol release; suggesting lipolysis.[1]

One study using a combination therapy known as Smilax noted significant reductions in weight loss associated with treatment; this study has not yet been replicated


10Safety and Toxicology

In a preliminary toxicology test, up to 13 weeks of daily consumption of Longan seed extract (up to 800mg/kg for 4 weeks and 500mg/kg for 13 weeks) was not associated with any overt toxicological effects (some fluctuations of food intake that were not dose or time dependent and thought to be due to chance, a random significant spike in eosinophil % in male mice).[28] Ingestion of 5g/kg in mice for up to 14 days was not associated with any toxicological signs.[28]

No apparent toxicity associated with Longan fruits in high doses

Scientific Support & Reference Citations

References

  1. Studies on the use of "slimax", a chinese herbal mixture, in the treatment of human obesity
  2. Rank MA, Li JT A case of food allergy due to longan fruit . Ann Allergy Asthma Immunol. (2007)
  3. Rangkadilok N, et al Evaluation of free radical scavenging and antityrosinase activities of standardized longan fruit extract . Food Chem Toxicol. (2007)
  4. Ho SC, et al Suppressive effect of a proanthocyanidin-rich extract from longan (Dimocarpus longan Lour.) flowers on nitric oxide production in LPS-stimulated macrophage cells . J Agric Food Chem. (2007)
  5. Park SJ, et al The memory-enhancing effects of Euphoria longan fruit extract in mice . J Ethnopharmacol. (2010)
  6. Soong YY, Barlow PJ Isolation and structure elucidation of phenolic compounds from longan (Dimocarpus longan Lour.) seed by high-performance liquid chromatography-electrospray ionization mass spectrometry . J Chromatogr A. (2005)
  7. Sudjaroen Y, et al Isolation and characterization of ellagitannins as the major polyphenolic components of Longan (Dimocarpus longan Lour) seeds . Phytochemistry. (2012)
  8. Zheng G, et al A new natural lactone from Dimocarpus longan Lour. seeds . Molecules. (2012)
  9. Okuyama E, et al Adenosine, the anxiolytic-like principle of the Arillus of Euphoria longana . Planta Med. (1999)
  10. Yang DJ, et al Antiobesity and hypolipidemic effects of polyphenol-rich longan (Dimocarpus longans Lour.) flower water extract in hypercaloric-dietary rats . J Agric Food Chem. (2010)
  11. Yi Y, et al Immunomodulatory activity of polysaccharide-protein complex of longan (Dimocarpus longan Lour.) pulp . Molecules. (2011)
  12. Yi Y, et al Physicochemical characteristics and immunomodulatory activities of three polysaccharide-protein complexes of longan pulp . Molecules. (2011)
  13. Jiang G, et al Structural characteristics and antioxidant activities of polysaccharides from longan seed . Carbohydr Polym. (2013)
  14. Jiang G, et al Structural characteristics and antioxidant activities of oligosaccharides from longan fruit pericarp . J Agric Food Chem. (2009)
  15. Rangkadilok N, et al Identification and quantification of polyphenolic compounds in Longan (Euphoria longana Lam.) fruit . J Agric Food Chem. (2005)
  16. Hsieh MC, et al Antioxidative activity and active components of longan (Dimocarpus longan Lour.) flower extracts . J Agric Food Chem. (2008)
  17. Chen J, Chen X, Qin J Effects of polysaccharides of the Euphoria Longan (Lour.) Steud on focal cerebral ischemia/reperfusion injury and its underlying mechanism . Brain Inj. (2011)
  18. Lin AM, et al Neuroprotective effects of longan ( Dimocarpus longan Lour.) flower water extract on MPP+-induced neurotoxicity in rat brain . J Agric Food Chem. (2012)
  19. Modlin RL Learning from leprosy: insights into contemporary immunology from an ancient disease . Skin Pharmacol Appl Skin Physiol. (2002)
  20. Zhong K, et al Evaluation of radicals scavenging, immunity-modulatory and antitumor activities of longan polysaccharides with ultrasonic extraction on in S180 tumor mice models . Int J Biol Macromol. (2010)
  21. Huang GJ, et al Antioxidant and Anti-Inflammatory Properties of Longan (Dimocarpus longan Lour.) Pericarp . Evid Based Complement Alternat Med. (2012)
  22. Wang BS, et al Inhibitory effects of water extract from longan twigs on mutation and nitric oxide production . Food Chem. (2012)
  23. Zheng SQ, et al Preliminary observations on the antifatigue effects of longan (Dimocarpus longan Lour.) seed polysaccharides . Phytother Res. (2010)
  24. Hou CW, et al Longan seed extract reduces hyperuricemia via modulating urate transporters and suppressing xanthine oxidase activity . Am J Chin Med. (2012)
  25. Hsu CP, et al Longan flower extract inhibits the growth of colorectal carcinoma . Nutr Cancer. (2010)
  26. Chung YC, et al The effect of Longan seed polyphenols on colorectal carcinoma cells . Eur J Clin Invest. (2010)
  27. Panyathep A, et al Inhibitory Effects of Dried Longan ( Euphoria longana Lam.) Seed Extract on Invasion and Matrix Metalloproteinases of Colon Cancer Cells . J Agric Food Chem. (2013)
  28. Worasuttayangkurn L, et al Safety evaluation of longan seed extract: acute and repeated oral administration . Food Chem Toxicol. (2012)
  29. Writing Group for the NINDS Exploratory Trials in Parkinson Disease (NET-PD) Investigators, et al Effect of creatine monohydrate on clinical progression in patients with Parkinson disease: a randomized clinical trial . JAMA. (2015)
  30. Taylor MJ1, et al Folate for depressive disorders . Cochrane Database Syst Rev. (2003)
  31. Godfrey PS1, et al Enhancement of recovery from psychiatric illness by methylfolate . Lancet. (1990)
  32. Kushwaha S1, Chawla P1, Kochhar A1 Effect of supplementation of drumstick (Moringa oleifera) and amaranth (Amaranthus tricolor) leaves powder on antioxidant profile and oxidative status among postmenopausal women . J Food Sci Technol. (2014)

(Common misspellings for Dimocarpus longan include Logan, Lonan)

(Editors who contributed to this page include shrillthrill, )