Uncaria tomentosa

Uncaria Tomentosa (Cat's Claw) is an Amazonian vine that has been traditionally recommended for antiinflammatory and fatigue syndromes.

This page features 47 unique references to scientific papers.

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How to Take

Recommended dosage, active amounts, other details

Studies using Cat's Claw tend to use 250-350mg of the ethanolic extract once a day. This is usually standardized to a Pentacyclic Oxindole Alkaloid content.

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Editors' Thoughts on Uncaria tomentosa

I cannot recommend this at this moment in time. The fact that two chemotypes of the same species exist with seemingly antagonistic alkaloids (either pentacyclic or tetracyclic, the latter suppressing the actions of the former) paired with the lack of human evidence makes the usage of Cat's Claw, in my opinion, very unreliable.

If you can somehow aquire a reliable source that routinely checks the pentacyclic oxindole alkaloid content, then by all means go for it. Standardization and sourcing of Cat's Claw is going to be important.

Kurtis Frank

Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects uncaria tomentosa has on your body, and how strong these effects are.

Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
White Blood Cell Count Minor - See study
An increase in white blood cell count has been noted with Cat's Claw by 9% over 9 weeks with a water extract, which is thought to be related to the immunoenhancing properties. The white blood cells that were increased were not assessed

1Sources and Composition

1.1. Sources

Uncaria Tomentosa (of the family Rubiaceae) is one of two herbs, the other being Uncaria guianensis, that have the common name of Cat's Claw; these two herbs are vines that grow in the Amazon forest and have traditional usage as anti-inflammatory agents,[1] with other traditionally claimed benefits extending to arthritis, bursitis, lupus, chronic fatigue syndrome, and both stomach and intestine disorders.[2] This article describes the properties of Uncaria Tomentosa unless otherwise specified.

There are two known chemotypes of Uncaria Tomentosa, which share the species name but may have differing chemical composition; due to this, benefits attributed to alkaloids may be variable due to which chemotype is being consumed.[3]

1.2. Composition

The components of Uncaria Tomentosa are:

  • Mitraphylline and Isomitraphylline, seen as the main bioactives and usually present in older leaves or the stem bark[3]

  • Rhynchophylline and Isorhynchophylline[4]

  • Isopteropodine[4]

  • Uncarine C (aka. Pteropodine), Uncarine D (Speciophylline)[3] and Uncarine F[4]

  • Alkaloids Hirsutine, Hirsuteine, Dihydrocorynantheine and Corynantheine at times in young leaves[3]

  • (Polyhydroxylated) Triterpenes Uncaric Acid, Floridic Acid, and 3β,6β,19α-trihydroxy-23-oxo-urs-12-en-28-oic acid[5] and two other unnamed triterpenoids in the stem[6]

  • The triterpenoid Quinivic Acid (around 0.11%[7]) and numerous glycosides (may total around 0.31%[7]),[8][9][10] as well as common triterpenoids ursolic acid and Oleanolic acid

  • Pyroquinovic acid and its glycosides, Tomentosides A and B (known as 27-nortriterpene glycosides)[11]

  • Quinic Acid[12]

  • Glucoindole alkaloids 3α-Dihydrocadambine and Dolichantoside[4] as well as 3,4-dehydro-5- carboxystrictosidine,[13] 5α-carboxystrictosidine,[14] and Lyaloside[13]

  • Epicatechin and Cinchonain Ia and Ib, known as procyanidines (as chains of them form Procyanidins)[15] as well as the Procyanidins A1, B1, B2, and B4[16]

The entire structural class of pentacyclic triterpenoids may be relevant (many named 'Uncarines' after the Uncaria genera), with Mitraphylline being most relevant to Cat's Claw; the structurally class of Glucoindole alkaloids are also plentiful

With some bioactives found in Uncaria Guianensis (possibly related to supplementation) being:

  • Also has a Mitraphylline and Isomitraphylline content[17]

  • Rhynchophylline and Isorhynchophylline,[3] except higher levels than that usually seen in Tomentosa[17]

  • Corynoxeine and Isocorynoxeine[3]

  • Quinovic acid as four glycosides (Glucose(3-1)Fucose with a Galactose, Fucose, Quinovose, and Fucose with a Galactose)[18]

The sum of all alkaloids appears to vary from 0.156 to 0.962%,[19] and may vary widely between the two chemotypes of Uncaria Tomentosa (with one higher in pentacyclic triterpenoids and the other tetracyclic).[3] Oddly, one study has suggested that a beneficial effect of pentacyclic oxindole alkaloids (promotion of leukocytes) is effectively antagonized by tetracyclic alkaloids.[20]

Both main species of Cat's Claw (tomentosa and guianensis) appear to share anti-inflammatory and anti-oxidant properties.[21][22][23]


2.1. Mechanisms

One study using isolated Quinic Acid (component of Cat's Claw, the Cinchonia genera, and Coffee) was found to prolong life of C.Elegans under heat (17.8%) and oxidative (29.7%) stress and extend the lifespan of C.Elegans by 15.7% independent of stress; with the latter thought to be related to induction of DAF-16.[12] An increase in DNA repair rates has also been noted in rats who were irradiated (to damage DNA) and then observed over 3 hours, where both single strand and double strand breaks over 3 hours were reduced in a dose-dependent manner with 40-80mg/kg oral intake;[24] this increased rate of DNA repair has been noted in human immune cells undergoing chemotherapy, where damage assessed by Comet Assay was reduced more than half.[25]

3Cardiovascular Health

3.1. Blood

One study in erythrocytes (red blood cells) noted that 250ug/mL of Cat's Claw (both ethanolic and aqueous extracts of the leaves and stems) were able to preserve Catalase activity in the presence of the pesticide 2,4-D-Na and its metabolites(2,4-DCP, Catechol)[26] that are known to reduce catalase activity;[27] these protective effects against 2,4-D-Na were noted elsewhere,[28] although a failure to exert anti-oxidative effects against organic radicals, such as semiquinones, was noted at 5-500ug/mL.[28]

Erythrocyte structural changes have been noted with concentrations of up to 250ug/mL, but were not seen as adverse (benign structural changes occur when polyphenolics embed themselves within a cellular membrane[29][30]); higher concentrations of 50-100ppm induced considerable morphological changes, however.[31] No Cat's Claw induced hemolysis is noted up to 500ug/mL[31][28]

Studies conducted in humans include 350mg of Cat's Claw for 6 weeks which failed to alter any serum reading related to red blood cells[32] and one trial using Uncaria Guianensis failing to note alterations in hematocrit or haemoglobin.[33]

4Inflammation and Immunology

4.1. Mechanisms

Mitraphylline (when fed to mice at 30mg/kg for 3 days) is able to reduce LPS-induced TNF-α release by 50%, IL-1α and IL-1β by 70%; this slightly underperformed relative to 2mg/kg Dexamethasone (active control).[34] IL-4 was also reduced 40% and IL-17 by 50%.[34]

Mitraphylline may be the active ingredient in suppressing inflammatory cytokine release from activated immune cells

4.2. Osteoarthritis

Cat's Claw appears to be one of the more popular herbal supplements recommended against inflammatory joint diseases.[1]

In isolated chondrocytes, 10μg/mL Uncaria tomentosa (Vincaria brand name) can increase IGF-1 levels by 67% when incubated over 48 hours and preserve up to half of IGF-1 levels when IL-1β is introduced;[35] IL-1β and other proinflammatory cytokines tend to suppress IGF-1 via silencing genomic transcription.[36][37]

4.3. Immune Cells

On normal blood mononuclear cells, concentrations between 50-250ug/mL of either the ethanolic or aqueous extracts appear to dose-dependently induce apoptosis, although only the ethanolic bark extract at 250ug/mL exceeded 10% apoptosis, although an increase in cell granularity was seen at 50ug/mL.[38]

One study noted that the pentacyclic oxindoles were able to induce endothelial release of factors (not named in study) to promote production of lymphocytes and weakly activated B and T cells while suppressing lymphoblasts;[20] these effects were antagonized by tetracyclic oxindole alkaloids.[20]

When human volunteers (n=4) are given Cat's Claw water extract (C-MED-100) at 350mg daily for 6 weeks, that a small increase in white blood cell count (6.60+/-0.35 to 7.18+/-0.50 WBC/109/L; 8.7% increase).[24] These researched followed up this small study with a proper trial, where 250-350mg of C-MED-100 increase leukocyte count over 6 weeks in healthy volunteers.[32]

A trial in women with breast cancer undergoing chemotherapy noted that the reductions in Leukocytes and Lymphocytes were attenuated, while levels of Neutrophils and Monocytes actually exceeded baseline levels despite chemotherapy.[25] This may be related to prolonging the survival of leukocytes (noted in vivo[39]), meaning the increase is indirect through reduced apoptosis of immune cells.

5Interactions with Cancer

5.1. Neutropenia

Cat's Claw is investigating for adjunct therapy (to be taken alongside chemotherapy to either enhance actions or attenuate side effects) due to its immunostimulating properties; this was first evidence when rats given Doxorubicin had lower rates of Leukopenia (depletion of leukocytes) when given Cat's Claw concurrently.[40]

In persons with breast cancer undergoing FAC Therapy (Fluorouracil, Doxorubicin, Cyclophosphamide) noted that the addition of 300mg Cat's Claw extract (70% ethanolic extract with 2.57% pentacyclic oxindole alkaloids) was able to reduce the degree of neutropenia and improve DNA repair relative to FAC paired with placebo.[25] This study noted that the reduction of immune cells over 6 cycles of chemotherapy in control (Leukocytes by 52%, Neutrophils by 70%, Lymphocytes by 44%, and Monocytes by 8%) was attenuated by 39% and 6.5% (Leukocytes and Lymphocytes) with both Neutrophils and Monocytes increasing to levels higher than baseline despite chemotherapy.[25] This is seen as promising since a Neutrophil count below 500cells/mm3[41] is the point when chemotherapy is discontinued on account of Neutropenia and excessive risk to the patient.[42] Another study in persons undergoing colon cancer chemotherapy (Fluorouracil/leucovorin with oxaliplatin; also underwent colectomy) with 300mg Uncaria Tomentosa noted a trend to increase neurophil count after six cycles but this failed to reach statistical significance, with all cycles prior to the end of the study also failing to note significant differences.[43]

May have potential as an adjunct therapy during chemotherapy to reduce the suppression on the immune system and genomic damage, seems to influence neutrophils more than other types of immune cells and help with Neutropenia. Despite human studies, it is still preliminary as the main bioactive is not yet known and it doesn't appear to be reliable

6Interactions with Hormones

6.1. Estrogen

Cat's Claw appears to have anti-estrogenic properties, as in a concentration dependent manner in vitro between 10-20mcg Cat's Claw noncompetitively inhibits the estrogen receptor (possibly by preventing formation of estrogen receptor complexes required for genomic signalling) with the higher concentration (20mcg) reducing binding of estradiol by 47.2%.[44] This was lesser than the active control of 20mcg Tamoxifen, a direct antagonist inhibiting 69.3% of signalling.[44]

7Nutrient-Nutrient Interactions

7.1. Maca

Lepidium meyenii, known as Maca, is able to increase IGF-1 levels in human chondrocytes by approximately 2.7 fold when a concentration of 50μg/mL is used; coadministration of 10μg/mL Cat's Claw increases this induction to 3.8 fold despite having weak effects in isolation.[35] The partial inhibition of IL-1β induced reductions in IGF-1 by both Maca and Cat's Claw (50 and 10μg/mL) is nearly absolute with the combination and similar normalizing effects were seen on IL-1β induced GAG release.[35]

At least one in vitro study suggests that Maca and Cat's Claw may have additive benefits in regards to osteoarthritis; synergism not yet demonstrated nor any trials in living systems

8Safety and Toxicology

8.1. General

The LD50 of Cat's Claw water extract in rats appears to be greater than 8g/kg.[24]

8.2. Pregnancy

In a rat model of endometriosis, Cat's Claw (2.8-4mg/kg bodyweight) was able to reduce the rate of growth of endometrial cells from primary to mature (seen in 100% of control) to 10%, halting 90% of rats in the primary stage of cell growth; this was comparable to the active control of Leuprolide Acetate at 1mg/kg.[45] Mature Corpus Luteum was similarly reduced from 100% in control to 10% in Cat's Claw, with the percentage of atrophied Corpus Luteums increased to 70%. Due to these mechanisms the authors hypothesized that Uncaria Tomentosa has anticontraceptive properties,[45] as the changes are similar to those observed after intake of well known contraceptives.[46]

Scientific Support & Reference Citations


  1. Akhtar N, Haqqi TM Current nutraceuticals in the management of osteoarthritis: a review. Ther Adv Musculoskelet Dis. (2012)
  2. Williams JE Review of antiviral and immunomodulating properties of plants of the Peruvian rainforest with a particular emphasis on Una de Gato and Sangre de Grado. Altern Med Rev. (2001)
  3. Laus G Advances in chemistry and bioactivity of the genus Uncaria. Phytother Res. (2004)
  4. Luna-Palencia GR, et al. Differential alkaloid profile in Uncaria tomentosa micropropagated plantlets and root cultures. Biotechnol Lett. (2013)
  5. Aquino R, et al. New polyhydroxylated triterpenes from Uncaria tomentosa. J Nat Prod. (1990)
  6. Two New 19-Hydroxyursolic Acid-type Triterpenes from Peruvian ‘Uña de Gato’ (Uncaria tomentosa).
  7. Pavei C, et al. HPLC-PDA method for quinovic acid glycosides assay in Cat's claw (Uncaria tomentosa) associated with UPLC/Q-TOF-MS analysis. J Pharm Biomed Anal. (2012)
  8. Aquino R, et al. Plant metabolites. Structure and in vitro antiviral activity of quinovic acid glycosides from Uncaria tomentosa and Guettarda platypoda. J Nat Prod. (1989)
  9. New Quinovic Acid Glycosides from Uncaria tomentosa.
  10. Triterpenes and quinovic acid glycosides from Uncaria tomentosa.
  11. Kitajima M, et al. Two new nor-triterpene glycosides from peruvian "Uña de Gato" (Uncaria tomentosa). J Nat Prod. (2003)
  12. Zhang L, et al. Quinic Acid Could Be a Potential Rejuvenating Natural Compound by Improving Survival of Caenorhabditis elegans under Deleterious Conditions. Rejuvenation Res. (2012)
  13. Kitajima M, et al. A new gluco indole alkaloid, 3, 4-dehydro-5-carboxystrictosidine, from Peruvian Uña de Gato (Uncaria tomentosa). Chem Pharm Bull (Tokyo). (2000)
  14. Aquino R, et al. Plant metabolites. New compounds and anti-inflammatory activity of Uncaria tomentosa. J Nat Prod. (1991)
  15. Wirth C, Wagner H Pharmacologically active procyanidines from the bark of Uncaria tomentosa. Phytomedicine. (1997)
  16. de Matta SM, et al. Alkaloids and procyanidins of an Uncaria sp. from Peru. Farmaco Sci. (1976)
  17. Alkaloids of Uncaria. V. Their occurrence and chemotaxonomy.
  18. Yépez AM, et al. Quinovic acid glycosides from Uncaria guianensis. Phytochemistry. (1991)
  19. Ganzera M, et al. Improved method for the determination of oxindole alkaloids in Uncaria tomentosa by high performance liquid chromatography. Planta Med. (2001)
  20. Wurm M, et al. Pentacyclic oxindole alkaloids from Uncaria tomentosa induce human endothelial cells to release a lymphocyte-proliferation-regulating factor. Planta Med. (1998)
  21. Sandoval M, et al. Anti-inflammatory and antioxidant activities of cat's claw (Uncaria tomentosa and Uncaria guianensis) are independent of their alkaloid content. Phytomedicine. (2002)
  22. Sandoval M, et al. Cat's claw inhibits TNFalpha production and scavenges free radicals: role in cytoprotection. Free Radic Biol Med. (2000)
  23. Rosenbaum CC, et al. Antioxidants and antiinflammatory dietary supplements for osteoarthritis and rheumatoid arthritis. Altern Ther Health Med. (2010)
  24. Sheng Y, Bryngelsson C, Pero RW Enhanced DNA repair, immune function and reduced toxicity of C-MED-100, a novel aqueous extract from Uncaria tomentosa. J Ethnopharmacol. (2000)
  25. Santos Araújo Mdo C, et al. Uncaria tomentosa-Adjuvant Treatment for Breast Cancer: Clinical Trial. Evid Based Complement Alternat Med. (2012)
  26. Bukowska B, et al. Uncaria tomentosa extracts protect human erythrocyte catalase against damage induced by 2,4-D-Na and its metabolites. Food Chem Toxicol. (2012)
  27. Bukowska B, et al. Catalase activity in human erythrocytes: effect of phenoxyherbicides and their metabolites. Cell Biol Int. (2000)
  28. Bors M, et al. Protective activity of the Uncaria tomentosa extracts on human erythrocytes in oxidative stress induced by 2,4-dichlorophenol (2,4-DCP) and catechol. Food Chem Toxicol. (2011)
  29. Hendrich AB Flavonoid-membrane interactions: possible consequences for biological effects of some polyphenolic compounds. Acta Pharmacol Sin. (2006)
  30. Koren E, Kohen R, Ginsburg I Polyphenols enhance total oxidant-scavenging capacities of human blood by binding to red blood cells. Exp Biol Med (Maywood). (2010)
  31. Bors M, et al. Evaluation of the effect of Uncaria tomentosa extracts on the size and shape of human erythrocytes (in vitro). Environ Toxicol Pharmacol. (2012)
  32. Sheng Y, et al. DNA repair enhancement of aqueous extracts of Uncaria tomentosa in a human volunteer study. Phytomedicine. (2001)
  33. Piscoya J, et al. Efficacy and safety of freeze-dried cat's claw in osteoarthritis of the knee: mechanisms of action of the species Uncaria guianensis. Inflamm Res. (2001)
  34. Rojas-Duran R, et al. Anti-inflammatory activity of Mitraphylline isolated from Uncaria tomentosa bark. J Ethnopharmacol. (2012)
  35. Miller MJ, et al. The chrondoprotective actions of a natural product are associated with the activation of IGF-1 production by human chondrocytes despite the presence of IL-1beta. BMC Complement Altern Med. (2006)
  36. De Benedetti F, et al. Effect of IL-6 on IGF binding protein-3: a study in IL-6 transgenic mice and in patients with systemic juvenile idiopathic arthritis. Endocrinology. (2001)
  37. Mix KS, et al. A synthetic triterpenoid selectively inhibits the induction of matrix metalloproteinases 1 and 13 by inflammatory cytokines. Arthritis Rheum. (2001)
  38. Bors M, et al. Studies of biological properties of Uncaria tomentosa extracts on human blood mononuclear cells. J Ethnopharmacol. (2012)
  39. Akesson Ch, Pero RW, Ivars F C-Med 100, a hot water extract of Uncaria tomentosa, prolongs lymphocyte survival in vivo. Phytomedicine. (2003)
  40. Sheng Y, Pero RW, Wagner H Treatment of chemotherapy-induced leukopenia in a rat model with aqueous extract from Uncaria tomentosa. Phytomedicine. (2000)
  41. Common Terminology Criteria for Adverse Events v3.0 (CTCAE).
  42. Crawford J, Dale DC, Lyman GH Chemotherapy-induced neutropenia: risks, consequences, and new directions for its management. Cancer. (2004)
  43. Farias IL, et al. Uncaria tomentosa for Reducing Side Effects Caused by Chemotherapy in CRC Patients: Clinical Trial. Evid Based Complement Alternat Med. (2012)
  44. Salazar EL, Jayme V Depletion of specific binding sites for estrogen receptor by Uncaria tomentosa. Proc West Pharmacol Soc. (1998)
  45. Nogueira Neto J, et al. Contraceptive effect of Uncaria tomentosa (cat's claw) in rats with experimental endometriosis. Acta Cir Bras. (2011)
  46. Bhowmik T, Mukherjea M Histological changes in the ovary and uterus of rat after injectable contraceptive therapy. Contraception. (1988)
  47. Sheng Y, Bryngelsson C, Pero RW Enhanced DNA repair, immune function and reduced toxicity of C-MED-100, a novel aqueous extract from Uncaria tomentosa. J Ethnopharmacol. (2000)

(Common misspellings for Uncaria tomentosa include cats, claw, undaria, tomatosa, tomantosa)