Rubus suavissimus

Rubus suavissimus (Chinese sweet leaf) is a plant whose leaves are used to brew a sweetened tea, and it is currently thought to be a decent weight loss aid in part due to suppressing the formation of body fat and in part due to its sweetness helping with food cravings.

This page features 18 unique references to scientific papers.

Summary

All Essential Benefits/Effects/Facts & Information

Rubus suavissimus is a plant in the raspberry family which contains a variety of natural sweeteners (the suaviosides) somewhat similar to the molecules in Stevia, another naturally sweet plant. In part due to the sweetness aiding somebody psychologically on a diet, the potential suppressive effects on weight gain seen in rats suggests that this tea may have anti-obese properties; more research would be needed to see if there is any promise for this herb though.

Beyond that, the tea appears to be traditionally used to help with symptoms of sickness (usually to attenuate allergies, relieve cough, and increase mucus production and aid in its clearnace from the body). The claims on cough, fever, and mucus have not yet been evaluated and while there appear to be some preliminary evidence to support a reduction in allergies the one accessible human study has failed to find such an effect.

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Things To Know

Also Known As

Chinese sweet leaf tea, Ten-cha

Do Not Confuse With

Rubus coreanus (same genera, different species)

Things to Note

  • As the name suggests, the leaves from this plant and the tea it is made from have a sweet taste

Is a Form Of

Caution Notice

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Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects rubus suavissimus 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.
Notes
Allergies - Very High See study
Although this tea appears to be a popular tea for the purpose of treating allergic rhinitus, the currently available human evidence does not support this conclusion.
Nasal Congestion - Very High See study
Due to the lone study failing to find benefit to allergic symptoms with 400mg of the leaf extract, there are no reported benefits to allergic rhinitus


1Sources and Composition

1.1. Sources

Rubus suavissimus (of the family Rosaceae) is a small fruit bearing plant that is sometimes called Ten-Cha (Japan)[1] or Chinese Sweet Leaf (China).[2] Ten-Cha is actually a generic term for sweet Chinese teas in Japan, and the tea using rubus suavissimus is more specifically called tenyoukenkoushi among other possible optios of dojosan (Hydrangea aspera), gyuhakuto (Hedyotis hedyotidea), and tasuiseikayou (Lithocarpus polystachyus).[1]

The leaves of this plant, almost always brewed as a tea, have been used traditionally to maintain kidney health, improve blood flow,[3] promote appetite, induce expectoration, stop cough, and alleviate fever.[1]

Rubus suavissimus is, essentially, a tea that has been used to improve symptoms of sickness and to aid the body in clearing mucus (coughing), clearing a fever, and improving appetite

1.2. Composition

The composition of rubus suavissimus leaves (unless otherwise specified) include:

  • Rubusoside (also known as desglucostevioside), the β-D-glucosyl ester of 13-O-β-D-glucosyl-steviol at around 4.87% dry weight[4][5] and present in the water extracts (tea);[6] structurally similar to the steviol glycosides from Stevia[7]

  • Steviol monoside (0.08% dry weight[4])

  • Suavioside A-J with C1, D1, and D2 specified;[8]

  • Gallic acid (0.13% dry weight[4]) and ellagic acid (0.71% dry weight)[4][2]

  • Rubusuaviins A-F (tannin structures)[9]

  • 1(β)-O-galloyl pedunculagin[9]

  • Strictinin[9]

  • Lambertianin A[9]

  • Sanguiin H-5, H-6, and 1-degalloylsanguiin H-6[9]

  • Rutin (0.11% dry weight[4])

  • Ent-13-hydroxy-kauran-16-en-19-oic acid and ent-kaura-16-en-19-oic-13-O-β-D-glucoside[10]

27% of the weight of the leaves consists of rubusoside, gallic acid, and ellagic acid in approximately a 17.2:1.8:1.[2]

The overall plant content appears to be mixed between diterpenoids and tannins; while the tannins likely confer a varity of health effects, the diterpenoids are structured similar to Stevia diterpenoids and confer a sweet taste to the leaf

1.3. Physicochemical Properties

Rubusoside appears to have a slightly bitter aftertaste but 115-fold higher sweetness than sucrose,[6] and this molecule underlies why rubus suavissimus is called 'Sweet tea' in China and Japan.

All suaviosides are sweet except for C1, D2, and F which possess a bitter taste.[8]

Most diterpenoids in this leaf are sweet and the overall taste is sweet, although some isolated diterpenoids are bitter in taste


2Pharmacology

2.1. Absorption

Due to appearing in the urine in their intact forms following oral administration to the rat rubusoside, ellagic acid, and gallic acid appear to be absorbed from the intestines.[2]

2.2. Excretion

After a dose of 1,000mg/kg rubus suavissimus extract (860mg rubusoside, 90mg ellagic acid, and 50mg gallic acid per 1,000mg extract) these three molecules appeared in the urine in an unmetabolized form;[2] pharmacokinetics were not evaluated.

It appears that the two most well known tannins and the main flavorant (rubusoside) are not metabolized in the rat body following oral ingestion


3Interactions with Glucose Metabolism

3.1. Absorption

The tannin structures in rubus suavissimus appear to have inhibitory potential on intestinal α-amylase, and at a concentration of 10µg/mL in vitro inhibitory potential appeared to be most potent with and rubusuaviin A and B (60.6-60.8%) with comparable inhibitory potential from rubusuaviin E (52.3+/-2.7%), 1(β)-O-galloyl pedunculagin (56.2+/-4.4%), and Lambertianin A (56.3+/-2.7%).[9]

The tannin structures in the leaves appear to inhibit the α-amylase enzyme with respectable potency, but there are no studies in living models at this point in time

3.2. Blood Glucose

In rats fed a high fed diet with or without 3% rubus suavissimus in the feed (maximum dose of 220mg/kg), there was no significant influence on fasting blood glucose over nine weeks.[2]


4Fat Mass and Obesity

4.1. Adipogenesis

In isolated 3T3-L1 adipocytes, a hot water extract of the leaves (0.5% of the medium) appears to promote the early phases of adipogenesis associated with increasing PPARγ expression to 137-191% of control when measured after 24-48 hours and increased its gene products.[11]

It appears that rubus suavissimus extract at 10μg/mL (86% rubusoside with the rest being ellagic and gallic acids) inhibits the growth of 3T3-L1 adipocytes by 20% yet causes a significant suppression of VEGF but not bFGF expression.[2] This suppression of VEGF is thought to reflect a reduction in angiogenesis and, secondary to that, less growth of body fat since the two are highly correlated.[12][13] This is probably related to the gallic acid content, as although adding 0.1-0.3% of the diet as gallic acid failed to inhibit angiogenesis (due to absorption issues) injections of 0.1% inhibited angiogenesis by 41%.[14]

While there are some influences on the level of the fat cell suggesting it should proliferate, the influences on blood vessels that innervate the fat cells appear to be anti-obese. More research on the particular mechanisms of action and the molecule mediating these effects is needed

4.2. Weight

Rubus suavissimus at 3% of the diet (maximum dose of 220mg/kg) over nine weeks in rats fed a high fat diet did not influence food intake yet reduced weight gain (22%) and fat mass gain (48%) relative to high fat control, reaching a final body weight comparable to the low fat fed control.[2]

The lone rat study noted pretty much an inhibition of the fat gain associated with a high fat diet in rats (being comparable to the normal chow control) suggesting a relatively potent anti-obese effect


5Inflammation and Immunology

5.1. Macrophages

In mouse macrophages transfected with a stable NF-kB reporter cell (to assess NF-kB interactions[15]), a crude rubus suavissimus extract at 500µg/mL fully prevented NF-kB activity albeit with some toxicity, but a 20% methanolic was also fairly potent without apparent toxicity.[16]

Possible antiinflammatory effects that occur at a high concentration and do not appear to be overly promising whatsoever

5.2. Mast Cells

In isolated mast cells stimulated with compound 48/80, rubus suavissimus is able to inhibit COX enzyme activity with an IC50 value of 170μg/mL (less than the reference drug of aspirin at 15μg/mL).[17] It inhibited histamine release but did not influence on histamine-induced vascular permeability was not significant despite the inhibition of histamine secretion reaching significance.[17] When tested elsewhere, the water extract of rubus suavissimus noted that 300μg/mL was able to inhibit release of histamine from stimulated mast cells (although to a potency that was noted with 100μg/mL of a 40% ethanolic garcinia mangostana extract) but failed to suppress PGE2 secretion.[18]

There appear to be some antiallergic properties associated with the tea extract, although it seems to be less potent than the reference drugs and other tested supplements

5.3. Allergies

Rubus suavissimus in persons with confirmed dust mite allergies, supplementation of 400mg of the extract daily over the course of four weeks noted reductions in nasal congestion and runiness as well as sneezing although not to a degree significantly better than placebo;[1] the overall rate of improvement was 31.9% in the rubus suavissimus group while it was 23.8% in placebo.[1]

The aforementioned study[1] did make note of two positive studies conducted by Ukai et al. (1995, 1998) which showed promise with 120mg of a supplement and 80mg of a tea in persons with perennial allergic rhinitus and cedar pollinosis, respectively; neither of these studies can be located online.

There appear to be two untracable studies noting benefit with the leaf extract, but the one accessible and controlled study on the subject matter failed to find a therapeutic effect of the tea on symptoms of allergies


6Safety and Toxicology

6.1. General

Ingestion of 3% of the rat diet as rubus suavissimus (maximal dose of 220mg/kg) for nine weeks has failed to exert any biochemical or clinical side effects.[2] There was an increase in serum potassium noted in the high fat fed supplement group that was not seen in high fat nor low fat control, but it was not deemed clinically relevant.[2]

Currently no known toxicity associated with this tea

Scientific Support & Reference Citations

References

  1. Yonekura S, et al A randomized, double-blind, placebo-controlled study of ten-cha (Rubus suavissimus) on house dust mite allergic rhinitis . Auris Nasus Larynx. (2011)
  2. Koh GY, et al Improvement of obesity phenotype by Chinese sweet leaf tea (Rubus suavissimus) components in high-fat diet-induced obese rats . J Agric Food Chem. (2011)
  3. Koh GY, Chou G, Liu Z Purification of a water extract of Chinese sweet tea plant (Rubus suavissimus S. Lee) by alcohol precipitation . J Agric Food Chem. (2009)
  4. Chou G, et al Quantitative and fingerprint analyses of Chinese sweet tea plant ( Rubus suavissimus S. Lee) . J Agric Food Chem. (2009)
  5. Rubusoside (beta-D-glucosyl ester of 13-O-beta-D-glucosyl-steviol), a sweet principle of Rubus chingii Hu (Rosaceae)
  6. Sugimoto N, et al Analysis of rubusoside and related compounds in tenryocha extract sweetener . Shokuhin Eiseigaku Zasshi. (2002)
  7. Ohtani K, et al Further study on the 1,4-alpha-transglucosylation of rubusoside, a sweet steviol-bisglucoside from Rubus suavissimus . Agric Biol Chem. (1991)
  8. Minor diterpene glycosides from sweet leaves of Rubus suavissimus
  9. Li H, et al Rubusuaviins A-F, monomeric and oligomeric ellagitannins from Chinese sweet tea and their alpha-amylase inhibitory activity . Chem Pharm Bull (Tokyo). (2007)
  10. Wang JX, Lü HC Studies on the chemical constituents of Rubus suavissimus S. Lee . Zhong Yao Cai. (2007)
  11. Ezure T, Amano S Rubus suavissimus S. Lee extract increases early adipogenesis in 3T3-L1 preadipocytes . J Nat Med. (2011)
  12. Adipose tissue angiogenesis as a therapeutic target for obesity and metabolic diseases
  13. Adipose tissue remodeling in pathophysiology of obesity
  14. Liu Z, et al Gallic acid is partially responsible for the antiangiogenic activities of Rubus leaf extract . Phytother Res. (2006)
  15. Zhang X, et al Rapid and sensitive assay of tumor necrosis factor-alpha gene transcription . Pharm Res. (2001)
  16. Bioassay-Guided Fractionation of Rubus suavissimus. Leaf Extracts Possessing NF-κ.B Inhibitory Activities and a Separable Cytotoxicity
  17. Fang YG, et al Anti-allergic effects of Rubus suavissimus extract . Zhong Yao Cai. (2008)
  18. Nakatani K, et al Inhibitions of histamine release and prostaglandin E2 synthesis by mangosteen, a Thai medicinal plant . Biol Pharm Bull. (2002)

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