Korean black raspberry
Rubus coreanus (Korean Black Raspberry) is a dark berry sometimes brewed as a wine called bokbunja ju; it has a high levels of anthocyanins of the cyanidin type, and other tannin structures that underlie its antioxidant and proerectile properties.
Sources and Structure
Rubus coreanus (of the family Rosaceae, synonymous with Rubus tokkura) is a plant pretty much exclusively grown in east asian countries (Japan, China, and most notably Korea) which bears fruits somewhat similar to raspberries (usually referred to as bokbunja or Rubi Fructus) with an astringent taste, and the fruits are called Korean Black Raspberries and the wine made from these berries (or those from Rubus occidentalis berries) is referred to as bokbunja ju. Since they are berries, they have also been made into jams and spreads as well as other non-alcoholic beverages.
Traditional medicinal usage of this plant includes the treatment of impotence, spermatorrhea, enuresis, asthma and allergic diseases and well as general use as a stomachic and tonic. It is also seen as an aphrodisiac both in fruit form and wine form. Similar to all dark berries (and many red berries), rubus coreanus is mostly a source of anthocyanins.
Rubus coreanus is a dark blue berry that is either consumed (in its unripe form) for medicinal properties or it is used as a commercial product to create wines or jams. It's medicinal uses are more related to circulatory health and promoting male sexuality
The berries of rubus coreanus (unless otherwise specified) include:
- Cyanidin as the glycosides 3-O-sambubioside (33.3mg/100g fresh weight), 3-glucoside (100mg/100g fresh weight]), 3-xylosylrutinoside (136mg/100g fresh weight, but measured as cyanidin-3-glucoside equivalents), and 3-rutinoside (468mg/100g fresh weight); 3-O-rutinoside is the major glycoside at 63% of anthocyanins and 50% higher than the cyanidin-3-glucoside content; total anthocyanins is around 17.93mg/g dry weight (cyanidin-3-glucoside equivalents)
- Gallic acid (38.57mg/g dry weight or 3.6mg/g water extract of unripe fruits) and ellagic acid, up to 4.1mg/g in an ethanolic extract of unripe fruits (higher in unripe than in ripe) and 425.1+/-2.34µg/50mg water extract in unripe
- The ellagitannin known as Sanguiin H-6 (Casuarictin dimer; each monomer composed of two Hexahydroxydiphenic acids and one gallic acid on a glucose) and Sanguiin H-4
- 23-hydroxytormentic acid (23-HTA; a 19α-hydroxyursane type saponin) and its 28-O-glucoside Nigaichigoside F1 (NIF1); 23-HTA differs from asiatic acid (Centella asiatica) by a lone hydroxyl at the 19 carbon, and NIF1 is also similar to asiaticoside
- 19α-hydroxyursolic acid
- Suavissimoside (named after its initial source, rubus suavissimus)
- 2,3-(S)-hexahydroxydiphenoyl (HHDP)-d-glucopyranose
- Quercetin (4.1+/-0.67µg/50mg water extract) and Rutin (31.6+/-7.2µg/50mg water extract)
- Luteolin (0.7+/-0.24µg/50mg water extract)
- Kaempferol (0.4+/-0.11µg/50mg water extract)
- Syringic acid
- p-coumaric and m-coumaric acids, ferulic acid, cinnamic acid
- Chlorogenic acid and caffeic acid (8.6+/-0.35µg/50mg water extract)
- Salicylic acid
The anthocyanins in this plant are very similar to aronia melanocarpa in the sense that it is pretty much just a hefty dose of cyanidin in its glycosides, although this plant has a lot of cyanidin-3-galactoside. Beyond that, there is a sizeable tannin content (usually found in raspberries) and some triterpenoids that are not commonly found in dark berries
When comparing species of rubus against one another, the total anthocyanin content of rubus occidentails (214–428mg/100g for the range of each cyanidin glycoside in the fresh weight) seems somewhat less variable than rubus coreanus (33.3-468mg/100g fresh weight) but overall somewhat comparable. Water and ethanolic extracts of the berries do possess a carbohydrate content (around 32-34%).
There are also bioactives in the pulp/seeds of the plant and their macerates or oils that are sometimes an industrial byproduct of wine making; some bioactives are also found in the root.
Variants and Formulations
The fruits of rubus coreanus appear to be selected based on stage of ripeness, and unripe samples appear to be more antiinflammatory than half-ripe and ripe samples and are similarly more effective as antioxidants.
Unripe fruits appear to have a higher antioxidant and antiinflammatory potential, which is likely due to the tannin content that degrades passively over time (generally a property of large tannin structures to degrade into smaller phenolics; also reduces bitterness)
The phenolics in rubus coreanus tend to be changed during the process of fermentation.
The total free and ester phenolic compounds are known to be increased, while the phenolics that are bound to insoluble portios are reduced; while the aforementioned two categories are increased in antioxidant potency due to more phenolics, the latter category experiences a reduction and the net change is not significant. When looking at molecular changes, the amount of detectable gallic acid in the free form increases (but ester form decreases; total unchanged) with protocatechuic acid having opposite changes but with an overall trend to increase; Hydroxycinnamic acids (ferulic, caffeic, cinnamic) tend to be slightly reduced in free form.
The phenolic composition is altered during fermentation towards more free phenolics and less glycosides, although the total phenolic and antioxidant capacity does not appear to be significantly altered
There appears to be a herbal mixture containing Houttuynia cordata, Rehmannia glutinosa, Betula platyphylla, and Rubus coreanus designated CP-001 and traditionally used in Korean medicine to treat circulation; in the studies that test its efficacy it seems to be standardized to 1.25% catalpol, 0.26% quercitrin, and 0.42% ellagic acid.
There is another formulation designated KH-204 which has shown efficacy in a rat model of hypertension (in regards to increasing erectile potency) which comprises rubus coreanus alongside Schisandra chinensis, cuscuta chinensis, cornus officinalis, and lycium chinense.
Few Korean medicinal formulations of which contain rubus coreanus, but their exact role in these formulations is not certain
Phase II Enzyme Interactions
Unripe rubus coreanus fruits (0.167% of the diet) alongside a high fat diet in mice has been noted to phosphorylize ERK (blocked by MEK inhibitor) which then influenced Nrf2/ARE signalling to produce more Phase II enzymes including Glutamate cysteine ligase (GCL) and both its catalytic and modifier subunits, Heme-oxygenase 1 (HO-1), and peroxiredoxin 1 (Prx1).
Heme-oxygenase 1 (HO-1) is an inducible heme oxygenase, to degrade heme and to liberate carbon monoxide (CO) as an antioxidant signalling molecule; HO-1 is known to suppress NF-kB, and blocking the induction of Nrf2/ARE signalling prevents antiinflammatory properties of rubus coreanus on NF-kB and its anti-atherosclerotic properties.
Appears to be able to activate Nrf2/ARE and induce the production of antioxidant enzymes, which is a mechanism of antioxidation that is independent of its in vitro potency that is comparable to vitamin C
In isolated PC-12 cells treated with 50μM H2O2 to induce cellular death (via oxidation), treatment with the isolated anthocyanins (10-100μg/mL) are able to reduce oxidation with a potency comparable to 10μg/mL Vitamin C.
Possesses neuroprotective properties in isolated cells, which is common for anything that can reduce lipid peroxidation (ie. anthocyanins)
In mice given either 100-300mg/kg of an unripe fruit extract or isolated 23-HTA or its glycoside (NIF1) thirty minutes prior to testing it was noted that all extracts as well as both isolated molecules caused analgesic effects with none being more potent than 100mg/kg aspirin or 10mg/kg morphine.
The pain killing effects of this berry appear to be somewhat weak
Expanding from their research on penile muscle, when 10-100µg/mL of unripe rubus coreanus extract is incubated in A7r5 (aortic) cells it appears that the fruits can reduce potassium chloride induced calcium release (26.1-59.8%) and vasopressin induced calcium release (up to 64%).
The inhibition of calcium release (which can drop below baseline values) seen in the penis also extends to the endothelium, which may underlie the traditional usage of this plant to improve blood flow
0.167% of a high fat diet (mice) consisting of unripe rubus coreanus is able to significantly attenuate atherosclerotic progression relative to high fat control over 14 weeks. This was thought to be due to Nrf2 activation (via ERK/MEK) signalling, since blocking the antioxidant enzymes from Nrf2 also blocked inflammatory signalling in macrophages (NF-kB) and Nrf2 activation was noted in atherosclerotic plaque of mice consuming the fruit.
Unripe fruit extracts are able to suppress the uptake of oxidized LDL in peritoneal macrophages (mouse) in the range of 2-10µg/mL associated with inhibiting JNK phosphorylation (with no influence on p38 nor ERK phosphorylation) which was not associated with GRP78 or antioxidant enzyme activity and the effects replicated by a specific JNK inhibitor.
This berry appears to benefit atherosclerosis by inhibiting LDL oxidation (antioxidative) and secondary to suppressing macrophage activation (antinflammatory); potency against other supplements is not yet established
In isolated HepG2 cells, unripe rubus coreanus at 5-20μg/mL is able to induce antioxidative enzymes (catalase and HO-1 measured) which was associated with a reduction in cholesterol uptake into the hepatocyte (25%); this occurred with a water extract only, and ripe berries were not able to reduce cholesterol uptake. Subsequently, the water extract of unripe berries was tested again in HepG2 cells where both intracellular and extracellular cholesterol were noted to be reduced (500-5,000ng/mL; with the highest dose nonsignificantly less potent than 10μM atorvastatin and higher doses of rubus coreanus seemingly less potent) and alongise this reduction in cholesterol was a reduction in both apolipoproteins (A1 and B) and reduced lipogenesis associated with less SREBP-1 activity and increase FOXo-1 and AMPK activation.
The bioactives in rubus coreanus appear to shift liver cells towards a reduction in cholesterol and fatty acids synthesis
Unripe rubus coreanus fruits (0.167% of the diet) alongside a high fat diet in mice appears slightly suppress the increase in triglycerides and total cholesterol with no influence on HDL-C.
The reduction in cholesterol synthesis may extend to oral ingestion of low doses of the berries
Interactions with Glucose Metabolism
A fermented filtrate of ripe rubus coreanus (ie. wine) is able to inhibit aldose reductase (inhibition of this enzyme being therapeutic for diabetic retinopathy) action in rat retinal cells with an IC50 value of 2µg/mL and IC90 value (90% inhibition) of 31.6µg/mL. The potency of the fermented extract was comparable to that of pure Quercetin.
Appears to be quite a potent aldose reductase inhibitor in vitro, which may be beneficial for diabetics who are at risk for diabetic retinopathy
500mg/kg of a 30% ethanolic extract of the berries for four weeks in mice then subject to a swim test has failed to alter glycogen content of the gastrocnemius and liver.
Does not appear to alter hepatic nor skeletal muscle glycogen stores in otherwise healthy mice subject to exercise
Skeletal Muscle and Physical Performance
A 30% ethanolic extract of the berries from rubus coreanus (500mg/kg) to mice for four weeks prior to a forced swim test noted a 24.7% increase in endurance relative to control associated with a reduction in plasma ammonia yet no changes in triglycerides, lactate, nor glucose. Another test utilizing an exhaustive training protocol noted that, after two days of consequtive exercise in mice, that the decline in performance seen in control was attenuated 20% when fed a ripe ethanolic extract (80%; 1,000mg/kg); water extracts do not appear to be effective.
Two studies have confirmed anti-fatigue effects of this berry in animal models of physical endurance, which may be related to the antioxidant effects
Bone and Joint Health
In osteoblastic cells (MC3T3-E1) is able to attenuate the suppressive influence of H2O2 on osteoblastogenesis secondary to its antioxidative properties in the range of 10-50µg/mL and appears to directly induce cell growth to a near doubling (16µg/mL) or tripling (63µg/mL) in a manner that is inhibited by both cycloheximide and tamoxifen (indicating that estrogenic signalling is synthesizing new proteins).
Appears to promote osteoblast proliferation (which should lead to bone growth) in a manner that involves estrogen signalling
Inflammation and Immunology
Interferons and Immunoglobulins
1,000mg/kg of the unripe water extract of rubus coreanus fruits to mice over 15 days is able to cause an increase in serum immunoglobulin G relative to control, and this was for the most part mimicked by ferulic acid in isolation.
There appears to be differential effects on the antiinflammatory properties in rubus coreanus based on stage of ripening, with unripe fruits causing concentration dependent antiinflammation in macrophages (nitrite formation and IL-6/TNF-α secretion from LPS stimulation) in the concentration range of 50-400µg/mL while half-ripe were less effective and ripe ineffective.
The unripe fruits of rubus coreanus are more effective antiinflammatory agents than the ripe fruits
It is known that NF-kB signalling in the macrophages of rats (located in the arteries) is reduced with oral ingestion of 0.167% of the diet as unripe berries and this is an effect that can be downstream of HO-1 induction which rubus coreanus is known to be able to do secondary to activatin ERK/MEK singalling and activating Nrf2/ARE signalling (which induces HO-1); it was later confirmed in macrophages that the antiinflammatory effects seen are due to HO-1 being increased.
Rubus coreanus appears to induce antioxidant enzymes of which includes HO-1, and when HO-1 is increased it is able to suppress NF-kB activity; this antioxidant effect of the berry underlies the antiinflammatory effect in macrophages
Natural Killer Cells
500µg/mL of rubus coreanus alongside a culture of natural killer cells for six days appears to increase their rate of proliferation 2-3 fold, which is thought to be due to the ferulic acid content.
May promote NK cell proliferation secondary to ferulic acid
500µg/mL of rubus coreanus (unripe water extract) appears to stimulate T cell production in a time dependent manner, which was thought to be in part due to ferulic acid (known to be active and confirmed when used as the reference).
Appears to promote the production of T cells in general; effects on the subtypes of T-cells not yet investigated
500µg/mL of rubus coreanus (unripe water extract) appears to stimulate B cell proliferation in a time dependent manner, which was thought to be in part due to ferulic acid (known to be active and confirmed when used as the reference).
Similar to NK cells and T cells, the B cells appear to also be stimulated
In isolated mast cells, ripe rubus coreanus berries (water extract) is able to reduce histamine release in the concentration range of 10-100µg/mL associated with inhibition of all MAPKs (ERK, JNK, and p38) and a concentration of 10-1,000µg/mL inhibiting TNF-α release (57-85%) in mast cells stimulated with anti-DNP IgE. This is associated with an increase in cAMP concentrations.
Ripe rubus coreanus berry hot water extract given to mice (10-1,000mg/kg) then stimulated with compound 48/80 significantly reduced mortality from 100% within an hour in control down to 20% with 100mg/kg and abolished it at 1,000mg/kg; appearing to be slightly effective if administered (injections) 5-20 minutes after compound 48/80 induced systemic allergic reactions. These beneficial effects were associated with reduced serum histamine and have been replicated elsewhere with intraperitoneal injections where 100mg/kg an hour before compound 48/80 abolished mortality.
Appears to have (surprisingly potent) anti-allergic properties associated with suppressing histamine relase from mast cells; has been confirmed in mice fed the berry extract
10-30mg/kg of 23-HTA or its glycoside (NIF1) appeared to induce anti-rheumatic effects as assessed by Freund's Complete Adjuvant-Induced Edema, and although the aglycone was more effective than NIF1 both were less effective than the reference drug (10mg/kg prednisone).
Possible anti-rheumatic properties, but not overly potent
A water extract of the berries, in HepG2 cells infected with hepatitis B, possesses antiviral effects with an EC50 of less than 128µg/mL and causes 29.4-95.9% inhibition of HBV surface antigen production (measure of hepatitis B DNA replication) in the concentration range of 64-512µg/mL.
When tested against noroviruses and specifically murine norovirus-1 (MNV-1) and feline calicivirus-F9 (FCV-F9) rubus coreanus juice exerted antiviral properties against infected macrophages (3-6% juice in medium) in a concentration dependent manner and with greater potency than the reference drug (cranberry juice). Rubus coreanus juice showed inhibitory properties against plaque formation, viral replication, and viral adhesion/internalization and this was not due to either gallic acid or quercetin.
Appears to hve antiviral effects of possibly relevant significance, pending in vivo evidence
Interactions with Hormones
A filtrate of ripe rubus coreanus extract (anthocyanin containing fraction) given to male rats at 100-500mg/kg over the course of 28 days was able to increase testosterone to 334.5-750% of baseline (lower dose being more effective) while the unripe filtrate at 100mg/kg increased testosterone to 427.6% of baseline (500mg/kg being a nonsignificant increase to 165.5% of baseline). This increase in testosterone was associated with an increase in sperm count, but no alteration in prostatic or seminal vesicle weight were noted.
The first human study to measure testosterone in response to 30g of the freeze dried berries (1.05g total phenolics) failed to find an increase over the course of four weeks in otherwise healthy men.
One overly promising rat study has been followed up by a failure for the berries to increase testosterone in otherwise healthy men
Interactions with Oxidation
47–55% of the antioxidant capacity in rubus coreanus appears to be attributable to the anthocyanin content (which, in isolation, are as potent as vitamin c on a weight basis in a DPPH assay) and when tested against other traditional Korean medicines it appears that the water extract of rubus coreanus is the most effective tested ex vivo (DHCF assays and chemiluminescence); exceeding that of Schisandra chinensis and terminalia chebula.
In a DPPH assay, the unripe berries at 1-10μg/mL appear to be more effective antioxidants than the ripe berries at the same concentration but similar to 100-1,000μg/mL of the ripe berry extract; both aforementioned concentrations were similar to the reference drug of Butylated hydroxytoluene (BHT).
Mostly due to the rich anthocyanin content, rubus coreanus appears to be a highly potent antioxidant compound (similar to how aronia melanocarpa or even blueberry are potent antioxidants due to their anthocyanin content). The tannin structures may also play a significant role
Fermented extracts of the ripe berries (ie. wine) also possess antioxidative properties, as the iron induced increases in lipid peroxidation are concentration dependently reduced with 3.2-100μg/mL of the extract (IC50 of 20µg/mL and fully abolished at 90µg/mL: comparable to pure BHA).
30g of freeze dried berries (conferring just over a gram of total phenolics) to otherwise healthy men over the course of four weeks is able to increase glutathione peroxidase activity (15.3%) which contributed to a reduced serum MDA concentration of 12% suggesting less lipid peroxidation.
Appears to both directly and indirectly (via glutathione peroxidase) suppress lipid peroxidation, and has been confirmed in humans to do so
Peripheral Organ Systems
A hydroalcoholic extract of rubus coreanus, when tested in vitro in the bullfrog lens at the concentration of maximal effects (600μg/mL), was noted to cause a significant increase in the ERG b-wave in both light and dark-adapted eyes (more prominent in the latter) and improved visual sensitivity by one log unit; this was not affected by picrotoxin but was abolished by kynurenic acid, and these events were associated with increased rhodopsin regeneration and reduced lipid peroxidation.
The anthocyanins may benefit eye health, although more research is needed on this topic
10-30mg/kg of either 23-HTA or its glycoside (NIF1) were able to dose-dependently reduce stomach ulceration induced by an ethanol and aspirin combination with less potency coming from NIF1 (5-36% inhibition) than the aglycone (32-61% inhibition) but neither outperforming the reference drug of 100mg/kg Cimetidine (92%); these antiulcer properties were associated with reductions in lipid peroxidation.
The anthocyanins of rubus coreanus (20-80mg/kg) to rats prior to an NSAID induced ulceration (Naproxen) are also able to reduce ulceration to near control levels associated with reductions in lipid peroxidation which was normalized to control at 20-50mg/kg yet reduced lower than control at 80mg/kg.
Both the triterpenoids and the anthocyanins can suppress ulcer formation, with the anthocyanins abolishing lipid peroxidation induced by NSAIDs
In otherwise healthy men consuming 30g of the freeze dried berries daily for four weeks, there was a mild reduction in serum levels of ALP (6%) with no influence on other liver enzymes measured.
May be hepatoprotective in otherwise healthy humans to a very mild degree, mechanisms not really known but possibly tied into a reduction in lipid peroxidation
In rats, 60-180µg/mL (but not 20µg/mL) of the polyphenols from rubus coreanus (isolated from wine via distillation) perfused into the adrenal vein for 90 minutes is able to hinder the acetylcholine and potassium evoked catecholamine release (to around 70-90% of baseline) without influencing basal catecholamine release. This was thought to be partly related to nitric oxide synthesis (possibly downstream of calcium influx into chromaffin cells), since incubation with L-NAME attenuated the effects of the rubus coreanus polyphenolics.
Male Sex Organs
500-4,000µg/mL of the unripe berry extract in isolated rabbit corpus cavernosum is able to dose-dependently reduce phenylephrine induced contractions which is also present in rat corpus cavernosum tissue.
The mechanisms appear to be partly dependent on the endothelium (thought to be nitric oxide signalling) as removal of the endothelium reduced the 37.2-70.2% relaxation (1-3mg/mL) to 13.2-41.9%, and since potassium channel blocking was without effect it is thought that the reduced calcium release from the sarcoplasmic retiulum underlied the observed effects. Rubus coreanus also reduced basal calcium release at concentrations as low as 1-100µg/mL (10-40%) and has been noted to be additive with sildenafil (Viagra; PDE5 inhibitor).
Secondary to suppressing calcium release from the sarcoplasmic reticulum, the berries appear to relax the penile tissue and promote erections in a manner additive with PDE5 inhibitors
Interactions with Cancer Metabolism
Proliferation and Angiogenesis
A methanolic extract of rubus coreanus berries has been noted to inhibit binding of VEGF to its receptor (IC50 of 27µg/mL) and the water extract appeared to inhibit KDR/Flk-1-Fc binding to immobilized VEGF165 (IC50 of 11µg/mL) due to a large polyphenolic known as Sanguiin H-6 which also blocked the latter VEGF165 receptor activation (IC50 300ng/mL) and demonstrated antiprolfierative effects against VEGF in isolated HUVEC cells (IC50 7.4µg/mL).
A large polyphenolic of questionable bioavailability is a potent inhibitor of proliferation
Water and 50% ethanolic extracts (of both ripe and unripe fruits) noted that only the unripe fruits reduce cell viability and more potency with the ethanolic extract in the range of 100-400µg/mL in both DU145 and LNCaP prostatic cancer cells associated with a reduction in Bcl-2 and Bcl-xL with an increase in Bax.
General and somewhat uneventful apoptosis in prostate cancer cells; practical significance unknown
The triterpenoid structure 23-hydroxytormentic acid (23-HTA), when fed to rats at 10mg/kg daily for two weeks prior to a cisplatin injection, appears to mostly preserve glutathione concentrations in the kidney while attenuating the increase in lipid peroxidation (20.4% attenuation) and hydroxyl radicals (41.3%) while NIF1 was ineffective; this is thought to be related to a preservation in Nrf2 signalling seen in vitro (renal epithelial LLC-PK₁ cells) in a concentration dependent manner between 25-200µM.
The antioxidant properties of this berry reduce the cytotoxic properties of cisplatin, but neither study assessed how selective it was for preserving normal cells versus not preserving cancer cells (there is a potential for antioxidants to preserve both types of cells)
Interactions with Aesthetics
In human fibroblasts treated with UV(B) radiation, a 95% ethanolic extract of the ripe fruits at a concentration of 5-10µg/mL is able to concentration-dependently preserve cell viability (to near normal levels, although 1µg/mL was ineffective) associated with higher collagen and procollagen levels alongside reduced factors that degrade collagen (MMP-1, MMP-8 and MMP-13).
Appears to have protective effects on the skin; potency against other agents and mechanisms are not clear at this moment in time
Sexuality and Pregnancy
Mechanistically, 1,000mg/kg of the unripe fruits (water extract) daily for 56 days noted a near two-fold induction of CREM protein levels in the rat testicle; a group of proteins and gene products highly expressed in male reproductive cells that is reduced and impaired during infertility and positively regulates spermatogenesis.
Supplementation of 100-500mg/kg of an extract from rubus coreanus over 28 days appears to case nonsignificant increases in sperm count with both the ripe (8.9-21.6% increase) and unripe (19.3-22.7% increase) extracts, although there is no reliable increase in seminal motility nor alterations in the weight of sex organs. A higher dose (1,000mg/kg for 56 days) has noted an increase in testicular parameters, but the increases in absolute (4.6%) and relative (5.2%) testicular weight were modest despite the large increase in sperm count (58.7%) and motility (37.2%).
Appears to promote seminal prodution and motility in rats to a surprisingly large degree. However, due to these studies also noting a remarkable increase in testosterone that failed in humans it would be prudent to wait for human studies to see if increased sperm production carries over
Safety and Toxicology
In mice fed rubus coreanus (Specifically, nanoparticle encapsulations) at the dose of 1g/kg bodyweight for 21 days, there were not apparent clinical side-effects associated with supplementation.
No known toxicity associated with the berries at this point in time, although toxicology data is lacking