Rubus coreanus, commonly known as Korean black raspberry or bokbunja, is a species of the Rubus genus in the Rosaceae family. Native to East Asia, particularly Korea, China, and Japan, it is renowned for its edible, dark purple to black fruits that resemble raspberries.

Botanical Classification:

• Kingdom: Plantae
• Order: Rosales
• Family: Rosaceae
• Genus: Rubus
• Species: R. coreanus

Plant Characteristics:
Rubus coreanus is a deciduous, perennial shrub characterized by its arching stems and compound leaves. The plant typically grows 1 to 2 meters in height and has thorny stems. The leaves are palmate with serrated edges. The flowers are white to pink and are usually small and clustered. The fruit, known for its deep color and distinctive flavor, is an aggregate of drupelets, typically harvested in late summer to early autumn.

Chemical Composition and Structure:
The fruit of Rubus coreanus is rich in various bioactive compounds:

Anthocyanins: These pigments contribute to the fruit's dark color and have antioxidant properties.

Polyphenols: Including flavonoids and phenolic acids, which provide antioxidant, anti-inflammatory, and antimicrobial benefits.

Vitamins: High in Vitamin C and other essential vitamins.

Minerals: Contains significant amounts of potassium, calcium, and magnesium.

Dietary Fiber: Promotes digestive health.

How to Cultivate It:

• Climate: Prefers temperate climates with well-defined seasons. It requires a cold period to induce dormancy.
• Soil: Thrives in well-drained, loamy soils with a slightly acidic to neutral pH.
• Sunlight: Requires full sun to partial shade.
• Watering: Regular watering is essential, particularly during dry periods, but overwatering should be avoided to prevent root rot.
• Pruning: Regular pruning helps maintain plant health and productivity by removing dead or diseased wood and encouraging new growth.

Uses and Benefits:

• Culinary Uses: The fruit is used in various culinary applications, including jams, juices, wines, and traditional Korean dishes.
• Medicinal Uses: In traditional medicine, it is used for its antioxidant and anti-inflammatory properties. It is believed to aid in digestion and improve overall vitality.
• Cosmetic Uses: Extracts are used in skincare products for their antioxidant and anti-aging effects.

INCI Functions:

Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance. The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants that can be added in the formulation.

Antioxidant agent. Ingredient that counteracts oxidative stress and prevents cell damage. Free radicals, pathological inflammatory processes, reactive nitrogen species and reactive oxygen species are responsible for the ageing process and many diseases caused by oxidation.

Applications:

• Food Industry: Used as a flavoring agent and in the production of beverages and preserves.
• Pharmaceutical Industry: Explored for its potential in developing supplements and functional foods due to its high antioxidant content.
• Agriculture: Cultivated for both commercial and ornamental purposes.

Environmental and Safety Considerations:

• Invasive Potential: Rubus coreanus can become invasive in non-native environments, potentially outcompeting local flora.
• Pests and Diseases: Susceptible to pests such as aphids and diseases like powdery mildew. Proper management practices are necessary to mitigate these issues.
• Safety: Generally considered safe for consumption. However, individuals with allergies to raspberries or related fruits should exercise caution.

References_____________________________________________________________________

Pyeon S, Kim OK, Yoon HG, Kim S, Choi KC, Lee YH, Lee J, Park J, Jun W. Water Extract of Rubus coreanus Prevents Inflammatory Skin Diseases In Vitro Models. Plants (Basel). 2021 Jun 17;10(6):1230. doi: 10.3390/plants10061230. PMID: 34204204; PMCID: PMC8235380.

Abstract. Atopic dermatitis (AD) is a chronic inflammatory skin disease caused by immune hypersensitivity reaction. The cause of AD is unclear, but its symptoms have a negative effect on quality of life; various treatment methods to alleviate these symptoms are underway. In the present study, we aimed to evaluate in vitro antioxidant and anti-inflammatory effects of Rubus coreanus water extract (RCW) on AD. Total phenolic compounds and flavonoid content of RCW were 4242.40 ± 54.84 mg GAE/g RCE and 1010.99 ± 14.75 mg CE/g RCW, respectively. RCW reduced intracellular reactive oxygen species level and increased the action of antioxidant enzymes, such as catalase, superoxide dismutase, and glutathione peroxidase in tumor necrosis factor-α (TNF-α)/interferon-γ (IFN-γ)-stimulated HaCaT cells. Moreover, mRNA expression of the pro-inflammatory cytokines, including TNF-α, interleukin-1β, and interleukin-6, was downregulated by RCW in the TNF-α/IFN-γ-stimulated cells. The levels of inflammatory chemokines (thymus- and activation-regulated chemokine; eotaxin; macrophage-derived chemokine; regulated on activation, normal T-cell expressed and secreted; and granulocyte-macrophage colony-stimulating factor) and intercellular adhesion molecule-1 were decreased in the TNF-α/IFN-γ-stimulated HaCaT cells after RCW treatment. Additionally, the mRNA expression levels of filaggrin and involucrin, proteins that form the skin, were increased by RCW. Furthermore, RCW inhibited the nuclear factor kappa-light-chain-enhancer of the activated B cells pathway in the TNF-α/IFN-γ-stimulated HaCaT cells. Collectively, the present investigation indicates that RCW is a potent substance that inhibits AD.

Bhandary B, Lee GH, So BO, Kim SY, Kim MG, Kwon JW, Song JY, Lee HK, Kim HR, Chae SW, Chae HJ. Rubus coreanus inhibits oxidized-LDL uptake by macrophages through regulation of JNK activation. Am J Chin Med. 2012;40(5):967-78. doi: 10.1142/S0192415X12500711. 

Abstract.Oxidized low-density lipoprotein (oxLDL) contributes to atherosclerosis in part by being taken up into macrophages via scavenger receptors and leading to foam cell formation. Herbal compounds that have been used to treat blood stasis (a counterpart of atherosclerosis) for centuries include extracts of medicinal plants in the Rosaceae and Leguminosae families. In this study, we investigated the effect of the unripe Rubus coreanus (Korean black raspberry) fruit extract on oxLDL uptake by murine macrophage cells. In the presence of Rubus coreanus extract (RCE), Dil-labeled oxLDL uptake was inhibited in a dose-dependent manner. SP600125, a specific JNK inhibitor, inhibited the uptake of Dil-oxLDL into macrophages. RCE also inhibited JNK phosphorylation in a time- and dose-dependent manner in macrophages treated with oxLDL. These results indicate that among the mitogen-activated protein kinases, JNK phosphorylation is inhibited by RCE, which is likely the mechanism underlying the RCE-induced inhibition of oxLDL uptake by macrophages.

Kim KJ, Jeong ES, Lee KH, Na JR, Park S, Kim JS, Na CS, Kim YR, Kim S. Unripe Rubus coreanus Miquel Extract Containing Ellagic Acid Promotes Lipolysis and Thermogenesis In Vitro and In Vivo. Molecules. 2020 Dec 16;25(24):5954. doi: 10.3390/molecules25245954.

Abstract. Previously, we demonstrated that a 5% ethanol extract of unripe Rubus coreanus (5-uRCK) and ellagic acid has hypocholesterolemic and antiobesity activity, at least partially mediated by the downregulation of adipogenic and lipogenic gene expression in high-fat diet (HFD)-fed animals. The present study investigated the thermogenic and lipolytic antiobesity effects of 5-uRCK and ellagic acid in HFD-induced obese C57BL/6 mice and explored its mechanism of action. Mice fed an HFD received 5-uRCK or ellagic acid as a post-treatment or pretreatment. Both post-treated and pretreated mice showed significant reductions in body weight and adipose tissue mass compared to the HFD-fed mice. The protein levels of lipolysis-associated proteins, such as adipose triglyceride lipase (ATGL), phosphorylated hormone-sensitive lipase (p-HSL), and perilipin1 (PLIN1), were significantly increased in both the 5-uRCK- and ellagic acid-treated mouse epididymal white adipose tissue (eWAT). Additionally, thermogenesis-associated proteins, such as peroxisome proliferator-activated receptor α (PPARα), carnitine palmitoyl transferase-1 (CPT1), uncoupling protein 1 (UCP1), and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α), in inguinal white adipose tissue (ingWAT) were clearly increased in both the 5-uRCK- and ellagic acid-treated mice compared to HFD-fed mice. These results suggest that 5-uRCK and ellagic acid are effective for suppressing body weight gain and enhancing the lipid profile.

Lee EJ, Yang JH, Choi JG, Chung HS. Augmented Antitumor Effect of Unripe Rubus coreanus Miquel Combined with Oxaliplatin in a Humanized PD-1/PD-L1 Knock-In Colorectal Cancer Mouse Model. Cells. 2022 Sep 14;11(18):2876. doi: 10.3390/cells11182876.

Abstract. Immune checkpoint inhibitors (ICIs) have been shown to be extraordinarily effective in patients with colorectal cancer (CRC). However, the current ICIs still have adverse effects and limited efficacy of ICI monotherapy. We used a natural product to overcome the vulnerability of ICIs and tried a combination therapy with oxaliplatin to enhance the programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) blockade anticancer effect. In the present study, we evaluated the T cell-mediated antitumor immunity with Unripe Rubus coreanus Miquel extract (RCE), which exerts anticancer properties via PD-1/PD-L1 blockade, combined with oxaliplatin in a co-culture cell model and allograft tumor humanized PD-1 mice. We found that RCE plus oxaliplatin apparently activates hPD-1 tumor-infiltrating CD8+ T cells, resulting in elevations of released interleukin-2 (IL-2) and granzyme B (GrB), and kills hPD-L1 MC38 CRC cells. RCE plus oxaliplatin considerably reduced tumor growth in humanized PD-1/PD-L1-expressing mouse MC38 CRC allograft. Moreover, RCE plus oxaliplatin remarkably increased the infiltration of CD8+ T cells in tumor tissues, as well as increasingly produced GrB of tumor-infiltrating CD8+ T cells in the tumor microenvironment. Our study delineated combination therapy with RCE as a PD-1/PD-L1 blockade and oxaliplatin to improve the response to immune checkpoint blockade therapy in conjunction with standard chemotherapy regimens in CRC.