Phellinus linteus (Mesima)
Refers to a medicinal mushroom fungus indigenous to several countries in East Asia, including Japan, Korea, and China. Its colloquial names include Mesima, “meshimaboku” (in Japanese), “song gen” in Mandarin Chinese, and “sanghwang” in Korean. It is often referred to as the “black hoof” mushroom in the English language as a result of its shape, color, and rough texture. Its half-moon or “kidney” shape is characteristic of some other types of common bracket (or “conk”) mushrooms, including the Ganoderma lucidum (also known as reishi or lingzhi) mushroom and the Ganoderma applanatum (otherwise known as the “artist’s conk”) mushroom.
Phellinus linteus typically grows on mulberry trees and is a polypore mushroom, meaning it releases spores from multiple pores on the underside of its fruiting body. It is able to reach an impressive fifteen inches in width, and displays an array of colors from dark brown and black to ruddy orange. The fungus has a long history of medicinal use in the traditions of China, Korea, and Japan, and its uses have been attributed to the successful treatment of ailments as varied as gastrointestinal distress to certain types of cancers. Bioactive extracts from Phellinus linteus are sometimes added to skin care and cosmetic formulations in order to alleviate dermatological irritation and/or inflammation. Some limited research also points to P. linteus as effective in the treatment of hyperpigmentation and other melanistic disorders.
Nine compounds have been isolated and proven to be bioactive (in other words, effective in terms of their anti-cancer, anti-inflammatory, and antioxidant activities) components of the P. linteus mushroom. These include protocateuchic aldehyde (a phenolic aldehyde compound also found in green tea), protocatechuic acid, davallialactone, hypholomine B (a neuraminidase inhibitor), interfungin A (a protein that controls cytokine production in fungi), inoscavin A (a potent antioxidant), caffeic acid (an organic hydroxycinnamic acid found in many plants and fungi), ellagic acid (an organic phenol antioxidant), and hispidin (a precursor to fungal luciferin, a bioluminescent compound).
In Korea, this mushroom is traditionally consumed as a component of brewed tea. However, Phellinus linteus is known to have a bitter or astringent taste. Further, preparations using grain alcohol to derive an alcohol-based tincture concentrate can emphasize the bitter taste of this mushroom. As such many prefer to receive the health benefits of P. linteus by ingesting the mushroom in powdered or capsule form, thus bypassing the bitterness.
A 2014 study published by Immune Network examined the anti-asthmatic effects of Phellinus linteus in an ovalbumin (OVA) laboratory mouse model. Researchers found that oral administration of Phellinus linteus suppressed inflammation in the eosinophilic airway by augmenting Th2 cytokines IL-4, IL-5, and IL-13, eotaxin, and adhesion molecules in lung tissue. These results suggest that Phellinus linteus may be effective as a therapeutic agent in the treatment of bronchial and allergic asthma.
Phellinus linteus has also been demonstrated to be possibly effective in suppressing cell-mediated anaphylactic reaction caused by asthma and allergic rhinitis. A 2006 study published by the Biological and Pharmaceutical Bulletin examined the effects of an aqueous extract of Phellinus linteus in mast cell-mediated anaphylaxis-like reactions. Researchers observed that oral administration of the extract inhibited ear-swelling response and cutaneous anaphylaxis in rats without inducing any toxicity to peritoneal mast cells. The extract also reduced histamine release, suggesting that it may be a potent therapeutic for allergic diseases.
A 2010 study published by International Immunopharmacology evaluated the inhibitory effects of Phellinus linteus in non-obese diabetic (NOD) mice. After oral administration of Phellinus linteus, NOD mice exhibited less pancreatic lymphocyte infiltration than control mice. Polysaccharides isolated from the mushroom also inhibited the expression of inflammatory cytokines (IFN-gamma, IL-2, and TNF-alpha by Th1 cells and macrophages) while upregulating IL-4 expression by Th2 cells in NOD mice. Researchers concluded that Phellinus linteus may inhibit the development of autoimmune diabetes via cytokine regulation.
A 2004 study published by Bioscience, Biotechnology, and Biochemistry yielded similar results. Researchers from KonKuk University and Hoseo University in ChungBuk-Do and ChungNam-Do, South Korea observed the effects of aqueous extracts from Phellinus linteus, Paecilomyces tenuipes, and Cordyceps militaris on insulin resistance in 90% pancreatectomized male Sprague Dawley rats. Results indicated that C. militaris and P. linteus decreased serum glucose levels and decreased insulin resistance (though C. militaris was more effective in decreasing resistance). Conversely, P. tenuipes increased insuling resistance more than placebo in Px rats.
A 2001 study published by Biotechnology Letters evaluated the hypoglycemic effect of a polysaccharide isolated from Phellinus linteus. Researchers found that an extracellular polysaccharide decreased plasma glucose, total cholesterol, and triacylglycerol concentrations in streptozotocin-induced diabetic rats. Conclusions recommend further research in terms of Phellinus linteus’s ability to ameliorate and prevent hyperglycemia in diabetic patients.
Eczema (Atopic Dermatitis)
In a study published by BMC Complementary and Alternative Medicine, researchers explored the immunomodulatory effects of Phellinus linteus on atopic dermatitis (or eczema) in vivo. For the purposes of this study, P. linteus was fractioned into methanol soluble, water soluble, and boiling water-soluble extracts. Results indicated that the water-soluble extract significantly reduced IgE (Immunoglobulin) antibody production in human myeloma U266B1 cells. Further, the water-soluble extract reduced symptoms such as ear swelling, dryness, and erythema and downregulated pathogenic cytokines (IL-4, IL-13, IL-12, and IFN-γ). Researchers concluded that a water-soluble extract of P. linteus may yield a protective effect against atopic dermatitis and possibly other allergic skin disease.
A 2007 study published by the Journal of the American Academy of Dermatology examined the immunomodulatory activity of a P. linteus extract grown on germinated brown rice in treating atopic dermatitis in children. Researchers administered the oral extract to thirty-five patients ages two to fourteen with mild to moderate eczema. After twelve weeks of study, researchers observed significant reductions in mean severity and symptom scores. Further, no adverse effects were observed aside from transient aggravation of skin lesions during the first four weeks of observation.
A clinical review published by Experimental and Therapeutic Medicine explored the anticancer activity of Phellinus linteus based on a series of in vitro and in vivo placebo-controlled trials. Among the studies reviewed was a 2001 trial from Dongguk University in South Korea, which observed both anticarcinogenic and chemoprotective activities in P. linteus extracts cultured as broth and/or mycelia. Research conducted at Dongeui University College of Oriental Medicine expanded upon this observation, revealing that a mycelium extract from P. linteus has the capacity to induce apoptosis in neuroblastima SK-N-MC tumor cell lines. Further, three epidemiological studies based in China, Korea, and Japan respectively demonstrated a possible inverse correlation between P. linteus supplementation and gastrointestinal and breast cancer.
A study published by the British Journal of Cancer explored P. linteus’s anticancer activity in terms of growth suppression of breast cancer cells. Researchers were able to elucidate the molecular mechanisms responsible for cancer cell inhibition – specifically, P. linteus suppressed the invasive behaviors of MDA-MB-231 breast cancer cell lines by restraining urokinase-plasminogen secretion. Further, P. linteus inhibited capillary morphogenesis, an early stage of cancer angiogenesis, by suppressing the secretion of vascular endothelial growth factor from the MDA-MB-231 cell lines.
Another study published by the British Journal of Cancer explored the molecular mechanisms responsible for Phellinus linteus-mediated apoptosis in LNCaP prostate cancer cell lines. The in vivo trial found that high doses of P. linteus activated the androgen receptor-dependent and independent apoptotic pathways in prostate cancer cells.
In a 2010 study published by PLos One, researchers observed the apoptotic effects of Phellinus linteus in athymic nude mice. After injecting P. linteus every other day for twelve days, researchers observed that, while treatment did not prevent the formation of inoculated tumors, it did dramatically inhibit the growth rate of prostatic tumors. Conclusions indicate that P. linteus has the capacity to attenuate tumor growth and possibly cause tumor regression via apoptosis.
A 2002 study published by Cancer Letters explored the cytotoxic mechanism of a protein-bound polysaccharide isolated from Phellinus linteus. Researchers found that P. linteus suppressed the proliferation of SW480 human colon cancer cells via cell cycle arrest at G2/M phase. Further, inhibition of colon cancer cell line production was associated with the suppression of protein cyclin B1 and an increase in the release of cytochrome c. These results indicate the potential of P. linteus to directly induce apoptosis in certain cell lines characteristic of human colon cancer.
A study published by the International Journal of Molecular Science yielded similar results. Researchers from Gachon University and Silla University in Busan, South Korea evaluated the antitumor capabilities of Phellinus linteus in the expression of the difficult-to-treat v-ki-ras2 Kirsten sarcoma. One of the few therapies demonstrating some efficacy in the treatment of this type of colon cancer is called cetuximab, a monoclonal antibody that binds to the epidermal growth factor receptor. For the purposes of this study, researchers prepared an extract of P. linteus grown on germinated brown rice and observed its ability to sensitize KRAS-mutated colon cancer cells to cetuximab. Results indicated that P. linteus combined with cetuximab treatment increased apoptosis and suppressed the KRAS protein. Further, in a follow-up in vitro mouse model, researchers observed that tumor growth was significantly suppressed by combined cetuximab and P. linteus co-treatment.
A recent study (conducted 2017-2018) further elucidated the mechanisms by which P. linteus extract is able to antagonize colon cancer cells. Researchers at The Center for Drug Discovery at Northeastern University in Boston, Massachusetts and the Cancer Molecular Targeted Herbal Research Center at Kyung Hee University in Seoul, South Korea observed that colon cancer cells HCT116 and HT29 were highly susceptible to cell death when exposed a co-dose of P. linteus extract and camptothecin11 (a chemotherapeutic agent). As was the case in the previously discussed study, P. linteus appeared to enhance camptothecin11’s inhibitory effect on tumor growth by degrading cancer cells in S phase of the cell cycle.
Phellinus linteus has been demonstrated to yield some antiviral activity. A 2012 study published by Mycobiology evaluated a culture broth from P. linteus for the presence of viral neuraminidase (which enable viruses to be released from their host cells) inhibitors. Researchers found that the culture broth exhibited significant inhibitory activity via Sephadex LH-20 column chromatography and high-performance liquid chromatography methods. Specifically, organic compounds hispidin and hypholomine B appeared to be primarily responsible for P. linteus’s antiviral capabilities.
Individuals with enlarged prostate should consult a physician and use Phellinus linteus with caution. Limited research has indicated that the mushroom’s side effect profile may include prostatic enlargement.
Phellinus linteus has some contraindications with other medications, specifically drugs that are metabolized by the liver’s cytochrome P450 enzyme system. The fungus may dramatically increase immune function, so individuals using medications that suppress immune function may want to avoid Phellinus linteus supplementation. Phellinus linteus may interact negatively with antibiotics, anticancer agents, antihistamines, anti-inflammatory, and/or cholesterol-lowering medications.