Burdock (Arctium) is a genus of biennial plants, which belongs to family Asteraceae. Burdock has dark green leaves that can grow up to 70 cm long. They are generally large, coarse and ovate, with the lower ones being heart-shaped. Burdock generally flowers from July through to October, and provide essential pollen and nectar for honeybees around August when clover is on the wane and before the goldenrod starts to bloom. Burdock has prickly heads, which provides an excellent mechanism for seed dispersal.
Burdock Is Used As Food
The taproot of young burdock plants can be harvested and eaten as a root vegetable. While generally out of favour in modern European cuisine, it remains popular in Asia. Burdock root is very crisp and has a sweet, mild, and pungent flavour with a little muddy harshness that can be reduced by soaking julienned or shredded roots in water for five to ten minutes. Immature flower stalks may also be harvested before flowers appear in late spring; their taste resembles that of artichoke, to which the burdock is related. The stalks are thoroughly peeled, and either eaten raw, or boiled in salt water. Leaves are also eaten in spring in Japan when a plant is young and leaves are soft. Burdock is today a soft drink that has long been popular in the United Kingdom, which has its origins in hedgerow mead commonly drunk in the mediæval period. In Europe, burdock root was used as a bittering agent in beer before the widespread adoption of hops for this purpose. In the second half of the 20th century, burdock achieved international recognition for its culinary use due to the increasing popularity of the macrobiotic diet, which advocates its consumption.
Active Ingredients of Burdock
The extracts from different parts of burdock have long been considered to be good for health. They help enhance the body’s immune system and improve metabolic functions. Biological activities and pharmacological functions reported for the Arctium species include antiinflammatory, anticancer, antidiabetic, antimicrobial and antiviral activities. With the advancement of different state-of-the-art analytical techniques, more active ingredients of burdock have been identified over the last decade. The major active ingredients isolated from this herb are: tannin, arctigenin, arctiin, beta-eudesmol, caffeic acid, chlorogenic acid, inulin, trachelogenin 4, sitosterol-beta-D-glucopyranoside, lappaol and diarctigenin. Apart from these compounds, burdock also contains various common nutrients.
Pharmacological Effects of Burdock
- Anti-inflammatory Effects
The extract of burdock has been shown to exhibit anti-inflammatory response by inhibiting degranulation and release of cysteinyl leukotrienes (Cys-LTs) by peripheral blood mononuclear cells (PBMCs). Lappaol F, diarctigenin and arctigenin, found in the seeds or leaves of burdock, are lignans that can inhibit NO production. The excessive production of NO by iNOS is involved in various inflammatory diseases such as rheumatoid arthritis, autoimmune disease, chronic inflammation and atherosclerosis. Arctigenin, a phenylpropanoid dibenzylbutyrolactone lignan, potently inhibits iNOS expression and NO production through suppression of NF-jB activation and inhibition of I-jBa phosphorylation and p65 nuclear translocation in LPS-activated macrophages.
- Anticancer Activities
Arctigenin, an active compound found in the seeds of burdock, has the ability to eradicate nutrient-deprived cancer cells. In addition to its broad spectrum of activities on different cancer cell lines, e.g., PANC-1 and AsPC-1, arctigenin seems to exhibit a highly preferential cytotoxicity to cancer cells that are bathed in glucose-deprived conditions. This is because arctigenin has a potent inhibitory effect on the phosphorylation of Akt, which is stimulated under glucosedeprived conditions. Hence, the rate of glucose formation in cancer cells is decreased, which in turn leads to cell death due to a lack of nutrients. Flavoniod-type antioxidants and some other active polyphenol antioxidants found in the root of burdock may account for the suppressive effects on cancer metastasis. It has been shown that extracts of the root protect cells from toxic substances and lower the mutations of cells.
- Antidiabetic Activity
Burdock has been used to treat diabetes by TCM practitioners. Several studies have suggested that the root or/and fruit are possible parts with hypoglycemic effect. Sitosterol-beta-Dglucopyranoside is considered to be the most potent and efficacious substance among the large profile of active compounds found in the root of burdock. It has demonstrated potent inhibitory effects on alpha glucosidase activities. Alpha glucosidases are involved in the processing of glycoprotein and glycogenolysis.
- Antimicrobial Activity
It has been reported that the lyophilized extract of the leaves of burdock exhibits antimicrobial activity against oral micro-organisms and is most effective against bacteria related to endodontic pathogens such as: Bacillus subtilis, Candida albicans, Lactobacillus acidophilus and Pseudomonas aeruginosa. Chlorogenic acid isolated from the leaves also show restraining effects on Escherichia coli, Staphylococcus aureus and Micrococcus luteus. Therefore, the leaves of burdock may be useful in treating tooth/gum diseases that are related to micro-organisms in the oral cavity. It is also a potential topical remedy for skin problems such as eczema, acne and psoriasis.
- Antiviral Activity
Constituents of burdock have also demonstrated antiviral activity. Phenolic constituents such as caffeic acid and chlorogenic acid possess strong inhibitory effect on herpesvirus (HSV-1, HSV-2) and adenovirus (ADV-3,ADV-11). Arctigenin, one of the lignanoid ingredients, has demonstrated activities against human immunodeficiency virus type-1 (HIV-1) both in vivo and in vitro. These suggest potential uses of these promising natural compounds isolated from burdock to treat infection by these viruses.
Burdock contains many active ingredients (isolated from different parts of the plant) that have been shown to possess many therapeutic effects for the treatment of various diseases. Multiple reports in the literature have demonstrated a wide range of possible clinical uses of this herb, because of its anti-inflammatory, antitumor/cancer, antidiabetic, antimicrobial and antiviral effects. However, it is also essential to be aware of the side effects of burdock including contact dermatitis and other allergic/inflammatory responses that might be evoked by burdock. It is expected that further investigations will lead to a better understanding of some other roles that burdock play in preventing and treating of human diseases, as well as the potential adverse effects and toxicity of the herb.
Reference:
Chan, Y.S.; Cheng, L.N.; et al. A review of the pharmacological effects of Arctium lappa (burdock). Inflammopharmacology, 2011, 19(5):245-254.
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