Bayberry is a common name for plants in the genus Myrica encompassing up to 50 species. It contains tannins that confer its mechanism of action. Traditionally, bayberry was used as a beverage due to its stimulant and tonic properties. The parts used for therapeutic purposes include the bark, leaves, and roots. However, the root bark is the essential part as it contains biologically active compounds including, triterpenes (taraxerol, taraxeron, and myrikadiol), flavonoids, tannins, and phenols. For instance, the dried bayberry root has traditionally be used as a nasal astringent to contract and dry tissues in the sinus cavity in order to dry the secretions. One of the flavonoids known as myricetin is specific to this genus. Other constituents include vitamin C, potassium, starch and calcium.
The main functions exhibited by Myrica species include astringent, antibiotic, antispasmodic, expectorant, diaphoretic, tonic and stimulant. The presence of high concentrations of tannins in the root bark of the bayberry plays a role not only in the protection against infection but also tightening of the mucous membranes.
Myricetin gives bayberry ability to prevent invasion by foreign bodies. In vitro studies have shown that red bayberry extract suppresses the growth and virulence gene expression of bacteria such as Vibrio cholerae. The dichloromethane extract of leaves of Myrica Serrata has also been shown to inhibit the growth of Bacillus subtilis and Escherichia coli in vitro. It promotes sweating that flushes out toxins and helps lower the fever as well. However, potency to treat particular infections is unclear. The bacteriostatic activity of C-methylated dihydrochalcones one of the constituents of Myrica has also contributed to its immune supporting function. Additionally, laboratory studies have shown the role of mycetrin in the stimulation of bile flow that may be useful in the management of conditions related to the liver and gallbladder. Myricetin also exhibits pain relieving effects in vivo. A root extract experimented on animal models demonstrated analgesic activity.
Notably, most of the health benefits are also due to the plant's astringent properties. The astringent properties assist in the management of respiratory symptoms such as coughing. Besides, Bayberry shows potency in the management of gastrointestinal inflammation. It supports the digestive and respiratory systems through maintenance of inflammation. The tannins component play a significant role in the regulating of the inflammatory processes. This function is mainly beneficial to the gastrointestinal system.
Cyanidin-3-O-glucosidase present in Chinese bayberry fruit regulates normal cell replication. Scavenging activity reduced cell proliferation, decreased cell adherence and induced abnormal morphological changes similar to apoptosis. Chinese bayberry fruit extract(CBFE) also alleviates oxidative stress thus inhibiting 1,2-dimethylhydrazine(DMH)-induced intestinal aberrant crypt foci (ACF) in rat colon carcinogenesis. This is due to the high content of phenolic compounds.
Bayberry bark is also used topically to manage the wound care process. Bruises respond well to the oil of bayberry. Direct application of a decoction on chronic sores or varicose veins is also beneficial. However, the species also show anticoagulant activity. In vivo studies with myricetin, has shown that it shows increases clotting time. Additionally, ant thrombin activity interferes with coagulation as well.
Bayberry is also used for the management of mouth and gum related problems. The incorporation of bayberry bark root powder in toothpaste preparations is one of the applications in the contemporary world.
The recommended dosage in synthetic preparations is up to 0.5g per day. Bayberry has an emetic function in high doses which functions as a treatment for poisoning such as in case of narcotic poisoning. However, excessively high doses can have adverse effects as a result of mineralocorticoid imbalance between sodium and potassium, resulting in fluid retention and hypertension in the long-run. Although safe, it is not recommended for pregnant or breastfeeding children or a child as it is a strong herb.