Illinois researchers are examining extracts from the fruit of four members of the heath family for their potential anticancer activity.
Cranberry (Vaccinium macrocarpon), bilberry (V. myrtillus), low-bush blueberry (V. angustifolium), and lingonberry (V. vitis-idaea) are rich sources of flavonoids, compounds known to have antioxidant and antitumor activity. Extracts of bilberry and lingonberry have inhibited the growth of cancer cells in laboratory experiments. In an attempt to identify anticarcinogenic constituents, researchers at the Department of Food Science and Human Nutrition at the University of Illinois at Urbana tested fruit extracts for their ability to neutralize poisons and inhibit an enzyme (ornithine decarboxylase) that has been shown to contribute to tumor promotion.
Although crude extracts of the fruits didn’t promote detoxification, a constituent of bilberry extracted with hexane and chloroform solvents did. The crude extracts of low-bush blueberry, cranberry, and lingonberry did inhibit the tumor-promoting enzyme, however, and the researchers attributed this result to flavonoids called proanthocyanidins. They are now studying the potential of these compounds to inhibit specific stages of chemically induced cancers in laboratory animals.(1)
The leaves of common thyme (Thymus vulgaris) may protect cells and tissues from harmful oxidation, according to a report from Japan. Antioxidants protect the body from harmful chemical reactions by neutralizing free radicals. The Japanese food industry is interested in herbal alternatives to synthetic antioxidants such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) as food preservatives because their use has been restricted due to their toxicity.
In examining phenolic compounds in thyme leaves, researchers at Fukuyama University and Maruzen Pharmaceutical Company found that two—the flavonoid eriodicytol and a biphenyl component—had extremely strong antioxidant activity. The oxidation of unsaturated fatty acids in cell membranes can lead to a decrease in membrane fluidity and disruption of membrane structure; over the long term, this cellular damage has been associated with coronary arteriosclerosis, diabetes mellitus, and aging, as well as cancer development. Because this preliminary study showed promising results, the researchers are moving on to studies using living organisms.(2)
The familiar witch hazel sold in U.S. pharmacies as an astringent is prepared by steam-distilling the twigs of Hamamelis virginiana and adding alcohol as a preservative. In Europe, where the extract contains both the twigs and leaves of witch hazel, it is used as both an astringent and an anti-inflammatory to treat minor skin injuries, eczema, burns, varicose veins, and other topical ailments.
Witch hazel’s healing qualities formerly were attributed to tannins, compounds also found in many other plants, but now researchers believe that other compounds may be responsible not only for these therapeutic benefits but also for the herb’s newly recognized ability to fight topical viruses such as herpes simplex.
Researchers at the Dr. Willmar Schwabe Company and the Johann Wolfgang von Goethe University in Germany found that a fraction of the European extract containing mostly proanthocyanidins (see “Anticancer Fruits”) inhibited the herpes simplex virus and also reduced inflammation to a greater degree than did fractions high in specific tannins.
Such studies help manufacturers improve extraction processes in an effort to make their products as effective as possible.(3)
(1) Bomser, J., et al. “In Vitro Anticancer Activity of Fruit Extracts from Vaccinium Species”. Planta Medica 1996, 62(3):212–216.
(2) Haraguchi, H., et al. “Antiperoxidative Components in Thymus vulgaris”. Planta Medica 1996, 62(3):217–221.
(3) Erdelmeier, C.A.J., et al. “Antiviral and Antiphlogistic Activities of Hamamelis virginiana Bark”. Planta Medica 1996, 62(3):241–245.