Apios americana
Apios americana, sometimes called the potato bean, hopniss, Indian potato, hodoimo, America-hodoimo, cinnamon vine, American groundnut, or groundnut (but not to be confused with other plants sometimes known by the name groundnut) is a perennial vine that bears edible beans and large edible tubers.[2] Its vine can grow to 1–6 m (3.3–19.7 ft) long, with pinnate leaves 8–15 cm (3.1–5.9 in) long with 5–7 leaflets.[2] The flowers are usually pink, purple, or red-brown, and are produced in dense racemes 7.5–13 cm (3.0–5.1 in) in length.[2] The fruit is a legume (pod) 5–13 cm (2.0–5.1 in) long.[2] Botanically speaking, the tubers are rhizomatous stems, not roots.[3] Its natural range is from Southern Canada (including Ontario, Quebec, and New Brunswick) down through Florida and West as far as the border of Colorado.[2] It is a larval host for the Epargyreus clarus.[4]
The tubers are highly palatable with culinary characteristics of a potato, although the flavor can be somewhat nuttier than a potato and the texture can be finer.[5] Studies in rats suggest that raw tubers should not be consumed. They contain harmful protease inhibitors that are denatured by cooking.[6] These tubers contain roughly three times the protein content of a potato (16.5% by dry weight), and the amino acid balance is good with the exception of cysteine and methionine.[7] Apios americana tubers were found to have a protein concentration of 15–30 mg/g (0.24–0.48 oz/lb).[8] This was similar to that of other species in the Apios genus, A. carnea and A. fortunei.[8] However, A. americana had larger levels of genistein than the other two species.[8] The fatty acid content of tubers is approximately 4.2% to 4.6%, with linoleic fatty acids predominating.[9] Thirty-six percent of the fresh weight of a tuber is carbohydrate (primarily starch).[10] The tubers are also an excellent source of calcium and iron.[10] Calcium content is 10-fold greater than a potato and iron is 2-fold greater than a potato, although vitamin C was considerably less than a potato.[10] The tuber and the flower also contain mono and oligosaccharides.[11] The tuber has more monosaccharides and oligosaccharides than the soybean, potato, and sweet potato.[11]
In addition, the tubers appear to have numerous health-promoting factors. Hypertensive rats that were fed powdered tubers as 5% of their total diet had a 10% decrease in blood pressure and also a reduction in cholesterol and triglycerides.[12] It has been shown that the tubers contain genistein and other isoflavones that have various health benefits, including an anti-carcinogenic function against colon, prostate, and breast cancer.[13][14] Genistein-7-O-gentiobioside is a novel isoflavone that is found in the American groundnut.[15] Extract from the American groundnut was shown to drive the anti-oxidative pathway in cells although it did not have anti-oxidative activity itself.[15] Human breast carcinoma MCF-7 cells were pretreated with the extract of A. americana for 24 hours.[15] Subsequent analysis showed an increase in expression of heme oxygenase-1, a protein induced during oxidative stress.[15] The American groundnut, like soybean, is a great source of isoflavone.[15]
Furthermore, a study on A. americana and its flower shows that the flower of the particular plant is not toxic to mice.[16] Consumption of the flower was shown to lower plasma glucose levels in diabetic mice.[16] The flower was shown to have an inhibitory activity on maltose and an anti-hyperglycemic effect in mice, suggesting that not only is it a viable and novel food source for the general population, but also in the prevention of diabetes.
