Gen info
• Vigna is a genus of plants in the legume family, Fabaceae, with a pantropical distribution. It is often confused with the genus Dolichos, but the two differ in stigma structure. On last count, the genus contains at least 90 species. (12)
• Vigna are herbs or occasionally sub-shrubs. The leaves are pinnate, divided into 3 leaflets. The inflorescence is a raceme of yellow, blue, or purple pea flowers. Fruit is a legume pod of varying shapes containing seeds.
• Etymology: The genus name Vigna honors Domenico Vigna, a 17th-century Italian botanist and director of the Orto botanico di Pisa. (12) The specific epithet unguiculata derives from Latin, meaning "with a small claw", which reflects the small stalks on the flower petals. (13)
• Vigna unguiculata is a member of the Vigna (peas and beans) genus.
• Despite the common name "yardlong", the pods are actually only about half a yard long.
• Sitaw is one of the plants in the classic lowland Tagalog folk song "Bahay kubo" that celebrates the traditional bamboo and nipa house and the 18 vegetable plants around it - all in this medicinal plant compilation.

Botany
• Sitaw is an herbaceous climbing plant grown for it strikingly long edible pods. Leaves are trifoliate, green, oval and smooth-edged. Flowers are purplish, about 1.5 centimeters long, giving out green and slender yardlong pods.

• Growth form: A climbing, annual vine reaching up to 2 to 4m in length.  Foliage: Leaves are alternately arranged along the stem and are trifoliate, the first two leaflets being asymmetrical in shape with the terminal leaflet being ovate and symmetrical in shape.  Stems: The stems have a twining growth form and are slightly ribbed. Flowers: Flowers are borne on axillary racemes, the flowers being yellowish in color. Fruit: The fruit is a pendant pod, inflated and succulent when immature and dry and constricted when mature. The immature pod is light green with red patches which turns light yellow-brown with brown patches when mature. (Flora & Fauna Web)

Distribution
- Cultivated, not naturalized.
- Widely cultivated in the Philippines for its edible pods and beans.
- Native to Ethiopia, Kenya.

Constituents
- Nutritive analysis per 100 g yielded: (Principle) energy 47 Kcal, carbohydrates 8.35g, protein 2.8 g, total fat 0.40 g, cholesterol 0 mg; (Vitamins) folate 62 µg, niacin 0.410 mg, pantothenic acid 0.055 mg, pyridoxine 0.024 mg, riboflavin 0.110 mg, thiamin 0.107 mg, vitamin A 850 IU, vitamin C 18.8 mg; (Electrolytes) sodium 4 mg, potassium 240 mg; (Minerals) calcium 50 mg, copper 0.048 µg, iron 0.47 mg, magnesium 44 mg, manganese 0.205 mg, phosphorus 59 mg, selenium 1.5 µg, and zinc 0.32 mg. (USDA National Nutrition Data Base) (6)
- Good source of protein, vitamin A, thiamin, riboflavin, iron, phosphorus and potassium. A very good source of vitamin C, folate, magnesium and manganese.

Properties
- Studies have suggested nutritive, antiproliferative, antiviral, antimicrobial, antioxidant properties.

Uses
Edibility
• Pods are eaten fresh or cooked, best when young and slender.
• An popular vegetable crop in South-East Asia.
Folkloric
• No reported folkloric medicinal use in the Philippines.
• Poultice of crushed leave used to heal and bond broken bones. (9)

Studies
• Antiproliferative / HIV-1 Reverse Transcriptase Inhibitory Activity: A lectin with a unique hemagglutinating activity was isolated from Vigna sesquipedalis cv ground bean. The ground bean lectin exhibited mitogenic activity on murine splenocytes. The viability of hepatoma (HepG2), leukemia (L1210 and M1) cells was reduced in the presence of ground bean lectin while also exerting an inhibitory activity toward HIV-1 reverse transcriptase IC50. (2)
• Lipids / Phytoconstituents: Dried edible seeds of six varieties of V unguiculata and two of P vulgaris were analyzed for chemical constituents. The paper highlights safety and nutritive values. Some composition values for VU were: protein 20.5-31%, fat 1.14-3.03%, fiber 1.70 -4.5%, carbohydrate 56-65.7%. Potassium was the most abundant element inn the seeds. (3)
• Antioxidant and Phenolic Activities: Study evaluated the antioxidant activities and total phenolic and flavonoid contents of ten ethanolic edible plants with varieties of colors. Results showed the purple color of plants, including ethanolic extracts of Brassica oleracea and Vigna sesquipedalis (4.52 ± 0.01%) significantly showed the highest TPC and TFC compared with same species and other species with different colors. Both presented with potential as source of cheap phenolics and flavonoids as antioxidant compounds. (7)
• Sesquin / Antimicrobial Peptide / Inhibitory Effect on Tumor Cells and RT: An antifungal peptide, sesquin, was isolated from ground beans (V. sesquipedalis cv.). The peptide exerted antifungal action (Botyris cinerea, F. oxysporum, and Mycossphaerella arachidicola) and antibacterial activity (E. coli, P. vulgaris, Mycobacterium phlei and B. megaterium). Peptide also exhibited antiproliferative activity toward breast cancer (MCF-7) cells and leukemia M1 cells, together with some inhibitory activity towards HIV-type 1 reverse transcriptase. (8)
• Antioxidant / Nutritional / Seeds: Study evaluated the nutritional and antioxidant properties of seeds of V. unguiculata subsp. sesquipedalis. The methanolic seed extract showed concentration-dependent radical scavenging activities against DPPH, ABTS, NO, OH and FRAP. Seed extract yielded nutritional and antioxidative phytochemicals viz., alkaloids, saponins, tannins, phenolics, flavonoids, ascorbic acid, etc. HP:C-MS yielded phenolic derivatives (gallic acid, pyrogallol, chlorogenic acid, catechol, etc.) that may contribute to antioxidantive property of the seeds. (11)
• Effect of Different Pods and Seed Colors on Nutritional Content and Antioxidant Capacities: Study evaluated the nutritional qualities, secondary metabolites, and antioxidant activities of 14 field-grown yardlong beans with differences in pod and seed colors. Analysis of variance significant effects on total phenol, DPPH, ABTS, and reducing power activities. In contrast, nutritional parameters, except for dietary fiber, were not significantly affected by pod and seed color variation. Consuming yardlong beans of different pod and seed colors may not affect overall nutrient intake. In general, yardlong beans with green pods and black seeds are good sources of antioxidants. Further metabolomic and genomics studies are suggested. (14)


Availability
- Seasonal produce.
- Seeds in the cybermarket.

Additional Sources and Suggested Readings
(1)
Vigna unguiculata / Wikipedia
(2)
Purification of a trypsin-stable lectin with antiproliferative and HIV-1 reverse transcriptase inhibitory activity / Biochemical and Biophysical Research Communications • Volume 301, Issue 2, 7 February 2003, Pages 545-550 / DOI: 10.1016/S0006-291X(02)03080-2
(3)
Lipids and other constituents of Vigna unguiculata and Phaseolus vulgaris grown in northern Nigeria /A Onwuliri and J A Obu / Food Chemistry • Volume 78, Issue 1, July 2002, Pages 1-7 • doi:10.1016/S0308-8146(00)00293-4
(4)
Vigna unguiculata subsp. (L.) Walp. subsp. sesquipedalis (L.) Verdc. / Chinese name / Catalogue of Life, China
(5)
Sorting Vigna names / Porcher Michel H. et al. 1995 - 2020, Sorting Vigna Names. Multilingual Multiscript Plant Name Database   (M.M.P.N.D)  - A Work in Progress. School of Agriculture and Food Systems. Faculty of Land & Food Resources. The University of Melbourne. Australia. 
(6)
Yard long beans nutrition facts / Nutrition-And-You
(7)
Antioxidant Activities and Total Phenolic Content of Multi-colored Fruits and Vegetables in Thailand / Sirikhwan Tinrat* / KKU Res.j. 2016; 21(1) : 1-11
(8)
Sesquin, a potent defensin-like antimicrobial peptide from ground beans with inhibitory activities toward tumor cells and HIV-1 reverse transcriptase/ Wong JH, Ng TB / Peptides, 2005, 26(7): pp 1120-1126 / DOI: 10.1016/j.peptides.2005.01.003
(9)
Vigna unguiculata sesquipedalis / Useful Tropical Plants
(10)
Vigna unguiculata subsp. sesquipedalis / KEW: Plants of the World Online
(11)
Nutritional and Antioxidant Properties of the Seeds of Vigna unguiculata subsp. sesquipedalis (L.) Verdc. – An Underutilized Legume of West Bengal / Sabnam Firdousi, Rakhi Chakraborty, Swarnendu rooy / NBU Journal of Plant Sciencesm 2021; Vol 13: pp 27-41 / ISSN: 0974-6927
(12)
Vigna / Wikipedia
(13)
Cowpea / Wikipedia
(14)
Nutritional Qualities, Metabolite Contents, and Antioxidant Capacities of Yardlong Beans (Vigna unguiculata subsp. sesquipedalis) of Different Pod and Seed Colors / Yu-Mi Choi, Myoung-Jae Shin, Taye Desta et al / Antioxidants (Basel), 2024; 13(9): 1134 / DOI: 10.3390/antiox13091134

DOI: It is not uncommon for links on studies/sources to change. Copying and pasting the information on the search window or using the DOI (if available) will often redirect to the new link page. (Citing and Using a (DOI) Digital Object Identifier)