Research Highlight

Green bean shield for cancer, AIDS

doi:10.1038/nindia.2012.0 Published online 18 January 2012

New research has shown that pectic polysaccharides isolated from the pods of green beans can boost the production of immune cells. This could be useful for designing drugs to fight immunodeficiency diseases such as AIDS.

Pectic polysaccharides (also known as pectins) are important structural components of higher plant cells, particularly fruits and vegetables, and are used in the food industry as gelling and thickening agents. Such polysaccharides have demonstrated the ability to lower lipid and sugar levels in the blood. In addition, polysaccharides isolated from sweet pepper can inhibit the activity of a protein that aids tumour growth. However, no studies have yet explored the medicinal value of these polysaccharides in widely consumed green beans.

The researchers first isolated a pectic polysaccharide from the pods of green beans (Phaseolus vulgaris L.). They then carried out experiments to study the polysaccharide's efficacy for activating the production of splenocytes and thymocytes in mouse cells. Proliferation of splenocytes and thymocytes is an indicator of immunostimulation. Splenocytes, a type of cell found in the spleen, produce white blood cells to boost the immune system. Thymocytes, a type of cell found in the thymus gland, also produce immunomodulating white blood cells. The researchers checked the polysaccharide's antioxidant activity through its ability to scavenge out 1,1-diphenyl-2-picryl hydrazyl (DPPH), a free radical.

The polysaccharide efficiently aided the proliferation of splenocytes at a concentration of 100 μg ml–1 and thymocytes at a concentration of 25 μg ml–1. It also scavenged the free radical at a concentration of 8 μg ml–1.

"These types of polysaccharides cannot kill cancer cells directly but may be used as an immunomodulating drug to stall carcinogenesis without harming normal cells," says lead researcher Syed S. Islam. They may also be used as nutraceuticals and antioxidant materials, he adds.


  1. Patra, P. et al. Structure elucidation of an immunoenhancing pectic polysaccharide isolated from aqueous extract of pods of green bean (Phaseolus vulgaris L.). Carbohydr. Polymer. 87, 2169-2175 (2012)