Drug Discov Ther. 2011;5(1):18-25. (DOI: 10.5582/ddt.v5.1.18)
Purification of innate immunostimulant from green tea using a silkworm muscle contraction assay.
Dhital S, Hamamoto H, Urai M, Ishii K, Sekimizu K
A polysaccharide was purified from a hot water extract of green tea leaves by measuring the immunostimulatory activity in silkworm larvae. Nuclear magnetic resonance and chemical analysis of acid hydrolysates revealed that the purified substance possessed a backbone containing polygalacturonic acids with methyl ester residues. Treatment with β-glucanase attenuated the muscle contraction activity of the purified sample, suggesting that the β-glucan structure, probably as a branched form, was required for its activity. The purified fraction stimulated the production of interleukin-6 by mouse peritoneal macrophages. These results suggest that measuring immunostimulation in silkworm larvae is useful for evaluating innate immunostimulants from various sources.