Acute, subchronic and genotoxicity studies conducted with Oligonol, an oligomerized polyphenol formulated from lychee and green tea extracts

Oligonol is a phenolic product derived from lychee fruit extract and green tea extract, containing catechin-type monomers and oligomers of proanthocyanidins, produced by a manufacturing process which converts polyphenol polymers into oligomers. The safety of Oligonol was assessed in acute and subchronic studies and genotoxicity assays. In a single dose acute study of Oligonol, male and female rats were administered 2000 mg/kg body weight (bw) Oligonol in water by gavage. Oligonol caused no adverse effects and body weight gain and food consumption were within normal range, thus the LD50 of Oligonol was determined to be greater than 2000 mg/kg. A 90 day subchronic study (100, 300 and 1000 mg/kg bw/day, oral gavage) in male and female rats reported no significant adverse effects in food consumption, body weight, mortality, clinical chemistry, haematology, gross pathology and histopathology. Similarly, no adverse effects were observed in mice fed diets providing 2, 20 or 200 mg/kg bw Oligonol or 200 mg/kg bw lychee polyphenol for 90 days. Oligonol did not show any potential to induce gene mutations in reverse mutation tests using Salmonella typhimurium TA98, TA100, TA1535, TA1537 and Escherichia coli WP2uvrA strains. Oligonol did not induce chromosomal aberrations in cultured Chinese hamster lung cells, but it showed increased polyploidy. In a micronucleus assay in mice, Oligonol did not induce any micronuclei or suppress bone marrow, indicating it does not cause chromosome aberrations. The results from these safety studies and previous reports support the safety of Oligonol for human consumption.