Blue-green algae (BGA) have been consumed as food and herbal medicine for centuries. However, 23
safety for their consumption has not been well investigated. This study was undertaken to evaluate 24
in vitro and in vivo toxicity of cultivated Nostoc commune var. sphaeroides Kützing (NO) and Spirulina 25
platensis (SP). Neither NO nor SP contained detectable levels of microcystin (MC)-LA, MC-RR, MC-LW 26
and MC-LR by LC/MS/MS. Cell viability remained 70–80% when HepG2 cells were incubated with 27
0–500 lg/ml of hexane, chloroform, methanol and water-extractable fractions of NO and SP. Four- 28
week-old male and female C57BL/6J mice were fed an AIN-93G/M diet supplemented with 0%, 2.5% 29
or 5% of NO and SP (wt/wt) for 6 months. For both genders, BGA-rich diets did not induce noticeable 30
abnormality in weight gain and plasma alanine aminotransferase (ALT) and aspartate aminotransferase 31
concentrations except a significant increase in plasma ALT levels by 2.5% NO supplementation in male 32
mice at 6 month. Histopathological analysis of livers, however, indicated that BGA did not cause signif- 33
icant liver damage compared with controls. In conclusion, our results suggest that NO and SP are free of 34
MC and the long-term dietary supplementation of up to 5% of the BGA may be consumed without evi- 35
Q1 dent toxic side-effects. 36