Safety evaluation of Chlorella sorokiniana strain CK-22 based on an in vitro cytotoxicity assay and a 13-week subchronic toxicity trial in rats

Safety assessment of Synechococcus sp. PCC 7002 biomass: genotoxicity, acute and subchronic toxicity studies

Synechococcus sp. PCC 7002 has the potential to be used as a new resource of food owing to its nutritional and functional benefits. However, little information has been published regarding the safety of Synechococcus sp. PCC 7002 biomass (SynB). The present study assessed genotoxicity, acute and subchronic toxicity of SynB for the first time. SynB did not show any genotoxicity based on the Ames test, mammalian erythrocyte micronucleus test, and mouse primary spermatocyte chromosome aberration test. SynB administered by gavage in mice at a dose of 10 g per kg body weight did not induce death or toxicity based on the acute toxicity study, indicating the median lethal dose value of SynB was over 10 g per kg body weight. In the 90-day subchronic toxicity study, no treatment-related mortality or clinical sign was noted with SynB at doses of 5 and 10 g per kg body weight in mice, and there was no adverse effect of SynB on food consumption, organ coefficients, blood biochemistry, urinalysis and histopathology. The Non Observed Adverse Effect Level for SynB in female and male mice was not less than 10 g per kg body weight per day based on subchronic toxicity. These results support the safe use of SynB as a new food raw material.

Treatment with Modified Extracts of the Microalga Planktochlorella nurekis Attenuates the Development of Stress-Induced Senescence in Human Skin Cells

More recently, we have proposed a safe non-vector approach to modifying the biochemical profiles of the microalga Planktochlorella nurekis and obtained twelve clones with improved content of lipids and selected pigments and B vitamins and antioxidant activity compared to unaffected cells. In the present study, the biological activity of water and ethanolic extracts of modified clones is investigated in the context of their applications in the cosmetic industry and regenerative medicine. Extract-mediated effects on cell cycle progression, proliferation, migration, mitogenic response, apoptosis induction, and oxidative and nitrosative stress promotion were analyzed in normal human fibroblasts and keratinocytes in vitro. Microalgal extracts did not promote cell proliferation and were relatively non-cytotoxic when short-term treatment was considered. Long-term stimulation with selected microalgal extracts attenuated the development of oxidative stress-induced senescence in skin cells that, at least in part, was correlated with nitric oxide signaling and increased niacin and biotin levels compared to an unmodified microalgal clone. We postulate that selected microalgal extracts of Planktochlorella nurekis can be considered to be used in skin anti-aging therapy.

Safety assessment of a lyophilized biomass of Tetraselmis chuii (TetraSOD®) in a 90 day feeding study

TetraSOD® is a powder of the lyophilized biomass of Tetraselmis chuii strain CCFM03, a marine microalga with a history of use as feed in the aquaculture industry. Recently, algae including T. chuii have been investigated for their potential use in human food. However, published toxicology studies addressing the safety of T. chuii as a food ingredient are not available. To address this issue, the toxicity of TetraSOD® was evaluated using a 90-day oral toxicology study in rats following the Organisation for Economic Co-operation and Development (OECD) test guideline 408. No treatment-related mortality or clinical signs were noted with TetraSOD® at doses of 625, 1667, or 2500 mg/kg/day. Additionally, no adverse effects on haematology, blood biochemistry, organ weights, gross or histopathology were observed. The Non Observed Adverse Effect Level (NOAEL) for TetraSOD® is greater than the highest tested dose of 2500 mg/kg/day.

A Toxicological Evaluation of Chlamydomonas reinhardtii, a Green Algae

There is a current worldwide interest in developing novel sustainable nonanimal nutritional sources, and one such source is the green algae Chlamydomonas reinhardtii, the only green algae that has been studied as a model organism for many biological processes ranging from photosynthesis to flagellar movement. However, its potential as a safe nutritional source for use in various foods has not been thoroughly investigated. To assess the safety of C reinhardtii for use as a nutritional human food ingredient, in accordance with internationally accepted standards, the genotoxic potential and repeated-dose oral toxicity of the dried C reinhardtii (THN 6) algal biomass was investigated. The following studies were conducted: (1) a bacterial reverse mutation test, (2) an in vitro mammalian chromosomal aberration test, (3) an in vivo mammalian micronucleus test, and (4) a 28-day repeated-dose oral toxicity study in rats. No evidence of mutagenicity or genotoxic activity was observed in the first 3 tests under the applied test systems. In the 28-day study, male and female Hsd.Han Wistar rats were exposed to daily doses of 0, 1,000, 2,000, and 4,000 mg/kg bw by gavage. Following 28 days of continuous exposure, no mortality or treatment-related adverse effects were observed and no target organs were identified. Therefore, a no observed adverse effect level was concluded as 4,000 mg/kg bw/day, the highest dose tested.