Various
water-soluble derivatives of fullerene-C60 (
C60) have been developed as detoxifiers for
reactive oxygen species (ROS), whereas
C60 incorporated in
liposome (Lpsm) has not been reported yet. We prepared the liposome-fullerene (0.2%
aqueous phase, Lpsm-Flln) which was composed of
hydrogenated lecithin,
glycine soja (
soybean)
sterols, and
C60 in the weight ratio of 89.7:10:0.3, then examined the photocytotoxicity and
bacterial reverse
mutagenicity, as comparing with the Lpsm containing no
C60. Photocytoxicity of Lpsm-Flln or Lpsm was examined using Balb/
3T3 fibroblastic cells at graded doses of 0.49-1000 mug/mL under the condition of UVA- or sham-irradiation. The cells were
irradiated with UVA (5 J/cm(2), 320-400 nm, lambda(max) = 360 nm) at room temperature for 50 min. The resultant cell viability (% of control) did not decrease dose-dependently to 50% or less regardless of the UVA-irradiation. These results show that Lpsm-Flln or Lpsm does not possess photocytotoxicity to Balb/
3T3 fibroblasts, and Lpsm-Flln may not exert a UVA-catalytic ROS-increasing action. A possibility for the
reverse mutation by Lpsm-Flln or Lpsm was examined on four histidine-demanding strains of
Salmonella typhimurium and a tryptophan-demanding strain of
Escherichia coli. As for the dosages of Lpsm-Flln or Lpsm (313-5000 mug/plate), the dose-dependency of the number of
reverse mutation colonies of each strain did not show a twice or more difference versus the negative control regardless of the
metabolic activation, and, in contrast, marked differences for five positive controls (
sodium azide, N-ethyl-N'-nitro-N-nitrosoguanidine, 2-nitrofluorene,
9-aminoacridine, and 2-aminoanthracene). The
growth inhibition of
bacterial strains and the deposition of Lpsm-Flln or Lpsm were not found. As a result, the
bacterial reverse
mutagenicity of Lpsm-Flln or Lpsm was judged to be negative under the conditions of this test. Thus, Lpsm-Flln and Lpsm may not give any significant biological
toxic effects, such as photocytotoxicity and
bacterial reverse
mutagenicity.
