Radioprotective effects of antioxidative plant flavonoids in mice

Evaluation of Athrixia bush tea for cytotoxicity, antioxidant activity, caffeine content and presence of pyrrolizidine alkaloids

“…Marnewick et al (2000) concluded that honeybush and rooibos herbal teas, in addition to being good dietary sources of natural antioxidants to counteract the damaging effects of free radicals, may also protect against mutagenesis. Shimoi et al (1996) suggested that plant flavonoids, which show potent activity in vitro, also function as antioxidants in vivo, and their protective effects may be attributed to their scavenging ability towards free radicals. However, further investigation is required to clarify the mechanism of action of plant flavonoids in vivo (Shimoi et al, 1996).…”

“…Shimoi et al (1996) suggested that plant flavonoids, which show potent activity in vitro, also function as antioxidants in vivo, and their protective effects may be attributed to their scavenging ability towards free radicals. However, further investigation is required to clarify the mechanism of action of plant flavonoids in vivo (Shimoi et al, 1996). It is known that flavonoids possess other biological activities that may or may not be related to their radical scavenging capacity.…”

A review of the bioactivity of south African herbal teas: rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia)

“…Pretreatment with 0.05-0.1% rooibos 1.0 mL daily for 28 days also significantly reduced MNRET frequencies 24-48 h after induction by either MMC or B(a)P. However, the 28 day pretreatment with rooibos tea had no apparent antimutagenic effects on 1.5 Gy γ-ray induced damage. A single gastric intubation of rooibos tea at 1.0 mL per mouse 2 h prior to γ-ray irradiation (1.5 Gy) did significantly reduce the frequency of MNRET in a different study (Shimoi et al, 1996). A flavonoidcontaining fraction, including luteolin and quercetin, isolated from rooibos tea also showed anticlastogenic activity in this experiment (n = 5) with a marked reduction in MNRET induction by γ-ray.…”

“…Sasaki et al (1993) and Shimoi et al (1996) examined the antimutagenic effects of rooibos in mice. Both studies employed the same preparation method: 50 g dried leaves in 1.5 L boiling water for 15 min.…”

Normal Tissue Protectors Against Radiation Injury

“…Flavonoids: Flavonoids are polyphenolic compounds, present in many edible plants, and are good antioxidants. A number of flavonoids (genistin, quercetin, luteolin and green tea flavonoids) were found to reduce the frequency of micronuclei induction in peripheral blood cells in irradiated mice 51 ; their radioprotective effect has been correlated to their antioxidant activity 52 . Extracts prepared from Podophyllum hexandrum and Hippophae rhamnoides have been studied extensively for their ability to render in vivo radioprotection.…”