DNA damage and susceptibility to oxidative damage in lymphocytes: effects of carotenoidsin vitroandin vivo

Abstract

Reports on the effects of carotenoids are conflicting. The present paper examines similarities and differences from contiguous studies in vitro and in vivo. Single-cell gel electrophoresis was used to measure the frequency of single-strand breaks (SSB) in the cell line MOLT-17 (as a model system) and human peripheral blood lymphocytes (PBL). MOLT-17 cells were supplemented with b-carotene, lutein or lycopene at a range of concentrations (0·00-8·00 mmol/l) using a liposome delivery method. Uptake was dose-dependent. b-Carotene concentration in the media had no effect on SSB in control cells, but incubation with lycopene or lutein (. 2·00 mmol/l) increased the numbers of SSB in control cells. MOLT-17 DNA was less susceptible to oxidative damage (100 mmol H 2 O 2 /l, 5 min, 4 8C) following incubation with carotenoids between 0·50 and 1·00 mmol/l; at . 1·00 mmol/l the effects were ambiguous. Apparently healthy male volunteers supplemented their habitual diets with lutein, b-carotene or lycopene (natural isolate capsules, 15 mg/d, 4 weeks) in three independent studies, raising plasma concentrations to different extents. Lycopene and lutein had no effect on SSB in control PBL or following oxidative challenge. However, increased plasma b-carotene was associated with more SSB in control cells whilst PBL DNA resistance to oxidative damage ex vivo was unaffected. These results suggest that the carotenoids are capable of exerting two overlapping but distinct effects: antioxidant protection by scavenging DNA-damaging free radicals and modulation of DNA repair mechanisms.Carotenoids: DNA damage and repair: Single-cell gel electrophoresis: Peripheral blood lymphocytes

Evaluation of antigenotoxic effects of carotenoids from green algae Chlorococcum humicola using human lymphocytes

“…毬-Carotene and flavonoids have been reported to prevent DNA damage against H 2 O 2 in human lymphocytes assessed by the comet assay [30] .…”

“…The pellet was aspirated gently and mixed with the fixative evenly using a Pasteur pipette. The tubes were incubated at 4 曟 for at least 30 min, after which the fixative was removed by centrifugation. The pellet was washed well 3-4 changes of fixative till a clear supernatant was obtained.…”

Astaxanthin prevents in vitro auto-oxidative injury in human lymphocytes

“…Not rare, non-provitamin A carotenoids such as lutein, lycopene, and astaxanthin are as active, and at times even more efficient, than β-carotene in enhancing cellmediated and humoral immune responses in animals and humans (Chew and Park 2004). However, uptakes of lutein, β-carotene, and lycopene by MOLT-17 lymphocytes were proven to be both carotenoidspecific and dose-dependent (Astley et al 2004). Dietary lutein consistently inhibits the growth of mammary tumors in mice and also prevents tumorinduced changes in subclasses of T-cell population, including Th, Tc, and IL-2R+T cells (Chew et al 1996).…”

β-Carotene and angiogenesis

“…β-Carotene, similarly to other carotenoids, is a potent scavenger of free radicals, protecting against cell damage during oxidative stress [37]. The down-regulation of BAX, and up-regulation of HO-1 genes by β-carotene ( [38], this issue) confirm the protective activity of β-carotene toward endothelial progenitors.…”