Saturday, April 16, 2011
As I noted Thursday:
Fruits and vegetables ... contain a lot of beneficial substances in addition to antioxidants (and see this and this).
The links point to the cell-protecting action of the pigments in brightly-colored fruits and veggies such as beta carotenoids (orange and yellow pigments), lycopene carotenoids (a red pigment) and anthocyanins (blue and purple pigments).
Interestingly, plants produce these compounds to protect themselves from damage.
As Kim D. Coder, Professor at the Warnell School of Forest Resources at The University of Georgia notes:
Carotenoids help protect the light gathering system of trees from overexposure to light, from damaging wavelengths of light, and from reactive oxygen problems. The light capturing and processing machinery in a tree revolve around chlorophyll. Light gathering machinery within a leaf is contained inside many micro-containers in each cell. Chlorophyll nets in these micro-containers absorb the energy of light particles with the proper wavelengths, quickly passing their energy to central chlorophylls units. Gathered energy cannot be held long without damaging the chlorophyll molecule or losing the energy back to the environment.
Everywhere along the light gathering nets of a leaf, you will find chlorophyll and carotenoids together. Carotenoids, being tougher than chlorophyll but much less efficient at light gathering, helps protect the valuable but fragile chlorophylls. Carotenoids can capture light particles of certain wavelengths and pass the energy to nearby chlorophylls. This "assessory pigment" role for carotenoids helps to funnel light-gathered energy to the chlorophylls for use. Carotenoids block some of the light that could damage chlorophyll molecules. Carotenoids can also bleed-off excess energy which the chlorophyll system cannot use, but cannot store.
Carotenoids brightly color many tree parts with red, oranges and yellows.
Anthocyanins are water soluble ("watercolor") phenolic pigments dissolved inside leaf cells. Anthocyanins are a group of different colored pigments where each base color changes as the cell environment changes. Anthocyanins generate red, pink, purple and blue colors.
***Anthocyanins filter out ultra-violet (UV) light and protect surrounding tissues from ultra-violet light damage. Bright light stimulates anthocyanin production. Many young tissues are protected with anthocyanins until they have a full complement of pigments and can properly function.