Minoxidil inhibits ocular cell proliferation and lysyl hydroxylase activity.

[resu]

http://www.ncbi.nlm.nih.gov/pubmed/8383644

Could this explain the darkness below the eyes? I would recommend everyone to make a vitamin C tonic (freshly made) to try and counter any possible side-effect.

It doesn't change the pigmentation, so the dark-circle claims are most likely genetic and most are from middle-eastern and other brown people whose dark-circles are a phenotype of their ethnic group.

Abstract

PURPOSE:

To examine the antiproliferative and lysyl hydroxylase-suppressing effects of minoxidil on cultured proliferating and density-arrested human retinal pigment epithelial cells (hRPE) and Tenon's capsule fibroblasts (hTCF).
METHODS:

Proliferating and density-arrested hRPE and hTCF, exposed to minoxidil (0.1-5 mM) for 15 min to 7 days, were examined by proliferation assays, [3H]thymidine incorporation, trypan-blue exclusion, and phase-contrast microscopy. The lysyl hydroxylase-suppressing effects were examined in confluent hRPE exposed to minoxidil (0.01-1 mM) using L-[4,5-3H]-lysine-labeled procollagen substrate and measuring the amount of tritium released as 3H2O after vacuum distillation.
RESULTS:

Minoxidil (0.1-5 mM) inhibited the proliferation of subconfluent cultures of hRPE and hTCF in a dose-dependent manner with a half-maximal effect at 1.5 and 2.5 mM, respectively. The antiproliferative effect, detectable within 24 hr, occurred with a limited exposure period and persisted even after removal of minoxidil from the culture medium. In contrast, 1-5 mM minoxidil had minimal effect on density-arrested hRPE and hTCF. However, at doses above 3 mM, although minoxidil had no effect on the number of density-arrested hRPE, morphologic and viability experiments indicated signs of cytotoxicity. Minoxidil (0.1-1 mM) caused a maximum of 71% reduction in the activity of lysyl hydroxylase, an enzyme needed for stable cross-links in collagen.
CONCLUSIONS:


Minoxidil may be a useful drug for the treatment of conditions such as proliferative vitreoretinopathy and bleb scarring after trabeculectomy, disorders with unwanted cell proliferation and collagen production.

Another interesting study:
http://www.academia.edu/7144779/Effects_of_Minoxidil_Gel_on_Burn_Wound_Healing_in_Rats

Mentioned:

"If tensile strength can be assumed to be directly related to collagen crosslinking, the inhibition of lysyl hydroxylase by minoxidil, as demonstrated to occur in-vitro, apparently did not occur in this in-vivo model."

So don't throw your minoxidil bottles in the bin yet!

 

[EricGerard]

Speaking as an Optometry student here!

The RPE is a layer of cells at the very back of your eye beneath many layers of retina. It serves the purposes of nourishing your photoreceptor cells as well as absorbing excess light that enters the eye and therefore is responsible for reducing glare. Tenon's capsule is the sheath of connective tissue that surrounds the white of your eye and serves as the attachment spot for the muscles which allow you to move your eyes. Changes by minoxidil in either the RPE or Tenon's capsule should really have no effect on how the skin looks beneath your eye because these tissues are so far removed from each other. So no, this wouldn't explain why some people note circles beneath their eyes.

 

[resu]

Thanks for the add up. The raccoon type of dark circles are hereditary and usually brown, if you look at old people the dark circles aren't a ring like the hereditary type, if minoxidil inhibits collagen then this would be the type that you would see or just darkness from the sunken skin under and around the eyes, usually bluish.