Rice proteins have been well documented for their antioxidative properties and bioactive components
that improve the ECM. Hyaluronic acid is a long unbranched polysaccharide component of the ECM.
Endogenously, it is synthesized by three types of hyaluronan synthases (HS). Black rice hydrolyzed peptides
have been shown to increase HS expression in keratinocytes in a dose-dependent manner. These
rice-derived proteins, termed Cohibin, also inhibit MMP activity in keratinocytes. Moreover, exogenous
rice wine can decrease homocysteine-induced MMP production in cells. In addition, germinated
brown rice has antioxidant properties and can block cell cycle re-entry as well as cell apoptosis.126
Exogenous hyaluronan can also induce the activity of HS, modifying and strengthening the ECM organization
and function. These molecules stimulate angiogenesis, stimulate skin cell proliferation, and
induce collagen I formation and collagen IV break down to promote scarless healing.
In one recent clinical study, rice bran extracts were entrapped in niosomes and created into gel and
cream formulations. The gel and cream were not irritating, and showed no sign of erythema or edema
on the skin of shaved rabbits. The use of these rice-based cosmeceuticals on 30 volunteers resulted in a
thicker epidermis in a majority of them, and skin lightening, more elasticity, and improvement of roughness
in a minority of the study group.
