Skin Anti-aging Assays of Proanthocyanidin Rich Red Rice Extract, Oryzanol and Other Phenolic Compounds

Abstract

Red rice is a variety of rice that has more nutritious than white or brown rice. It is also a good source of many potent anti-aging phytochemicals. However, the compounds in red rice extract that exhibit skin anti-aging properties have not been investigated. In this study, the main bioactive compounds in red rice extract (RRE) including proanthocyanidin, catechin, hydroxybenzoic acid, vanillic acid and oryzanol were studied in order to determine their anti-skin aging properties. The effects on skin degradation were assessed by inhibitory enzymatic activity against collagenase and matrixmetalloproteinase-2 (MMP-2). The production levels of collagen and hyaluronic acid obtained from human skin fibroblasts were determined by ELISA. Anti-melanogenesis activity of the bioactive compounds were investigated in B16-F10 mouse melanoma cells. The activity of collagenase and MMP-2 was strongly inhibited by proanthocyanidin and catechin, while hydroxybenzoic acid, vanillic acid and oryzanol had no effect. Moreover, proanthocyanindin and catechin significantly induced collagen and hyaluronic acid synthesis in human fibroblast cells. Proanthocyanidin and oryzanol reduced the melanin content in B16-F10 mouse melanoma cells. Proanthocyanidin, but not oryzanol, significantly decreased cellular tyrosinase activity. However, the bioactive compounds obtained from red rice extract had no effect on mushroom tyrosinase activity. In addition, proanthocynidin and catechin, exhibited strong DPPH radical scavenging activity, whereas oryzanol slightly inhibited this action. Taken together, these results suggest that proanthocyanidin, catechin, and oryzanol are the bioactive compounds in red rice that exhibit the greatest levels of anti-skin aging properties.

Anthocyanins and Proanthocyanidins in Natural Pigmented Rice and Their Bioactivities

“…On the other hand, a study performed involving five different varieties of Thai pigmented rice demonstrated that all rice crude extracts with 50% ethanol exhibited a weak level of activity on tyrosinase inhibition [23]. This result is similar to our findings which demonstrated that proanthocyanidin and oryzanol could reduce melanin content but had no effect on mushroom tyrosinase activity [22]. However, our results have produced experimental data to support that proanthocyanidin decreased cellular tyrosinase activity leading to a decrease in melanin content.…”

“…The red rice extract also inhibited collagenase and MMP-2 activity. In another study our group [22] has elucidated the skin antiaging properties of the main bioactive compounds in red rice extract including proanthocyanidin, catechin, hydroxybenzoic acid, vanillic acid, and oryzanol. The results showed that collagenase and MMP-2 activity were strongly inhibited by proanthocyanidin and catechin, whereas hydroxybenzoic acid, vanillic acid, and oryzanol had no effect.…”

“…The major bioactive compounds that are found in red, black, purple, and brown rice include gallic, protocatechuic, hydroxybenzoic, and vanillic acid, cyanidin 3-O-glucoside, peonidin-3-O-glucoside, proanthocyanidin, flavanol, catechin and epicatechin, carotenoids, and γ-oryzanol content. Several research findings have reported on the biological modulating effects of pigmented rice seeds and bran phytochemicals, including anti-inflammatory activities [7,8], anticancer activities that have suppressed tumor growth in mice and several human cancer cell lines [9][10][11][12][13], the anti-metastasis properties of cancer cell invasion [14][15][16], antiaging effects with the reduction of oxidative stress in both in vitro and in vivo models [17,18], the modulation of serum lipid profiles and the enhancement of mRNA expression levels of fatty acid metabolism-related genes [19], a reduction of platelet hyperactivity and hypertriglyceridemia in dyslipidemic rats [20], and skin antiaging treatments [21][22][23][24].…”

The Proanthocyanidin-Rich Fraction Obtained from Red Rice Germ and Bran Extract Induces HepG2 Hepatocellular Carcinoma Cell Apoptosis

“…The total proanthocyanidin content was estimated by a vanillin assay; the proanthocyanidin profile was qualified by HPLC chromatography, showing gallocatechin (GC), epigallocatechin (EGC), catechin (C) and epicatechin (EC) peaks [ 4 ]. Interestingly, we clarified that PRFR prepared from red rice grain extract, which was dehulled without removing germ and bran, still exhibited its anti-cancer invasive properties in human breast cancer, MDA-MB-231 cells [ 4 ] and revealed anti-oxidant capacity in primary human skin fibroblasts [ 12 ]. We hypothesized that the germ and bran of whole grained rice are the primary sources of beneficial phytochemicals including proanthocyanidin.…”

“…Moreover, in LPS-treated Raw 264.7 macrophage cells, red rice grain extract could suppress the production of IL-6, TNF-α, NO, iNOS and COX-2, inhibiting the MAPK signaling pathway by reducing NF-κB and AP-1 activation [5]. Consistently, the proanthocyanidin- rich fraction obtained from red rice grain extracts exhibited anti-oxidant and anti-aging properties in primary human skin fibroblasts [12]. Therefore, proanthocyanidin derived from red rice could be potent natural products serving as an alternative option for cancer chemotherapy.…”