Abstract
Secondary metabolites in black, red, brown, and white rice grown in the Camargue region of France were investigated using HPLC-PDA-MS2. The main compounds in black rice were anthocyanins (3.5 mg/g), with cyanidin 3-O-glucoside and peonidin 3-O-glucoside predominating, followed by flavones and flavonols (0.5 mg/g) and flavan-3-ols (0.3 mg/g), which comprised monomeric and oligomeric constituents. Significant quantities of γ-oryzanols, including 24-methylenecycloartenol, campesterol, cycloartenol, and β-sitosterol ferulates, were also detected along with lower levels of carotenoids (6.5 μg/g). Red rice was characterized by a high amount of oligomeric procyanidins (0.2 mg/g), which accounted >60% of secondary metabolite content with carotenoids and γ-oryzanol comprising 26.7%, whereas flavones, flavonols and anthocyanins were <
9%. Brown and white rice contained lower quantities of phytochemicals, in the form of flavones/flavonols (21–24 μg/g) and γ-oryzanol (12.3–8.2 μg/g), together with trace levels of the carotenoids lutein and zeaxanthin. Neither anthocyanins nor procyanidins were detected in brown and white rice. By describing the profile of the heterogeneous mixture of phytochemicals present in different rice varieties, this study provides a basis for defining the potential health effects related to pigmented and nonpigmented rice consumption by humans.