Standardization of açaí extracts for in-vitro assays based on anthocyanin quantitation

Abstract

Euterpe oleracea Mart., commonly known as açaí, is a fruit that grows on a palm tree native to the Amazon region. Quantitation of bioactive constituents is a crucial preliminary step before utilizing extracts for biological assays so they may be normalized and administered according to a specific constituent concentration. Açaí has four main anthocyanin analytes: cyanidin 3-glucoside, cyanidin 3-sambubioside, cyanidin 3-rutinoside, and peonidin 3-rutinoside. This is the first comparison of açaí anthocyanin profiles between fresh fruits, processed powders, and botanical dietary supplement capsules. The materials examined shared a similar anthocyanin profile, with cyanidin 3-rutinoside being the most abundant (0.380 ± 0.006 - 15.1 ± 0.01 mg/g), followed by cyanidin 3-glucoside (0.0988 ± 0.0031 - 8.95 ± 0.01 mg/g). Among the botanical dietary supplement capsules, the two formulations varied greatly in anthocyanin concentration despite both being aqueous extracts (0.650 ± 0.011 - 0.924 ± 0.010 mg/g versus 1.23 ± 0.01 - 1.27 ± 0.02 mg/g). Previous LC-MS methods range from 35-120 min per injection, while we report a 10 min quantitative method for analysis of anthocyanins in various açaí materials that is fast, reproducible, and accurate. The method produced is useful to assure the quality, efficacy and safety of food and dietary supplement materials containing açaí.

Keywords: Arecaceae; Euterpe oleracea Mart; cyanidin 3-glucoside; cyanidin 3-rutinoside; cyanidin 3-sambubioside; mass spectrometry; peonidin 3-rutinoside.

Fig. 1.

Structures of anthocyanins, cyanidin 3-glucoside (1), cyanidin 3-sambubioside (2), cyanidin 3-rutinoside (3), and peonidin 3-rutinoside (4).

Fig. 2.

Extracted ion chromatogram of anthocyanins 1 (A), 2 (B), 3 (C), and 4 (D) present in acidic methanol extracts of Euterpe oleracea Mart. raw materials (MRAC), anthocyanin standards (E-H), and internal standard (IS) reserpine (I).

Fig. 3.

Depiction of average anthocyanin stability in acidic methanol for 30 days at −80°C. Data shows is percent analyte recovery calculated by dividing the anthocyanin concentration on day 30 by the anthocyanin concentration on day 0 and multiplying by 100.

Fig. 4.

Illustration of differences in average anthocyanin stability for various extract types stored in acidic methanol for 30 days in −80°C. Data shows is percent analyte recovery calculated by dividing the anthocyanin concentration on day 30 by the anthocyanin concentration on day 0 and multiplying by 100.