Z. Y. Ju and Y.-H. P. HSIEH. Dept. of Nutrition, Food & Exercise Sciences, Florida State Univ., 436 Sandels Bldg., Tallahassee, FL 32306-1493
Cornus officinalis Sieb. et Zucc. is a naturally growing dogwood species in Asia. The semi-dried fruit has been directly used as an ingredient in traditional Chinese herbal medicines for two thousand years. Although the fruit has long been known for its tonic, analgesic, diuretic, antitumor and antimicrobial effects, little information is available concerning its phytochemical content, particularly phenolic compounds, and its antioxidant properties.
The objectives of this study were: 1) to determine the total phenolic and anthocyanin content of Cornus fruits; 2) to identify individual phenolic compounds present; and 3) to determine the antioxidant activities, of the fruit extract.
Three Cornus fruit samples were collected from LinAn, Zhejiang, China in different years (2001 to 2002), pitted, sun-dried to approximately 17% moisture content and then frozen at -20oC until use. The semidried fruits were soaked in D.I. water, blended and extracted at 50oC for 1 h in a sonicator, then centrifuged at 5000 rpm for 10 min. The supernatants were used to determine total phenolics and total anthocyanins using spectrophotometric assays at 726 nm and 510/700 nm, respectively. The antioxidant activity was measured by the ORAC method. Phenolic components including anthocyanins, phenolic acids, hydroxycinnamates and flavonols were analyzed by HPLC over a range of wavelengths.
Cornus fruit contains a high level of total phenolic compounds (20.9 - 33.4 mg/g semi-dried fruit), with high antioxidant activity (916-1704 µM TE/g), but is low in total anthocyanin (0.34-1.41 mg/g), which parallels the loss of the fruit's red pigment over time. At least 16 phenolic compound peaks were detected by HPLC in the water extract. Several identified compounds were myricetin-3-arabinose, quercetin-3-galactoside, pelargonidin-3-galactopyranoside, and gallic acid. The storage time appears to have a significant effect on the active phytochemical content and the associated antioxidant properties.
This result is a substantial contribution to our understanding of the medicinal value and health benefits of this widely used herbal medicine ingredient.
Session 33F, Nutraceuticals & Functional Foods: Antioxidants and phytochemical analysis