4-O-Caffeoylquinic acid as an antioxidant marker for mulberry leaves rich in phenolic compounds

• Published in: Yàowu shi͡p︡in fenxi Vol. 26; no. 3; pp. 985 - 993
• Main Authors: Ganzon, Jerome G., Chen, Lih-Geeng, Wang, Ching-Chiung
• Format: Journal Article
• Language: English
• Published: China (Republic : 1949- ) Elsevier B.V 01.07.2018; Food and Drug Administration; Taiwan Food and Drug Administration
• Subjects: 4-O-Caffeoylquinic acid; Antioxidant; Antioxidants; Bioassays; Caffeoylquinic acid; Content analysis; Fingerprinting; Food; Harvest time; Harvesting; Heat stroke; Herbal tea; Leaves; Leaves location; Morus alba; Organic chemistry; Original; Pharmacy; Phenols; Phytochemicals; Polyphenols; Precipitation; Rutin; Scavenging; Tea; United States > US; Japan; Taiwan; Leaves location; Harvest time; Morus alba; Antioxidant; 4-O-Caffeoylquinic acid
• ISSN: 1021-9498; 2224-6614
• DOI: 10.1016/j.jfda.2017.11.011

Mulberry (Morus alba L.) leaves are widely used as herbal tea to prevent heat stroke. Potential chemical markers of the antioxidant properties and its correlation with harvesting times and leaf location were explored in this study. A 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay guided isolation of mulberry leaves extract provided five phenolic compounds: 5-O-caffeoylquinic acid (1), 4-O-caffeoylquinic acid (2), gastrodin (3), isoquercetin (4) and rutin (5). The 50% radical-scavenging concentrations (SC50) of these compounds were 32.76 ± 0.27, 11.41 ± 0.48, 404.30 ± 4.92, 10.63 ± 0.96, and 10.57 ± 0.61 μg/mL, respectively. Chromatographic fingerprinting allowed content analysis of 1–5 in samples over a 12-month period. Compounds 1–5 were abundance in apical leaves (0–10 cm) in January and February at temperatures < 20 °C. Contents of 2 and 5 were highest in these months and were strongly correlated to the antioxidant property. Therefore, we suggested that the mulberry leaves harvested during January and February have high yield of 4-O-caffeoylquinic acid and this compound can be used as antioxidative marker in mulberry leaves. [Display omitted] •Seasonal variation of five phenolic compounds in mulberry leaves was analyzed.•Mulberry leaves harvested during January and February have high yield of 4-O-caffeoylquinic acid.•The content of 4-O-caffeoylquinic acid and rutin was good correlation with antioxidant activity.•Mulberry leaves rich in 4-O-caffeoylquinic acid as a suitable antioxidant marker.