Variation of polyphenols and antioxidant activity in mulberry leaves

Mulberry (Morus alba L., Moraceae) tea is considered as healthy beverage in Thailand. In order to identify the good source of Mulberry tea, seven cultivars grown in Thailand were studied for their total polyphenolic content and antioxidant activity using Follin-Ciocalteu and DPPH methods, respectively. The results showed that Khunphai, the native cultivar, had the highest total polyphenols (41.88±0.45 gGA/kg) and antioxidant activity (with IC₅₀ value of 93.42±13.17mg/L). The young mulberry leaves contained 2–3 fold higher level of total polyphenols as well as antioxidant activity comparing to older leaves. Seasonal variations of total polyphenolic content in mulberry leaves were also observed. The leaves were collected in three commercial harvest seasons i.e. summer (April-July 2005), rainy season (July-September 2005) and winter (October-December 2005). The total polyphenols and antioxidant activity were not different in dry periods (winter and summer) while significantly decreased in rainy period.