Effects of Drying Temperature on the Amount
of Secondary Metabolites and Antioxidant Activity
of Orthosiphon aristatus (Blume) Miq. Tea Extracts


Narin Taokaenchan1*, Sakchai Satienperakul2, Yuto Ueda3,
Shuhei Tsutsumi3, and Shin Yasuda3

1Department of Medicinal Plant Science, Faculty of Agricultural Production
2Department of Chemistry, Faculty of Science
Maejo University, Chiang Mai 50290, Thailand
3Department of Bioscience, School of Agriculture
Tokai University, Kumamoto City, Kumamoto 862-8652 Japan


*Corresponding Author: This email address is being protected from spambots. You need JavaScript enabled to view it.




Orthosiphon aristatus (Blume) Miq. tea is a traditional herbal tea in Thailand. This herb is used to prevent and treat a wide range of diseases such as diuresis, hypertension, and diabetes. In this study, three different drying temperatures used for herbal tea processing were evaluated (40, 50, and 60 °C) for their secondary metabolites [total phenolic content (TPC), caffeic acid (CA), rosmarinic acid (RA), and total flavonoid content (TFC)] and antioxidant activity. The herbal tea processed at 40 °C showed significantly (P < 0.05) higher TPC [485.26 ± 49.43 mg gallic acid equivalent (GAE)/ 100 g], CA (202.17 ± 1.00 mg/kg), RA (469.99 ± 1.56 mg/kg), TFC [356.86 ± 41.81 mg catechin equivalent (CE)/ 100 g], and 2,2-diphenylpicrylhydrazyl (DPPH) radical scavenging activity than those at other drying temperatures. Therefore, a drying temperature of 40 °C was the optimum condition for the Orthosiphon aristatus (Blume) Miq. leaves because it retained the secondary metabolite content with strong antioxidant potential.



In recent decades, herbal teas have become more familiar in many countries outside of Thailand, as they are an essential source of antioxidants and secondary metabolites (Moraes-de-Souza et al. 2008; Poswal et al. 2019). Various researchers have found that Thai herbal teas may cure diseases such as cancer, diabetes, and hypertension (Chusri et al. 2015; Tipduangta et al. 2019). The Orthosiphon aristatus (Blume) Miq. tea is the most famous tea in Thailand because of its preventative and . . . read more