Reduction of safrole content of Cinnamomum porrectum leaves by blanching and the effect on the antioxidant and anti-inflammatory activities of its herbal tea

Abstract

Background: Cinnamomum porrectum (C. porrectum) is an aromatic medicinal plant from southern Thailand. While many Cinnamomum species demonstrate medicinal properties such as anti-inflammatory effects, some species are known to contain safrole, a group 2B carcinogen. Although the leaves of C. porrectum are used to produce herbal tea, there is no scientific data to support its properties as a functional food or any guarantee of its safety. Objective: To determine the effect of blanching before drying of C. porrectum leaves on their safrole content, phenolic profile, total phenolic content (TPC), and total flavonoid content (TFC), antioxidant and anti-inflammatory activities were compared to leaves dried with hot air. Methods: In the first part of the study, the leaves were dried in three conditions: freeze dried (F), hot air dried at 60 °C (C), and blanched for 60 seconds at 100 °C (B) before being dried at 60 °C until the moisture content reached 5-7% and then were ground and sieved to make powders. The F, C, and B were extracted by methanol and redefined as FM, CM, and BM, for the determination of their chemical constituents by GC-MS using C. porrectum wood oil (CWO) as the safrole standard. In the second part of the study, the C and B powders were analyzed for their proximate composition and were also used to make herbal tea infusions (CT and BT respectively) which were analyzed for their phenolic profile, TPC, TFC, antioxidant activities, cytotoxicity, and anti-inflammatory activity in RAW 264.7 cells. Results: Significantly decreased safrole contents of 89% and 82% were found in the BM sample when compared with CM and FM respectively. The CT and BT had similar phenolic profiles but different contents. The TPC, TFC, ABTS, and FRAP activities, in addition to cell viability and the nitric oxide inhibition of BT were higher than that of CT. Conclusion: The results demonstrate how blanching C. porrectum leaves before drying can decrease the safrole content when compared to freeze dried and hot air-dried leaves, thereby leading to a decrease of cytotoxicity in RAW 264.7 cells. Additionally, BT demonstrated a more intense phenolic profile, TPC, ABTS, and FRAP compared with the un-blanched control sample.