Evaluation of antioxidant activity, phenol content and flavonoid extract of Artemisia annua L. Under the influence of different drying methods

Drying is one of the most important post-harvest processes for medicinal plants. to study the effect of different drying methods on the antioxidant and phytochemical activity of flowering branches and leaves of Artemisia annua, an experiment based on a completely randomized design with four treatments and ten replications was conducted at Sari Agricultural Sciences and Natural Resources University in 2020. Aerial parts of the plant were obtained from natural habitat in Shirgah region of Mazandaran (238 meters above sea level) in January. Different parts of the plant were dried using four methods shade - sun, oven (45°C), indirect heating (28-32 ° C) and microwave (520 w). All extracts were prepared by soaking in methanol. In the first stage, antioxidant activity (DPPH), phenolic (Folin–Ciocâlteu) and flavonoid (aluminum chloride) content were evaluated for all samples. The results showed that there was a significant difference between different drying methods. The highest content of total antioxidants was observed in flowering branches (70.92%) and leaves (70.66%) for indirect heat sampels. The highest amount of total phenol (2.56 and 3.09 mg gallic acid per 100g of dry matter, respectively) belonged to the samples dried using sun-shade and indirect heat. The highest total flavonoid content was also found in samples dried under indirect heating and microwave (1.45 and 3.73 mg of quercetin per 100g of dry matter, respectively). The lowest amount of total phenol, total flavonoids and antioxidant activity were observed in oven-dried flowering and leafy branches at 45°c. In the second stage of the experiment, the best sample regarding antioxidant activity, phenol and flavonoid was chosen and evaluated using chromatography. The most composition of the extract was arteannuic acid (15.63%). In general, indirect heat drying could preserve antioxidant and bioactive compounds more effectively, while other methods may reduce or even degrade these compounds.