Effect of Mucilage Removal on Phenolic Content and Antioxidant Activity in Tilia cordata Inflorescences

Introduction: Tilia cordata Mill. is a naturally growing broadleaved tree with a wide distribution in central and eastern Europe as well as in Lithuania [1]. Its inflorescences are ethnopharmacologically highly valued due to significant amounts of mucilage, terpenic and phenolic compounds [2]. The plant material is used for treating inflammation, as sedative, antispasmodic for digestion, respiratory system disorders, anxiety [2]. Developing extraction that first isolates mucilage and subsequently recovers phenolic compounds could therefore support zero-waste and sustainable use of Tilia flowers. The aim of this study was to evaluate how mucilage removal affects phenolic content and antioxidant activity. Materials and methods: Tilia cordata Mill. flowers collected from Toliūnai village, Pasvalys district, Lithuania during the flowering period in July. Extracts were prepared using 0,2 g of material (powders passed through a 355µm sieve and particles at 5600 µm sieve) and 20 mL of 70% ethanol. The total phenolic-mm size compounds were determined according to Folin-Ciocalteu assay and antioxidant activity – ABTS spectrophotometric assay. Results (and discussion): The results shown that the greatest amount of phenolic compounds were determined in plant powders before removing mucilage 92,19±2,53 GAE mg/g, the lowest amount of phenolic compounds was in materials with 1-5 mm dried particle size after demucilagation 12,99±0,48 GAE mg/g and in powder after removing mucilage 25,49±6,30 GAE mg/g. Plant material with particles from 1 to 5 mm after demucilagation had an antioxidant activity of 263,53±9,70 µmol/g, whiles the powder after removing mucilage had significantly lower values (194.37±28.75 µmol/g). The powders before demucilagation resulted in the greatest antioxidant activity of 838.50±24.74 µmol/g. Conclusions: The study demonstrated that both particle size and mucilage removal significantly affect the total phenolic content and antioxidant activity of Tilia cordata flower extract.