Abstract
The waste solids remaining after the ethanolic extraction of arnica were proposed as raw material for the recovery of the remaining phenolic fraction. Greener processes based on intensification extraction, with microwave (MHG) and ultrasound (UAE) assistance and pressurized hot water extraction under subcritical conditions (AH), were studied. The entire process provided approximately 28% of phenolics for the sequence when MHG was used, 22% in the sequence where AH was employed, and the extracts showed up to 60% the ABTS radical scavenging capacity of Trolox. However, the cytotoxic effects on the cell growth of tumoral cells were only moderate. Therefore, considering a possible external topical application, extracts containing selected arnica extracts were further used to develop polymer-based gelled matrices formulated with either chitosan or polyvinyl alcohol. Rheological testing indicated that all proposed matrices exhibited relatively high mechanical features, even better than those determined with matrices prepared with their counterpart commercial arnica tinctures. Overall, the shear-thinning behavior of gelled matrices loaded with arnica extracts obtained by MHG or AH stages was enhanced compared to those containing ethanolic extracts, whereas the viscoelastic features became smoother for polymeric matrices incorporated with arnica extracts recovered at the highest MHG irradiation powers or at the highest set point temperatures of AH treatments.
Highlights
Arnica montana L. is a traditional medicinal plant and its flowers are used to alleviate pain and treat skin disorders for due to the fact of its tissue regeneration and healing capacity properties
The suspension was separated by filtration, the phenolics content was analyzed in the liquid phase, and the solid phase was split for the extraction process: pressurized hot water and microwave hydrodiffusion gravity-ultrasound assisted extraction
The waste solids after ethanolic production of arnica were treated by ultrasound-assisted extraction (RS-ET-UAE)
Summary
Arnica montana L. is a traditional medicinal plant and its flowers are used to alleviate pain and treat skin disorders for due to the fact of its tissue regeneration and healing capacity properties. The main anti-inflammatory and analgesic activity of arnica is due to the sesquiterpene lactones helenalin and 11, 13-dihydrohelenalinester, the flavonoid and phenolic fractions could be of interest because their additional antioxidant and antimicrobial effects could act synergistically with sesquiterpene lactones [7,12,14]. Arnica montana is rich in biologically active acidic polysaccharides and their glycoconjugates, which possess anticoagulant, antioxidant, anti-inflammatory and antitussive effects without any cytotoxicity effect in model cells [2]. The conventional extraction processes using organic solvents or alkaline solutions were replaced by greener extraction stages Both antioxidant and antitumoral properties were assessed, and based on the results, the formulation and rheological performance of novel chitosan or PVA gelled matrices loaded with arnica extract for external use was proposed
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