Analysis of Brazilian Propolis by Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA). Characteristics of Crude Resin, Ethanolic Extracts, Wax and Isolated Compounds

Abstract

Introduction Propolis is a resinous material of different colours ranging from yellow, brown, green and red, composed of resins produced by plants, added to the secretions of bees and mixed with wax. Propolis is used mainly in the construction and preservation of hives (Marcucci et al., 2000). Propolis resin is characterized by naturally occurring chemical compounds, including different phenolic bioactive compounds, waxes, ashes and volatile substances, among others, whose content may widely vary depending on the existing differences in plant ecosystems (Fabris et al., 2013; Fikri et al., 2019; Marcucci et al., 2000). Brazilian green propolis collected from Baccharis dracunculifolia (Tomazzoli et al., 2020) in the central Regions is rich in p-coumaric acid, prenylated cinnamic acis, such as Artepillin C, caffeic and caffeoylquinnic acids and flavonoids (Carvalho et al., 2019; Veiga et al., 2017). Brown propolis collected from Araucaria heterophylla and, sometimes, from B.dracunculifolia and A. heterophylla, in the southern Regions, contains high levels of vanillin, crysin, pinocembrin and cinnamic acid derivatives, for example, Artepillin C (Marcucci et al., 2008), while red propolis collected from Daubergia ecastophyllum and Symphonia globulifera (Ccana-Ccapatinta et al., 2020) in the northern Regions are rich in flavonoids, isoflavones and prenylated benzophenones (Vieira de Morais et al., 2021) (Figure 1). All these propolis may present biological activities, including some antimicrobial and antioxidant (Batista et al., 2016; Dantas Silva et al., 2017; do Nascimento et al., 2019a; Ripari et al., 2021; Schnitzler et al., 2010; Touzani et al., 2018; Vieira de Morais et al., 2021), anti-inflammatory (Wang et al., 2015) and antitumoral properties (Nani et al., 2018; Watanabe et al., 2011). Some types of propolis have high market value for their medicinal properties, such as Brazilian green propolis (Berretta et al., 2020). Because there are so many variations in its chemical composition, in particular, regarding bioactive compounds, the characterization of propolis is very important in order to meet quality control standards.