# Propolis Hydroalcoholic Extracts: Biochemical Characterization and Antifungal Efficacy
## 1 Introduction  
Usually, management of fungal pathogens primarily relies on the use of synthetic fungicides [1]. However, excessive fungicide use poses serious food safety and environmental risks due to persistent chemical residues and may also lead to the development of pathogen resistance phenomena [2]. In response to these concerns, the European Plant Health Regulation (EU 2016/2031) [3] and the European Green Deal have been introduced to accelerate the transition to a more sustainable food system. These initiatives advocate a 50% reduction in the use of pesticides and a 25% increase in the area devoted to organic farming by 2030. As a result, there is growing interest in exploring alternative management strategies, such as the use of natural compounds, to address the challenges posed by synthetic fungicides.  
Propolis is produced by bees (_Apis mellifera_), and it is renowned for its mechanical and antimicrobial properties [4]. For these reasons, it emerges as a promising solution to the above-reported challenges [5]. Comprising over 300 different compounds, including phenols, tannins, polysaccharides, terpen and fatty acids, propolis offers a rich source of bioactive compounds having potential antifungal properties [6]. It is important to note that the composition of propolis varies considerably depending on the geographical area and the type of substrate from which the raw materials are derived. This variability poses a challenge in achieving a definitive biochemical characterization [7]. In addition, propolisis can be considered as an adjuvant substance for use in agriculture because it enhances plant defences [8]. Several studies have investigated the efficacy of propolis extracts in preserving the quality of fruits and vegetables [9], applied topically or incorporated into edible coatings or food formulations [10]. Propolis was shown to prevent lipid oxidation and improve the shelf life of citrus fruits [11]. Thus, propolisis holds promise as a natural and sustainable alternative for the management of postharvest fruit grey mould [11].  
_Botrytis cinerea_, the causal agent of grey mould symptoms, has the ability to infect over 1400 different hosts [12] and causes significant agricultural and economic losses worldwide. The impact of this pathogen is particularly pronounced in the postharvest phase, where infections often lie dormant until favourable environmental conditions trigger widespread deterioration [13]. This dormancy poses a significant challenge to crop production and postharvest management, as apparently healthy produce may only show signs of infection after harvest, resulting in significant losses [14]. _Botrytis cinerea_ of berries presents a multifaceted challenge, because it affects crops during both pre- and postharvest phases [15]. In the field, the pathogen can infect different plant parts, such as flowers and young fruits. However, it is during postharvest handling, transport and storage that the true extent of grey mould disease becomes apparent [16]. Grapes, being highly perishable, are susceptible to damage and the presence of _B. cinerea_ can rapidly lead to visible grey mould formation on the fruit surface. This not only affects the quality and marketability of the grapes but also accelerates rotting, resulting in significant economic losses for growers and traders [17]. Similarly, blueberry (_Vaccinium_ spp.) crops face the same pathogen infection in the field and during postharvest storage, where _B. cinerea_ causes significant production losses [18; 19; 20].  
Based on these broad premises, the aim of the present study was to evaluate the efficacy of different propolisis, collected in different environments, against _B. cinerea_ through in vitro and in vivo experiments on grapes and blueberries. In addition, one of the main objectives was to characterize the phenolic and volatile profile of each propolis tested in order to study in depth the biodiversity related to the efficacy against the target pathogen.