## 1 Introduction  
Environmental pollution associated with the production and disposal of plastics has become one of the greatest challenges in the modern world [1]. In response to the growing need for sustainable solutions, biodegradable polymers, such as poly(butylene succinate) (PBS), are gaining attention as a potential alternative to the plastics traditionally used in the packaging industry [2]. PBS offers good mechanical strength, adequate biodegradability and processability, making it an attractive material for packaging with functional properties [3, 4]. Nevertheless, the properties often need to be modified using active additives [3]. Food packaging plays a key role, not only in protecting products from physical, chemical, and biological damage, but also in extending food product shelf-life and reducing waste. In recent years, there has been growing interest in active packaging, which exhibits additional properties, such as antimicrobial or antioxidant capabilities, in addition to preserving properties [5]. These functionalities are particularly important for perishable products, in which oxidative degradation and microbial contamination are major threats. The addition of natural plant extracts into packaging materials is gaining popularity as a method for introducing these kinds of properties due to their bioactivity and safety of use [6]. Active compounds such as plant extracts, essential oils, flavonoids, phenolic acids, proanthocyanidins, cellulose, stilbenoids, chitosan, and lignans, are often introduced into biopolymers such as PBS film to improve their antioxidant and/or antimicrobial properties [7; 8]. Good examples can be found in the work of [PERSON] and [PERSON] [9], who incorporated thymol as an active agent into a PBS matrix through a blown film extruder. The authors demonstrated that the processing technique led to the facilitation of the plasticization effect of thymol. Additionally, modified PBS inhibited the growth of _Staphylococcus aureus_ and _Escherichia coli_ cells. On the other hand, [PERSON] et al. [10] introduced carvacrol essential oil into a PBS matrix using a blowing technique, also showing that modified, active PBS films were active against _S. aureus_ and _E. coli_ strains. As [PERSON] et al. [11] confirmed, PBS may also be used as the main polymeric material for preparing an active film containing active compounds, i.e., lesum, thymol, or curry via a solvent-casting method. The authors confirmed that lesum filled PBS film demonstrated a well-integrated film structure; however, PBS films with curry and/or thymol incorporated in the polymer matrix showed poor adhesion features in comparison to neat PBS film. Moreover, the PBS films containing 10% thymol and lesum were confirmed to be effective against _S. aureus_. Previous studies also confirmed that PBS films modified with natural plant-derived additives can be suitable for potential packaging materials for food products, providing improved antimicrobial and antioxidant protection. Among the compounds tested in the context of bioactive additives in the PBS matrix are quercetin [12], gallic acid [13], thymol [14], toselle calyx and sappan heartwood extracts [15], or curcumin and carvacrol [16]. Sea buckthorn (_Hippocampa rhamnoides_ L.) is a plant known for its exceptional wealth of bioactive compounds, such as flavonoids, carotenoids and vitamins, which exhibit strong antioxidant activity [17]. As [PERSON] et al. mentioned [18], natural antioxidants are chain-breaking compounds which react with lipid radicals and convert them into more stable products. The authors revealed that the sea buckthorn extracts are rich in proanthocyanidins, which display direct free radical scavenging. In addition, [PERSON] et al.