## 1 Introduction  
Antimicrobial agents represent one of the most significant achievements of modern medicine, playing a key role in the treatment of infections and substantially reducing infection-related mortality [1]. They encompass a broad spectrum of compounds--antibiotics, antivirals, antifungals and antiprotozoan agents--whose mechanisms of action target either the inhibition of microbial growth or the elimination of pathogenic microorganisms [2]. Despite their effectiveness, antimicrobial agents face increasing challenges due to the rise of antimicrobial resistance (AMR)--a phenomenon where microorganisms develop resistance mechanisms against traditionally effective drugs [3]. AMR arises from both natural evolutionary processes and human-driven factors, such as inappropriate antibiotic use in healthcare and agriculture, as well as inadequate hygiene and sanitation practices [2]. As the prevalence of multidrug-resistant microorganisms increases, treatment options become more limited, exacerbating the burden of infectious diseases. Globally, AMR is associated with higher mortality rates, increased treatment complications and prolonged hospital stays, leading to severe public health and economic consequences [4,5]. Current projections indicate that by 2050, AMR will account for approximately 10 million deaths annually, highlighting the urgent need for innovative therapeutic strategies [6]. In recent years, there has been a growing scientific interest in natural compounds as potential alternatives to synthetic antimicrobial agents. An increasing body of evidence suggests that plant extracts and essential oils contain bioactive constituents with notable antimicrobial, antiviral, antifungal and immunomodulatory properties [7, 8, 9]. Among them, the essential oils of oregano (_Origanum vulgare_) and thyme (_Thymus vulgaris_) exhibit particularly strong activity, attributed primarily to the presence of carvacrol and thymol [10, 11, 12]. The selection of oregano (_Origanum vulgare_) and thyme (_Thymus vulgaris_) essential oils in the present study is based not only on their well-established antimicrobial activity but also on their chemical composition, dominated by the phenolic monoterepenes carvacrol and thymol. These compounds are structural isomers that, despite sharing the same molecular formula, differ in hydrophobicity, hydroxyl group positioning and their mode of interaction with microbial cell membranes [13,14].Studies have shown that both isomers disrupt membrane integrity, leading to ion gradient loss and leakage of cellular contents, although with varying degrees of effectiveness depending on the pathogen [14,15]. Moreover, when used in combination, they demonstrate additive or synergistic effects, which increases interest in their potential as co-agents with other biologically active substances such as vitamin C for enhanced antimicrobial efficacy [16,17]. The antimicrobial activity of vitamin C is well-documented [18,19], and its combination with the selected essential oils represents a promising strategy for achieving a synergistic effect.It is hypothesized that high concentrations of vitamin C may lower intracellular pH in microorganisms, potentially amplifying the effects of essential oils. A similar mechanism has been observed with weak organic acids, such as acetate and lactate, which penetrate microbial cells and cause intracellular acidification, compromising their physiological functions [20]. While this specific effect has not been extensively studied in the context of vitamin C, similar mechanisms involving weak organic acids have been described previously [21]. Preliminary studies indicate that short-chain fatty acids (SCFAs) in acidic environments can enhance the efficacy of azide antifungals and antibiotics against _Candida albicans_ and _Escherichia coli_[20,22].