β-glucans are known as biological response modifiers. However, different sources can result in structural differences and as a result differences in their biological activity. The hot water extraction method allows to obtain, high molecular weight β-glucans without altering their structure by using strong chemicals, such as alkalis or acids. Analysis of β-glucans by FT-IR and NMR spectroscopy in solid state is superior to analysis in solution as it allows researchers to study the preserved structure of the extracted polysaccharides. FT-IR spectroscopy was used in this study to make side-by-side comparison analysis of hot water extracted β-glucans from different yeast sources. NMR spectroscopy was used to confirm findings made by FT-IR spectroscopy. Extracted β-glucans exhibit characteristic structure of β-1,3/1,6-linked glucans with noticeable levels of proteins, possibly in a form of oligopeptides, chitin and other impurities. β-glucans obtained from C. guilliermondii, P. pastoris and S. pastorianus exhibited higher protein content. Differences in mannan, chitin and α-glucan content were also observed; however, the species-specific structure of obtained β-glucans could not be confirmed without additional studies. Structural analysis of high molecular weight β-glucans in solid state by FT-IR spectroscopy is difficult or limited due to band intensity changes and overlapping originating from different molecules.

β-glucans are widely known for their biological activities. However, the choice of extraction method can significantly influence their structural characteristics, thereby potentially impacting their biological functions. In this paper, three fractions of β-glucans were obtained from Candida lusitaniae yeast via alkali and hot-water extraction methods and were analyzed using solid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy. Solid-state NMR spectroscopy was used as a nondestructive technique that preserves the structure of the analyzed molecules. The results suggest that differences in the β-glucan structure are affected by the choice of extraction method. The main difference occurred in the 82–92 ppm region with signal presence suggesting that β-glucans have a linear structure when hot-water-extracted, which is absent in alkali-extracted fractions resulting in the acquisition of β-glucans with an ordered, possibly helical structure. A hot-water extracted water-insoluble (HWN) fraction consists of linear β-1,3-glucans with other signals indicating the presence of β-1,6-linked side chains, chitin and small amounts of α-glucan impurities. For those that are alkali-extracted, alkali-insoluble (AN) and water-soluble (AWS) fractions are structurally similar and consist of an ordered β-1,3-glucan structure with β-1,6-linked side chains and a significant amount of α-glucan and chitin in both fractions.

Essential oils are widely used in cosmetic products and are valued for their antimicrobial properties. In this study, the in vitro antimicrobial activity of five pure essential oils (EOs) and five commercially available EO blends was comparatively evaluated against six skin-associated pathogens: Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa, Candida lusitaniae and Candida guilliermondii. Chemical profiling of volatile constituents was performed using gas chromatography–mass spectrometry; antimicrobial activity was assessed by broth microdilution to determine minimum inhibitory concentration (MIC), as well as spot-inoculation to determine minimum bactericidal concentration (MBC). Results revealed microorganism-dependent inhibitory and bactericidal activity of the tested essential oils. Candida spp. and E. coli were the most susceptible microorganisms, whereas P. aeruginosa exhibited the lowest susceptibility to essential oils. Pinus sylvestris showed comparatively lower MIC and MBC values across most tested microorganisms. Commercial EO blends showed comparable antimicrobial activity to individual essential oils. Overall, this study provides a comparative in vitro screening of selected essential oils and commercial blends relevant to cosmetic applications, indicating that EO blends do not exhibit superior antimicrobial activity over pure oils under the tested conditions.