Antibacterial and Oxidative Stress-Protective Effects of Five Monoterpenes from Softwood

Abstract

Volatile organic compounds (VOC) affect the quality of indoor air. Terpenes and especially monoterpenes are the main molecules emitted from softwood material (coniferous species), which is widely used in construction. The corneal epithelium is one of the first human membranes to encounter VOCs in the air. Moreover, the industrial use of pleasant-scented monoterpenes in cosmetics, food, and detergents exposes people to monoterpenes in their daily lives. In the present study, the health effective properties of five monoterpenes from softwood were tested; cytotoxicity and oxidative stress-protective effects of α- and β-pinenes, R- and S-limonene, and 3-carene were tested in a human corneal epithelial (HCE) cell model system and with two additional in vitro antioxidant tests: oxygen radical absorbance capacity (ORAC) and hydrogen peroxide (H2O2) scavenging. Antibacterial efficacies were tested with two bioluminescent bacterial biosensor strains (Escherichia coli K12+pcGLS11 and Staphylococcus aureus RN4220+pAT19) and with minimum inhibitory concentration (MIC) test against Escherichia coli. Only very high concentrations of monoterpenes (0.3–0.5 mg/mL) demonstrated cytotoxicity against HCE cells. Contrary to the original hypothesis, monoterpenes did not exhibit strong antioxidant properties in tested concentrations. However, biosensors and MIC tests indicated clear antibacterial activities for all tested monoterpenes.

Valorizing Assorted Logging Residues: Response Surface Methodology in the Extraction Optimization of a Green Norway Spruce Needle-Rich Fraction To Obtain Valuable Bioactive Compounds

“…A similar range of antibacterial results has been obtained, for example, in the case of unpurified bark extracts using the same bacterial method by Välimaa et al. 70 For the water extracts, the results are low, 3.4–11.1% for E. coli and 9.6–19.5% for S. aureus , but comparable to those received using the same bacterial method for E. coli with pure α- and β-pinene by Muilu-Mäkelä et al 71 with 0.8–1.6 mg/mL concentration. For S. aureus , the results obtained in this study are lower, suggesting that the used 1 mg/mL concentration of the samples is insufficient for unpurified extraction products.…”

“…aureus, but comparable to those received using the same bacterial method for E. coli with pure α- and β-pinene by Muilu-Mäkelä et al with 0.8–1.6 mg/mL concentration. For S.…”

“…Limonene extracts could not be tested against bacteria due to the strong antibacterial activity of the solvent itself . Coniferous species have been shown to harbor various compounds with broad-acting antimicrobial properties including volatiles such as terpenoids, polyphenolic compounds, and piperidine alkaloids. − In the response surface model for water extracts with E. coli (Figure B), there is a sink at the approximate middle point of the surface.…”

“…The findings of this study exhibit a similar trend with Na 2 CO 3 + NaHSO 3 addition, where the alkalic pH can, at least partly, contribute to the increase in the antioxidant and antibacterial activities. Limonene itself has been found to possess both antioxidant and antibacterial properties and is primarily used for the extraction of nonpolar compounds such as lipids. , For instance, pressurized limonene extraction was considered an interesting solvent alternative for extracting lipids from marine algae, with extraction efficiency dependent on the microalgae species chosen . However, in this study, our focus was on bioactivity maximization.…”

Identification and Pharmacological Activities of Secondary Metabolites of Phytochemicals

“…Different authors have evaluated potential usefulness of terpenes and terpenoids to exhibit anti-inflammatory, antioxidant, antidiabetic, anticancer, geroprotector, and antiatherosclerotic effects [28][29]. D-limonene, Linalool, αpinene, camphor, myrcene, citral, cucurbitacin B have been reported to be active in inflammatory and oxidative stress diseases [29][30][31]. Carotenoids, are important natural pigments in carrot, tomatoes etc., pro-vitamin A are rich sources of antioxidant [32].…”