Poly ethylene oxide (PEO)/gelatin nanofibers loaded with shirazi thyme essential oil showed antimicrobial activity and cell proliferation

Shirazi Thyme ( zataria multiflora, ZM ) antimicrobial effects are known to locals, living predominantly in central parts of ancient Persia, from prehistoric times. It has exploited in traditional medicine long before discovery of antibiotics. Here, essential oil extracted from wild type plants (aerial parts) by combination of steam and hydro distillation method. This is in contrast to common practices of steam and hydro distillations alone as well as solvent extraction of, predominantly, leaves. It is plausible that this simple strategy preserve the most heat sensitive compounds such as Gamma-Terpinene, a cyclohexane monoterpene and strong antioxidant ingredient, from heat degradation by oxidation acceleration and structural changes. Electrospinning performed on water soluble, biocompatible and cost-effective polymers such as PEO and gelatin for fibers production, Poly vinyl alcohol (PVA) used as essential oil emulsifier. After fibers formation, crosslinking performed by Glutaraldehyde vapor to improve mechanical properties of fiber mats. Gas chromatography-Mass spectroscopy (GC-MS) revealed high concentrations of Thymol (46.11 %) and Carvacol (13.58 %) constituents with natural inhibitory microbial effects. Nanofiber mats holding essential oil rendered Staphylococcus aureus and Escherichia coli proliferation (disk diffusion method). Meanwhile, cell viability assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), for 3 % loading confirmed non-toxicity and showed cell growth (Mouse L-929 cell line) up to 126 %. The novelty of this combinatorial essential oil extraction method is to reach an appropriate gamma-terpinene (15.65 %) concentration (not high enough for inhibition effects), with antioxidant, immunomodulatory and vasorelaxant properties that promote cell proliferation up to 26 % more than control one. Above medicinal plant loaded in nanofibers at 3 % concentration demonstrated less than 20 % burst effect in 24 h and represents a promising alternative for anti-pathogenic, epithelial cell proliferative applications such as wound dressing products. • A unique essential oil composition obtained from Shirazi Thyme, rich in Thymol, Carvacol, Gamma Terpinene and Cymene. • Nanofibers prepared based on electrospinning of poly (ethylene oxide) and Gelatin. • PVA emulsified essential oil loaded into the nanofibers. • Antibacterial and cell viability experiments revealed bacterial inhibition and cell viability increase.