Glandular trichomes, essential oil composition, anti-Aspergillus and antioxidative activities of Lamium purpureum L. ethanolic extracts

Abstract

The aim of this study was to investigate the structure of glandular trichomes and essential oil composition of Lamium purpureum L. (Lamiaceae) and to determine potential biological activities of its different extracts. The micromorphology and distribution of trichomes on vegetative plant parts were investigated using scanning electron microscopy (SEM). Two types of trichomes were identified: non-glandular (simple, uniseriate, multicellular) and glandular (both peltate and capitate). The essential oil of L. purpureum was isolated by hydrodistillation and analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The main compounds were trans-anethole (59.61%), fenchone (6.54%), α-pinene (6.14%) and β-pinene (4.98%). The total phenol and flavonoid contents of 10%, 30% and 50% ethanol extracts were determined spectrophotometrically. The free radical scavenging and reducing power activity of extracts were analyzed using the DPPH and ABTS radical scavenging methods, and the ferric reducing antioxidant power (FRAP) and total reducing power (TRP) assays. The 50% ethanolic extract exhibited the strongest antioxidative activity while the lowest was determined for the 10% ethanolic extract. Antifungal activity of L. purpureum hydroalcoholic extracts was evaluated against eight Aspergillus species by the microdilution method. Light microscopy (LM) demonstrated structural abnormalities of the tested Aspergilli. While the plant extracts did not exhibit fungicidal activity, morphophysiological changes (sporulation loss and depigmentation of conidial heads) were observed in all tested isolates.