Antifungal and antibacterial activities of Lippia callicarpifolia Kunth essential oils and influence of phenological stage on chemical composition

Abstract

Background: Lippia callicarpifolia Kunth (Verbenaceae) is an aromatic perennial shrub popularly known as “flor de aire”, “mostranzo”, and “rosa de castilla” in the community of Tonatico, State of Mexico, Mexico. This study examined the influence of phenological stage on the chemical composition of essential oils (EOs) obtained from aerial parts collected at three different developmental periods and the impact on their antimicrobial activity against bacteria and yeasts of medical importance, including microorganisms isolated from clinical cases. Methods: GC‒MS, retention indices, and standard compounds were employed to identify 38 constituents. The antimicrobial activity of the EOs was evaluated following the Clinical and Laboratory Standard Institute M100 guidelines (2018). Results: During the pre-flowering stage (September), the essential oil of fresh leaves/stems (LSEP) was composed mainly of β-caryophyllene. In contrast, β-phellandrene, β-caryophyllene, and α-pinene were the major compounds in the EOs of leaves/stems and flowers collected during full bloom in November (LNOV and FNOV, respectively) and at the end the flowering stage in February (LFEB and FFEB, respectively). All EOs studied exhibited antibacterial and anticandidal activities. Determination of minimal inhibitory concentrations (MICs) and bactericidal or fungicidal concentrations (MBCs or MFCs) revealed that the most significant antimicrobial activity was observed for the essential oils LNOV and FNOV. LNOV showed the highest level of antifungal activity, significantly inhibiting the growth of Candida glabrata (with an MIC value of 0.5 mg/mL). In addition, the essential oil of flowers FNOV exhibited a broader antibacterial spectrum, effectively inhibiting the development of all gram-negative and gram-positive bacteria studied, including multidrug-resistant strains isolated from clinical cases. The LSEP, LNOV, and FNOV EOs inhibited C. glabrata biofilm formation. Conclusions: The EOs of L. callicarpifolia Kunth may be a viable alternative source of naturally occurring antimicrobial agents for effectively combating infectious diseases that offer an affordable approach to treatment. This study examines for the first time the chemical composition of L. callicarpifolia EOs during different growth stages, including vegetative and flowering stages, along with their antimicrobial activity.