Agave amica (Medik.) Thiede & Govaerts (Asparagaceae)-Insights into Its Valuable Phenolic Profile and In Vitro Antimicrobial, Antibiofilm, Antioxidative, and Antiproliferative Properties

Abstract

Background/Objectives: Agave amica (Medik.) Thiede & Govaerts (Asparagaceae family) is an ornamental bulbous species, widely used for its fragrance but less studied as a medicinal species. This study is aimed at assessing the phenolic profile and selected biological properties of ethanolic extracts obtained from the aerial parts and bulbs of A. amica cultivated in Romania. Methods: The phenolic composition was characterized by spectrophotometric methods and LC/MS analysis. The antioxidant activity was evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity) and FRAP (Ferric reducing antioxidant power) tests, while the in vitro antimicrobial capacity was investigated by the agar-well diffusion, the broth microdilution, and the antibiofilm assays. Cytotoxicity was tested on a colorectal adenocarcinoma cell line (DLD-1) by a CCK-8 assay. Results: Both ethanolic extracts showed important polyphenol content and caffeic acid as their main compound. Significantly higher amounts of total polyphenols (44.25 ± 1.08 mg/g), tannins (12.55 ± 0.34 mg/g), flavonoids (9.20 ± 0.19 mg/g), caffeic acid derivatives (19.95 ± 0.05 mg/g), and also antioxidant activity (IC₅₀ = 0.82 ± 0.02 mg/mL, and 79.75 ± 1.80 µM TE/g, respectively) were found for the aerial parts extract compared to the bulbs one (p < 0.001). Notable anti-Candida albicans activity and moderate efficacy against Listeria monocytogenes and Staphylococcus aureus were displayed by both extracts against planktonic cells and biofilm. A dose-dependent cytotoxicity towards the colorectal adenocarcinoma cell line was recorded as well. Conclusions: This study brings novelty to the scientific literature by characterizing the phenolic profile and in vitro antimicrobial, antibiofilm, antioxidant, and antiproliferative activities of the ethanolic extracts obtained from A. amica, thus highlighting this herbal species's medicinal potential.

Keywords: A. amica; antibacterial; antibiofilm; antifungal; antioxidant; cytotoxic; phenols.

Figure 1

The effect of A. amica aerial parts extract on the growth inhibition of DLD cells was evaluated by incubating the cells with different concentrations of the extract (Pta5—0.130 μmol GAE/μL, Pta4—0.260 μmol GAE/μL, Pta3—0.390 μmol GAE/μL, Pta2—0.520 μmol GAE/μL, Pta1—0.650 μmol GAE/μL) for 24 h. Cell proliferation was measured using the CCK-8 assay. Doxorubicin was utilized as a positive control, and statistical significance was determined with ** p ≤ 0.01, and *** p ≤ 0.001. The IC₅₀ value through dose-response analysis revealed an inhibitory concentration of 0.580 μmol GAE/μL.

Figure 2

The effect of A. amica b extract on the growth inhibition of DLD cells was evaluated by incubating the cells with different concentrations of the extract (Ptb5—0.087 μmol GAE/μL, Ptb4—0.174 μmol GAE/μL, Ptb3—0.261 μmol GAE/μL, Ptb2—0.348 μmol GAE/μL, Ptb1—0.435 μmol GAE/μL) for 24 h. Cell proliferation was measured using the CCK-8 assay. Doxorubicin was utilized as a positive control, and statistical significance was determined with ** p ≤ 0.01, and *** p ≤ 0.001. The IC₅₀ value through dose-response analysis revealed an inhibitory concentration of 0.285 μmol GAE/μL.