Abstract
The significance of medicinal plants in inhibiting microbial growth in food and agricultural production as well as their economic viability cannot be overstated. These plants contain secondary metabolites, which are abundant in antimicrobial compounds, such as flavonoids, tannins, saponins, and alkaloids, and their extracts have demonstrated antimicrobial properties against a variety of plant pathogens.
The primary objective of this study was to explore the possibility of using bioactive compounds in plant defenses and their biological applications. To achieve this, antifungal polyphenolic bioactive compounds were extracted from the stems and leaves of L. tridentata using conventional methods. The total polyphenol and antioxidant potential of the extracts were assessed and characterized using high-performance liquid chromatography (HPLC).
This study compared the polyphenolic constituents of extracts from emerging maceration and Soxhlet extraction techniques in the leaves and stems of Larrea tridentata. The extracts were evaluated for total polyphenolic content (hydrolyzable (HT) and condensed tannins (CT)) and antioxidant activity (ABTS, FRAP, and DPPH). Reverse-Phase High-Performance Liquid Chromatography Electrospray Ionization coupled with mass spectrometry (RP-HPLC-ESI-MS) was used for qualitative identification of antimicrobial phytochemicals. Furthermore, the extracts were analyzed in vitro for antifungal activity against Fusarium oxysporum and Alternaria alternata.
The results revealed that 60:40 ethanol:water macerated leaf extract gave the highest hydrolysable tannins (6.41 ± 0.08 mg GAE/g), while its equivalent showed the highest condensed tannins (2.81 mg CE/g). Soxhlet ethyl acetate leaf (SOX ELL) extract showed 1.14 times more condensed tannin content than that of the stems. The antioxidant potential of the extract increased with increasing polarity of the extraction solvent. SOX ELL had higher antifungal effects against F. oxysporum and A. alternata, whereas the 60:40 ethanol: water ratio resulted in 52% inhibition against A. alternata and 43% inhibition against F. oxysporum. Polyphenols with antifungal properties were found in the extracts, including caffeic acid 4-O-glucoside, rhamnetin, protocatechuic acid 4-O-glucoside, kaempferol, (+)-gallocatechin, luteolin, guteolin 7-O-(2-apiosyl-glucoside), gallic acid 4-O-glucoside, cumaric acid 4-O-glucoside, quercetin, NDGA, piceatannol 3-O-glucoside, pterostilbene, tetramethylscutellarein, and cirsimaritin.
L. tridentata leaf extracts exhibit potential effectiveness in the development of biological control agents, which can not only enhance crop protection, but also contribute to overall agricultural sustainability.