Study the effect of phenolic compounds extracted from some wild Iraqi plants as anti-leishmaniasis in vitro

Background: As natural compounds, especially from plants, are considered a rich source of therapeutic importance, researchers have reported the benefits of using such products in treatments for diseases affecting humans and other organisms for many years. The study included the extraction of phenolic compounds from four genera of plants of the Compositae family growing wild in western Iraq, including:  Achilliea fragrantissima, Herba-alba Artemisia (wormwood),   Lactuca serriola (Wild lettuce ), and Silybum marianum. Methods: Hydro-alcoholic extraction was employed by the cold maceration method with 75% Ethanol. A general chemical analysis of the secondary metabolites in the crude ethanolic extract was conducted for each of the four plants separately. Thin layer chromatography (TLC) was used to estimate the types of phenolic compounds qualitatively, and the total phenols in each extracted residue were quantified using a colorimetric method with a standard curve plotted for the phenol standard (Gallic acid). The HPLC technique was also employed to identify the types and concentrations of phenolic compounds extracted from each plant residue. The effect of total phenolics extracted from each plant on cultures of the Leishmanial parasite was also studied in 24-hour in vitro experiments, using different concentrations of each plant's extract. The violet color was then read at the wavelength (620 nm) using an ELISA Reader device to obtain the inhibition rates, as the intensity of the color is an expression of the number of living cells. Results: The results showed that the plants contain phenols, flavonoids, tannins, glycosides, saponins, and alkaloids; however, the wormwood extract yielded a negative result for alkaloids. The results of thin-layer chromatography analysis showed that the phenolic extracts of the four plants contained, qualitatively, Pyrogallol, Cinnamic acid, gallic acid, and Hydroquinone in varying proportions. The extract also contained some types of flavonoids. Results for HPLC showed that the four plants are rich in these phenolic compounds. For quantitative total phenolic compound results, Artemisia, the wormwood plant, contained the highest percentage, 1464.72 mg% dry plant powder. In contrast, the lowest percentage was found in the Silybum plant, at 223.86 mg% dry plant powder. The activity against Leishmania growth inhibition rate showed that each plant extract exhibited a different mode of inhibiting the parasite cultures, with Silybum plant showing the best effects, and no significant difference was observed across all concentrations.  These vary depending on the type of phenolic compounds and the flavonoids present in each plant, as well as their concentration. Conclusion: The four plant genera of the Compositae family growing wild in western Iraq, including:  Achilliea fragrantissima, Herba-alba Artemisia (wormwood),   Lactuca serriola (Wild lettuce), and Silybum marianum, are rich with phenolic compounds and different types of flavonoids which may help in parasite diminution, as these secondary active metabolites possess notable effects in free radical scavenging and antioxidant activity.