Pharmacognostic, Phytochemical, and DNA Protection Assays of Eclipta alba, Ageratum conyzoides, Calendula officinalis, and Conyza bonariensis

Asteraceae is the most famous family of ornamental flowering plants. Most of the plants included in this family have medicinal properties. The current research aimed to investigate the pharmacognostic and phytochemical standards of Eclipta alba L., Ageratum conyzoides L., Calendula officinalis L., and Conyza bonariensis L. to ensure their purity, safety, and efficacy as medicinal agents. The investigated parameters included pharmacognostic characterization, that is, powder microscopy, preliminary phytochemical analysis, physicochemical analysis, and in vitro DNA protection assay. The pharmacognostic characteristics evaluated via microscopy included the presence of fibers, linear covering trichomes, and glandular trichomes. Preliminary phytochemical screening confirmed the presence of different classes of phytoconstituents, such as glycosides, flavonoids, phenols, and triterpenoids. The DNA damage protection assay revealed that the crude methanolic extracts of these plants effectively protected human DNA from oxidative stress generated by free radicals of the oxidizing agent (Fenton’s reagent).