Phytochemical Investigation, Antioxidant Properties and In Vivo Evaluation of the Toxic Effects of Parthenium hysterophorus

Phytochemical and Biological Characterization of the Fractions of the Aqueous and Ethanolic Extracts of Parthenium hysterophorus

In this study, the fractions of the aqueous (AE) and ethanolic (EE) crude extracts of Parthenium hysterophorus were evaluated for their phytochemical composition, cytotoxic, and antioxidant activity. The two extracts were subjected to a fractionation by vacuum liquid chromatography, obtaining seven fractions for each extract. These fractions were evaluated for the presence of phenolic compounds by reverse phase high performance liquid chromatography coupled to mass spectrometer (RP-HPLC-MS) analysis. Their cytotoxic activity was tested with a hemolysis assay. The antioxidant activity was evaluated with the Trolox equivalent antioxidant capacity (TEAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and hydroxyl radical (–OH) scavenging assays. In addition, the effect of the fractions on the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), from human erythrocytes, was evaluated. The phytochemical screening by RP-HPLC-MS mainly showed the presence of flavonoids and hydroxycinnamic acids. The hemolysis assay exhibited a low cytotoxic activity by the fractions of the AE, but the fractions of the EE exhibited a hemolytic effect. The fractions of the AE and EE showed significant antioxidant activity to inhibit radicals in the three radical scavenging assays. Moreover, only some fractions of the AE showed a significant increase in the activity of the SOD enzyme, while the activity of CAT exhibited a significant increase by the fractions of the two extracts. The fractions of the AE and EE of P. hysterophorus have phytochemicals with antioxidant activity to inhibit radicals and increase the activity of in vitro antioxidant enzymes.

Documentation of Phytotoxic Compounds Existing in Parthenium hysterophorus L. Leaf and Their Phytotoxicity on Eleusine indica (L.) Gaertn. and Digitaria sanguinalis (L.) Scop

The utilization of the invasive weed, Parthenium hysterophorus L. for producing value-added products is novel research for sustaining our environment. Therefore, the current study aims to document the phytotoxic compounds contained in the leaf of parthenium and to examine the phytotoxic effects of all those phytochemicals on the seed sprouting and growth of Crabgrass Digitaria sanguinalis (L.) Scop. and Goosegrass Eleusine indica (L.) Gaertn. The phytotoxic substances of the methanol extract of the P. hysterophorus leaf were analyzed by LC-ESI-QTOF-MS=MS. From the LC-MS study, many compounds, such as terpenoids, flavonoids, amino acids, pseudo guaianolides, and carbohydrate and phenolic acids, were identified. Among them, seven potential phytotoxic compounds (i.e., caffeic acid, vanillic acid, ferulic acid, chlorogenic acid, quinic acid, anisic acid, and parthenin) were documented, those are responsible for plant growth inhibition. The concentration needed to reach 50% growth inhibition in respect to germination (EC_g50), root length (EC_r50), and shoot length (EC_s50) was estimated and the severity of phytotoxicity of the biochemicals was determined by the pooled values (rank value) of three inhibition parameters. The highest growth inhibition was demarcated by caffeic acid, which was confirmed and indicated by cluster analysis and principal component analysis (PCA). In the case of D. sanguinalis, the germination was reduced by 60.02%, root length was reduced by 76.49%, and shoot length was reduced by 71.14% when the chemical was applied at 800 μM concentration, but in the case of E. indica, 100% reduction of seed germination, root length, and shoot length reduction occurred at the same concentration. The lowest rank value was observed from caffeic acids in both E. indica (rank value 684.7) and D. sanguinalis (909.5) caused by parthenin. It means that caffeic acid showed the highest phytotoxicity. As a result, there is a significant chance that the parthenium weed will be used to create bioherbicides in the future.