Phytochemical analysis and phytotoxic evaluation of Chenopodium glaucum L.

Abstract

Plant secondary metabolites such as alkaloids, flavonoids, glycosides, saponins, tannins, and terpenoids with medicinal properties can be investigated as botanical herbicides. Therefore, we have investigated phytochemicals profile and phytotoxicity of aqueous, ethyl acetate, n-hexane and methanol extracts (5 mg/mL and 10 mg/mL) of Chenopodium glaucum L. (C. glaucum) on radish under laboratory conditions. Initial screening of the extracts showed the occurance of several phytochemicals like alkaloids, flavonoids, anthraquinone, cardiac glycosides, saponins, tannins and terpenoids. Alkaloids and tannins content was higher in methanol extract followed by ethyl acetate and n-Hexane extracts. Elemental analysis revealed that the presence of minerals like magnesium 0.725 mg/100 g DW, calcium 2.25 mg/100 g DW, potassium 6.55 mg/100 g DW, sodium 0.375 mg/100 g DW, iron 225 mg/100 g DW, zinc 51 mg/100 g DW, copper 12 mg/100 g DW, and manganese 119 mg/100 g DW was found. In phytotoxicity assay, the extracts at 10 mg/mL showed inhibitory effects on the growth of radish. Maximum decrease in seed germination (%), seed germination index, seedling fresh and dry weight was caused by the methanolic extract at 10 mg/mL. The chlorophyll a content was decreased while chlorophyll b content was increased with increasing concenteration of the extracts. Phenolics content of the seedlings was higher with the application of 10 mg/mL of the extracts. Powder microscopy of C. glaucum showed the presence of calcium oxalate crystal, pieces of trichome, fragments of cork cells, starch granules, phloem fibers and lignified xylem vessels with annular thickenings. Microscopic study of abaxial surface of leaf showed the presence of anisocytic type of stomata, surrounded by subsidiary cells. Stomatal size was measured 25.017 µm and the mean density was 570.66/mm2. Findings of this study concluded that phytochemicals found in C. glaucum extracts were highly phytotoxic on seed germination and seedling growth of radish. It is therefore recommended to isolate and characterize such novel compounds from this plant species for the development of new biodegradable botanical herbicides.