Portulaca oleracea Exposed to Polycyclic Aromatic Hydrocarbon Pollution: Mapping Down Nutraceutical and Histochemical Changes

Aim: Polycyclic aromatic hydrocarbons (PAHs) are extremely carcinogenic environmental pollutants which have now become a global environmental problem. Such pollutants can accumulate in soil and can adversely affect the growth and physiology of plants. The current study aims to investigate the effect of such pollutants on the plants secondary metabolism with special emphasis on the production of nutraceutical principles. Materials and Methods: A well‑known dietary plant Portulaca oleracea was collected from agricultural land in close vicinity to thermal power units, and results were compared to a background sample. Pigment estimation, evaluation of total phenolics/flavonoids, and Non-enzymatic antioxidant principles, namely ascorbic acid and α‑tocopherol were carried out. Primary metabolites, such as total proteins and carbohydrates, were also estimated. The identification of individual phenolic and flavonoid principles were also carried out. Results were supported with real‑time histochemical evidence and scanning electron microscopy (SEM) studies. Results: Chlorophyll a showed a significant reduction of 40.85% when compared to control and so was the case with β‑carotene, which recorded a decline of 33.5% when compared to control. Total phenolics and flavonoids, ascorbic acid, and α‑toopherol showed a decline of 42.25%, 28.17%, 45.5%, and 81.9%, respectively, when compared to control. Gallic acid, p‑coumaric acid, ferulic acid, naringenin, quercetin, ellagic acid, and rutin were found to be significantly lesser in pollution exposed plants. Significant cell death was evident from histochemical studies as well, along with blockage of stomata as reflected from SEM studies. Conclusion: P. oleracea exposed to PAH pollution showed a significant decline in the production of phytochemicals with special emphasis on nutraceutical contents.