Hexavalent chromium is a highly soluble environmental contaminant. It is a widespread anthropogenic chromium species that is 100 times more toxic than trivalent chromium. Leather, chrome plating, coal mining and paint industries are the major sources of hexavalent chromium in water. Hexavalent chromium is widely recognised as a carcinogen and mutagen in humans and other animals. It is also responsible for multiorgan damage, such as kidney damage, liver failure, heart failure, skin disease and lung dysfunction. The fate of the toxicity of hexavalent chromium depends on its oxidation state. The reduction of Cr (VI) to Cr (III) is responsible for the generation of reactive oxygen species (ROS) and chromium intermediate species, such as Cr (V) and Cr (IV). Reactive oxygen species (ROS) are responsible for oxidative tissue damage and the disruption of cell organelles, such as mitochondria, DNA, RNA and protein molecules. Cr (VI)-induced oxidative stress can be neutralised by the antioxidant system in human and animal cells. In this review, the authors summarise the Cr (VI) source, toxicity and antioxidant defence mechanism against Cr (VI)-induced reactive oxygen species (ROS).

Sphaeranthus indicus is an important medicinal plant, widely used in traditional medicine for its therapeutic potential, particularly its antiviral, antimicrobial, anti-inflammatory and anticancer activities. Despite its medicinal importance, there is a need for developing efficient propagation methods to ensure its large-scale cultivation and conservation. This study aims to develop a protocol direct shoot organogenesis from nodal explants of Sphaeranthus indicus. In vitro regeneration through direct shoot organogenesis offers an efficient method for the propagation of medicinally valuable plants. Explants were subjected to surface sterilization followed by culture on MS medium (Murashige and Skoog medium) supplemented with different concentrations of BAP (6-Benzylaminopurine) for shoot induction. Root initiation was achieved on MS medium with α-naphthaleneacetic acid (NAA), and regenerated plantlets were successfully acclimatized and shifted to greenhouse and open field conditions. High shoot induction frequency of 91.6% with the lowest concentration of 1 mg/L BAP highlights the efficient regeneration protocol and initiate a pathway for micropropagation and cultivation of multipotential medicinal plant, S. indicus in large-scale. During the present investigation, an efficient in vitro regeneration protocol is developed