Comparative study on phenolic, flavonoids and in vitro antioxidant activity of wild edible plants from Loktak Lake wetland ecosystem under North East Indian Himalayan Region.

The present study investigates the antioxidant activity of 28 wild edible plants (WEPs) resources of Loktak Lake wetland ecosystem of Manipur, North East Indian Himalayan Region and their correlation with phenolics and flavonoids. Antioxidant activity was measured by DPPH, ABTS and FRAP assay. The antioxidant capacity was found to wide ranges of 1.71 to 263.7 µM TEAC/g fresh weight. In three assays, maximum antioxidant capacity is in same order Jussiaea repens L. > Gynura cusimbua (D. Don) Moore > Polygonum sagitattum L. ranging from 99.5 to 263.7 µM TEAC/g fresh weight. The correlation study established that all the three antioxidant assays are positively correlated and phenolics have contributed more in antioxidant activity than flavonoids. Among 28 WEPs, Jussiaea repens L. and Gynura cusimbua (D. Don) Moore were found to be most promising. These plants can be used as source of natural antioxidant additives, nutritional supplements or ingredients of functional foods.

Reactive oxygen species scavenging mechanisms associated with polyethylene glycol mediated osmotic stress tolerance in Chinese potato.

Influence of polyethylene glycol (PEG) mediated osmotic stress on reactive oxygen species (ROS) scavenging machinery of Chinese potato (Solenostemon rotundifolius (Poir.) J. K. Morton) was investigated. Five genotypes of Chinese potato were raised in Murashige and Skoog (MS) basal medium containing 6-benzylaminopurine (BAP, 1 mg L-1) along with various concentrations of PEG-6000 mediated stress conditions (0, -0.2 and -0.5 MPa) and evaluated for osmotic stress tolerance in vitro. The medium containing PEG-6000 had a detrimental effect on plantlet growth and development while compared with the control. Accumulation of H2O2 was lower in Sreedhara and Subala and higher in Nidhi under PEG stress, which was evident by in situ detection in leaves. Lipid peroxidation product such as malondialdehyde (MDA) content was increased due to PEG stress which was more in susceptible genotype than that in tolerant ones. An enhanced ROS-scavenging antioxidant enzyme was observed under stress with respect to the control. The enzymes of ascorbate-glutathione cycle showed an important role in scavenging ROS. The imposition of PEG stress also increased the non-enzymatic antioxidants viz., the ascorbate and reduced glutathione content which was prominent in tolerant genotypes in comparison to susceptible. The present study indicated that, Sreedhara and Subala showed more tolerance to osmotic stress with better ROS scavenging machineries which would be the lines of interest for augmenting future breeding strategies in this climate resilient minor tuber crop.