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Extreme nature of climate and topographical conditions may affect soil properties at cold desert high altitude. Hence, the present investigation was undertaken to know altitudinal variations in soil physico-chemical properties at cold desert high altitude region. For this, agriculture soils were collected from different altitude viz. site I (10000-11000 ft), site II (11000-12000 ft) and site III (>12000 ft amsl) at Leh-Ladakh (cold desert high altitude region), India. Interestingly, sand percentage in soil was significantly high at site III and decreased gradually with the altitude. In contrast to sand level, silt concentration was high at site I and decreased significantly (p<0.05) with increasing altitude. There was no significant (p<0.05) difference in bulk density (BD) and electrical conductivity (EC) among all study sites. However, the highest pH, total dissolved solid (TDS), and CaCO 3 value was recorded at site I while higher soil organic matter (SOM) was at site III. Pearson correlation coefficient analysis showed the negative correlation (p<0.01, p<0.05) of clay, silt, and pH, whereas positive correlation of sand and SOM (p<0.01) with altitude. Hence, our findings suggest the altitudinal variations in soil physico-chemical properties at cold desert high altitude.

Fourteen saxicolous lichens from trans-Himalayan Ladakh region were identified by morpho-anatomical and chemical characteristics. The n-hexane, methanol and water extracts of the lichens were evaluated for their antioxidant capacities. The lichen extracts showing high antioxidant capacities and rich phenolic content were further investigated to determine their cytotoxic activity on human HepG2 and RKO carcinoma cell lines. The ferric reducing antioxidant power (FRAP), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide (NO) radical scavenging capacities and β-carotene-linoleic acid bleaching property exhibited analogous results where the lichen extracts showed high antioxidant action. The lichen extracts were also found to possess good amount of total proanthocyanidin, flavonoid and polyphenol. The methanolic extract of Lobothallia alphoplaca exhibited highest FRAP value. Methanolic extract of Xanthoparmelia stenophylla showed the highest ABTS radical scavenging capacity. The n-hexane extract of Rhizoplaca chrysoleuca exhibited highest DPPH radical scavenging capacity. Highest antioxidant capacity in terms of β-carotene linoleic acid bleaching property was observed in the water extract of Xanthoria elegans. Similarly, Melanelia disjuncta water extract showed highest NO scavenging capacity. Among n-hexane, methanol and water extracts of all lichens, the methanolic extract of Xanthoparmelia mexicana showed highest total proanthocyanidin, flavonoid and polyphenol content. From cytotoxic assay, it was observed that the methanolic extracts of L. alphoplaca and M. disjuncta were exhibiting high cytotoxic effects against cancer cell growth. Similarly, the water extract of Dermatocarpon vellereum, Umbilicaria vellea, X. elegans and M. disjuncta and the methanolic extract of M. disjuncta and X. stenophylla were found to possess high antioxidant capacities and were non-toxic and may be used as natural antioxidants for stress related problems. Our studies go on to prove that the unique trans-Himalayan lichens are a hitherto untapped bioresource with immense potential for discovery of new chemical entities, and this biodiversity needs to be tapped sustainably.

Hypoxia has been reported to cause hippocampal neurodegeneration resulting in learning and memory deficits. In the present study, we investigated the potential of salidroside, a glucoside derivative of tyrosol, in ameliorating hypoxia-induced neurodegeneration and memory impairment. Morris water maze test showed improvement in learning and spatial memory of salidroside-treated hypoxic rats correlating with increased dendritic intersections and arborization. Salidroside administration increased phosphorylation of insulin receptor subunit A (IRA) at Y972, Y1162/63, and Y1146 sites and subsequent activation of AMP-activated protein kinase (AMPK) a subunit isoforms pAMPKa1 and pAMPKa2 resulting in mitochondrial biogenesis. Contrarily, silencing of IRA in salidroside-supplemented hypoxic hippocampal cells could not improve cell viability or alter pAMPKa1 and pAMPKa2 expression. Rats administered with salidroside showed elevated expression of phosphorylated cAMP response elementbinding protein in the hippocampus. Salidroside administration also resulted in increased sirtuin 1 (SIRT1) activity through a cytochrome P4502E1 (CYP2E1)-regulated mechanism that was independent of pIRA. Taken together, these findings suggest a synergistic role of pIRA and SIRT1 in salidrosidemediated neuroprotection, mitochondrial biogenesis, and cognitive improvement during hypoxia.