Antioxidant Capacities, Phenolic Profile and Cytotoxic Effects of Saxicolous Lichens from Trans-Himalayan Cold Desert of Ladakh

Abstract

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.

Anti‐inflammatory and anti‐insulin resistance activities of aqueous extract from Anoectochilus burmannicus

“…The ABTS + scavenging ability was determined according to the method of Jatinder Kumar et al., (2014). A mixture of 7 mmol/L ABTS + stock solution with 2.45 mmol/L potassium persulfate (1:1, v/v) was left in the dark at room temperature for 12–16 hr until the reaction was complete and the absorbance was stable.…”

Endolichenic fungi: the lesser known fungal associates of lichens

“…Lichens are an attractive source of unique secondary metabolites (Kumar et al 2014); so far, more than 1000 secondary metabolites have been extracted from lichens found growing from the Arctic to the tropics (Stocker-Wörgötter 2008). About 0.1–5% of the dry weight of lichen thallus is composed of secondary metabolites derived from the acetyl polymalonyl, mevalonic and shikimate pathways (Stocker-Wörgötter 2008).…”

R amalina Lichens and Their Major Metabolites as Possible Natural Antioxidant and Antimicrobial Agents

“…The antioxidant capacity of the 14 lichen species in different solvent extracts has been investigated in the literature (Kumar et al 2014). The 14 lichens are Dermatocarpon vellereum, Umbilicaria vellea, Rhizoplaca chrysoleuca, Rhizoplaca melanophthalma, Pleopsidium flavum, Xanthoparmelia mexicana, Acarospora badiofusca, Xanthoria elegans, Lecanora frustulosa, Lobothallia alphoplaca, Physconia muscigena, Melanelia disjuncta, Xanthoparmelia stenophylla and Peccania coralloides.…”