UPLC–MS/MS quantitative analysis and structural fragmentation study of five Parmotrema lichens from the Eastern Ghats

Abstract

Comparative phytochemical analysis of five lichen species [Parmotrema tinctorum (Delise ex Nyl.) Hale, P. andinum (Mull. Arg.) Hale, P. praesorediosum (Nyl.) Hale, P. grayanum (Hue) Hale, P. austrosinense (Zahlbr.) Hale] of Parmotrema genus were performed using two complementary UPLC-MS systems. The first system consists of high resolution UPLC-QToF-MS/MS spectrometer and the second system consisted of UPLC-MS/MS in Multiple Reaction Monitoring (MRM) mode for quantitative analysis of major constituents in the selected lichen species. The individual compounds (47 compounds) were identified using Q-ToF-MS/MS, via comparison of the exact molecular masses from their MS/MS spectra, the comparison of literature data and retention times to those of standard compounds which were isolated from crude extract of abundant lichen, P. tinctorum. The analysis also allowed us to identify unknown peaks/compounds, which were further characterized by their mass fragmentation studies. The quantitative MRM analysis was useful to have a better discrimination of species according to their chemical profile. Moreover, the determination of antioxidant activities (ABTS inhibition) and Advance Glycation Endproducts (AGEs) inhibition carried out for the crude extracts revealed a potential antiglycaemic activity to be confirmed for P. austrosinense.

Secondary metabolites from lichen as potent inhibitors of advanced glycation end products and vasodilative agents

“…Besides, synergistic, activity-enhancing effects due to the presence of several active compounds as found in crude lichen extracts have not been studied but may have significant impact. Recently the crude acetonitrile extract of Parmotrema austrosinense has been reported to exhibit notable inhibitory effects on the formation of pentosidine-like AGEs [15]. The same study also reported atranorin (3), methyl-orcinol--carboxylate (20) and lecanoric acid as its major constituents.…”

“…The depsidone diploicin for example has inspired the development of clofazimine (Lamprene®) and the group of riminophenazine antibiotics [21]. In regard to AGEs, Kumar et al have recently reported the inhibition of their formation by crude extracts of Parmotrema species [15], however, to the best of the authors' knowledge, the present work is the first evaluation of that kind on single lichen constituents.…”

“…Moreover, many promising candidates show additional antioxidant or radical scavenging activities [14], and belong to different chemical families such as polyphenols [11], terpenes, and alkaloids [9]. While plants and their anti-AGEs effects have been thoroughly studied, the impact of lichens and their secondary metabolites remains mostly unexplored [15]. Lichens are symbiotic organisms comprising filamentous fungi and photosynthetic partners such as eukaryotic algae or cyanobacteria.…”

“…This unique combination yields very particular metabolites that cannot be found in the isolated partners or elsewhere in nature. Many of these compounds do exhibit notable biological activities like anti-inflammatory, antioxidant, antibacterial, and cytotoxic effects [16][17][18][19], however, very little is known about their effect on the formation of AGEs [15]. With this in mind, the present study evaluated thirty-seven secondary lichen metabolites as well as five semisynthetic derivatives of usnic acid (a major metabolite found in many lichen species) for their potential anti-AGE effects in a fluorescence-based Maillard reaction assay [20].…”

Study on Chemical Constituents of the Lichen Parmotrema Tinctorum (Nyl.) Hale (Parmeliaceae)

“…Hale. Previous studies on its chemical constituents reported the presence of flavoxanthin, β-citraurin, atranorin, lecanorol, lecanoric acid, isolecanoric acid, salazinic acid, and some monocyclic aromatic compounds such as orsellinic acid, ethyl orsellinate and methyl β-orsellinate [4][5][6][7][8][9][10]. Moreover, P. tinctorum extracts showed presence of carbohydrates, phenols, flavanoids, tannins, terpenoids, coumarins and saponins which may be basis of its biological effects [11].…”