Find in Library

The present study was intended for the identification of secondary metabolites in acetone extract of the lichen <i>Hypotrachyna cirrhata</i> using UPLC-ESI-QToF-MS/MS and the detection of bioactive compounds. This study led to the identification of 22 metabolites based on their MS/MS spectra, accurate molecular masses, molecular formula from a comparison of the literature database (DNP), and fragmentation patterns. In addition, potent antioxidant and α-glucosidase inhibitory potentials of acetone extract of <i>H. cirrhata</i> motivated us to isolate 10 metabolites, which were characterized as salazinic acid (<b>11</b>), norlobaridone (<b>12</b>), atranorin (<b>13</b>), lecanoric acid (<b>14</b>), lichesterinic acid (<b>15</b>), protolichesterinic acid (<b>16</b>), methyl hematommate (<b>17</b>), iso-rhizonic acid (<b>18</b>), atranol (<b>19</b>), and methylatratate (<b>20)</b> based on their spectral data. All these isolates were assessed for their free radicals scavenging, radical-induced DNA damage, and intestinal α-glucosidase inhibitory activities. The results indicated that norlobaridone (<b>12</b>), lecanoric acid (<b>14</b>), methyl hematommate <b>(17</b>), and atranol (<b>19</b>) showed potent antioxidant activity, while depsidones (salazinic acid (<b>11</b>), norlobaridone (<b>12</b>)) and a monophenolic compound (iso-rhizonic acid, (<b>18</b>)) displayed significant intestinal α-glucosidase inhibitory activities (<i>p</i> < 0.001), which is comparable to standard acarbose. These results were further correlated with molecular docking studies, which indicated that the alkyl chain of norlobaridione (<b>12</b>) is hooked into the finger-like cavity of the allosteric pocket; moreover, it also established Van der Waals interactions with hydrophobic residues of the allosteric pocket. Thus, the potency of norlobaridone to inhibit α-glucosidase enzyme might be associated with its allosteric binding. Also, MM-GBSA (Molecular Mechanics-Generalized Born Surface Area) binding free energies of salazinic acid (<b>11</b>) and norlobaridone (<b>12</b>) were superior to acarbose and may have contributed to their high activity compared to acarbose.