GC-MS analysis of the alkaloid extract of Epdedra equisetina and in silico anti-inflammatory activity of its alkaloids

Epdedra equisetina is a potential medicinal plant in Tajikistan. It was used for a long time in Tajik folk medicine for colds, joint pain, rheumatism, malaria, stomach and  liver disorders. The alkaloid extract of Epdedra equisetina was obtained by acid-base extraction and analyzed by gas chromatography-mass spectrometry (GC-MS) and column chromatography (CC). The alkaloid extraction yield of Ephedra equisetina was equal to 1.57%. Four alkaloids, namely ephedrine (pseudoephedrine), 2,3,4-trimethyl-5-phenyloxazolidine, trans-1.2-dimethyl-3-phenylaziridine and 3,4-dimethyl-2,5-diphenyloxazolidine were identified in the alkaloid extract of Epdedra equisetina. In silico anti-inflammatory activity of E. equisetina alkaloids was tested against inhibition of cyclooxygenases-1 enzyme (COX-1) (PDB code 3N8Z), cyclooxygenases-2 enzyme (COX-2) (PDB code 3LN1), and P38 mitogen-activated protein kinase (p38MAPK) (PDB code 1OZ1). The celecoxib drug was used as a positive control. Molecular docking values of alkaloids in Epdedra equisetina ranged between -5.2 and -9.4 kcal/mol. The value for the reference drug (celecoxib) ranged between -6.6 and -12.2 kcal/mol. 3,4-Dimethyl-2,5-diphenyloxazolidine shows the highest molecular docking values of -7.0, -9.4, and -7.8 kcal/mol for COX-1, COX-2, and p38MAPK proteins, respectively. 3,4-Dimethyl-2,5-diphenyloxazolidine can act as a natural alternative inhibitor of the COX-2 protein.