NMR characterization and free radical scavenging activity of pheophytin ‘A’ from the leaves of Dissotis rotundifolia
Dissotis rotundifolia is used traditionally in various parts of Africa for the treatment of various ailments. The air dried and pulverized leaves of Dissotis rotundifolia was extracted with distilled n-hexane and ethylacetate, using Soxhlet apparatus. Isolation and purification were carried out using column and thin layer chromatographic techniques. Fraction B14 gave a single spot on thin layer chromatography with a retention factor (Rf) value of 0.57. Characterization of B14 was doneusing 1H-NMR, 13C-DEPT, COSY, HSQC, HMBC and by direct comparison with literature values and pheophytin A was proposed as the structure of the compound. Pheophytin A exhibited a free radical scavenging activity of 10.10±0.05 and 19.51±0.02% at minimum and maximum concentrations of 1.00 and 4.00 mg/mL, respectively. The acclaimed ethnomedicinal uses of D. rotundifolia by the African natives could be linked to the presence of pheophytin A and other phytoconstituents in the plant. This is the first report of the isolation of pheophytin A from D. rotundifolia.
KEY WORDS: Dissotis rotundifolia, Pheophytin A, Chromatographic techniques, Free radicals, NMR
Bull. Chem. Soc. Ethiop. 2021, 35(1), 207-215.