Page 232 - Demo

236 PROCEEDINGS OF INTERNATIONAL SCIENTIFIC CONFERENCE ON APPLIED BIOTECHNOLOGY3. DISCUSSIONFive pure compounds have been isolated from avocado leaves (Persea americana Mill.). Their chemical structures were determined based on nuclear magnetic resonance (NMR) spectroscopy combined with a comparison of spectral data from the literature.Compound 1 was obtained as yellow needle-shaped crystals. The 1H-NMR spectrum of compound 1 shows signals for 6 aromatic protons with chemical shifts ranging from 6.22 to 7.40 ppm. Among them, 2 proton signals interacting with each other appear as doublets with a coupling constant of 1.5 Hz, indicating that they are located in a meta-position relative to each other on an aromatic ring; 1 proton at a chemical shift of 6.92 ppm appears as a doublet with a coupling constant of 8.5 Hz, suggesting this proton is in the ortho-position and interacts with 1 proton in another aromatic ring. The signal of 1 proton as a singlet at dH 6.55 indicates that this proton is not attached to the two aromatic rings mentioned above. Thus, the proton signals suggest the presence of a flavone framework. Correspondingly, in the 13C-NMR spectrum of compound 1, signals for 15 carbon atoms of the flavone framework appear. The carbonyl group has a chemical shift at dC 183.87 ppm and the 4 carbon atoms attached to the OH group have chemical shifts dC at 163.21 (C-5); 166.37 (C-7); 147.05 (C-3%u2019) and 151.01 (C-4%u2019). Based on the analysis of the spectral data obtained for compound 1, combined with a comparison with the literature [9], compound 1 was identified as luteolin. Luteolin has been reported to possess many valuable biological activities, including antioxidant, anticancer, and antiinflammatory activities [9].Compound 2 was obtained as a pale yellow solid. The 1H-NMR spectrum of compound 2 shows signals for 2 protons in