Isolated compounds
The methanol and hydroethanolic extracts from the stem bark and leaves of D. edulis, respectively, were subjected to silica gel and Sephadex LH-20 column chromatography (CC) to yield 16 known compounds (1–16) (Fig. 1). The structures of the isolates were determined from their spectroscopic data (UV, IR, NMR and MS) and by comparison with those of similar compounds reported in the literature.
Lichexanthone (1): white powder, HR-ESI-MS (positive mode, m/z): 287.0935 [M + H]+, (calcd 287.0914 for C16H15O5). 1H-NMR (Pyridin-d5, 500 MHz): 2.91 (3H, s, -CH3), 3.78 (3H, d, J = 1.5 Hz, -OCH3), 3.81 (3H, d, J = 1.5 Hz, -OCH3), 6.55 (1H, d, J = 2.1 Hz, H-2), 6.60 (1H, d, J = 2.1 Hz, H-4), 6.79 (1H, d, J = 2.4 Hz, H-5), 6.86 (1H, d, J = 2.2 Hz, H-7), 13.91 (1H, -OH). 13C-NMR (Pyridin-d5, 125 MHz): 23.8 (C-15), 56.2 (C-16), 56.2 (C-14), 92.8 (C-4), 97.8 (C-2), 99.5 (C-5), 104.7 (C-10), 113.4 (C-13), 116.3 (C-7), 143.8 (C-8), 157.7 (C-11), 160.0 (C-12), 164.7 (C-6), 164.8 (C-1), 166.8 (C-3), 183.0 (C-9) [16].
Griseoxanthone C (2): white powder, HR-ESI-MS (positive mode, m/z): 274.0837 for [M + 2H]+, (calcd 274.0836 for C15H14O5).1H-NMR (CDCl3, 600 MHz): 13.39 (1H, OH), 6.68 (1H, s, H-7), 6.66 (1H, s, H-5), 6.35 (1H, s, H-4), 6.31 (1H, s, H-2), 3.86 (3H, s, OCH3), 2.88 (3H m, -CH3). 13C-NMR (CDCl3, 150 MHz): 182.6 (C-9), 165.9 (C-3), 163.8 (C-1), 163.7 (C-6), 159.4 (C-11), 156.9 (C-12), 143.5(C-8), 115.6 (C-7), 113.0 (C-13), 104.2 (C-10), 98.5 (C-5), 96.8 (C-2), 92.1 (C-4), 55.7 (C-14), 23.6 (C-15) [17].
3,3′-O-Dimethylellargic acid (3): white powder, HR-ESI-MS (positive mode, m/z): 353.0268 for [M + Na]+, (calcd 353.0260 for C16H10O8Na). 1H-NMR (Pyridin-d5, 500 MHz): 3.59 (3H, s, -OCH3), 4.17 (3H, s, -OCH3), 4.99 (1H, -OH), 8.04 (1H, s) [18].
3,3′,4-Tri-O-methylellagic acid (4): white powder, HR-ESI-MS (positive mode, m/z): 367.0425 for [M + Na]+. (calcd 367.0424 for C17H12O8Na). 1H-NMR (Pyridin-d5, 500 MHz): 3.85 (3H, s, -OCH3), 4.13 (3H, s, -OCH3), 4.19 (3H, s, -OCH3), 7.82 (1H, -OH), 8.03 (1H, s). 13C-NMR (Pyridin-d5, 125 MHz): 56.4 (-OCH3), 61.1 (-OCH3), 61.3 (-OCH3), 107.8 (C-5′), 111.6 (C-1′), 112.6 (C-1), 112.9 (C-5), 113.6 (C-6′), 114.1 (C-6), 141.1 (C-2), 142.1 (C-3′), 141.8 (C-2′), 142.1 (C-3), 154.1 (C-4′), 154.3 (C-4), 158.9 (C-7′), 159.0 (C-7) [18].
3,3′′-Di-O-methylellargic acid 4-O-(3′′-galloyl)-β-D-xylopyranoside (5): white powder, HR-ESI-MS (positive mode, m/z): 637.0839 for [M + Na]+, (calcd 637.0806 for C28H22O16Na). 1H-NMR (MeOD, 600 MHz): 8.66 (1H, s, H-5), 8.36 (1H, s, H-5′), 7.85 (2H, s, H-2′′ and H-6′′), 6.20 (2H, d, J = 7.4 Hz), 5.91 (2H, d, J = 9.3 Hz, H-1′′), 4.73 (1H, dd, J = 11.1; 5.2 Hz), 4.53 (1H, dq, J = 9.5, 4.4 Hz), 4.46 (1H, d, J = 6.9 Hz), 4.38 (1H, t, J = 10.7 Hz), 4.88 (3H, s, OCH3), 4.87 (3H, s, OCH3). 13C-NMR (MeOD, 150 MHz): 174.9 (C-7‴), 168.0 (C-7), 167.9 (C-7′), 162.5 (C-4′), 160.5 (C-4), 155.0 (C-3‴/5‴), 151.5 (C-6), 151.2 (C-6′), 150.5 (C-5), 149.7 (C-5′), 147.7 (C-4‴), 129.4 (C-1‴), 124.1 (C-2), 122.4 (C-2′), 122.6 (C-1′), 121.5 (C-1), 121.2 (C-3), 120.6 (C-3′), 118.3 (C-2‴), 118.3 (C-6‴), 110.9 (C-1″), 86.7 (C-3″), 80.7 (C-2″), 76.9 (C-4″), 75.2 (C-5″), 71.2 (OCH3), 70.5 (OCH3) [19].
3,4-Dihydroxybenzoic acid (6): white powder, 1H-NMR (MeOD, 600 MHz): 7.45 (1H, d, J = 2.0 Hz, H-2), 7.44 (1H, d, J = 2.1 Hz, H-6), 6.82 (1H, d, J = 7.9 Hz, H-3). 13C-NMR (MeOD, 150 MHz): 170.0 (CO), 151.3 (C-4), 145.9 (C-5), 123.6 (C-1), 122.9 (C-3), 117.5 (C-6), 115.5 (C-2) [20].
Confluentic acid (7): white powder, HR-ESI-MS (positive mode, m/z): 523.2336 for [M + Na] +, (calcd 523.2302 for C28H36O8Na). 1H NMR (CDCl3, 600 MHz): 11.36 (OH), 6.62 (1H, d, J = 2.0 Hz, H-5′), 6.56 (1H, d, J = 2.1 Hz, H-3′′), 6.49 (1H, d, J = 2.6 Hz, H-3), 6.32 (1H, d, J = 2.6 Hz, H-5), 4.10 (2H, s, H-8), 2.75 (2H, m, H-8′′), 2.44 (2H, m, H-10), 1.65 (2H, m, H-9′), 1.55 (2H, m, H-11), 1.36 (4H, m, H-10′′ and H-11′′), 1.22 (2H, m, H-12 and H-13), 0.91 (3H, m, H-12′′), 0.85 (3H, t, J = 7.1 Hz, H-14). 13C-NMR (CDCl3, 150 MHz) : 207.1 (C-9), 170.5 (C-7′′), 169.2 (C-7), 166.6 (C-2), 164.9 (C-4), 157,8 (C-2′′), 151.4 (C-4′′), 144.5 (C-6′′), 138.9 (C-6), 119.9 (C-1′′), 115.2 (C-5′′), 113.4 (C-5), 104.2 (C-1), 103.1 (C-3′′), 100.1 (C-3), 56.4 (-OCH3), 55.5 (-OCH3), 51.2 (C-8), 42.6 (C-10), 33.8 (C-8′′), 31.6 (C-10′′), 31.3 (C-12), 30.7 (C-9′′), 23.4 (C-11), 22.5 (C-11′′), 22.4 (C-13), 14.0 (C-14), 13.9 (C-12′′) [21].
Glyceryl-1-tetracosanoate (8): white Powder, HR-ESI-MS (positive mode, m/z): 465.4543 for [M + Na]+.1H-NMR (CDCl3, 500 MHz) : 4.21 (1H, dd, J = 11.7, 4.5 Hz, H-1), 4.15 (1Hb, dd, J = 11.7, 6.2 Hz, H-1), 3.93 (1H, tt, J = 6.0, 4.2 Hz, H-2), 3.69 (1Ha, dd, J = 11.4, 4.0 Hz, H-3), 3.60 (1H, dd, J = 11.4, 5.8 Hz, H-3), 2.35 (2H, t, J = 7.6 Hz, H-2′), 1.63 (2H, q, J = 7.5 Hz, H-3ʹ), 1.25 (nH, brs, H-4ʹ/H-23ʹ), 0.88 (3H, t, J = 7.0 Hz, H-24ʹ). 13C-NMR (CDCl3, 125 MHz): 174.4 (C-1ʹ), 70.2 (C-2), 65.2 (C-1), 63.6 (C-3), 34.3 (C-2ʹ), 24.9 (C-3ʹ), 29.7–32.0 (C4ʹ-23ʹ), 14.1 (C-24ʹ) [22].
Auranthiamide acetate (9): white powder, HR-ESI-MS (positive mode, m/z): 455.2156 for [M + H]+, (calcd 523.2122 for C27H29O4N2). 1H-NMR (CDCl3, 500 MHz): 7.71 (1H, s, H-3), 7.52 (1H, s, H-3), 7.44 (2H, dddd, J = 8.5, 6.7, 1.6, 1.0 Hz, H-3), 7.25 (1H, d, J = 3.2 Hz, H-3), 7.17 (2H, ddt, J = 8.0, 6.6, 1.3 Hz, H-3), 6.71 (1H, d, J = 7.6 Hz, H-3), 5.90 (1H, d, J = 8.6 Hz, H-3), 3.93 (1H, dd, J = 11.3, 4.9 Hz, H-1), 3.82 (1H, dd, J = 11.3, 4.2 Hz, H-3), 3.22 (1H, dd, J = 13.7, 5.9 Hz, H-3), 3.05 (1H, dd, J = 13.7, 8.5 Hz, H-3). 13C-NMR (CDCl3, 125 MHz): 170.7 (C-2), 170.2 (C-6), 167.1 (C-9), 136.7 (C-1ʹ), 136.6 (C-1″), 132.0 (C-1‴), 129.3 (C-4‴), 129.1 (C-4ʹ), 129.1 (C-3‴/5‴), 128.7 (C-2‴/6‴), 128.6 (C-3″/5″), 128.5 (C-2ʹ/6′), 127.1 (C-2″/6″), 127.0 (C-3ʹ/5′), 126.7 (C-4″), 64.5 (C-3), 55.1 (C-7), 49.4 (C-4), 38.3 (C-11), 37.4 (C-10), 20.8 (C-1ʺ) [23].
Ethyl gallate (10): white powder, 1H-NMR (MeOD, 600 MHz): 7.06 (2H, s), 4.29 (2H, q, J = 7.1 Hz), 1.36 (3H, t, J = 7.1 Hz). 13C-NMR (MeOD, 150 MHz): 167.1(CO), 145.1 (C-3,5), 138.3 (C-4), 120.2 (C-1), 108.4 (C-2,6), 60.2 (CH2), 13.0 (CH3) [20].
β-Amyrinacetate (11): white powder.1H-NMR (CDCl3, 600 MHz,): 5.20 (1H, t, J = 3.7 Hz,), 4.55–4.50 (1H, m), 2.07 (7H, s), 1.60 (2H, s), 1.15 (3H, s), 0.98 (2×3H, d, J = 2.9 Hz), 0.90 − 0.88 (4×3H, m), 0.85 (2H, s). 13C-NMR (CDCl3, 150 MHz,): 171.4 (CO), 145.8 (C-13), 121.8 (C-12), 80.9 (C-3), 55.3 (C-5), 47.6 (C-9), 47.2 (C-18), 46.8 (C-19), 41.7 (C-14), 39.8 (C-8), 38.3 (C-1), 37.7 (C-4), 37.1 (C-22), 36.8 (C-10), 34.8 (C-21), 33.5 (C-17), 32.6 (C-7), 31.2 (C-20), 28.4 (C-28), 28.1 (C-23), 26.9 (C-2), 26.1 (C-15), 26.0 (C-16), 25.9 (C-27), 23.7 (C-11), 23.6 (C-29), 23.5 (C-30), 21.4 (CH3CO), 18.3 (C-6), 16.8 (C-24), 16.7 (C-25), 15.6 (C-26) [24].
β-Amyrin (12): white powder, 1H-NMR (CDCl3, 600 MHz) : 5.63 (1H, dd, J = 5.2, 2.9 Hz), 3.46 (1H, dd, J = 3.5, 2.3 Hz), 1.27–1.23 (3H, m), 1.15 (6H, d, J = 10.6 Hz), 1.09 (3H, s), 1.04 (3H, s), 1.00 (6H, d, J = 7.8 Hz), 0.95 (3H, s), 0.85 (3H, s). 13C-NMR (CDCl3, 150 MHz): 141.7 (C-13), 122.0 (C-12), 76.4 (C-3), 49.7 (C-5), 47.5 (C-9), 43.1 (C-18), 40.9 (C-19), 39.3 (C-14), 38.9 (C-8), 37.8 (C-1), 36.1 (C-4), 35.1 (C-22), 34.8 (C-10), 34.6 (C-21), 34.5 (C-17), 33.1 (C-7), 32.4 (C-20), 32.1 (C-28), 32.0 (C-23), 30.4 (C-2), 30.1 (C-15), 28.9 (C-16), 28.3 (C-27), 27.8 (C-11), 25.5 (C-29), 23.6 (C-30), 19.6 (C-6), 18.4 (C-24), 18.2 (C-25), 16.2 (C-26) [24].
Masticadienonic acid (13): white powder, HR-ESI-MS (positive mode, m/z): 455.3526 for [M + H]+. 1H-NMR (CDCl3, 600 MHz): 6.93 (1H, m, H-24), 5.67 (1H, m, H-7), 2.52 (1H, m, H-2), 0.93 (1H, dd, J = 6.4, 1.6 Hz, H-27), 0.83 (1H, d, J = 1.6 Hz, H-22). 13C-NMR (CDCl3, 150 MHz): 219.1 (C-3), 173.2 (C-26), 148.9 (C-8), 145.5 (C-24), 126.6 (C-25), 121.2 (C-7), 52.9 (C-17), 52.3 (C-5), 52.0 (C-14), 47.0 (C-4), 45.4 (C-9), 44.0 (C-13), 34.2 (C-2), 18.2 (C-27) [25].