Table 2.
Antioxidant capacities of Tamanu oil resin extracts, neutral (NTR) and acidic (ATR) subfractions and selected isolated metabolites by the DPPH and TRAP assays.
| Compounds | DPPH | TRAP | % by Weight in TO a or EtTO b | % by Weight in Subfractions | AlogP c |
|---|---|---|---|---|---|
| Oils and fractions | IC50 (mg/mL) d | TE e | |||
| TO | 432 ± 1.1 | 67 ± 11 | |||
| Sesame oil | 668 ± 1.2 * | 28 ± 6 * | |||
| DTO | >800 * | ~0 | ~60 | ||
| MeTO | 40.2 ± 1.1 *# | 112 + 14 *# | 18.2 a | ||
| EtTO | 26.1 ± 0.1 | 280 ± 12 * | 15.7 a | ||
| NTR | 10.2 ± 1.1 *# | 172 + 14 *# | 50.0 b | ||
| ATR | 5.1 ± 0.4 *# | 340 ± 11 *# | 48.3 b | ||
| NTR metabolites | IC50 (µM) | TE | % by weight in NTR | AlogP | |
| Inophyllum P | 26.2 ± 3.1 | 4.11 ± 0.10 | 0.05 | 0.121 | 4.56 |
| Fraction P f | 40.9 ± 1.1 | 3.57 ± 0.39 | 0.04 e | 0.102 | ND g |
| Tamanolide D | 779 ± 7 | 1.36 ± 0.20 | 0.02 | 0.038 | 4.45 |
| Inophyllum C | 701 ± 9 | 0.21 ± 0.04 | 0.042 | 0.078 | 4.55 |
| Inophyllum E | 481 ± 7 | 0.91 ± 0.04 | 0.014 | 0.029 | 4.55 |
| Calophyllolide | ~890 | 0.48 ± 0.08 | 0.019 | 0.038 | 5.3 |
| Calanolide GUT 70 | ~900 | 0.30 ± 0.03 | 0.024 | 0.048 | 4.96 |
| Calanolide A | ~950 | 0.40 ± 0.02 | <0.02 | 0.021 | 4.18 |
| Calanolide D | >1000 | ND | 0.007 | 0.015 | 4.31 |
| 12-Oxocalanolide A | >1000 | ND | 0.005 | 0.011 | 4.31 |
| ATR metabolites | IC50 (µM) | TE | % by weight in ATR | AlogP | |
| Inocalophyllin B | 583 ± 17 | 1.07 ± 0.06 | 0.063 | 0.2 | 4.7 |
| Standards | IC50 (µM) | TE | AlogP | ||
| Trolox | 21.2 ± 0.8 | 1 | 2.75 | ||
| Sesamol | 66.9 ± 3.1 | 1.34 ± 0.09 | 0.89 | ||
| BHA | 94.9 ± 6.1 | 3.46 ± 0.20 | 4.14 | ||
| Caffeic acid | 18.1 ± 0.21 | 2.98 ± 0.14 | 2.6 | ||
| Quercetin | 14.1 ± 0.21 | 6.31 ± 0.24 | 1.81 |
Data represent the mean ± SEM of 3–6 independent experiments performed in triplicate. a,b Extracts and metabolites content are expressed as a percentage by weight (in g/100 g) of a TO or b EtTO. c Determined using the Virtuel Computational Chemistry Laboratory software at: ALOGPS 2.1 homepage. Available online: (http://www.vcclab.org/lab/alogps/). (accessed on 3 July 2020) d IC50 defined as the concentration resulting in a 50% decrease in the initial DPPH concentration. e Data are given in Trolox equivalent (TE). For oils and resin fractions, the reported TE values represent the activity of a solution at 1 g/L relative to 1 µM Trolox. For metabolites and standards compounds, TE values represent the activity of a 1 µM-solution relative to 1 µM Trolox. f Inophyllum P accounts for ~70% in fraction P. g ND, not determined. Statistics: * p < 0.05 vs. TO and # p < 0.05 vs. EtTO, by one-way ANOVA followed by Newman–Keuls test.