Table 2.
Discriminant phenolic compounds according to the comparison ‘cold’ vs ‘boiled’ brewing and considering both green and red rooibos tea. Compounds were identified by the VIP (variable importance in projection) approach following OPLS-DA discriminant analysis and are provided together with VIP scores (measure of variable’s importance in the OPLS-DA model), LogFC values (obtained by Fold Change analysis) and accumulation.
| VIP Marker (OPLS-DA) | VIP Score | LogFC | Accumulation | |
|---|---|---|---|---|
| Green Rooibos | ||||
| Flavonoids | Isorhamnetin-3-O-rutinoside; Chrysoeriol-7-O-glucoside | 1.79 ± 0.36 | −2.73 | Down |
| Formononetin | 1.73 ± 0.46 | −0.17 | Down | |
| Cyanidin-3-O-galactoside | 1.69 ± 0.55 | −1.24 | Down | |
| Fisetin; Luteolin | 1.54 ± 0.64 | −0.51 | Down | |
| Kaempferol | 1.54 ± 0.64 | −0.51 | Down | |
| Hispidulin; Chrysoeriol | 1.50 ± 0.52 | −2.39 | Down | |
| 8-Prenylnaringenin | 1.41 ± 0.75 | −1.91 | Down | |
| Gardenin B | 1.39 ± 0.54 | −2.51 | Down | |
| Hemiphlorin; Naringenin-6-C-glucoside; Naringenin-7-O-glucoside | 1.23 ± 0.91 | −0.03 | Down | |
| Cyanidin-3-O-(6’’-caffeoyl-glucoside) | 1.87 ± 0.24 | −0.02 | Down | |
| Petunidin-3-O-galactoside | 1.18 ± 0.95 | −0.81 | Down | |
| Genistein | 1.03 ± 0.73 | −3.56 | Down | |
| Peonidin-3-O-galactoside | 1.61 ± 0.53 | 5.32 | Up | |
| Daidzin | 1.58 ± 0.72 | 0.07 | Up | |
| Isorhamnetin-3-O-glucoside-7-O-rhamnoside | 1.53 ± 0.64 | 0.44 | Up | |
| Myricetin-3-O-arabinoside | 1.47 ± 0.63 | 3.83 | Up | |
| Kaempferol-3-O-acetyl-glucoside | 1.46 ± 0.57 | 0.76 | Up | |
| Petunidin-3-O-(6’’-acetyl-galactoside) | 1.45 ± 0.77 | 0.45 | Up | |
| Cyanidin-3,5-O-diglucoside | 1.37 ± 0.53 | 0.05 | Up | |
| Sakuranetin | 1.31 ± 0.75 | 0.35 | Up | |
| Chrysin | 1.24 ± 0.84 | 1.40 | Up | |
| Cyanidin-3-O-(6’’-acetyl-galactoside) | 1.23 ± 1.03 | 0.39 | Up | |
| 3-Hydroxyphloretin 2’-O-xylosyl-glucoside | 1.16 ± 1.19 | 1.03 | Up | |
| 6-Geranylnaringenin | 1.11 ± 0.66 | 0.68 | Up | |
| Quercetin 3,4’-O-diglucoside | 1.09 ± 0.82 | 0.42 | Up | |
| 5,6-Dihydroxy-7,8,3’,4’-tetramethoxyflavone | 1.08 ± 1.04 | 0.40 | Up | |
| (-)-Epigallocatechin-3-O-gallate | 1.01 ± 0.88 | 1.30 | Up | |
| 3-Methoxysinensetin | 1.00 ± 0.85 | 0.75 | Up | |
| Lignans | Todolactol A | 1.09 ± 0.72 | −1.18 | Down |
| Dimethylmatairesinol | 1.00 ± 1.17 | 0.80 | Up | |
| Other polyphenols | Sinapaldehyde; Caffeic acid ethyl ester | 1.68 ± 0.52 | −0.80 | Down |
| Rosmanol | 1.32 ± 0.83 | −0.89 | Down | |
| Demethyloleuropein | 1.15 ± 0.75 | −1.26 | Down | |
| Benzoic acid; 4-Hydroxybenzaldehyde | 1.74 ± 0.65 | 2.38 | Up | |
| Isopimpinellin | 1.25 ± 0.44 | 0.26 | Up | |
| p-Anisaldehyde | 1.08 ± 0.51 | 0.08 | Up | |
| Phenolic acids | Caffeic acid ethyl ester; Sinapaldehyde | 1.68 ± 0.52 | −0.80 | Down |
| Protocatechuic acid-4-O-glucoside | 1.33 ± 0.44 | −3.41 | Down | |
| 3,4,5-Trihydroxycinnamic acid; Hydroxycaffeic acid | 1.08 ± 0.74 | −1.26 | Down | |
| Benzoic acid; 4-Hydroxybenzaldehyde | 1.74 ± 0.65 | 2.38 | Up | |
| p-Coumaroyl glycolic acid | 1.15 ± 1.22 | 3.59 | Up | |
| Stilbenes | Piceatannol | 1.42 ± 0.79 | 2.80 | Down |
| Red Rooibos | ||||
| Flavonoids | Chrysoeriol; Hispidulin | 1.99 ± 0.65 | −2.39 | Down |
| Quercetin-3-O-xyloside | 1.53 ± 0.77 | −0.84 | Down | |
| Gardenin B | 1.47 ± 0.65 | −2.51 | Down | |
| Fisetin; Luteolin | 1.38 ± 0.60 | −0.51 | Down | |
| Kaempferol-3-O-(6’’-acetyl-galactoside)-7-O-rhamnoside | 1.38 ± 0.69 | −0.77 | Down | |
| Delphinidin-3-O-galactoside | 1.36 ± 0.93 | −8.53 | Down | |
| Kaempferol-7-O-glucoside | 1.35 ± 0.87 | −1.21 | Down | |
| Peonidin 3-O-(6’’-p-coumaroyl-glucoside) | 1.33 ± 0.78 | −2.88 | Down | |
| Isorhamnetin-3-O-glucuronide | 1.32 ± 0.88 | −0.19 | Down | |
| Xanthohumol; Isoxanthohumol | 1.32 ± 0.83 | −7.87 | Down | |
| Peonidin | 1.32 ± 0.60 | −1.60 | Down | |
| Petunidin-3-O-rhamnoside | 1.31 ± 0.97 | −1.43 | Down | |
| Cyanidin-3-O-galactoside | 1.06 ± 0.82 | −1.24 | Down | |
| Cyanidin-3-O-(6’’-caffeoyl-glucoside) | 1.00 ± 1.13 | −0.02 | Down | |
| Myricetin-3-O-arabinoside | 2.16 ± 0.41 | 3.83 | Up | |
| Daidzin | 1.13 ± 0.94 | 0.07 | Up | |
| Quercetin-3,4’-O-diglucoside | 1.04 ± 1.43 | 0.42 | Up | |
| Other polyphenols | Rosmanol | 2.02 ± 0.43 | −0.89 | Down |
| Demethyloleuropein | 1.74 ± 0.68 | −1.26 | Down | |
| 4-Hydroxycoumarin | 1.53 ± 1.11 | −0.16 | Down | |
| Esculin | 1.22 ± 0.88 | −0.25 | Down | |
| 5-Pentadecylresorcinol | 1.36 ± 1.24 | 0.77 | Up | |
| p-Anisaldehyde | 1.35 ± 1.17 | 0.08 | Up | |
| Oleoside dimethylester | 1.32 ± 0.71 | 1.07 | Up | |
| Phenolic acids | Hydroxytyrosol | 1.15 ± 0.96 | 0.26 | Up |
| Isopimpinellin | 1.00 ± 1.62 | 0.26 | Up | |
| 3,4,5-Trihydroxycinnamic acid; Hydroxycaffeic acid | 1.68 ± 0.66 | −1.26 | Down | |
| Protocatechuic acid-4-O-glucoside | 1.04 ± 0.68 | −3.41 | Down | |
| 4-Hydroxybenzoic acid | 1.14 ± 1.0 | 0.19 | Up | |
| Stilbenes | Pallidol | 1.49 ± 1.23 | −1,07 | Down |
| Piceatannol | 1.23 ± 1.23 | 2.80 | Up |