What Essential Oils Are High in Phenols?

3. Antioxidant Capacity of EOs Enriched with Polyphenol Mixes

All unenriched polyphenol mixes, with the exception of rosemary’s polyphenol mix, showed antagonistic effects because their IC50 values were lower than anticipated. Flavonoid-flavonoid interactions may be the cause of this, as H-bonding between flavonoids reduces the availability of -OH groups [18]. Consequently, there is less chance of interacting with the DPPH radical, which lowers the antioxidant capacity that results. All polyphenol mixes, excluding those containing grape seed, demonstrated synergistic effects in the ORAC assay. It has been observed that the addition of a third flavonoid with a low reduction potential energy greatly raises the ORAC value of the first two flavonoids [19]. Additionally, because the compounds removed electrons without quickly donating them to the AAPH radical, mixtures of compounds with comparable reduction potential energies have demonstrated lower antioxidant activities [20]. This could explain why there is conflict in the grape seed mixture. The ORAC assay involves the transfer of an atom of hydrogen, but it also involves the transfer of an electron, which emphasizes the significance of examining the compounds’ reduction potentials.

With the exception of pimento berry (HE-PIM-01, 0), all EO/grape seed mix enrichments demonstrated synergistic effects in the DPPH assay. 074 mg/mg DPPH), which showed additive effects. In the ORAC assay(), all enrichments demonstrated synergistic effects, with the exception of oregano (HE-ORI-03, 1219). 40 μmol TE/g sample), which exhibited antagonistic effects. Eugenol-containing EOs (HE-CLO-01 for clove, HE-PIM-01 for pimento berry, and HE-CAN-01 for Ceylon cinnamon) all displayed comparable IC50 and ORAC values, while EOs without it (Table S1) showed lower ORAC values. This implies that the eugenol in the EOs interacted with the epicatechin and catechin in the mixture. As was previously mentioned, in the ORAC assay, the oregano (HE-ORI-03)/grape seed mix demonstrated antagonistic effects, while all other enrichments demonstrated synergistic effects. Thus, enriching the grape seed polyphenol mix with EOs (apart from oregano, HE-ORI-03) mitigates the antagonistic effects observed in situ in the ORAC assay. It is possible that this antipathy stems from the significant amount of 20% CE%B1-pinene (55%) that is found in the EO%20[6]. Thus, the co-oxidizing activity of α-pinene further reduces the antioxidant activity in addition to the antagonism in the grape seed mix.

Of all the enrichments, the EOs enriched with the green tea mix() had the lowest IC50 values and moderate to high ORAC values (6208). 5–13,681. 0 μmol TE/g sample). The combination of green tea and pimento berries (HE-PIM-01) displayed the maximum total antioxidant capacity (IC50 = 0). 009 mg/mg DPPH; ORAC Value = 13,681. 0 μmol TE/g sample). The synergistic effects of this combination and its low IC50 value may be attributed to the contributions of methyleugenol and other minor components of the EO. Since clove oil (HE-CLO-01) contains more eugenol (93. 5% versus 86. 4%), its decreased activity indicates that other substances are affecting pimento berry%E2%80%99s%20(HE-PIM-01)%20activity%20[6]. When oregano (HE-ORI-03) and yellow sage (HE-SAU-01-02) were added to the green tea mix, the ORAC values were low and antagonistic. This is because the chemical profiles of these plants lack phenols, and/or they contain pro-oxidants, which can produce reactive species like hydrogen peroxide that quench fluorescein and lower antioxidant capacity [21].

The DPPH assay revealed no antagonistic effects for EOs enriched with the apple polyphenol mix(); however, the ORAC assay revealed antagonistic effects when oregano was enriched (HE-ORI-03, 1151). 6 μmol TE/g sample), white thyme (HE-THY-03, 1156. 4 μmol TE/g sample), and yellow sage (HE-SAU-01-02, 601. 6 μmol TE/g sample), with the least active enrichment being the final one. This conflict may have resulted from the synergist(s) oxidizing the primary antioxidant(s) or from the former regenerating the latter [7]. Given that yellow sage (HE-SAU-01-02) showed low, antagonistic ORAC values when combined with rutin and chlorogenic acid (), it’s possible that both enrichments caused oxidation or regeneration, and that any effective antioxidant was virtually eliminated when combined. Furthermore, the antagonism may have resulted from yellow sage’s potential pro-oxidant monoterpene content. In both tests, the enrichment of clove (HE-CLO-01) with the apple mix demonstrated synergistic effects (IC50 = 0). 013 mg/mg DPPH; ORAC Value = 12,720. 5 μmol TE/g sample), while the pimento berry (HE-PIM-01) enrichments (IC50 = 0 104 mg/mg DPPH; ORAC value = 11,740. IC50 = 0 for Ceylon cinnamon (HE-CAN-04) and 0 μmol TE/g sample 116 mg/mg DPPH; ORAC Value = 11,338. In the DPPH/ORAC assays, 5 μmol TE/g sample) demonstrated additive/synergistic and synergistic/additive effects, respectively. Due to their synergistic interactions with their eugenol, these EOs showed ORAC values more than ten times greater than the other EOs when combined with the apple mix. In fact, as the EOs’ eugenol contents rise, the ORAC values rise as well (clove, HE-CLO-01, 93). 5% > pimento berry, HE-PIM-01, 86. 4% > Ceylon cinnamon, HE-CAN-04, 84. 6%) [6].

In the DPPH assay, none of the EOs combined with the rosemary polyphenol mix() showed any antagonistic behavior. Even though they were all synergistic, this enrichment produced some of the highest IC50 values. The high absolute values of the IC50 of these enrichments were possibly caused by the 80% of the mix that consisted of p-coumaric acid, which was demonstrated to have poor antioxidant activity on its own (%) because a catechol group was absent from its structure. All EO enrichments showed additive and synergistic effects in the ORAC assay, with the exception of those containing yellow sage (HE-SAU-01-02, 8620). 0 μmol TE/g sample). The ORAC values of the Pimento berry (HE-PIM-01) and Ceylon cinnamon (HE-CAN-04) EOs were higher (16,148). 0 μmol TE/g sample, 18,477. 00 μmol TE/g sample, respectively) than EOs lacking eugenol. However, the enrichment of clove EO (ORAC value = 12,482. 5 μmol TE/g sample) produced additive effects even though it contained 93 times more eugenol. 5% versus 86. 4%, 84. 6%, respectively), suggesting that their synergistic effects were influenced by interactions with minor oxygenated compounds, like alcohols.

3. 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) Radical Scavenging Assay

The DPPH assay was performed using the protocol that Brand-William et al. [8] with modifications. Antioxidants were added to Tris-HCl buffer (450 µL, pH 7) at different concentrations. 4). DPPH (0. After adding 1 mM) to each sample, the samples were allowed to sit at room temperature for 30 minutes in the dark. 30 minutes was found to be the ideal duration in early trials for reaching the steady state of scavenging. The absorbance was then measured with a Beckman spectrophotometer at 517 nm. Water was used as the blank. In the negative control, 2010% methanol in Tris-HCl buffer was utilized. The positive control was 2 mg/mL of α-tocopherol in ethanol. The following formula was used to calculate the inhibition ratio: inhibition ratio (%) = [(Ac%20%E2%88%92%20As)/Ac]%20%C3%97%20100(1)

where Ac represents the control absorbance and As the sample absorbance.

Antioxidant concentrations were plotted versus estimated inhibition ratio. It was determined that the IC50 was the concentration needed to lower the DPPH by 5%. The IC50 was expressed as mg sample/mg DPPH.

Phenols Chemistry Functional Group | Essential Oil Chemistry

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