Background
Methods
Chemical reagents and solvents
Plant materials and extraction procedure
Chemical analysis of the essential oils
Gas chromatography
Gas chromatography-mass spectrometry
Qualitative analysis
Quantitative analysis
Determination of radical scavenging and antioxidant activity
Determination of total phenolic content (TPC)
Ferric reducing antioxidant power (FRAP) assay
DPPH Radical scavenging assay (RSA)
Determination of the anti-inflammatory activity: inhibition of albumin denaturation
Statistical analysis
Results and discussion
Extraction yields of essential oils
Components | RI | Relative percentage (%) | |||
---|---|---|---|---|---|
A. cepa
|
A. sativum
|
D. gossweileri
|
P. brazzeana
| ||
2,4-dimethylthiophene | 884 | - | 0.63 | 0.03 | - |
Diallyl sulfide | 888 | 1.38 | 7.10 | 0.11 | - |
2,5-dimethyl thiophene | 908 | 0.82 | - | - | |
Allyl methyl disulfide | 918 | - | - | 0.01 | - |
Methyl propyl disulfide | 922 | - | 1.19 | - | - |
N,N’-Dimethyl thiourea | 951 | - | - | 0.01 | - |
Benzaldehyde | 962 | - | - | 0.28 | - |
dimethyl trisulfide | 964 | - | 0.58 | - | - |
2-Phenyl furan | 978 | - | 0.48 | - | - |
Octyl aldehyde | 990 | 2.26 | - | - | - |
phenylacetaldehyde | 1026 | 2.69 | - | 0.06 | - |
Limonene | 1029 | - | 0.62 | - | - |
2-propenyl propyl disulfide | 1032 | 5.15 | 0.20 | 0.02 | - |
2,5-dimethyl-1,3,4-thiadiazole | 1037 | - | 0.74 | - | - |
Terpinolene | 1059 | - | - | 0.02 | - |
Phenylmethanol | 1081 | - | - | 0.01 | - |
Diallyl disulfide | 1088 | - | 19.74 | - | |
Trans-propenyl propyl disulfide | 1091 | 2.86 | - | - | - |
Linalool | 1101 | - | 0.88 | - | - |
Dipropyl disulfide | 1109 | 2.71 | 0.62 | - | - |
1-propenyl propyl disulfide | 1114 | 3.77 | - | - | - |
3,5-dimethyl-1,2,4-trithiolane | 1118 | 1.81 | - | - | - |
Campholenol | 1124 | - | - | 0.03 | 0.31 |
Allyl methyl trisulfide | 1149 | - | 12.95 | - | - |
Methyl propyl trisulfide | 1153 | 8.14 | - | - | - |
Benzylcyanide | 1157 | 2.52 | - | 35.72 | 0.86 |
3,4-Dihydro-3-vinyl-1,2-dithiin | 1165 | - | 1.37 | - | - |
Dimethyl tetrasulfide | 1224 | 1.32 | 1.59 | 0.02 | - |
2,5-Dimethylthiazole | 1265 | 4.62 | - | - | - |
Diallyl trisulfide | 1319 | 22.17 | 41.62 | - | - |
3-Methoxyoctane | 1327 | - | 0.62 | - | - |
Dipropyl trisulfide | 1334 | 11.11 | - | - | - |
1-propenyl propyl sulfide | 1345 | 1.26 | - | - | - |
Allyl propyl sulfide | 1377 | - | 1.30 | - | - |
Di-1-propenyl sulfide | 1382 | 1.71 | 2.08 | - | - |
Benzylisothiocyanate | 1393 | - | - | 63,19 | 97.63 |
p-methoxybenzylcyanide | 1395 | - | 0.85 | - | 1,2 |
Β-caryophyllene | 1398 | - | 0.23 | - | - |
2-methyl-3-isothiozolone | 1435 | 2.23 | - | -- | - |
Germacrene D | 1484 | - | - | 0.02 | - |
γ-cadinene | 1506 | - | 0.39 | - | - |
2-methyl-3,4-dithiaheptane | 1527 | 9.88 | - | - | |
Β-sesquiphellandrene | 1550 | - | - | 0.05 | - |
Diallyl tetrasulfide | 1558 | - | 4.22 | - | - |
p-methoxybenzylisothiocyanate | 1575 | 3.55 | - | - | - |
Dipropyl tetrasulfide | 1649 | 8.07 | - | - | - |
Benzyl sulfide | 1856 | - | - | 0.06 | - |
Methyl linolenate | 2013 | - | - | 0.06 | - |
Total identified (%) | 98.77 | 100 | 99.70 | 100 | |
EOs extraction yields (%) | 0.007 | 0.2 | 0.04 | 0.02 |
Chemical composition
Determination of radical scavenging and antioxidant activity
Determination of total phenolic content (TPC)
TPC (μg AAE/mg) | FRAP (μg AAE/mg) | |
---|---|---|
Essential oil | Essential oil | |
A. cepa
| 429.33 ± 1.31 b | 2.75 ± 0.02 b |
A. sativum
| 463.38 ± 1.24 a | 5.33 ± 0.01 a |
D. gossweileri
| 365.38 ± 0.66 c | 0.76 ± 0.03 c |
P. brazzeana
| 342.20 ± 0.99 d | 0.08 ± 0.03d |
Ferric reducing antioxidant power (FRAP)
DPPH Radical scavenging assay (RSA)
Regression curve’s equations | Coefficient of determination : R2 | SC50(μg/ml) | AAI | |
---|---|---|---|---|
A. cepa
| y = 192.3 × + 11.96 | 0.927 | 0.20 | 12.626 |
A. sativum
| y = 191.6 × + 12.73 | 0.919 | 0.19 | 12.886 |
D. gossweileri
| y = 194.0 × + 11.10 | 0.931 | 0.20 | 12.821 |
P. brazzeana
| y = 190.2 × + 14.15 | 0.904 | 0.19 | 13.298 |
Ascorbic acid | y = 19.12 × + 12.19 | 0.934 | 1.98 | 1.262 |
Relationship between TPC and FRAP, FRAP = f (TPC) | Relationship between TPC and RSA, SC50 = f (1/TPC) | |||
---|---|---|---|---|
Regression curve Equation | Coefficient of determination : R2 | Regression curve equation | Coefficient of determination : R2 | |
Essential oil | y = 0.016× - 0.434 | 0.22 | y = 0.782 × + 0.189 | 0.21 |
Determination of the anti-inflammatory activity
A. cepa
|
A. sativum
|
D. gossweileri
|
P. brazzeana
| Diclofenac sodium | |
---|---|---|---|---|---|
Concentration (μg/ml) | Inhibition percentage (%) | ||||
3.125 | 7.33 ± 1.15b | 4.00 ± 0.00a | 4.00 ± 0.00a | 7.56 ± 2.00b | 7.33 ± 0.00b |
6.25 | 9.33 ± 1.15a | 6.00 ± 2.00a | 8.67 ± 2.31a | 16.477 ± 1.15b | 9.33 ± 1.15a |
12.5 | 14.00 ± 2.00a | 14.00 ± 2.00a | 13.33 ± 3.05a | 26.94 ± 2.00b | 14.00 ± 0.00a |
25 | 33.33 ± 1.15c | 22.66 ± 2.30b | 19.33 ± 1.15a | 38.95 ± 1.15d | 18.00 ± 0.00b |
50 | 54.67 ± 3.05c | 38.00 ± 2.00b | 28.00 ± 2.00a | 52.52 ± 1.15c | 24.00 ± 0.00a |
75 | 82 ± 1.04e | 57 ± 1.08c | 42 ± 0.11b | 72.87 ± 0.98d | 36 ± 2.00a |
100 | - | 76 ± 0.91c | 56 ± 0.76b | - | 48 ± 1.00a |
125 | - | 95 ± 1.02c | 70 ± 2.14b | - | 60 ± 1.73a |
Regression curve equations | y = 1.070x + 2.579 | y = 0.753x – 3.637 | y = 0.525x + 3.642 | y = 0.907x + 8.587 | y = 0.430x + 5.090 |
R2 = 0.991 | R2 = 0.976 | R2 = 0.991 | R2 = 0.973 | R2 = 0.982 | |
IC50 value (μg/mL) | 44.31 | 61.577 | 88.30 | 45.66 | 104.44 |