“Lamiaceae” is widely distributed throughout the Mediterranean, Irano-Turanian, and Euro-Siberian regions [
Verma et al. proposed that, among the genus
The plant material under investigation was oregano (
Geographical data of cultivation sites.
Parameters | Auli | Pithoragarh | Haldwani |
---|---|---|---|
Altitude (m) | 2744 | 1524 | 412 |
Latitude | 30.52°N | 29.58°N | 29.22°N |
Longitude | 79.57°E | 80.22°E | 79.52°E |
Five hundred grams of the fresh aerial parts of
Fifty grams of the powdered plant material was soaked in 250 mL methanol (ALC) and double-distilled water (AQ) separately. The solution was placed in an incubator shaker for 24 h. It was centrifuged at 2000 rpm and filtered using Whatman filter paper. Afterward, the solvent was evaporated to dryness on the water bath maintained at 60°C. The dried extracts OV1 (ALC), OV2 (ALC), and OV3 (ALC) and OV1 (AQ), OV2 (AQ), and OV3 (AQ) were used to carry out the antioxidant analyses.
Various physical properties such as oil yield (%), density, refractive index (RI), and color were measured for all the essential oils. The density and RI of the oils were measured with the help of a densitometer (DA-135N) and refractometer (RA-600).
GC/MS and GC/FID instruments were utilized for both qualitative and quantitative examinations of the EOs. The quantitative analysis was performed with GC/FID model 2010 (Shimadzu, Japan) equipped with a CombiPAL AOC-20i/s autosampler (CTC Analytics, Zwingen, Switzerland). One microliter of the neat essential oil was injected by the autosampler. The compounds were separated on an Rxi®-5Sil MS capillary column (30 m length, 0.25 mm inner diameter, and 0.25
The compounds isolated by GC and fragmented by using the mass spectrometer were identified by comparing the mass spectra and WILEY8.LIB and NIST14 libraries as well as looking at maintenance records (RI) comparative with the homologous alkane standard arrangement (C9–C33) and previous literature data [
Antioxidant activity of the essential oils, and methanolic and aqueous extracts was evaluated by measuring the free radical scavenging activity of various radicals such as DPPH, ABTS, and reducing power [
Mean values and standard deviations (SD) were calculated using MS Excel. Duncan’s multiple range tests were applied to compare the mean values with the help of one-way ANOVA by SPSS (16.0) at a significance level of
The result of the total fresh plant yield, % moisture of the fresh and dried plant, and % ash is given in Table
Percent (%) moisture and weight of the fresh and dried plant material.
Locations | Plot size ( | Fresh plant weight (kg) ± SD | % moisture of the fresh plant ± SD | % moisture of the dried plant ± SD | % ash ± SD | |
---|---|---|---|---|---|---|
Auli | 3.43c ± 0.25 | 57.30a ± 2.48 | 12.37c ± 0.25 | 9.12b ± 1.22 | ||
Pithoragarh | 2 × 2 | 2.70b ± 0.26 | 65.50b ± 2.37 | 3.43a ± 0.32 | 13.03a ± 0.48 | |
Haldwani | 0.90a ± 0.20 | 73.61c ± 0.58 | 9.40b ± 0.29 | 11.96a ± 0.76 |
The mean values within the same column followed by different alphabets (a–c) in the superscript are significantly different at a significance level of 0.05; SD = standard deviation.
The findings of Morshedloo et al. showed that the oil yield of
Physical parameters and yield of the oils.
Cultivations | Appearance | Oil yield (%) ± SD | RI (25°C) ± SD | Density (g/mL) ± SD |
---|---|---|---|---|
OV Auli | Pale yellow | 1.17c ± 0.15 | 1.4817a ± 0.00 | 0.9204a ± 0.00 |
OV Pithoragarh | Pale yellow | 0.87b ± 0.02 | 1.4854b ± 0.00 | 0.9217b ± 0.00 |
OV. Haldwani | Pale yellow | 0.08a ± 0.01 | 1.4874c ± 0.00 | 0.9316c ± 0.00 |
The mean values within the same column followed by different alphabets (a–c) in the superscript are significantly different at a significance level of 0.05; SD = standard deviation.
Correlation between oil yield, altitude, and temperature of the cultivation sites.
Oil yield | Temperature | Altitude | |
---|---|---|---|
Oil yield | 1 | −0.818 | 0.947 |
Temperature | 1 | −0.953 | |
Altitude | 1 |
The extracted oils were pale yellow in color. The refractive index varied from 1.4817 to 1.4874, while the density of the oils ranged between 0.920 and 0.931 g/mL (Table
The essential oil of the plant mainly contained monoterpenoid constituents, but their concentrations vary with geographic location and other factors such as climate, soil, and altitude [
Gas chromatogram of the essential oil of
Gas chromatogram of the essential oil of
Gas chromatogram of the essential oil of
Chemical constituents identified in the EO of
S. no. | Compound | Class of the compound | RIcal | RIlit | Percentage of oil ± SD | Percentage of oil ± SD | Percentage of oil ± SD |
---|---|---|---|---|---|---|---|
OV1 | OV2 | OV3 | |||||
1 | MH | 924 | 924 | 2.89b ± 0.02 | 1.80a ± 0.02 | 1.76a ± 0.03 | |
2 | MH | 930 | 932 | 1.35b ± 0.03 | 0.6a ± 0.03 | 2.12c ± 0.01 | |
3 | Camphene | MH | 945 | 946 | 0.12 | 0.04 ± 0.01 | 0.29 |
4 | Sabinene | MH | 970 | 969 | 0.52c ± 0.03 | 0.16a ± 0.02 | 0.19b ± 0.01 |
5 | MH | 974 | 974 | 0.32c ± 0.04 | 0.16a ± 0.01 | 0.20b ± 0.01 | |
6 | Octen-3-ol | ALC | 982 | 974 | 0.42a ± 0.03 | 0.46b ± 0.04 | ND |
7 | 3-Octanone | KET | 988 | 979 | ND | ND | 5.44 ± 0.03 |
8 | MH | 988 | 988 | 3.35c ± 0.04 | 2.50a ± 0.03 | 3.26b ± 0.01 | |
9 | MH | 1005 | 1002 | 0.42b ± 0.05 | ND | 0.27a ± 0.02 | |
10 | MH | 1018 | 1014 | 2.52a ± 0.01 | 2.75a ± 0.04 | 3.3b ± 0.01 | |
11 | MH | 1028 | 1020 | 9.49b ± 0.04 | 4.81a ± 0.05 | 9.97c ± 0.02 | |
12 | MH | 1030 | 1024 | 0.69a ± 0.04 | 0.05 | 0.87b ± 0.02 | |
13 | MH | 1050 | 1044 | 1.95a ± 0.01 | ND | 9.47b ± 0.02 | |
14 | MH | 1067 | 1054 | 13.60b ± 0.02 | 14.39c ± 0.04 | 12.63a ± 0.02 | |
15 | Linalool | OM | 1105 | 1095 | 13.00c ± 0.2 | 8.51b ± 0.06 | 4.61a ± 0.02 |
16 | Camphor | OM | 1146 | 1141 | ND | 1.98 ± 0.01 | ND |
17 | Borneol | OM | 1171 | 1165 | 0.08 | ND | 0.36 ± 0.02 |
18 | Terpinen-4-ol | OM | 1181 | 1174 | ND | 0.94a ± 0.01 | 2.65b ± 0.02 |
19 | OM | 1195 | 1186 | 0.10 | ND | 1.54 ± 0.01 | |
20 | Indole | AM | 1295 | 1290 | 0.37 | ND | ND |
21 | Thymol | OM | 1310 | 1289 | 38.81b ± 0.03 | 52.83c ± 0.06 | 31.86a ± 0.01 |
22 | Carvacrol | OM | 1312 | 1298 | 0.04 | ND | 1.09b ± 0.01 |
23 | Thymol acetate | OM | 1370 | 1370 | 0.38c ± 0.01 | 0.24b ± 0.04 | 0.15a ± 0.01 |
24 | Caryophyllene | SH | 1417 | 1417 | 4.50c ± 0.07 | 3.87b ± 0.02 | 1.41a ± 0.01 |
25 | SH | 1460 | 1452 | 0.23a ± 0.02 | 0.74b ± 0.05 | ND | |
26 | Germacrene D | SH | 1481 | 1484 | 1.19b ± 0.03 | 0.85a ± 0.04 | ND |
27 | Farnesene <( | SH | 1503 | 1505 | 0.32 ± 0.01 | ND | ND |
28 | SH | 1505 | 1505 | ND | ND | 1.57 ± 0.04 | |
29 | SH | 1509 | 1513 | 0.09b ± 0.02 | ND | 0.18a ± 0.01 | |
30 | Caryophyllene oxide | OS | 1578 | 1582 | 0.58 ± 0.03 | ND | ND |
31 | Cadin-4-en-10-ol | OS | 1640 | 1635 | 0.11a ± 0.01 | ND | 0.24b ± 0.01 |
32 | SH | 1682 | 1685 | 0.29 ± 0.04 | ND | ND | |
Total compounds identified | 28 | 18 | 24 | ||||
Total % | 97.73 | 97.68 | 95.43 |
RIcal = retention index (RI) calculated relative to
Correlation between major components of the essential oil and the climatic condition.
Linalool | Thymol | 3-Octanone | Oil yield | Temperature | Altitude | |||||
---|---|---|---|---|---|---|---|---|---|---|
1 | 0.720 | −0.044 | −0.969 | −0.934 | −0.878 | 0.571 | −0.333 | −0.248 | −0.058 | |
1 | −0.724 | −0.868 | −0.426 | −0.964 | 0.981 | −0.885 | 0.494 | −0.734 | ||
Linalool | 1 | 0.287 | −0.315 | 0.515 | −0.845 | 0.940 | −0.957 | 0.999 | ||
Thymol | 1 | 0.819 | 0.968 | −0.755 | 0.551 | 0.003 | 0.300 | |||
1 | 0.650 | −0.241 | −0.020 | 0.577 | −0.302 | |||||
1 | −0.893 | 0.739 | −0.245 | 0.527 | ||||||
3-Octanone | 1 | −0.954 | 0.654 | −0.852 | ||||||
Oil yield | 1 | −0.818 | 0.947 | |||||||
Temperature | 1 | −0.953 | ||||||||
Altitude | 1 |
The total phenolic, total flavonoid, and total tannin content in the methanolic extracts of the samples are expressed in terms of mg CAE/g, mg QE/g, and mg TA/g, respectively. The highest amount of total phenolics, flavonoids, and tannins was obtained in the Pithoragarh cultivation, followed by Auli cultivation and Haldwani cultivation, respectively (Table
Chemical composition of methanolic (OVM) extracts of
Sample | Total phenolics (mg CE/g) | Total flavonoids (mg QE/g) | Total tannins (mg TA/g) |
---|---|---|---|
OV1 (Auli) | 11.03b± | 6.21e± | 2.59h± |
OV2 (Pithoragarh) | 12.66c± | 7.08f± | 2.87i± |
OV3 (Haldwani) | 7.67a± | 5.40d± | 2.44g± |
Mean values followed by different letters (a–i) are significantly different at the level of
Total antioxidant constituents, i.e., phenolics, flavonoids, and tannins, in alcoholic (ALC) extracts of
In another investigation by Jain and Bhagia, the total phenolic and total flavonoid content in the oregano extract varied from 23.48 to 98.86 mg GAE/g and 14.45 to 19.53 mg quercetin/g, respectively [
The essential oils, as well as their alcoholic and aqueous extracts, were examined for their ability to trap the free radicals and reactive oxygen species (ROS). The results showed that the EOs as well as the extracts possessed remarkable antioxidant activity. Previous studies on the oregano essential oil and its extracts also revealed that they are potent antioxidants and are used worldwide as an essential ingredient in formulations of medicinal and health products [
IC50 and EC50 values for antioxidant assays of essential oils (EOs), aqueous extracts (AQ), and methanolic extracts (ALC) of
Sample | Antioxidant activity IC50 value (mg/mL) | ||
---|---|---|---|
DPPH (mg/mL) | ABTS (mg/mL) | Reducing power (mg/mL) (EC50) | |
OV Auli EO | 1.07f | 0.12c | 0.46i |
OV Pithoragarh EO | 0.83e | 0.06b | 0.35e |
OV Haldwani EO | 1.42g | 0.27d | 1.86j |
OV Auli AQ | 0.74d | 0.56i | 0.38f |
OV Pithoragarh AQ | 0.49c | 0.44g | 0.33d |
OV Haldwani AQ | 0.75d | 0.72j | 0.44h |
OV Auli ALC | 0.50d | 0.43f | 0.32c |
OV Pithoragarh ALC | 0.39b | 0.32e | 0.29b |
OV Haldwani ALC | 0.86e | 0.52h | 0.39g |
Ascorbic Acid | 0.052a | 0.032a | 0.027a |
Mean values within a column followed by different letters (a–j) are significantly different at the level of
IC50 plot of DPPH radical scavenging activity of essential oil (EO) and alcoholic (ALC) and aqueous (AQ) extracts of
IC50 plot of ABTS radical scavenging activity of essential oil (EO) and alcoholic (ALC) and aqueous (AQ) extracts of
EC50 plot of the reducing power ability of essential oil (EO) and alcoholic (ALC) and aqueous (AQ) extracts of
Correlation between essential oil components and antioxidant activity.
p-Cymene | Linalool | Thymol | 3-Octanone | Oil yield | Temperature | Altitude | DPPH | ABTS | RP | ||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
p-Cymene | 1 | 0.720 | −0.044 | −0.969 | −0.934 | −0.878 | 0.571 | −0.333 | −0.248 | −0.058 | 0.820 | 0.769 | 0.902 |
1 | −0.724 | −0.868 | −0.426 | −0.964 | 0.981 | −0.885 | 0.494 | −0.734 | 0.947 | 0.996 | 0.947 | ||
Linalool | 1 | 0.287 | −0.315 | 0.515 | −0.845 | 0.940 | −0.957 | 0.999 | −0.547 | −0.669 | −0.467 | ||
Thymol | 1 | 0.819 | 0.968 | −0.755 | 0.551 | 0.003 | 0.300 | −0.922 | −0.901 | −0.980 | |||
1 | 0.650 | −0.241 | −0.020 | 0.577 | −0.302 | −0.586 | −0.491 | −0.690 | |||||
1 | −0.893 | 0.739 | −0.245 | 0.527 | −0.964 | −0.980 | −0.997 | ||||||
3-Octanone | 1 | −0.954 | 0.654 | −0.852 | 0.891 | 0.962 | 0.867 | ||||||
Oil yield | 1 | −0.818 | 0.947 | −0.760 | −0.851 | −0.702 | |||||||
Temperature | 1 | −0.953 | 0.293 | 0.427 | 0.192 | ||||||||
Altitude | 1 | −0.559 | −0.680 | −0.480 | |||||||||
DPPH | 1 | 0.950 | 0.970 | ||||||||||
ABTS | 1 | 0.966 | |||||||||||
RP | 1 |
In spite of the fact that
The study concludes that
The GC-FID and GC-MS data used to support the findings of this study are included within this manuscript.
The authors declare that they have no conflicts of interest.
The authors are grateful to the Director, DIBER, Haldwani, and Head, Department of Chemistry, DSB Campus, Kumaun University, Nainital, for providing necessary laboratory facilities. The authors are also thankful to the Director, DIBER, Haldwani, for the financial support.