Table 1.
Examined Mentha spicata samples from Iran: codes, locations, and GPS coordinates
| Sample | Location | Coordinates (latitude/longitude) | Altitude (m) | Avg high/low °C (August) | Humidity (%) | Location description |
|---|---|---|---|---|---|---|
| S1 | Sonqor (Kermanshah) | 34.78 N/47.60 E | ∼1,450 m | ∼36°C/∼21°C | 35%–45% | Semi-arid climate with warm summers and cold winters; collected on 05.08.2024 |
| S2 | Mashhad (Razavi Khorasan) | 36.30 N/59.61 E | ∼1,000 m | ∼34°C/∼20°C | 25%–35% | Temperate-dry, moderate humidity; collected on 12.08.2024 |
| S3 | Ilam (Ilam Province) | 33.64 N/46.42 E | ∼1,350 m | ∼33°C/∼20°C | 30%–40% | Semi-humid mountainous western area with mild summers, collected on 07.08.2024 |
| S4 | Shaft (Gilan Province) | 37.17 N/49.40 E | ∼80 m | ∼30°C/∼24°C | 70%–85% | Humid Caspian (subtropical) high annual rainfall, collected on 15.08.2024 |
| S5 | Kermanshah (Kermanshah Province) | 34.33 N/47.10 E | ∼1,320 m | ∼36°C/∼21°C | 30%–40% | Semi-arid moderate continental climate, fertile soils, collected on 06.08.2024 |
| S6 | Sangar (Gilan Province) | 37.18 N/49.70 E | ∼50 m | ∼30°C/∼24°C | 75%–90% | Coastal plain, humid subtropical climate, collected on 21.08.2024 |
| S7 | Iranshahr (Sistan–Baluchestan) | 27.20 N/60.69 E | ∼600 m | ∼41°C/∼29°C | 15%–25% | Hot-arid desert climate with strong sunlight and minimal rainfall; collected on 25.08.2024 |
| S8 | Langrood (Gilan Province) | 37.20 N/50.15 E | ∼5 m | ∼30°C/∼25°C | 75%–90% | Very humid coastal near the Caspian Sea, mild temperatures; collected on 01.09.2024 |
Figure 1.
Collection sites of eight Mentha spicata samples (S1–S8) across Iran. Each point corresponds to a population used for essential oil extraction and GC-MS analysis.
Table 2.
Essential oil yields of Mentha samples collected from different regions of Iran
| Sample | Location | Plant material (g) | EO volume (mL) | EO yield (% v/w) |
|---|---|---|---|---|
| S 1 | Sonqur, Kermanshah | 10 | 0.10 | 1.0 |
| S 2 | Mashhad | 10 | 0.06 | 0.6 |
| S 3 | Ilam | 10 | 0.03 | 0.3 |
| S 4 | Shaft, Gilan | 10 | 0.04 | 0.4 |
| S 5 | Kermanshah | 10 | 0.03 | 0.3 |
| S 6 | Sangar, Gilan | 10 | 0.08 | 0.8 |
| S 7 | Iranshahr, Sistan, and Baluchistan | 5 | 0.08 | 1.6 |
| S 8 | Langrood, Gilan | 5 | 0.06 | 1.2 |
Table 3.
Major compounds (above 0.5 %) of the essential oil of different Iranian spearmints
| Compound (%) * | RT (min) | S 1 | S 2 | S 3 | S 4 | S 5 | S 6 | S 7 | S 8 |
|---|---|---|---|---|---|---|---|---|---|
| α-pinene | 4.2 | 1.9 | 1.5 | 2.1 | 0.9 | 1.1 | 1.5 | 1 | |
| Camphene | 5 | 0.8 | |||||||
| β-pinene | 5.9 | 2.2 | 1.4 | 1.7 | 0.9 | 0.8 | 1.2 | 1.3 | |
| β-phellandrene | 6.2 | 1.4 | 1 | 1.1 | 0.6 | 0.5 | 0.8 | ||
| β-myrcene | 7.3 | 0.9 | 0.8 | 1.6 | 1 | 1.3 | 0.7 | ||
| D-limonene | 8 | 17.1 | 8.1 | 23.1 | 12.0 | 28.7 | 25.9 | 21.3 | 34.2 |
| 1,8-cineole | 8.2 | 13.6 | 4.4 | 7 | 66.8 | 7.3 | 4.6 | ||
| Trans-β-ocimene | 9 | 1.7 | |||||||
| β-ocimene | 9.4 | 0.6 | |||||||
| p-cymene | 9.8 | 1 | |||||||
| 3-octanol | 13.5 | 0.6 | 0.9 | 0.8 | |||||
| 1-menthone | 15.2 | 0.7 | |||||||
| Isomenthone | 16 | 1.3 | |||||||
| β-bourbonene | 16.7 | 0.5 | |||||||
| Caryophyllene | 18.9 | 1.2 | 2 | 1.3 | 0.7 | 1.2 | |||
| Dihydrocarvone | 19.4 | 1.2 | 4.3 | 1.7 | 0.8 | 0.5 | 1.4 | ||
| Pulegone | 20.5 | 4.2 | 5.3 | 4.6 | |||||
| Dihydrocarveol acetate | 21.3 | 0.7 | |||||||
| Dihydrocarvyl acetate | 21.3 | 1 | |||||||
| D-germacrene | 22.1 | 3 | |||||||
| Isoborneol | 22.1 | 0.6 | 1.5 | 2.3 | |||||
| Endo-borneol | 22.1 | 2.8 | |||||||
| Isogermacrene D | 22.1 | 0.9 | |||||||
| α-terpineol | 22.2 | 0.8 | |||||||
| Piperitone oxide | 22.3 | 3.2 | |||||||
| Carvone | 23 | 58.4 | 29.9 | 49.6 | 21.2 | 56.8 | 64.7 | 62.3 | 50.8 |
| Dihydrocarveol | 23.5 | 1.1 | 0.6 | 2.4 | |||||
| Cis-carvone oxide | 25.7 | 0.7 | |||||||
| p-mentha-1,8-dien-3-one | 25.7 | 1.3 | |||||||
| Trans-carveol | 25.8 | 0.5 | |||||||
| Carveol | 26.6 | 1.2 | |||||||
| p-menthane-1,2,3-triol | 27.6 | 2.7 | |||||||
| Piperitenone | 27.8 | 4.7 | 0.9 | 0.6 | 0.90 | ||||
| Carvone oxide (low resolution) | 28.9 | 25.7 | |||||||
| Unidentified | 30.3 | 0.7 | 0.6 | ||||||
| Total identified (%) | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 99.8 | 100.0 | 99.9 |
Figure 2.
PCA of Mentha spicata essential oils collected from different regions of Iran. The scatter plot (PC 1 vs. PC 2) shows the distribution of samples based on their essential oil composition. Samples: S1 – Sonqur (Kermanshah), S2 – Mashhad, S3 – Ilam, S4 – Shaft (Gilan), S5 – Kermanshah, S6 – Sangar (Gilan), S7 – Iranshahr (Sistan and Baluchistan), S8 – Langrood (Gilan). PC 1 (73.45%) and PC 2 (21.02%) together explain 94.47% of the total variance.
Figure 3.
Loading plot of the first principal component (PC 1) obtained from the PCA of Mentha spicata essential oils. The plot shows the contribution of individual chemical constituents to the variability explained by PC 1 (73.45%).
Figure 4.
Loading plot of the second principal component (PC 2) obtained from the PCA of Mentha spicata essential oils. The plot shows the contribution of individual chemical constituents to the variability explained by PC 2 (21.02%).