Chemicals
3(4,5-dimethylthiazol-2-yl) 2,5-diphenyl-tetrazolium bromide (MTT; Sigma-Aldrich, USA); 2,2-diphenyl-1-picrylhydrazyl (DPPH), rutin, gallic acid, Folin-Ciocalteu reagent, Aluminum chloride, penicillin G-streptomycin and Fetal Bovine Serum (FBS) all from Sigma Aldrich (Germany), RPMI 1640 from Gibco, UK, Phosphate Buffer Saline (PBS), Muller Hinton Agar Medium (MERCK) and Trypsin–EDTA (Gibco, Paisley, UK) were purchased. All other reagents and chemicals were of analytical grade. Solvents used for extraction and tests purchased from Caledon and Scharlau. ELISA plate reader (BioTeck, Bad Friedrichshall, Germany) was used for anti-proliferative test. (DPPH) reagent (C18H12N5O6 formula, molecular weight 394) (Sigma-Aldrich, Germany), also were used in this paper.
Collection and identification of plant material
The chopped aerial parts of S. atropatana were gathered in May 2013, at altitudes above 1600 m from Spiran region in East Azerbaijan province. Voucher specimen after identifying (Tbz- fph- 8962) has been retained at the Herbarium of the Department of Pharmacognosy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Iran.
Extraction and Fractionation
Powdered aerial parts of
S. atropatana were extracted by Soxhlet to obtain n-hexane (n-hex), dichloromethane (DCM) and methanol (MeOH) extracts, successively. For further investigations, the potent extract (inhibited strongly growth of the malignant cells) was subjected to Vacuum Liquid Chromatography (VLC) method for fractionation (
20-
23). VLC is a method to obtain different fractions of non-polar extracts. In this method, first VLC hopper was connected to Buchner filter, and then a filter paper was put on the filter. In the next step, the silica gel was loaded into the 2/3 of the tightened hopper. Subsequently, the vacuum pomp was used to compact the silica gel. Another filter paper was placed on the silica gel column. After these preparations, 150 mL methanol, 150 mL ethyl acetate, and 150 mL 10% ethyl acetate (10% EtOAc and 90% n-hex) were passed over the silica gel, respectively. Then, the filter paper over the column was removed. Afterwards, DCM extract was solved in adequate 10% EtOAc in n-hex and then the solution was loaded over the column and then step by step several concentrations of EtOAc in n-hex (10%, 20%, 40%, 60%, 80% and 100%) were passed through the column and were collected in separate containers.
Moreover, the polar extracts which had high free radical scavenging activity and total phenolic contents were fractionated by Solid Phase Extraction (SPE) method. Two grams of MeOH extract was loaded on a Sep-pak (10 g: C18) cartridge (Waters, Ireland) and eluted by increasing step gradients of MeOH-water mixtures. For removing the solvents, Rotary evaporator (Heildolph, Schwabach, Germany) at a maximum temperature of 45 °C and in a low pressure was used. For further investigations, the samples were stored in a freezer at -20 °C.
Distillation of plant materials
Shed-dried plant material of the aerial parts of S. atropatana was subjected to hydro-distillation for 3 h using a Clevenger-type apparatus. Resulted essential oil (EO) was subsequently dehydrated using anhydrous sodium sulphate and kept at low temperature (4 °C) in dark until analysis.
Gas Chromatography-Mass Spectrometry (GC-MS) analysis and identification of compounds
The analysis of the EO and cytotoxic DCM extract and its potent fractions was performed using a Shimadzu GC-MS-QP5050A fitted with a fused DB-1 capillary column (methyl phenyl syloxane, 60 m, 0.25 mm id, film thickness 0.25 µm). Helium was used as a carrier gas at a flow rate of 1.3 mL/min, as well as split ratio 1.29. Temperatures of the injector and detector were set at 250 °C and 260 °C, respectively. The column temperature was kept at 50 °C for 2 min, and then programmed to increase to 230 °C at a rate of 2 °C/min and then kept constant for 8 min. The MS spectral parameters were as follows: ionization energy 70 eV; ion source temperature 200 °C; quadrupole 100 °C; solvent delay 3 min; EV voltage 3000 v. Qualitative identification of constituents was based on direct comparison of the retention indices, Kovats indices and Mass spectral with those for standard compounds and computer matching with the NIST NBS54K Library, as well as by comparison with published papers (
4,
6). Flame ionization detector (FID) was used for calculating relative percentage amounts. The FID detector condition was set on the same GC-MS operational conditions.
Antimicrobial assay
In-vitro anti-microbial activity of all samples (n-hex, DCM, MeOH and EO) of
S. atropatana was assessed against following organisms: Two strains of gram negative species,
Pseudomonas aeroghinosa (ATCC 9027) and
Escherichia coli (ATCC 8739), as well as the gram positive species namely
Staphylococcus epidermidis (ATCC 12228) and
Staphylococcus aureus (ATCC 6538), and a fungi (
Candida albicans) (ATCC 10231) which were purchased from the institute of Pasture, Type Culture Collection (Iran). Agar disc diffusion method as the qualitative antibacterial assay was used for this aim. Cultured bacteria in to the Muller Hinton Broth was incubated at 37 °C for 24 h. Then, the centrifuged pellets re-suspended in saline solution to provide an optical density equal to 10
6 CFU/mL. Test organisms were cultured in a suitable Muller Hinton Agar Medium. Sterile 6.0 mm diameter discs were impregnated with 50 µL of different test substances. Subsequently, the plates for 30 min were kept in a refrigerator to allow the diffusion of extracts, and then they were incubated at 37 °C for 24 h. The quantitative antimicrobial potency of the samples was assessed by measuring the diameter of the inhibition zones in comparison to DMSO and Amikacin as a negative and positive control groups. All experiments were performed in duplicate and mean ± SD value was calculated (
24).
Anti -proliferative activity
Malignant and nonmalignant cells including SW480 (colon carcinoma) MCF-7 cells (human breast carcinoma cell line) and L-929 (normal cell line) from Pasture Institute, Tehran, Iran were cultured in RPMI 1640 medium with suitable additives containing 10% Fetal Bovine Serum (FBS), 100 mg/mL streptomycin and 100 units/mL penicillin G. They were incubated at 37 °C in a humidified air/carbon dioxide (95:5) atmosphere. MTT colorimetric assay was used for assessing viability of the cells. The cells in the exponential growth stage were sub-cultured at 1 × 10
4/well on to 96-well plates (Nunc, Denmark). Then, the cell suspensions were treated with different dilutions of all extracts for 24 and 48 h. Four hours before the end of the time, the medium was replaced with a fresh culture containing 20 μL of MTT solution (5 mg/mL in PBS). Then after this period, the supernatants were removed and 100 µL of DMSO solvent was added to dissolve the formazan crystals completely. Finally, the absorbance of the metabolized MTT production (formazan crystals) was read at 570 nm with microplate reader (BioTeck, Bad Friedrichshall, and Germany). (BioTeck, Bad Friedrichshall, and Germany). The IC
50 values were defined as the concentration of the samples required to induce a 50% reduction in viability of the cells absorbance and evaluated from a dose-response curve plotted in the SigmaPlot 11 software (
25,
26). Methotrexate was used as positive control.
| Extracts or fractions | Total phenol content (mg g-1) | Flavonoid content (mg g-1) | Antioxidant activity (RC50; mg mL )-1 ** |
|---|
| MeOH* | 68.37 ± 0.06 | 52.04 ± 0.42 | 0.143 ± 0.09 |
| DCM* | 27.29 ± 1.02 | - | 0.681 ± 0.02 |
| n-hexane | 3.21 ± 0.30 | - | 0.576 ± 0.008 |
| 10% SPE fraction | 7.44 ± 0.20 | 5.60 ± 0.31 | 1.164 ± 0.20 |
| 20% SPE fraction | 42.54 ± 0.45 | 25.66 ± 0.33 | 0.092 ± 0.00 |
| 40% SPE fraction | 146.65 ± 2.34 | 120.12 ± 2.25 | 0.046 ± 0.00 |
| 60% SPE fraction | 127.52 ± 0.31 | 100.23 ± 4.43 | 0.102 ± 0.00 |
| 80% SPE fraction | 24.76 ± 0.32 | 14.23 ± 1.12 | 0.194 ± 0.02 |
| 100% SPE fraction | 4.76 ± 0.21 | 3.05 ± 0.01 | 0.534 ± 0.26 |
| Samples | IC50 Values (µg/mL)
|
|---|
MCF-7
| L929
|
|---|
| 24 h | 48 h | 24 h | 48 h |
|---|
| 10% VLC | 123.7 ± 0.98 | 113.8 ± 43.7 | >500 | 220.00 ± 32.01 |
| 20% VLC | 103.59 ± 17.83 | 94.3 ± 13.42 | >500 | 190.23 ± 15.45 |
| 40% VLC | 247.5 ± 62.08 | 205.7 ± 39.88 | >500 | 300.00 ± 46.71 |
| 60% VLC | 148.85 ± 31.60 | 208.05 ± 38.53 | >500 | 380.23 ± 49.22 |
| 80% VLC | 98.105 ± 25.59 | 88.53 ± 12.85 | >500 | 230.45 ± 56.28 |
| 100% VLC | 62.29 ± 4.29 | 60.7 ± 10.79 | >500 | 198.20 ± 43.25 |
| Methotrexate | 0.16 ± 0.09 (48 h) | 0.24 ± 0.01 (48 h) |
| Area (%) | RT (min) | KI(a) | Molucular formula | Compounds | Number |
|---|
| 0.03 | 10.29 | 800 | C5H4O2 | Furfural | 1 |
| 0.03 | 16.40 | 912 | C6H12O | 2-Pentanone، 3-methyl | 2 |
| 0.01 | 18.42 | 941 | C6H14O | Isobutylmethylmethanol | 3 |
| 0.12 | 19.02 | 950 | C7H14 | Cyclopropane،1،1،2،3-tetramethyl | 4 |
| 0.02 | 19.12 | 952 | C7H14 | -1Pentene، 2،4-dimethyl | 5 |
| 0.14 | 19.23 | 953 | C7H12O | -1Hepten-3-one | 6 |
| 0.23 | 19.80 | 962 | C8H16O | -1Octen-3-ol | 7 |
| 0.02 | 20.85 | 977 | C9H14O | 2-Pentylfuran | 8 |
| 0.15 | 20.96 | 979 | C8H16O | Cyclooctyl alcohol | 9 |
| 0.10 | 22.83 | 1006 | C8H8O | Benzeneacetaldehyde | 10 |
| 0.03 | 24.35 | 1026 | C10H16 | beta.-trans-Ocimene | 11 |
| 0.08 | 25.17 | 1037 | C10H16 | beta.-cis-Ocimene | 12 |
| 0.09 | 26.41 | 1054 | C10H20 | 1-Octene،3،7-dimethyl | 13 |
| 0.03 | 28.16 | 1077 | C10H16 | α- Terpinolen | 14 |
| 2.14 | 28.51 | 1082 | C9H18O | Nonanal | 15 |
| 18.82 | 28.87 | 1087 | C10H18O | Linalool | 16 |
| 0.28 | 32.35 | 1133 | C10H18O | 2-Decenal، (E) | 17 |
| 0.20 | 34.04 | 1156 | C10H22O | 1-Decanol | 18 |
| 0.20 | 34.30 | 1159 | C10H18O | 1-Terpinen-4-ol | 19 |
| 4.14 | 35.19 | 1171 | C10H18O | alpha.-Terpineol | 20 |
| 0.54 | 36.14 | 1184 | C10H20O | Capraldehyde | 21 |
| 0.13 | 36.46 | 1188 | C10H16O | Carvomenthenal | 22 |
| 0.13 | 36.87 | 1194 | C10H16O | beta-cyclocitrat | 23 |
| 1.57 | 38.03 | 1209 | C10H18O | cis-Geraniol | 24 |
| 5.68 | 39.91 | 1235 | C10H18O | 1،6-octadien-3-ol،3،7-dimethyl | 25 |
| 0.26 | 41.65 | 1259 | C9H18O2 | 3-Ethylheptanoic acid | 26 |
| 0.33 | 41.78 | 1261 | C9H18O2 | Nonanoic acid | 27 |
| 0.15 | 42.21 | 1267 | C11H20 | 1،3-Nonadiene،5،5-dimethyl | 28 |
| 0.11 | 43.18 | 1280 | C9H10O2 | Vinylguaicol | 29 |
| 0.38 | 43.68 | 1287 | C10H16O | 2،4-Decadienal، (E،E) | 30 |
| 0.26 | 45.78 | 1317 | C10H16O2 | Lilac aldehyde D | 31 |
| 0.37 | 47.30 | 1339 | C11H20O | 2-Undecen-1-al | 32 |
| 0.26 | 48.18 | 1352 | C10H20O2 | n-Capric acid | 33 |
| 0.79 | 48.77 | 1360 | C13H18O | 2-Buten-1-one1-(2،6،6-trimethyl-1،3-cyclohexadien-1-yl)-، (E) | 34 |
| 0.12 | 49.31 | 1368 | C13H20 | 2-Carene،4-.alpha.-isopropenyl | 35 |
| 0.09 | 50.59 | 1387 | C13H26O | Pseudoionone hexahydro | 36 |
| 0.10 | 50.66 | 1388 | C13H26O | Tridecanal | 37 |
| 0.21 | 51.18 | 1395 | C13H20O | 6،8-Nonadien-2-one،6-methyl-5-(1-methylethylidene) | 38 |
| 0.42 | 53.35 | 1428 | C13H22O | Dihydropseudoionone | 39 |
| 0.36 | 55.55 | 1462 | C13H20O | beta-lonone | 40 |
| 0.17 | 57.27 | 1488 | C14H26 | cis،cis-5،9-Tetradecadiene | 41 |
| 0.20 | 57.40 | 1490 | C13H26O | Tridecanal | 42 |
| 0.67 | 60.99 | 1547 | C15H26O | trans-Nerolidol | 43 |
| 0.14 | 63.78 | 1592 | C16H32O | Hexadecanal | 44 |
| 0.18 | 67.70 | 1658 | C16H34O | 1-Decanol، 2-hexyl | 45 |
| 0.05 | 68.11 | 1665 | C15H26O | alpha.-Bisabolol | 46 |
| 0.14 | 69.84 | 1694 | C15H30O | Pentadecanal | 47 |
| 0.29 | 70.18 | 1700 | C17H36 | Heptadecane | 48 |
| 0.48 | 72.69 | 1745 | C15H30O2 | Pentadecanoic acid | 49 |
| 0.14 | 75.58 | 1796 | C16H32O | Palmitaldehyde | 50 |
| 0.13 | 75.78 | 1800 | C18H38 | Octadecane | 51 |
| 0.23 | 77.11 | 1825 | C16H22O4 | Phthalic acid، diisobutyl ester | 52 |
| 3.65 | 77.40 | 1830 | C18H36O | 2-Pentadecanone trimethyl | 53 |
| 0.10 | 79.60 | 1872 | C18H38O | Hexadecane،1-methoxy-13-methyl | 54 |
| 0.10 | 81.55 | 1909 | C17H34O2 | Hexadecanoicacid،methyl ester | 55 |
| 0.66 | 83.42 | 1945 | C18H36O2 | Octadecanoic acid | 56 |
| 0.20 | 86.23 | 2001 | C19H40O | Nonadecanol | 57 |
| 0.07 | 95.69 | 2100 | C21H44 | Heneicosane | 58 |
| 0.10 | 89.84 | 2124 | C19H32O2 | Linolenic acid، methyl ester | 59 |
| 2.92 | 91.06 | 2125 | C20H40O | Phytol | 60 |
| 2.58 | 100.52 | 2223 | C22H46 | Pentadecane، 8-heptyl | 61 |
| 0.12 | 104.42 | 2400 | C24H50 | Tetracosane | 62 |
| 1.09 | 108.53 | 2800 | C28H58 | Octacosan | 63 |
| 37.15 | 110.76 | 3100 | C31H64 | Hentriacontane | 64 |
| 0.09 | 112.47 | 3600 | C36H74 | Hexatriacontane | 65 |
| 90.77% | Total identified |
| 37.11 | Terpenoids |
| 60.66 | Non-terpenoid |
| Samples | Compounds | RT(a) | Area (%) |
|---|
| Neophytadiene | 27.83 | 4.59 |
| 3,7,11,15-Tetramethyl-2-hexadecen-1-ol | 28.74 | 1.3 |
| n-Hexadecanoic acid | 29.98 | 4.6 |
| Menthol | 33.27 | 2.04 |
| DCM extract | 9-Octadecenoic acid | 33.52 | 2.47 |
| n-Nonadecane | 40.32 | 1.47 |
| n-Octadecane | 43.49 | 3.38 |
| n-Tetratriacontane | 46.82 | 53.77 |
| Octacosane | 48.69 | 4.26 |
| Loliolide | 22.13 | 38.83 |
| 80% VLC fraction | Neophytadiene | 24.76 | 32.62 |
| Octadecanoic acid | 26.89 | 28.55 |
| n-Pentadecane | 11.73 | 7.24 |
| Eicosane | 16.98 | 9.58 |
| Loliolide | 22.14 | 35.27 |
| n-Heneicosane | 23.10 | 5.71 |
| 100% VLC fraction | Neophytadiene | 24.77 | 9.93 |
| 3,7,11,15-Tetramethyl-2-hexadecen-1-ol | 25.68 | 3.47 |
| n-Hexadecanoic acid | 26.94 | 23.99 |
| Phytol | 30.23 | 1.98 |
| 1,2 Benzenedicarboxylic acid, ditridecyl ester | 37.52 | 2.83 |
Assay for Total Phenolics Content (TPC)
Total phenol content was evaluated by modified Folin-ciocalteu reagent method and gallic acid as standard. Concisely, 1 mL of each total extracts (5 mg in 60% aqueous acetone) were mixed thoroughly and shacked with 2 mL of 10% Folin Ciocalteu reagent and 1 mL of 5% aqueous Na
2CO
3 (which was prepared by dissolving Na
2CO
3 in water) in a volumetric flask. Subsequently, the mixtures were centrifuged in 1200 rpm for 5 min and allowed to incubate for 30 min at 25
oC. Afterwards, absorbance of upper mixture was assessed at constant wavelength 750 nm. The same procedure was applied to different concentrations of Gallic acid solutions as a standard and calibration curve was drawn. TPC was reported as Mg gallic acid equivalent per gram of dried extract (
27).
Estimating of total flavonoid contents by colorimetric assay (TFC)
Total flavonoid contents of the samples were determined by leading a modified aluminium chloride colorimetric method and also
Rutin as a standard. Briefly, 2 mL of different extracts and fractions (which were prepared in 80% methanol) were mixed with 400 μL of water, 400 mg Sodium acetate, 183 mg Aluminium chloride and were kept in dark place at 25
oC for 30 min for complete reaction. In addition, the absorbance of all solutions was read at 430 nm. Rutin standard (which was prepared in 5-25 µg/mL dilutions) was applied for calibration curve quantitatively. TFC was calculated as Rutin equivalents per gram of the dried plant material (
28).
Brine Shrimp Lethality Test (BSLT)
BSLT as a simple, low cost, high sensitive, and convenient pharmacologic guide was applied in a laboratory bioassay for screening general toxicity through the assessment of the 50% fatal concentration following the modified Meyer method and previous works (
7). Concisely, the hatching eggs which were obtained from Fisher Center, Tabriz, Iran, were prepared in 35% salt water and incubated under well aerated, flask for 48 h. Subsequently, the different herbal extracts were dissolved in DMSO and normal saline for obtaining variable concentration of the samples. (It is worth to mention that ultimate DMSO concentration of did not overpass 0.05%). One milliliter of main prepared sample solution along with 10 mL of sea water was added to each sterile vial. In addition, approximately, 10 nauplii as amateur shrimps were transferred in to the vials and incubated for 24 h. Finally, number of dead nauplii at each dosage were counted as percent of mortality of the extracts. The LC
50 was estimated using linear regression analysis by Microsoft Excel software.
Free radical scavenging activity test (FRST)
Free radical scavenging potential of all test samples was estimated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) reagent (C18H12N5O6 formula, molecular weight 394) (Sigma-Aldrich, Germany) which was adopted with slight modification (29, 30). DPPH solutions (0.08 mg/mL) for non-polar and polar extracts were prepared in chloroform and MeOH, respectively. Different concentrations of extracts and fractions (5 × 10-1, 2.5 × 10-1, 1.25 × 10-1, 6.25 × 10-2, 3.13 × 10-2 and 1.56 × 10-2 mg/mL) were obtained by serial dilutions, then mixed with 0.08 mg/mL DPPH solution. The mixtures were incubated for 30 min in 25 °C for complete reaction. The UV absorbance of all samples was measured at a constant 517 nm. The reduction of free radical capacity was calculated by the following formula:
R% = (A Blank – A Sapmle)/A Blank) × 100 (1)
Subsequently, 50% inhibition capacity value was resulted from the graph plotting reduction percentage against different concentrations of the extracts. Quercetin was used as a positive control. All of the experiments were followed in the same manner for positive control. The experiment was repeated in triplicate.
Statistical Analysis
All experiments were conducted in triplicate measurements and presented as the mean ± SD. Data were analyzed by Microsoft Excel and SigmaPlot 2010. The IC50 value was calculated from nonlinear regression analysis.