Application of GC-MS in Quantitative Analysis of Some Carminative Syrups
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The document details a study on the quantitative analysis of carminative syrups using gas chromatography-mass spectrometry (GC-MS). Various essential oils were analyzed, showing specific calibration curves for their components, and the methodological validation was performed with recovery tests and limits of detection. The study confirms the effectiveness of GC-MS in determining the concentrations of active ingredients in medicinal products containing essential oils.
![Application of GC-MS in Quantitative Analysis of Some Carminative Syrups
DOI: 10.9790/3008-10634246 www.iosrjournals.org 43 | Page
by Unipharma Pharmaceutical Industries for the National Arabian Company for Pharmaceutical Agencies
(NAPHA) (Cairo, Egypt).
2. Equipments
Gas Chromatography-Mass Spectroscopy: Shimadzu GC-MS, Model QP-2010 Ultra, equipped with
head space AOC-5000 auto injector, Kyoto, Japan.
Column:Rtx-5 MS (0.25mm x 30 m), 0.25 µmdf, Restek, USA.
Electronic Balance: Model AUY220, Shimadzu Instrument, Kyoto, Japan
Ultrasonic bath: NSXX Sonics Model NS-A-12-7H, Germany.
III. Chemical Reagents:
All chemical, reagents and standards used were GC grade. Pure standards of Volatile oil were obtained as
follow:1,8-Cineol, Trans-Anethole 99%, (R)-(-)-Carvone 98% and (-)-α-Bisabolol 95% were purchased from
Sigma-Aldrich. Thymol 99%, (±)-Menthol 99% and (R)-(+)-Limonene 90%
purchasedfromFluka.Cinnamaldehyde> 98% was obtained from Merck.Hexane97% was HPLC and GC grade
from Sigma Aldrich.
IV. Experimental
4.1. Chromatographic conditions:
The GC/MS analysis was carried out using Shimadzu GC-MS, Model QP-2010 Ultra, equipped with
head space AOC-5000 auto injector, under the following condition:
Column: Rtx-5 MS (0.25mm x 30 m), 0.25 umdf, Restek, USA.
Injection volume: 5 µl.
Flow rate: 0.99 ml/min.
Injection Temp.: 210C.
Injection Mode:Splitless
Split ratio: 10
Carrier gas: Helium.
Oven Temperature Program:
Rate (C/min) Temperature (C) Hold Time (min)
---- 40 2
5 210 5
[GCMS-QP2010 Ultra] [MS Table]
Ion SourceTemp: 230C Start Time: 2.5 min
Interface Temp.: 280C End Time: 41 min
Solvent Cut Time: 2 min ACQ Mode: Scan
Detector Gain Mode: Relative Event Time: 0.3 sec
Detector Gain: +0.00 kV Scan speed: 1666
Threshold: 0 Start m/z: 35
End m/z: 500
4.2. Method Validation:
4.2.1. Calibration curves:
The stock standard solution of each standard pure was prepared as follows: about 10-30 mg of each
compound was accurately weighed and placed into a 25 ml volumetric flask. n- Hexane was added and the
solution diluted to volume with the same solvent.
Calibration curves were established on five data points covering the concentration range of 60–
1200µg/ml for Trans-Anethole, 60– 1200 µg/ml for Carvone, 60–1200µg/ml for Cinnamaldehyde, 40–
800µg/ml for Menthol, 20–400µg/ml for 1,8- Cineol, 40–400 µg/ml for (-)-α-Bisabolol, 80–400 µg/ml for
Thymol, 112–560 µg/ml for R-(+)-Limonene.
5 microliter aliquots of each standard solution were used for GLC analysis. Triplicate injections were
made for each standard solution. Each calibration curve was obtained by plotting the peak area of the essential
oils at each level prepared versus the concentration of the sample.
(Dilution was done case related).](https://image.slidesharecdn.com/i010634246-151214050113/85/Application-of-GC-MS-in-Quantitative-Analysis-of-Some-Carminative-Syrups-2-320.jpg)
![Application of GC-MS in Quantitative Analysis of Some Carminative Syrups
DOI: 10.9790/3008-10634246 www.iosrjournals.org 46 | Page
8.540
8.60
430Menthol0.02 gPeppermint oil
2.546
2.55
510Carvone0.005 gDill oil
2.995
3.00
600Cinnamaldehyde0.005 gCinnamon oil
1.788
1.80
360Cineol0.005 gCardamom oil
Follow Cease Syrup:
Determined
Conc. mg/100g syrup
Expected
mg/100g syrup
mg/g
RM
Active Constituent
g/100g
syrup
Raw material
RM
0.548
0.550
5.5Thymol0.1 gThymus Extract
0.138
0.140
7.0Cineol0.02 gEucalyptus Extract
4.297
4.30
430Menthol0.01gPeppermint oil
19.24
19.50
650R-(+)-Limonene0.03 gCitrus Lemon oil
V. Results and Discussion
The used method GC-MS for the analysis of pharmaceutical product(syrup) proved that it is an
accurate, precise, fast and easy method for the quality control of complex herbal pharmaceutical products
containing volatile oils such as carminative syrups.
This fact is clear and can be deduced the obtained results of Calibration curves table (1) where we can
found the upper and lower value of linearity (20-1200 µg/ml), slope (1.3494-9.8720), intercept (49.5837-
33.7650) and the correlation coefficient (0.9967-0.9998).
The percentage recoveries table (2) range form (97.97-102.42%). Limit of detection (LOD) and limit of
quantification (LOQ) table (3) where we can found the upper and lower value of LOD (5.00-33.33 µg/ml) and
LOQ (15-100 µg/ml) as well as the reducibility of the obtained results for the different raw material as well as
tested syrups table (5).
IV. Conclusion
The applied GC-MS method is of great value for the quality control of the herbal pharmaceutical
products containing complex mixture of volatile oils.
References
[1]. Gobel H et al. Effect of peppermint and eucalyptus oil preparations on neuro-physiological and experimental algesimetric headache
parameters. Cephalgia, 1994; 14:228-234.
[2]. Valeria R., Maria L., and Diana I. Chemical Composition of the Volatile Oil from different plant parts of Antheumgraveolens L.
cultivated in Romania, Farmacia, 2010; Vol. 58, (5): 594-600.
[3]. Ana C., Adrian S., Monica H., Auca M., Violeta F., Vasile D. and Ursula S. The Chemical properties of essential oils obtained from
fennel fruits (Foeniculumvulgare Mill), Farmacia, 2010, Vol. 58, (1): 46 – 53.
[4]. Dalvi SS et al. Effect of peppermint oil on gastric emptying in man: a preliminary study using a radiolabelled solid test meal. Indian
Journal of Physiology and Pharmacology, 1991, 35:212–214.
[5]. Sakai K et al. Effect of extracts of Zingiberaceae herbs on gastric secretion in rabbits. Chemical and Pharmaceutical Bulletin, 1989;
37: 215-217.
[6]. Mahady GB et al. In vitro susceptibility of Helicobacter pylori to botanicals used traditionally for the treatment of gastrointestinal
disorders. Phytotherapy Research, 2005; 19:988-991.
[7]. Carle R, Gomaa K. Chamomile: A Pharmacological and Clinical Profile. Drugs of Today, 1992, 28:559–565.
[8]. Vollmer H. UntersuchungenüberExpektorantien und den MechanismusihrerWirkung. KlinischeWochenschrift, 1932, 11:590–595.
[9]. Pharmacopoeia of the People’s Republic of China (English ed.). Guangzhou, GuangdongScience and Technology Press, 1992.
[10]. May B et al. Efficacy of a fixed peppermint oil/caraway oil combination in non-ulcer dyspepsia. Arzneimittel-Forschung, 1996,
46:1149–1153.](https://image.slidesharecdn.com/i010634246-151214050113/85/Application-of-GC-MS-in-Quantitative-Analysis-of-Some-Carminative-Syrups-5-320.jpg)
Application of GC-MS in Quantitative Analysis of Some Carminative Syrups
- 1. IOSR Journal of Pharmacy and Biological Sciences (IOSR-JPBS) e-ISSN: 2278-3008, p-ISSN:2319-7676. Volume 10, Issue 6 Ver. III (Nov - Dec. 2015), PP 42-46 www.iosrjournals.org DOI: 10.9790/3008-10634246 www.iosrjournals.org 42 | Page Application of GC-MS in Quantitative Analysis of Some Carminative Syrups 1 Mokhtar M. Bishr, 2 Mohamed A. El-Degwy, 3 Mohamed A. Amin and 4 Mohamed H.Mourad 1,2,3,4 Arab Company for Pharmaceuticals and Medicinal Plants, (Mepaco-Medifood), Egypt. Abstract: Gas chromatographic analysis was applied for the quantitative estimation of the essential oil(s) present in some carminative syrups in the Egyptian market. Depending on the fact that each essential oil has its unique component(s);the unique component was used as a marker compound in the quantitative determination of such oil. A calibration curve for each standard material was constructed to be used in these analyses. Thymol(r2 =0.9981) for Thyme;R-(-)-Carvone(r2 = 0.9991)for Caraway or Dill separately;Cinnamaldehyde(r2 =0.9998) for Cinnamon; Trans-Anethole (r2 = 0.9988) for Fennel;(±)Menthol (r2 =0.9988) for Peppermint;1,8- Cineol(r2 =0.9980) for Cardamom or Eucalyptus separately;(-)-α-Bisabolol(r2 =0.9984) for Chamomile and R- (+)-Limonene(r2 =0.9967) for Lemon oil. A validated GC-MS method was successfully applied for the quantitative determination of the components of different essential oils either as a separate raw material or within the pharmaceutical product(syrup). Key words:Essential oils, syrups, GC-MS. I. Introduction Volatile oils are known to have antispasmodic and carminative action as they stimulate the intestinal motility by increasing muscle tones. Over years, many medicinal herbs such as Cinnamon, Caraway, Fennel, Chamomile, Cardamom, Peppermint, Thyme, Eucalyptus, Lemon, and Dill have a focus of interest due to their volatile oil content. It was reported that the essential oils have various activities, such as carminative, anti- spasmodic, analgesic and other indications(1).The well-known properties of Dill in traditional medicine stated that it is used as carminative, stomachic and diuretic. Also, it was reported that Dill has antibacterial and antioxidant activity (2). Fennel is a well-known medicinal and aromatic plant the volatile oil of fennel has antispasmodic;antiflatulence properties, it is used for dyspeptic complaints and as hepatoprotective drug (3). The peppermint oil has smooth muscle relaxant activity; conforming its antispasmodic activity (4). Ethanolic extract of cardamom as well as its essential oil had shown antispasmodic activity (5). Also, antiulcer activity was observed upon use of the aqueous or methanol extracts of cardamom seeds to mice (6). Chamomile oil has been used for symptomatic treatment of digestive ailments such as dyspepsia, epigastric-bloating impaired digestion and flatulence (7). Thyme extract has been used to treat dyspepsia and other gastrointestinal disturbances; cough, bronchitis, laryngitis and tonsillitis (8). Cinnamon was used for treatment of dyspeptic conditions, fullness and flatulence, loss of appetite and abdominal pain with diarrhea, and amenorrhea and dysmenorrheapains (9).A double-blind study involving 45 patientswith non-ulcer dyspepsia assessed the change in pain intensity and ClinicalGlobal Impression after treatment with an enteric-coated capsule containinga combination of different essential oils (90 mg) and caraway oil (50 mg). After4 weeks of treatment, 63% of patients were free of pain; 89.5% had less pain; and94.5% showed improvements. Inanother study, oral administration of the essential oil (0.2 ml) delayed the gastricemptying time in healthy volunteers and in patients with dyspepsia (10). II. Materials& Methods 1. Three Pharmaceutical Products (syrups) containing volatile oils were purchased from the Egyptian Pharmaceutical Market, these are: Carminex syrup, Three batches were used 050514, 060514 and 070514;each 100 g contains 0.1 g Cinnamon oil, 0.1 g Caraway oil and 0.1 g Fennel oil, manufactured by Arab Company for Pharmaceuticals and Medicinal Plants (Mepaco-Medifood) (Cairo, Egypt). Top Calm syrup, Three batches were used83008, 83009 and 83011;each 100 g contains 0.01 g Chamomile oil, 0.005 g Dill oil, 0.005 g Cardamom oil, 0.005 g Cinnamon oil and 0.02 g Peppermint oil manufactured by EIMC United Pharmaceutical for Tetrapharm Company for Pharmaceutical & Chemical Industries (Cairo, Egypt). Followcease syrup, Three batches were used3556, 3680 and 3689;each 5 g contains 0.005 g Thymus Extract, 0.001 g Eucalyptus Extract, 0.0005 g Peppermint oil and 0.0015 g Citrus Lemon oil, manufactured
- 2. Application of GC-MS in Quantitative Analysis of Some Carminative Syrups DOI: 10.9790/3008-10634246 www.iosrjournals.org 43 | Page by Unipharma Pharmaceutical Industries for the National Arabian Company for Pharmaceutical Agencies (NAPHA) (Cairo, Egypt). 2. Equipments Gas Chromatography-Mass Spectroscopy: Shimadzu GC-MS, Model QP-2010 Ultra, equipped with head space AOC-5000 auto injector, Kyoto, Japan. Column:Rtx-5 MS (0.25mm x 30 m), 0.25 µmdf, Restek, USA. Electronic Balance: Model AUY220, Shimadzu Instrument, Kyoto, Japan Ultrasonic bath: NSXX Sonics Model NS-A-12-7H, Germany. III. Chemical Reagents: All chemical, reagents and standards used were GC grade. Pure standards of Volatile oil were obtained as follow:1,8-Cineol, Trans-Anethole 99%, (R)-(-)-Carvone 98% and (-)-α-Bisabolol 95% were purchased from Sigma-Aldrich. Thymol 99%, (±)-Menthol 99% and (R)-(+)-Limonene 90% purchasedfromFluka.Cinnamaldehyde> 98% was obtained from Merck.Hexane97% was HPLC and GC grade from Sigma Aldrich. IV. Experimental 4.1. Chromatographic conditions: The GC/MS analysis was carried out using Shimadzu GC-MS, Model QP-2010 Ultra, equipped with head space AOC-5000 auto injector, under the following condition: Column: Rtx-5 MS (0.25mm x 30 m), 0.25 umdf, Restek, USA. Injection volume: 5 µl. Flow rate: 0.99 ml/min. Injection Temp.: 210C. Injection Mode:Splitless Split ratio: 10 Carrier gas: Helium. Oven Temperature Program: Rate (C/min) Temperature (C) Hold Time (min) ---- 40 2 5 210 5 [GCMS-QP2010 Ultra] [MS Table] Ion SourceTemp: 230C Start Time: 2.5 min Interface Temp.: 280C End Time: 41 min Solvent Cut Time: 2 min ACQ Mode: Scan Detector Gain Mode: Relative Event Time: 0.3 sec Detector Gain: +0.00 kV Scan speed: 1666 Threshold: 0 Start m/z: 35 End m/z: 500 4.2. Method Validation: 4.2.1. Calibration curves: The stock standard solution of each standard pure was prepared as follows: about 10-30 mg of each compound was accurately weighed and placed into a 25 ml volumetric flask. n- Hexane was added and the solution diluted to volume with the same solvent. Calibration curves were established on five data points covering the concentration range of 60– 1200µg/ml for Trans-Anethole, 60– 1200 µg/ml for Carvone, 60–1200µg/ml for Cinnamaldehyde, 40– 800µg/ml for Menthol, 20–400µg/ml for 1,8- Cineol, 40–400 µg/ml for (-)-α-Bisabolol, 80–400 µg/ml for Thymol, 112–560 µg/ml for R-(+)-Limonene. 5 microliter aliquots of each standard solution were used for GLC analysis. Triplicate injections were made for each standard solution. Each calibration curve was obtained by plotting the peak area of the essential oils at each level prepared versus the concentration of the sample. (Dilution was done case related).
- 3. Application of GC-MS in Quantitative Analysis of Some Carminative Syrups DOI: 10.9790/3008-10634246 www.iosrjournals.org 44 | Page Table (1):Statistical analysis for the calibration curves of the standards in the essential oil r2 Intercept, bSlope, aLinearity range (µg/ml)Compound 0.99981.29591.764560-1200Cinnamaldehyde 0.9991-0.24191.667560-1200Carvone 0.998833.76501.349460-1200T- Anethole 0.9984- 4.32539.872040-400Bisabolol 0.9988- 49.58375.081540-800Menthol 0.9980- 0.47885.314420-400Cineol 0.99671.74303.7252112-560Limonene 0.9981- 0.72417.855880-400Thymol S.D. values are given in parenthesis. a for each curve the equation is y = ax + b, where y is the peak area, x is the concentration of the analyte (µg/ml), a is the slope, b is the intercept and r2 is the correlation coefficient. 4.2.2. Recovery The accuracy of the method was evaluated with the recovery test. This involved the addition of known quantities of essential oils standards to known amounts of Carminative Syrup. The samples were then extracted and analyzed with the proposed GC-MS method. The percentage recovery was determined by subtracting the values obtained for the control matrix preparation from those samples that were prepared with the added standards, divided by the amount added and then multiplied by 100. Table (2): Results of the recovery test for the used essential oil & extract R.S.D. (%)Mean (n = 5)Recovery (%)Spiked amount (mg)Compound 1.62100.0199.50-101.320.525Cinnamaldehyde 1.82101.6298.82-102.420.552Carvone 1.7199.9297.97-100.460.542T- Anethole 1.46100.8898.68-101.880.742Bisabolol 1.43100.7199.65-101.240.624Menthol 1.2999.1798.26-100.580.764Cineol 0.98100.9897.70-102.250.524Limonene 1.69100.8598.22-101.870.662Thymol R.S.D. (%) = (standard deviation/mean)×100. 4.2.3. Limits of detection and quantification Limits of detection (LOD) were calculated according to the expression 3.3σ/S, where σ is the standard deviation of the response and S is the slope of the calibration curve. Limits of quantification (LOQ) were established by using the expression 10σ/S. LOD and LOQ were experimentally verified by injections of pure standard at the LOD and LOQ concentrations. Table (3): Limit of detection (LOD) and limit of quantification (LOQ) LOQ (µg/ml)LOD (µg/ml)Compound 4013.33Cinnamaldehyde 4013.33Carvone 4013.33T- Anethole 3010.00Bisabolol 206.67Menthol 155.00Cineol 10033.33Limonene 6020.00Thymol 4.3. Standard Preparation: 10-30 mg of each of the following standards was accurately weighed and transferred into 25 ml volumetric flask; then dissolved in hexaneand sonicated for 5 minutes, and then the volume was completed to 25 ml with hexane.
- 4. Application of GC-MS in Quantitative Analysis of Some Carminative Syrups DOI: 10.9790/3008-10634246 www.iosrjournals.org 45 | Page (Dilution was done case related). 4.4. Raw Material: Sample Preparation: Essential oils: Accurately weighed separately 100mg Cinnamon oil, Caraway oil, Fennel oil, chamomile oil, Dill oil, peppermint oil, lemon oiland transfer each oil separately into 50 ml volumetric flask; then dissolved in hexane and sonicated for 5 minutes. Then completed to50 ml with hexane and mixed well. (Dilution was done case related). Extracts: Accurately weigh separately50 gm of Thymus extract and Eucalyptus extract; transfer each extract separately to a separating funnel and extract three successive times each of 15 ml n-hexane. The combined hexane of each extract was then separately filtered over phase separation paper and transferred into 50 ml volumetric flask. Then the filtrate volume was completed to 50 ml volumetric flask with hexane. (Dilution was done case related). Table (4): Results of the analysis of the active raw materials: Raw material Active principal Limit% Average %6 assays Concentration mg/g Cinnamon oil Cinnamaldehyde 55-75 60 600 Caraway oil Carvone 50-65 55 550 Fennel oil T. Anethole 55-75 67 670 Chamomile oil Bisabolol 10-65 45 450 Peppermint oil Menthol 30-55 43 430 Dill oil Carvone 43-63 51 510 Cardamom oil Cineol 25-45 36 360 Lemon oil Limonene 56-78 65 650 Thymus extract 1:1 1.2 % VO Thymol 0.44-0.66 0.55 5.5 Eucalyptus extract 1:1 1.5% VO Cineol 0.5-0.8 0.70 7.0 4.5. Syrups Sample Preparation: The content of six bottles (2 from each batch) of each syrupwere mixed well; then 100 gof each syrup was accurately transferred into 250 ml conical flask. Extraction of the volatile oil content of the syrup was done using three portion of hexane each of 15 ml. The combined hexane extract was then filtered over phase separation paper and transferred into 50 ml volumetric flask. Then the filtrate volume was completed to 50 ml volumetric flask with hexane and sonicated for 5 min. Both the samples and the standards were injected at least three times. Table (5): Results ofcarminative syrups of analysis: Carminex Syrup: Determined Conc. mg/100g syrup Expected mg/100g syrup mg/g RM Active principal g/100g syrup Raw material RM 59.930 60.0 600Cinnamaldehyde0.1 gCinnamon oil 55.001 55.0 550Carvone0.1 gCaraway oil 66.887 67.0 670T. Anethole0.1 gFennel oil Top Calm Syrup: Determined Conc. mg/100g syrup Expected mg/100g syrup mg/g RM Active Constituent g/100g syrup Raw material RM 4.485 4.50 450Bisabolol0.01 gChamomile oil
- 5. Application of GC-MS in Quantitative Analysis of Some Carminative Syrups DOI: 10.9790/3008-10634246 www.iosrjournals.org 46 | Page 8.540 8.60 430Menthol0.02 gPeppermint oil 2.546 2.55 510Carvone0.005 gDill oil 2.995 3.00 600Cinnamaldehyde0.005 gCinnamon oil 1.788 1.80 360Cineol0.005 gCardamom oil Follow Cease Syrup: Determined Conc. mg/100g syrup Expected mg/100g syrup mg/g RM Active Constituent g/100g syrup Raw material RM 0.548 0.550 5.5Thymol0.1 gThymus Extract 0.138 0.140 7.0Cineol0.02 gEucalyptus Extract 4.297 4.30 430Menthol0.01gPeppermint oil 19.24 19.50 650R-(+)-Limonene0.03 gCitrus Lemon oil V. Results and Discussion The used method GC-MS for the analysis of pharmaceutical product(syrup) proved that it is an accurate, precise, fast and easy method for the quality control of complex herbal pharmaceutical products containing volatile oils such as carminative syrups. This fact is clear and can be deduced the obtained results of Calibration curves table (1) where we can found the upper and lower value of linearity (20-1200 µg/ml), slope (1.3494-9.8720), intercept (49.5837- 33.7650) and the correlation coefficient (0.9967-0.9998). The percentage recoveries table (2) range form (97.97-102.42%). Limit of detection (LOD) and limit of quantification (LOQ) table (3) where we can found the upper and lower value of LOD (5.00-33.33 µg/ml) and LOQ (15-100 µg/ml) as well as the reducibility of the obtained results for the different raw material as well as tested syrups table (5). IV. Conclusion The applied GC-MS method is of great value for the quality control of the herbal pharmaceutical products containing complex mixture of volatile oils. References [1]. Gobel H et al. Effect of peppermint and eucalyptus oil preparations on neuro-physiological and experimental algesimetric headache parameters. Cephalgia, 1994; 14:228-234. [2]. Valeria R., Maria L., and Diana I. Chemical Composition of the Volatile Oil from different plant parts of Antheumgraveolens L. cultivated in Romania, Farmacia, 2010; Vol. 58, (5): 594-600. [3]. Ana C., Adrian S., Monica H., Auca M., Violeta F., Vasile D. and Ursula S. The Chemical properties of essential oils obtained from fennel fruits (Foeniculumvulgare Mill), Farmacia, 2010, Vol. 58, (1): 46 – 53. [4]. Dalvi SS et al. Effect of peppermint oil on gastric emptying in man: a preliminary study using a radiolabelled solid test meal. Indian Journal of Physiology and Pharmacology, 1991, 35:212–214. [5]. Sakai K et al. Effect of extracts of Zingiberaceae herbs on gastric secretion in rabbits. Chemical and Pharmaceutical Bulletin, 1989; 37: 215-217. [6]. Mahady GB et al. In vitro susceptibility of Helicobacter pylori to botanicals used traditionally for the treatment of gastrointestinal disorders. Phytotherapy Research, 2005; 19:988-991. [7]. Carle R, Gomaa K. Chamomile: A Pharmacological and Clinical Profile. Drugs of Today, 1992, 28:559–565. [8]. Vollmer H. UntersuchungenüberExpektorantien und den MechanismusihrerWirkung. KlinischeWochenschrift, 1932, 11:590–595. [9]. Pharmacopoeia of the People’s Republic of China (English ed.). Guangzhou, GuangdongScience and Technology Press, 1992. [10]. May B et al. Efficacy of a fixed peppermint oil/caraway oil combination in non-ulcer dyspepsia. Arzneimittel-Forschung, 1996, 46:1149–1153.