Journal of Medicinal Plants Research Vol. 5(23), pp. 5646-5648, 23 October, 2011 Available online at http://www.academicjournals.org/JMPR ISSN 1996-0875 ©2011 Academic Journals Short Communication Volatile constituents and antimicrobial activities of Pterocephalus canus Hooshang Vahedi*, Maliha Nasrabadi, Jalil Lari and Majid Halimi Chemistry Department, Payame Noor University, 19395-4697 Tehran, I. R. of Iran. Accepted 23 June, 2011 The volatile constituents from the aerial parts of Pterocephalus canus growing wild in Iran was obtained by hydrodistillation and analyzed by GC and GC-MS. Twenty three components representing 95.3% of the oil were identified. The main constituents of the oil were naphthalene (42.4%), tridecanoic acid (7.9%), hexadecanoic acid (7.9%), tetradecamethylcycloheptasiloxane (3.4%), 2,3-butanediol (3.1%) and dodecanoic acid (2.1%). Antimicrobial activity of the oil against 6 Gram-positive and negative bacteria was determined by measuring the growth inhibition zone. The oil showed significant antimicrobial activity against Staphylococcus saprophyticus and Escherichia coli. The bacteria Staphylococcus aureus, Sataphylococcus epidermidis, Salmonella typhi and Shigella flexnery were insensitive to the oil. Key words: Pterocephalus canus, Dipsacacae, essential oil composition, antimicrobial activity. INTRODUCTION The genus Pterocephalus, one of the most important genus of Dipsacacae family is widely used in flavouring and folk medicine all around the world (Ghahreman, 1995). Its main habitat being in sunny, dry, rock crevices mostly found in Western Asia (Iran, Turkey). Its leaves belong to elliptic, entire, tomentose. The floral heads are 25 mm in diameter and with height of 5 to 10 cm which blossoms at summer time. Pterocephalus species was known to exhibit various biological activities such as antioxidant activities. Antibacterial, spasmolytic, hemostatic, astringent and many other activities of some Pterocephalus species have been reported (Zargari, 1992; Newall and Anderson, 1996; Bisset, 1994; Perry et al., 2003; Graikou et al., 2002; Hung et al., 2006; Li, 1998). Recently more attention has been directed to the water soluble biologically active components of this genus (Tian et al., 1993; Zheng et al., 2004). A literature survey revealed that no chemical and biological studies had been performed on the essential oil of Pterocephalus Canus. The aim of our study was to evaluate the chemical composition of P. canus essential oil and its *Corresponding author. E-mail: h_vahedi@pnu.ac.ir or hooshangvahedi@yahoo.co.uk. Tel: +98-511 8683002. Fax: +98-511 8683001. antimicrobial activities. EXPERIMENTAL Plant material Aerial parts of P. Canus were collected at the flowering stage from Tehran, Iran in June 2007 and identified at the Research Institute of Forest and Rangelands, Tehran, Iran. A voucher specimen has been deposited in the Herbarium of Research Institute for Forests and Rangelands (voucher specimen number is 25418). Isolation of the essential oil Aerial parts of P. Canus were air-dried for 5 days before isolation of essential oil. The plant material (100 g) was cut into small pieces and the essential oil obtained by hydrodistillation with a Clevengertype apparatus until there was no significant increase in the volume of the oil collected (5 h). The yield of the yellow oil was 0.02% (w/w) based on the dry weight of the plant. GC and GC-MS analysis GC analysis of the oil from the aerial parts of the plant was performed using a Shimadzu 14A gas chromatograph equipped with flame ionization detector (FID) and a DB-5 fused silica column (30 m × 0.25 mm i.d., film thickness 0.25 m). The oven temperature was programmed 50 to 250°C at a rate of 5°C/min; the injector Vahedi et al. 5647 Table 1. Percentage composition of the essential oils isolated from aerial parts of Pterocephalus Cannus. S/N 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 a Compounds 3-Hydroxy-2-butanone 2,3-Butanediol 1,1-Diethoxy ethane 4-Hydroxy-4-methyl-2-pentanone Ethyl formate Linalool Naphthalene α - Terpineol Geraniol Dodecamethyl cyclohexasiloxane E-β -Damascenone Tetradecamethylcycloheptasiloxane Dodecanoic acid Caryophyllen oxide Nonanoic acid Tetradecanoic acid Isopropyl myristate 1,2-Benzendicarboxylic acid Tridecanoic acid Hexadecanoic acid Ethyl linoleate Tetracosane Hexatriacontane a RI 707 780 806 933 855 1103 1179 1191 1285 1321 1385 1498 1573 1585 1770 1771 1828 1870 1971 1972 2145 2302 3600 Yield (%) 1.4 3.1 1.4 0.5 0.2 1.1 42.4 0.3 0.2 1.0 0.2 3.4 2.1 1.1 2.1 2.0 0.2 0.9 7.9 7.9 1.8 1.8 0.8 Retention indices on HP-5 MS. and detector temperatures were 260°C; the carrier gas was helium with a flow rate of 1 ml/min. The sample was injected using the split sampling technique of 1:50. The percentage composition of the oil was calculated automatically from peak areas without any correction. GCMS analysis was carried out on a Hewlett-Packard 5890 GC with an HP5970 MSD system using an HP-5MS column (30 m × 0.25 mm i.d., film thickness 0.32 m). The oven temperature was as earlier mentioned, the transfer line temperature was 260°C; ionization energy in mass was 70 eV; mass range was 40 to 300 amu and scan time was 1 s. Retention indices (RI) of compounds were determined by comparing to the retention times of a series of n-alkanes with linear interpolation. Identification of the oil components was obtained by comparison of their mass spectra with the Wiley GC-MS library as well as by comparing with those reported in the literature. The identification of each component was confirmed by comparison of its retention index either with those of authentic compounds or with data in the literature (Jennings and Shibamoto, 1980; Adams, 1995; Davies, 1990). Antimicrobial assay The antibacterial activities of the essential oil of P. Canus were determined by measuring the growth inhibitory zones (well method) (Baver et al., 1986) against 6 Gram-positive and negative bacteria. The Gram-positive bacteria included S. aureus PTCC1113, S. epidermidis PTCC1349, and S. saprphyticus PTCC1379, and Gram-negative bacteria included Salmonella typhi PTCC1185, Shigella flexnery PTCC1234 and E. coli PTCC1330. The microorganisms were obtained from the Research Center of Science and Industry, Tehran, Iran. Microorganisms (obtained from enrichment culture of the microorganisms in 1 ml Mueller–Hinton broth incubated at 37°C for 12 h) were cultured on Mueller–Hinton agar medium. The inhibitory activity was compared with that of standard antibiotics such as tetracycline (30 g) and gentamicine (10 g) which were obtained from the Iran Daru Company, Tehran, Iran. The essential oil of P. Canus was dissolved at 10% in n-hexane, and 50 l of solution were poured into each well. After 24 h of incubation at 37°C, the diameter of the inhibition zone was measured to the nearest millimeter. Each test was carried out in triplicate and the average was calculated for inhibition zone diameters. A blank containing only n-hexane showed no inhibition in a preliminary test. RESULTS AND DISCUSSION From the aerial parts of P. canus at flowering stage, a yellowish oil was obtained at a yield of 0.02% (w/w). 23 components were identified accounting for 95.3% of the total oil. The oil of P. Canus was characterized by naphthalene (42.4%), tridecanoic acid (7.9%), hexadecanoic acid (7.9%) as the major components followed by tetradecamethylcycloheptasiloxane (3.4%), 2,3-butanediol (3.1%), dodecanoic acid (2.1%), nonanoic acid (2.1%), linalool (1.1%) and caryophyllene oxide 5648 J. Med. Plants Res. Table 2. Antimicrobial activities of Pterocephalus Canus oil. Microorganisms Staphylococcus aureus PTCC 1113 (GP) Staphylococcus epidermidis PTCC 1349 (GP) Staphylococcus saprophyticus PTCC 1379 (GP) Salmonella typhi PTCC 1185 (GN) Shigella flexnery PTCC 1234 (GN) Escherichia coli PTCC 1330 (GN) a Growth inhibitory zone (mm) 12 10 a Standard antibiotics b 16 19b 23b b 26 24c c 25 b GP: Gram- positive; GN: Gram-negative; values are the mean diameter of inhibitory zones (mm); gentamicine; tetracycline, (-) resistant. (1.1%). The percentage composition of the various oil components are listed in Table 1. Antimicrobial activities The antimicrobial activities of P. Canus oil was assayed against 6 Gram (±) bacteria and results presented in Table 2 were compared with standard antibiotics. The present study revealed that the plant showed only antibacterial activity on Staphylococcus saprophyticus and Escherichia coli. This study confirms the importance of the correlation between the chemical content of the oils and antibacterial activities. Conclusions The aerial parts of P. Canus wildly grown in Iran was hydrodistilled and analyzed by GC and GC-MS. It was found that the main constituents of the oil were naphthalene (42.4%), tridecanoic acid (7.9%), hexadecanoic acid (7.9%), tetradecamethylcycloheptasiloxane (3.4%) and 2,3butanediol (3.1%). The results of the antimicrobial activity of the oil against 6 Gram-positive and negative bacteria showed significant antimicrobial activity against S. saprophyticus and E. coli. A comparsion of antimicrobial activities between P. canus and other species of this family showed antimicrobial activity on E. coli, Salmonella typhimurium and S. aureus for Pterocephalus pulverulentus (Talib and Mahasneh, 2010) and on S. aureus, S. epidermidis, E. coli, Pseudomonas aeruginosa and Enterobacter cloacae for Pterocephalus perennis (Graikou et al., 2002). This study confirms the importance of the correlation between the chemical content of the oils and antimicrobial activities. ACKNOWLEDGEMENTS The authors are grateful to Dr V. Mozafarian for identification of the plant material and to the Payame Noor University (PNU) for the financial support. REFERENCES Adams RP (1995). Identification of essential oil components by gas chromatography/mass spectrometry. Allured, Carol Stream, IL. Bisset NG (1994). Herbal drugs and phytopharmaceuticals. CRC Press: Stuttgart. Baver AW, Kirby WM, Sherris JE, Turck M (1986). Antibiotic susceptibility testing by a standardized single disk method. Am. J. Clin. Pathol., 45: 493-496. Davies NW (1990). Gas chromatographic retention indices of monoterpenes and sesquiterpenes on methyl silicone and carbowax 20M phases. J. Chromatogr., 503: 1-24. Ghahreman A (1995). Flora of Iran. Research institute of forest and rangelands. Tehran University Press, Tehran. Graikou K, Aligiammis N, Chinou IB, Harvala C (2002). Cantleyosidedimethyl-acetal and other iridoid glucosides from Pterocephalus perennis, antimicrobial activates. Z. Naturforsch., 57: 95-99. Hung TN, Thung PT, Su ND, So KD, Song KS, Seong YH, Bae K (2006). Antioxidont activity of caffeoyl quinic acid derivatives form roots of dipsacus wall. J. Ethnopharmacol., 24: 188-192. Jennings W, Shibamoto J (1980). Qualitative analysis of flavour and fragrance volatile by capillary gas chromatography. Academic Press, New York. Li LN (1998). Biologhically active components from traditional Chinese medicines. Pure Appl. Chem., 70: 547-554. Newall CA, Anderson LA (1996). Herbal medicines. A guide for healthcare professionals. Pharmaceutical Press, London. Perry NSL, Bollen C, Perry EK, Ballard C (2003). Salvia for dementia therapy: review of pharmacological activity and pilot tolerability clinical trial. Pharm. Biochem., 75: 651-659. Tian J, Wu FE, Qiu MH, Nie RL (1993). Two triterpenoid saponins from Pterocephalus bretschneidri. Phytochemistry, 32: 1539-1542. Talib WH, Mahasneh AM (2010). Antimicrobial, cytotoxicity and phytochemical screening of Jordanian plants used in traditional medicine. Molecules, 15: 1811-1824. Zargari A (1992). Medicinal plants. Tehran University Press, Tehran. Zheng Q, Koike K, Han LK (2004). New biologically active triterpenoid saponine from Scabiosa tschiliensis. J. Nat. Prod., 67: 604-613.