Muhammad Qasim Samejo

Chemical composition of essential oils from Alhagi maurorum

Alhagi maurorum Medik. (Alhagi camelorum, Alhagi pseudalhagi) belongs to the Fabaceae family and is the species of Alhagi used in folk medicine as a diaphoretic, expectorant, laxative, purgative, and diuretic 1–3 . Literature survey revealed that flavonoids, fatty acids, coumarins, sterols, vitamins, and alkaloids are the active constituents of Alhagi species [3]. A. maurorum shows antiulcer [4], pharmacological [1], antidiarrheal [5], anti-inflammatory [6], urease-inhibition [7], analgesic [8], antiproliferative [9], antioxidant [10], and antinociceptive activities [11]. Phytochemical studies on A. maurorum show carbohydrates, tannins, unsaturated sterols, triterpenes, flavonoids, and flavanone glycosides [2]. The essential oils are used as raw material in different fields, including cosmetics, phytotherapy, aromatherapy, nutrition, perfumes, and spices [12]. The present investigation of A. maurorum describes the chemical constituents of the essential oil from leaves and stems using GC-MS 13 . Leaves and stems of the Alhagi maurorum plant were collected from Jamshoro (Sindh) in January 2011 and identified by Prof. Dr. Muhammad Tahir Rajput Dean, Faculty of Natural Sciences, University of Sindh, Jamshoro. A voucher specimen (1540) of the plant was deposited in the herbarium of the Institute of Plant Sciences, University of Sindh Jamshoro, Pakistan. Air-dried leaves and stems of the plant (70 g of each part) were subjected separately to dry steam distillation [24] for 3 h. The oil was separated from the water using n-hexane (HPLC grade), dried over analytical reagent grade anhydrous Na2SO4 and then stored at 4 C in sealed vials before GC-MS analysis. An agilent 6890 N GC instrument coupled with an MS-5975 inert XL mass selective detector and an auto sampler 7683-B injector was used for GC-MS analysis of the essential oil of A. maurorum. An HP-5MS column with dimensions of 30 m 0.25 mm i.d. and film thickness 0.25 m was used for the analysis. The temperature of the oven was held at 80 C for 2 min, raised to 200 C at 5°C/min (1 min hold), and then to 280 C at 20 C/min (3 min hold). A 1.0L sample was injected using a split mode (split ratio, 1:10). Helium gas was used as a carrier gas at a flow rate of 1.5 mL/min. An electron ionization mode with ionization energy of 70 eV was used for MS detection. The injector and MS transfer line temperatures were set at 220 and 290 C, respectively. The chemical composition of the essential oils obtained from the fresh parts of Alhagi maurorum (leaves and stems) is presented in Table 1. Sixteen compounds in leaves and 21 compounds in stems were identified, constituting over 56.8 and 76.7% of oils composition from both parts of A. maurorum, respectively. The volatile fractions of A. maurorum consisted of a complex mixture of different substances, with ketones (leaf – 4.4%, stem – 5.2%), acid derivatives (leaf – 1.5%, stem – 1.8%), terpenoids (leaf – 26.8%, stem – 18.7%), and hydrocarbons (leaf – 19.3%, stem – 50.6%). Also, heterocyclics (5.2%) were present in leaves, and aldehydes (0.2%) in stems. In the leaf oil, drimenol (23.2%), 9-octylheptadecane (9.3%), 4-hexyl-2,5-dihydro-2,5-dioxo-3-furanacetic acid (5.2%), 2-nonadecanone (4.4%) and pentacosane (4.3%) were found as the major constituents. In the stem oil, neophytadiene (39.3%), trans-ionone (5.4%), 6,10,14-trimethyl-2-pentadecanone (5.2%), actinidiolide (4.9%), and nonacosane (4.3%) were the main components. Drimenol, octadecane, eicosane, docosane, tetracosane, and squalene were common volatile constituents of the essential oils. The chemical class distributions of the volatile constituents are summarized in Table 1.

Chemical composition of essential oil from Calligonum polygonoides Linn.

The essential oil from air dried buds and roots of Calligonum polygonoides Linn., has been extracted from dry steam distillation and analysed for chemical composition by gas chromatography–mass spectrometry. In total, 27 and 10 compounds were analysed qualitatively and quantitatively, accounting for 68.42% and 82.12% total contents of the essential oils of buds and roots, respectively. It contains a complex mixture of terpenoids, hydrocarbons, phenolic compounds, acid derivatives and ketones. The main component of essential oil was ethyl homovanillate (11.79%) in buds and drimenol (29.42%) in roots.

Identification of hydrocarbons from Abies pindrow leaves

The genus Abies family Pinaceae consists of 51 species ranged mainly in temperate and boreal regions of the northern hemisphere, chiefly in mountainous regions [1]. The literature data on phytochemical and biological investigations of the genus of Abies revealed that up to now, 277 compounds were isolated from 19 plants of Abies species. The chemical constituents are mostly terpenoids, flavonoids, and lignans, together with minor constituents of phenols, steroids, and others. The crude extracts and metabolites have been found to possess various bioactivities, including insect juvenile hormone, antitumor, antimicrobial, antiulcerogenic, antiinflammatory, antihypertensive, antitussive, and CNS (central nervous system) activities [2]. Abies pindrow Royle, commonly known as west Himalayan fir, is a large evergreen tree growing up to 40–60 m tall with a trunk diameter of up to 2–2.5 m. It has a conical crown with level branches. In Pakistan, Abies pindrow Royle, known as partal or palundar, is widely distributed at elevations between 2000 and 3000 m throughout the western Himalayas from Afghanistan to Nepal [3]. Pindrow species of Abies is regarded as carminative, stomachic, astringent, expectorant, tonic, antispasmodic, and antiperiodic [4]. Phytochemical studies of the species resulted in the isolation of glucopyranoside, hydroxyflavanone, chalcone glycoside, bioflavonoids, flavonoids and pindrolactone [5], and pentacyclic triterpenoids [6]. Different extracts from the leaves of Abies pindrow Royle exhibited anti-inflammatory, analgesic, and hypnotic activities in rats, attenuated swim stress in mice, and produced hypotension in dogs. Abies pindrow Royle leaves also have an antiulcerogenic effect on the cold-restrained gastric ulcer model in rats [5]. A review of the literature revealed that no hydrocarbons have yet been reported from Abies pindrow Royle. We have previously reported the fatty acid composition of the ethanol extract of the leaves of Abies pindrow Royle. A total of 11 fatty acids, including eight saturated and three unsaturated, was characterized [4]. The present investigation of aerial part (leaves) of Abies pindrow Royle describes the occurrence of long chain hydrocarbons. The presence of these hydrocarbons is detected by GC-MS and supported by FTIR. A careful look at the fragmentation pattern in the mass spectral data reveals the presence of saturated and unsaturated hydrocarbons. These hydrocarbons have been reported for the first time from Abies pindrow Royle. The GC-MS of the hexane fraction revealed the presence of tricosane, eicosane, heneicosane, docosane, tetracosane, nonadecane, octadecane, 1-docosene, 1-octadecene, heptadecane, and 2,6,10,14-tetramethylhexadecane. The identity of these common hydrocarbons was made by comparison of these peaks with the standards by gas chromatography and confirmed by comparison of the fragmentation pattern with those of standard mass spectrum. FTIR analysis supported the structures of these hydrocarbons. The FTIR spectrum exhibits the diagnostic peaks relating to C-H stretching at 2956 cm–1, 2923 cm–1, and 2852 cm–1, C-H bending (scissoring) at 1465 cm–1, C-H methyl rocking at 1378 cm–1, and long-chain methyl rocking at 722.9 cm–1. These peaks verify the required data regarding the hydrocarbons. The GC-MS study of major peaks revealed the presence of straight-chain saturated hydrocarbons. It showed the presence of 11 compounds. The GC-MS pattern showed 11 major peaks along with small peaks. All major peaks were detected as hydrocarbons by GC-MS at different retention times.

Chemical composition of the essential oils from Tamarix dioica and determination of its antibacterial activity

ABSTRACT In this study, investigations of hydro-distilled essential oils of Tamarix dioica flowers and leaves performed by gas chromatography-mass spectrometry (GC-MS) revealed 31 volatile constituents. Nearly 24 (comprising 77.15% of the total volatiles) and 14 compounds (encompassing 63.15% of the total volatiles) were identified in flowers and leaves, respectively. Major constituents in flower were 1-hexadecene (6.93%), hexahydrofarnesyl acetone (5.64%), octadecane (5.60%), dodecanoic acid (5.22%), E-15-heptadecenal (4.98%), docosane (4.76%), 2-methoxy-4-vinylphenol (4.44%), 1-tetradecene (4.29%), tetracosane (4.00%), 1-docosene (3.89%), hexadecane (3.76%), nonanal (3.69%), nonanoic acid (1.33%), dihydroactindiolide (3.33%), and cyclotetracosane (3.04%), whereas the major constituents in leaves were 2-methoxy-4-vinylphenol (17.70%), dihydroactindiolide (10.27%), megastigmatrienone (5.53%), 1-hexadecene (5.10%), β-lonone (4.28%), safranal (3.35%), vitispirane (3.35%), trans-geranylacetone (2.72%), and hexahydrofarnesyl acetone (2.03%). These essential oils were screened in vitro against gram negative (G−ve) bacteria Escherichia coli (E. coli) and gram positive (G+ve) bacteria Staphylococcus aureus (S. aureus) by using disc diffusion method to determine minimum inhibitory concentration (MIC). However, it is noteworthy that essential oils from Tamarix dioica flower and leaves showed a higher activity against E. coli (MIC at 10 μg/mL) compared to S. aureus (MIC at 100 μg/mL).