Chemical Composition of Rhizome Essential Oil of Curcuma longa L. Growing in North Central Nigeria

Pulverized rhizome of Curcuma longa on hydrodistilation, afforded oil in the yield of 1.24% v/w. The oil was investigated by GC and GC/MS. Hydrocarbon monoterpenes (46.9%) constituted bulk of the oil. The major constituents of the oil were, $-bisabolene (13.9%), trans-ocimene (9.8%), myrcene (7.6%), 1,8-cineole (6.9%), "-thujene (6.7%) and thymol (6.4%). Key word: Index: curcuma longa % Zingiberaceae % $-bisabolene % 1,8-cineole % Trans-ocimene % Thymol INTRODUCTION climatic conditions [15]. It is on the basis of these, we Curcuma longa L. (Zingiberaceae) is a rhizomatous Nigerian grown C. longa. herbaceous perennial plant widely grown in Nigeria. It is commonly known as Ajo, laali pupa or Obedo by the Experimental Yorubas [1]. The plant is used in ethno medicine for the Plant Materials: The fresh rhizome of Curcuma longa treatment of several ailments like Jaundice, gastric ulcer, were obtained in Ilorin, Kwara State, North skin diseases, joint inflammation, diabetics, cold and flu Central Nigeria. Identification was carried out at symptoms [2]. The therapeutic properties of this plant the herbarium of Forestry Research Institute of have been established by various workers. For Nigeria (FRIN), Ibadan where voucher specimens were instance, the plant extracts were found to possess antideposited. inflammatory, antitumor, anti-diabetic, antimicrobial, hypotensive and vasorelaxant properties [3-10]. Larvicidal Oil Isolation: Pulverized rhizome were hydrodistilled and insect repellant properties of the extract have also for 3h in a Clevenger-type apparatus, according to been reported [11, 12]. the British Pharmacopoeia (1980) specification [16]. Phytochemical investigations of the plants, revealed The resulting oil was collected, preserved in a the presence of curcumin, demethoxy curcumin and bissealed sample tube and stored under refrigeration until demethoxy curcumin [9]. Tumerone and carvacrol have analysis. been reported as the most abundant constituents of rhizome essential oil of yellow and red varieties of Gas Chromatography: GC analysis were performed on Bangladesh grown C. longa [13]. Oguntimehin et al. an orion micromat 412 double focusing gas (1990) have identified "-phellandrene and terpinolene as chromatography system fitted with two capillary the predominant constituents of leaf oil of south-west columns coated with CP-Sil 5 and CP-Sil 19 (fused Nigerian grown C. longa [14]. Earlier work on rhizome silica, 25m × 0.25mm, 0.15μm film thickness) and flame essential oil of south-west Nigerian grown plant also ionization detector (FID). The volume injected was 0.2μL revealed the presence of ar-tumerone as the most and the split ratio was 1:30. Oven temperature was abundant constituent [11]. programmed from 50°C-230°C respectively. Qualitative It has been established that composition pattern of data were obtained by electronic integration of FID area essential oil could be affected by the geographical and percents without the use of correction factors. investigate the rhizome essential oil of North central World J. Chemistry, 4 (2): 178-181, 2009 179 Gas Chromatography/Mass Spectrometry: A Hewlett Table 1 shows retention indices, relative percentages Packard (HP 5890A) GC interfaced with a VG Analytical and the identities of the constituents of the oil. A total 70-250S double focusing mass spectrometer was used. of 22 compounds representing 96.5% of the oil were Helium was the carrier gas at 1.2ml/min. The MS operating identified from their retention indices and mass spectra. conditions were: ionization voltage 70ev, ion source Hydrocarbon and oxygenated monoterpenes temperature 230°C. The GC was fitted with a 25m×0.25mm, constituted 46.9 and 15.4% of the oil. Percentage fused silica capillary column coated with CP-Sil 5. composition of hydrocarbon sesquiterpenes and The film thickness was 0.15μm. the GC operating aromatic compounds were 24.3 and 9.9% respectively. conditions were identical with those of GC analysis. The Trans-ocimene (9.8%), myrcene (7.6%), "-thujene (6.7%), MS data were acquired and processed by online desktop limonene (5.3%) and car-2-ene (4.0%) were the abundant computer equipped with disk memory. The percentage hydrocarbon monoterpenes in the oil. Other notable compositions of the oil were computed in each case from hydrocarbon monoterpenes were; $-phellandrene (3.1%), GC peak areas. The identification of the components was "-pinene (2.8%) and (-terpinene (2.6%). based on the retention indices (determined relative to the The most abundant oxygenated monoterpenes in the retention times of series of n-alkanes) and mass spectra oil was 1,8-cineole (6.9%). Borneol (3.3%), terpine-4-ol with those of authentic samples and with data from (2.1%) and "-terpineol (2.0%) existed in appreciable Literature [17-19]. quantities. The two carbonyl monoterpenes, geranial RESULTS AND DISCUSSION abundant aromatic compound in the oil was thymol Pulverized rhizome of Curcuma longa on amount. $-bisabolene (13.9%) was the most abundant hydrodistilation afforded oil in yield of 1.24% v/w. hydrocarbon sesquiterpene. Meanwhile, zingiberene The yield compared favourably with the yield from (5.2%) and $-sesquiphellandrene (5.2%) were found in yellow type of Bangladesh grown C. longa [13]. appreciable quantities. and neral were found in trace amounts. The most (6.4%), while tumerone (3.5%) existed in significant Table 1: Chemical composition (%) of rhizome oil of Curcuma longa Compound RI Percentage composition Mass spectra a b "-thujene 923 6.7 105, 91, 77, 73, 51 "-pinene 931 2.8 121, 105, 93, 79, 41 $-pinene 973 2.4 121, 107, 93, 79, 67 Myrcene 989 7.6 107, 93, 80, 69, 53 Car-2-ene 1002 4.0 121, 93, 79, 65, 51 $-phellandrene 1027 3.1 120, 93, 77, 67, 51 Limonene 1028 5.3 107, 93, 79, 67, 60 1,8-cineole 1029 6.9 108, 81, 59, 55, 43 cis-ocimene 1035 2.6 105, 93, 79, 67, 53 Trans-ocimene 1050 9.8 121, 100, 91, 79, 53 Iso-Artemisia ketone 1053 1.1 120, 100, 83, 69, 55 (-terpinene 1057 2.6 121, 105, 93, 69, 51 Borneol 1162 3.3 121, 110, 95, 81, 55 Terpineol 1176 2.1 107, 93, 81, 67, 55 "-terpineol 1180 2.0 121, 93, 81, 67, 59 Neral 1237 Tr 135, 95, 69, 53, 41 Geranial 1267 Tr 123, 95, 83, 59, 41 Thymol 1290 6.4 150, 135, 77, 60, 51 Zingiberene 1495 5.2 161, 133, 119, 77, 41 $-bisabolene 1508 13.9 119, 105, 93, 79, 69 Sesquiphellandrene 1525 5.2 120, 105, 91, 69, 41 Turmerone 1611 3.5 216, 201, 173, 132, 119