Physico-chemical properties , fatty acid and tocopherol composition of oils from some Sudanese oil bearing sources By

Se analizan siete aceites procedentes de plantas y semillas de Sudán: Albizia lebbek Oil (ALO), Cassia obtusifolia Oil (COO), Cassia occidentalis Oil (CCO), Abutilon pannosum Oil (APO), Mitracarpus villous Oil (MVO), Ipomea indica Oil (IIO) y Sesamum alatum Oil (SAO). Las semillas se recolectaron en el estado de Ghibaish, North Kordofan. Además del contenido en aceite (12.8, 7.0, 3.2, 7.1, 11.5, 8.8, y 21.3 %, respectivamente), se determinaron los ácidos grasos mediante cromatografía de gases y los tocoferoles mediante HPLC. Los aceites contenían, respectivamente, 16.4, 20.0, 14.3, 16.8, 19.4, 19.9 y 10.9 % de ácido palmitito, 21.0, 24.4, 22.1, 10.9, 27.7, 34.0, 45.1 % de ácido oleico, 43.8, 38.2, 45.0, 63.9, 34.6, 33.5 y 36.3 % de ácido linoleico y trazas de ácido linolenico. El contenido en tocoferol total fue de 85.6, 48.2, 32.7, 163.5, 52.5, 30.9, y 26.4 mg/100 g oil, respectivamente. Alfatocopherol fue el predominante en los aceites de Albizia lebbek, Cassia obtusifolia), Cassia occidentalis, y Abutilon pannosum, mientras γ-tocopherol fue el mayoritario en los aceites de was the predominant tocopherol in the oil of Mitracarpus villous, Ipomea indica y Sesamum alatum.


INTRODUCTION
Albizia lebbek (L Benth.), family Mimosaceae is a fast growing nitrogen-fixing, heavy shade tree, recommended for reforestation and firewood plantations.It is native to tropical Africa, Asia, and northern Australia, widely planted and naturalized throughout the tropics (NAS 1980).Bark containing saponin can be used in making soap, and containing tannin, can be used for tanning.According to Hartwell (1967Hartwell ( -1971) ) the tree is used in folk remedies for abdominal tumors, cough, eye ailments, flu, and lung ailments.The seed oil is used for leprosy, the powdered seed to scrofulous swellings.Seeds have yielded 5.3-6.8 % fixed oil or fat, the endosperm 11 %.The oil contains 9.6 % stearic, 10.9 % arachidic, 39.3 % oleic, and 32.9 % linoleic acid (Watt and Breyer-Brandwijk, 1962).Bark contains 5-15 % tannin (leaves contain ca 4 %) and saponins.The saponin from the seed yields oleanolic acid and albizziagenin (Mitchell and Rook, 1979).Fernandez et al, (1996) reported the use of Albizia lebbek seed pods for water softening by the adsorption of calcium at 25 °C and they mentioned that the adsorption increased with the pH value.The seeds of Albizia lebbek contain 33.60 % crude protein and 3.13% crude fat, while the pods contain 17.86 % crude protein and 2.6 % crude fat.Prohibitive levels of toxic compounds were not detected in any of the plant parts analyzed (Roskoski et al 1980).
Cassia obtusifolia family Leguminosae (Fabaceae) is widely distributed in Africa and the Americas.In the Sudan it is found mostly on the clay plains of the central rain lands and in the southern regions.The plant has a compound, pinnate leaf, composed of three pairs of leaflets.Flowers are yellow to orange and the pod is slender, slightly curved and may reach 20cm long.The plant has a slender stem and may grow up to 2.0 m high.The plant commonly known in Sudan as Kawal (Dirar 1993).The fruit is a slender pod up to 18 cm long, 5 mm wide, 4-angled in cross section and usually curved downward.The pods are green and turn brown as the seeds mature, the seeds are 4-6 mm (Hall et al, 2006).Cassia obtusifolia and its seeds, common contaminants of agricultural commodities, are toxic to cattle and poultry.Toxicity has been attributed to anthraquinones which are major constituents of Cassia obtusifolia (Kenneth and Lucas 1991).Cassia obtusifolia leaves, seeds, and root are used medicinally, primarily in Asia.It is believed to possess a laxative effect, as well as to be beneficial for the eyes.The plant's seeds are a source of cassia gum, a food additive usually used as a thickener.As a folk remedy, the seeds are often roasted, then boiled in water to produce a tea.Roasted and ground seeds have also been used as a substitute for coffee (www.hptt wikipedia.com)Cassia occidentalis belonging to family Caesalpinaceae and commonly known in Sudan as Soreib.The pods are 10-13 cm long and up to 0.8 cm in diameter containing dark olive green seeds.The C. occidentalis seeds are rich source of galactomannan (Gupta et al 2005).In India, it has been reported to be used as antidote of poison, blood purifier, expectorant, anti-inflammatory agent and a remedy for the treatment of liver diseases.The composition of the seed oil has also been described (Akhtar et al 1988) Abutilon pannosum (family Malvaceae) is an erect, 1.5-3 m tall perennial herb to shrub leaves 4-13 cm across, broadly ovate, 7-9 nerved.Flowers appearing in racemes or panicles in terminal branches by the reduction of leaves; pedicel 1-3.5 cm long, uniformly hairy, articulate from below the middle to near the apex.Fruit globose, 10-15 mm.Seeds are three in each mericarp, 2-2.5 mm long, 2 mm broad.The seeds of Abutilon pannosum contained 13.4 % oil, and 23.0 % protein.The respective seed oil had iodine values of 118.4 and saponification value of 194.3, acid value 1.9 with refractive index of 1.4652 at 30 °C.The fatty acid composition (wt %), as determined by gas liquid chromatography was: palmitic 21.3, stearic 2.8, oleic 10.2; linoleic 60.7, malvalic 2.2, and dihydrocum sterculic 1.3 (Kittur et al, 1982) Mitracarpus villosus family Rubiaceae a climbing plant with red flowers, the leaves 3-5 cm long, reproduces by seeds.M. villosus is a common weed in upland areas from the forest to the savanna zones.It is widespread in Sudan.Ethanolic extracts of Mitracarpus villosus leaves showed antifungal activities (Irobi and Daramola 1993).The crude extracts also showed antibacterial activities using agar diffusion and tube dilution techniques against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Streptococcus faecalis (Irobi and  Daramola 1994).
Ipomea indica belongs to the Convolvulaceae which has over 600 species ranging from annuals, herbs, climbers, shrubs and trees.They occupy tropical and warm temperate regions but predominantly from the Americas.Some species contain alkaloids and other drugs, including strong purgatives, others have hallucigenic properties.Ipomoea indica is a perennial with heart-shaped leaves and with flowers produced daily from a dense clustered inflorescence.There are others which are annuals and widely grown as decorative plants.Ipomoea 'Heavenly Blue' is probably the favorite with sky-blue flowers and, when grown in pots in a cool conservatory, gives endless pleasure with its huge disc-like flowers throughout the summer, Ipomoea indica is described as a herbaceous climber but it does not die down to the ground.Instead new growths appear from the main stems each spring, but, in an ambient temperature, growth continues all year round.The flowers appear from the leaf axils.Twining perennial vine with stems to more than 7 m long.Plants hairy.Leaves with blade ovate in outline, 4-17 cm long, 3-16 cm wide, base heart-shaped, margins entire to deeply 3-lobed; leaf stalk 2-18 cm long.Capsule globeshaped, about 10 mm wide, with 3 chambers (http://www.weeds.org.au).

Oil extraction
The oil was extracted from the ground seeds by extraction with petroleum ether in a Soxhlet apparatus for 6 hr following the AOCS official methods (1993)

Physico-chemical properties
The following physicochemical properties of African oils were determined following the AOCS Official methods (1993) as given below.
Refractive index.Official method Cc7-25 was followed to determine the refractive index of the oils at 30 °C.
Specific gravity.Official method Cc 10 a-25 was followed for determination of specific gravity of oils at 60 °C.
Free fatty acids.Free fatty acids (FFA%) were determined using the AOCS official method Ca 5a-4.In brief, 3-10 grams of the sample were dissolved in 50 ml of a mixture consisting of ethanol and diethyl ether (1:1, v/v) neutralized with 0.1 N KOH against phenolphthalein indicator.Then the solution was titrated with a 0.1 sodium hydroxide solution.
Fatty acid composition (FA).The fatty acid composition of seven African oils was determined following the ISO draft standard ISO/FIDS 5509 (1997).In brief, one drop of the oil was dissolved in 1 mL of n-heptane, 50 µl 2M sodium methanolate in methanol were added, and the closed tube was agitated vigorously for 1 min.After addition of 100 µL of water, the tube was centrifuged at 4500 g for 10 min.and the lower aqueous phase was removed.After that 50 µL 1 M HCl were added to the heptane phase, the two phases were shortly mixed and the lower aqueous phase was rejected.About 20 mg of sodium hydrogen sulphate (monohydrate, extra pure, Merck, Darmstadt, Germany) were added, and after centrifugation at 4500 g for 10 min the top n-heptane phase was transferred into a vial and injected in a Varian 5890 gas chromatograph with a capillary column, CP-Sil 88 (100 m long, 0.25 mm ID, film thickness 0.2 µm).The temperature programme was: from 155 °C heated to 220 °C (1.5 °C/min.), 10 min isotherm; injector 250 °C, detector 250°C; carrier gas 1.07 mL/min hydrogen; split ratio 1:50; detector gas 30 mL/min hydrogen; 300 mL/min air and 30 mL/min nitrogen; manual injection volume less than 1 µL.The integration software computed the peak areas and percentages of fatty acid methyl esters (FAME) were obtained as weight percent by direct internal normalization.
Tocopherols (TOC).For determination of tocopherols a solution of 250 mg of studied samples oil in 25 mL n-heptane was directly used for the HPLC.The HPLC analysis was conducted using a Merck-Hitachi low-pressure gradient system, fitted with an L-6000 pump, a Merck-Hitachi F-1000 Fluorescence Spectrophotometer (detector wavelengths for excitation 295 nm, for emission 330 nm) and a D-2500 integration system; 20 µL of the samples were injected by a Merck 655-A40 Autosampler onto a Diol phase HPLC column 25 cm x 4.6 mm ID (Merck, Darmstadt, Germany) using a flow rate of 1.3 mL/min.The mobile phase used was n-heptane/tert, butyl methyl ether (99+1, v/v) (Balz et al., 1992).

Statistical Analysis
The analyses were performed with three replicates.The mean values and standard deviation (mean ± SD) were calculated and tested using Duncan's test (P < 0.05).Statistical analysis of variance (ANOVA) was performed on all values using the statistical program Statgrafics® Statistical Graphics System version 4.0 (Statgraphics®1985-1989).
On the whole, the oil content of the seeds is very low compared with that of common oil seeds.Therefore, from an economical point of view, the production of oil from such seeds could not be interesting unless some genetic modifications could be applied.

Physico-chemical properties
Some of the chemical and physical properties of the crude oils of ALO, COO, CCO, APO, MVO, IIO and SAO from Ghibaish, North Kordofan state, Sudan samples are presented in Table 1.The seven samples were similar in most of their physicochemical properties except unsaponifiable values were higher in APO and ALO samples.The other five oils were low in unsaponifiable matter.The seven samples had relatively similar specific gravity values, and had average values for refractive index and free fatty acids.
. The obtained oils were stored at 4 °C until further investigation.

Table 3 Fatty acid composition (% of total) of seven oil-bearing seeds
mean value ± standard deviation (n = 3); n.d not detected.For other abbreviations, see table 2.

Table 4 Summary of the important fatty acid parameters of oil-bearing seeds mean
value ± standard deviation (n = 3); PUFA, Polyunsaturated fatty acids; TSFA, Total saturated fatty acids.TUSFA; Total unsaturated fatty acids.For other abbreviations, see Table2