Variations in the composition of sterols,tocopherols and lignans in seed oils from fourSesamum species

Seeds from different collections of cultivatedSesamum indicum Linn and three related wild species [specifically,S. alatum Thonn.,S. radiatum Schum & Thonn. andS. angustifolium (Oliv.) Engl.] were studied for their oil contents and fatty acid composition of the total lipids. The oils from wild seeds were characterized by higher percentages of unsaponifiables (4.9, 2.6 and 3.7%, respectively) compared toS. indicum (1.4–1.8%), mainly due to their high contents of lignans. Total sterols accounted forca. 40, 22, 20 and 16% of the unsaponifiables of the four species, respectively. The four species were different in the relative percentages of the three sterol fractions (the desmethyl, monomethyl and dimethyl sterols) and in the percentage composition of each fraction. Campesterol, stigmasterol, sitosterol and Δ⁵-avenasterol were the major desmethyl sterols, whereas obtusifoliol, gramisterol, cycloeucalenol and citrostandienol were the major monomethyl sterols, and α-amyrin, β-amyrin, cycloartenol and 24-methylene cycloartanol were the main dimethyl sterols in all species. Differences were also observed among the four species in sterol patterns of the free sterols compared to the sterol esters.Sesamum alatum contained less tocopherols (210–320 mg/kg oil), andS. radiatum andS. angustifolium contained more tocopherols (ca. 750 and 800 mg/kg oil, respectively) than didS. indicum (490–680 mg/kg oil). The four species were comparable in tocopherol composition, with γ-tocopherol representing 96–99% of the total tocopherols. The four species varied widely in the identity and levels of the different lignans. The percentages of these lignans in the oils ofS. indicum were sesamin (0.55%) and sesamolin (0.50%).Sesamum alatum showed 1.37% of 2-episesalatin and minor amounts of sesamin and sesamolin (0.01% each).Sesamum radiatum was rich in sesamin (2.40%) and contained minor amounts of sesamolin (0.02%), whereS. angustifolium was rich in sesangolin (3.15%) and also contained considerable amounts of sesamin (0.32%) and sesamolin (0.16%).     

大豆油返酸、返色影响因素分析

为对大豆油适度精炼和精准加工提供参考,对精炼生产过程中不同工序大豆油的返酸、返色程度以及一级大豆油中磷脂、残皂、不皂化物等组分对其返酸、返色程度的影响进行分析。结果表明：大豆原油返酸和返色程度均最高,中和油最低;磷脂含量越高,大豆油返酸、返色程度越深;不皂化物含量越高,越有助于延缓大豆油返酸、返色;含皂量对大豆油返酸影响不显著,但会影响大豆油返色。综上,在大豆油生产中应控制磷脂含量和含皂量,减少不皂化物的损失,以延缓大豆油返酸、返色。     

A simple and sensitive method for detecting avocado seed oil in various avocado oils

The presence of avocado seed oil in various avocado oils was detected by thin-layer chromatography (TLC). An unsaponifiable compound, called Component-C, was identified in the avocado seed oil. This compound is unique to avocado seed and has a blue color when developed on the TLC plate. At least 9.2 μg of avocado seed unsaponifiables were needed at a single TLC spot to detect the unique blue color definitely. Admixtures of as little as 0.16% avocado seed oil in various avocado oils can be detected by the proposed procedure.     

葡萄籽油中脂肪酸和非皂化物的GC／MS分析研究

本文采用ＧＣ／ＭＳ联用仪结合快速层析技术和化学衍生法对葡萄籽油中脂肪酸和非皂化物成分进行分析研究，鉴定了８种脂肪酸甲酯，４种甾醇乙酰化物和１１种烃类化合物。     

Saturated Sterols (Stanols) in Unhydrogenated and Hydrogenated Edible Vegetable Oils and in Cereal Lipids*

The content of saturated sterols (stanols) was investigated in a small number of samples of hydrogenated fats and oils, and in the ‘free’ and ‘bound’ lipids of various samples of cereals. The sterols, after saponification of the total lipids, were analysed as trimethylsilyl derivatives by GC and identified by GC–MS. Among the hydrogenated fats and oils, coconut oil contained the largest amounts of sitostanol followed by soybean oil (c 80 and 20 g kg⁻¹ of total unsaponifiables, respectively). No sitostanol could be detected in hydrogenated palm oil under the present analytical conditions. Both ‘free’ and ‘bound’ lipids in various samples of wheat, except for wheat germ, contained c 70–120 g kg⁻¹ campestanol and 100–150 g kg⁻¹ sitostanol in total unsaponifiables. In lipids of oats and barley, no campestanol or sitostanol could be detected. Rye total lipids contained 60–90 g kg⁻¹ of campestanol and 100–150 g kg⁻¹ of sitostanol of total unsaponifiables in ‘free’ and ‘bound’ lipids, respectively.     

Chemical characterization of lysyl oxidase inhibitor from avocado seed oil

The active factor of lysyl oxidase inhibition was separated from unsaponifiables of avocado seed oil and characterized by gas chromatography-mass spectrometry. Results indicated the presence of furan-containing lipids in the active factor mixture and also showed a structural difference compared to previously reported furan-containing lipids of avocado which relates to the length of the hydrocarbon chain substituent. Another structural difference evinced was the availability of the hydroxyl group in the aliphatic moiety of the investigated substances. A purified mixture of furan-containing compounds was testedin vitro for inhibitory activity on pure bovine aorta lysyl oxidase. It was shown that mixing furan-containing lipids in Tween 80 reversibly inhibited pure bovine aorta lysyl oxidase activity against tritiated recombinant tropoelastin with the I₅₀ value of inhibition of 105 μM. Thesein vitro studies suggested that the mixture of avocado seed oil furan-containing lipids was not a substrate-specific inhibitor of lysyl oxidase, and it might prove to be useful as a potential antifibrotic drug. Moreover, the unique chemistry of the studied compound for lysyl oxidase inhibition should enable the designing of new probes of the active site of this important enzyme.     

茶叶籽油中角鲨烯的定性与定量分析

采用GC-MS分析茶叶籽油中不皂化物的成分,并采用高效液相色谱法对茶叶籽油中的角鲨烯进行定量分析。结果表明:茶叶籽油不皂化物的主要成分为角鲨烯、α-生育酚,另外还有合金欢醇、香叶里拉醇、羊毛甾醇、茉莉酮、D12齐墩果烯、2,4-二叔丁基苯酚及2,5-二叔丁基-1,4-苯醌等物质。通过C18柱分离样品中的角鲨烯,当流动相为甲醇/乙腈(60+40,V/V)、检测波长210 nm、流速2 m L/min、柱温30℃时,能有效分离茶叶籽油样品中的各组分,再经HPLC测得茶叶籽油中角鲨烯含量为4.1 mg/kg。当角鲨烯质量浓度在20~500 mg/L之间时,峰面积和质量浓度的线性关系较好,线性相关系数(R~2)为0.999 0;平均加标回收率为84.2%~90.1%,相对标准偏差(RSD)小于6.98%(n=4),此方法的测定低限(LOQ)为2.7 mg/kg。     

Thin-layer chromatographic separations of seed oil unsaponifiables from fourSesamum species

A new, two-dimensional thin-layer chromatographic system was established to provide good separation of the unsaponifiable fractions from the seed oils of three wildSesamum species, [S. alatum, Thonn.;S. radiatum, Schum and Thonn.; andS. angustifolium, (Oliv.) Engl.] and of the cultivatedS. indicum, L. The system utilizes silica gel plates and n-hexane/diethyl ether (7:3, v/v) and chloroform/diethyl ether (9:1, v/v) as mobile phases in the first and second directions, respectively. The system could be used for qualitative studies and as a preparative technique for subsequent quantitative gas chromatographic separations in chemotaxonomic and related studies onSesamum spp.     

Camelina oil and its unusual cholesterol content

The oil in Camelina sativa L. Crantz has a combined linolenic and linoleic acid content that is greater than 50% and a relatively low saturated FA content (∼10%). Although the FA composition has been reported, no information is available on the sterol composition of camelina oil. The derivatized plant sterols were separated and quantified with capillary GC and their identity confirmed with GC-MS. The refined camelina oil sample contained approximately 0.54 wt% unsaponifiables, and over 80% of the unsaponifiables were desmethylsterols. Perhaps the most unusual characteristic of camelina oil is its relatively high content of cholesterol, particularly for a vegetable oil, since it contains several times the cholesterol found in other “high-cholesterol” vegetable oils. Camelina oil also contains relatively large amounts of another unusual sterol, brassicasterol. The major sterols identified in the camelina oil included cholesterol (188 ppm), brassicasterol (133 ppm), campesterol (893 ppm), stigmasterol (103 ppm), sitosterol (1,884 ppm), and Δ⁵-avenasterol (393 ppm).