Sterols and the phytosterol content in oilseed rape - Journal of Cell ...

Journal of Cell and Molecular Biology 5: 71-79, 2006. 

Haliç University, Printed in Turkey. 

Sterols and the phytosterol content in oilseed rape (Brassica napus L.) 

Muhammet Kemal Gül *1 and Samija Amar 2 

1 Çanakkale Onsekiz Mart University Department of Field Crops, 17020 Çanakkale, Turkey 

2 Goettingen Georg-August University Department für Nutzpflanzenwisschenschaften, A b t e i l u n g 

Pflanzenzüchtung Von-Siebold Str. 8 37075 Goettingen/, Germany (*author for correspondence) 

Received 23 February 2006; Accepted 12 July 2006 

Abstract 

Sterols are natural, organic compounds with a molecular nucleus of 17 carbon atoms and a characteristic threedimensional 

arrangement of four rings. From the chemical point of view sterols are steroid alcohols and their name 

is derived from Greek stereos, which mean solid with ending –ol, which is the suffix for alcohols. As essential 

constituents of cell membranes, they are widely distributed in all eukaryotic organisms. Playing a structural role in 

cellular membranes, they present a significant part of the organism membrane biomass, while their functional role is 

evident through the participation in the control of membrane-associated metabolic processes, such as: regulations of 

membrane permeability and fluidity, signal transduction events and the activity of membrane-bound enzymes. 

Sterols are the precursors of steroid hormones and bile acids in humans, brassinosteroids - phytohormones in plants 

and, as the recent identifications of sterol mutants have shown, they are involved in important growth and 

developmental processes in living organisms. In recent years increased interest in phytosterols lies in their potential 

to reduce plasma low-density lipoprotein cholesterol level, decreasing coronary mortality and therefore acting as 

naturally preventive dietary product. In the last decades, more than 40 different sterols were well identified in 

different cultivars. These sterols are called phytosterols and they are predominantly present in oilseed plants. The 

phytosterol content range between 1.41-15.57 gr/ kg oil and this depends to plant species. Oilseed rape is one of the 

most important oil seed crop in the world. phytosterol content in new oilseed rape varieties rang between 5.13 and 

9.79 gr/kg oil. 

Key Words: Sterol, phytosterol oilseed rape, plant, human 

Kolza bitkisinde (Brassica napus L.) sterol ve fitosterol içeri¤i 

Özet 

Steroller organik bileflikler olup 17 karbon atomundan ve 3 boyutlu dört halka dizisinden oluflmufllard›r. Kimyasal 

aç›da bak›ld›¤›nda steroller steroid alkolü olup, sterol ad› Yunanca’da stereos, dayan›kl› yada bozulmayan anlam›na 

gelmektedir. Sterolün sonuna eklenen –ol tak›s› ise alkolden gelmektedir. Hücre membranlar›n›n özel yap›s›ndan 

dolay› steroller tüm okaryotik canlilarda bulunurlar. Hücre membran›nda yap›sal bir rol oynad›klar›ndan steroller 

organizmalar›n membranlar›n›n önemli bir k›sm›n› teflkil ederken, hücre membran› geçirgenli¤inde önemli görevler 

alarak bu sistem içinde görev alan enzimlerin aktif hale getirmektirler. Son olarak sterollerin insanlarda öncü steroid 

hormanlar› ile safra asitlerini, bitkilerde brassinosteroidler ile fitohormonlar› etkiledi¤ini, son yap›lan çal›flmalarda 

da sterollerin canl› organizmalar›n önemli büyüme ve geliflme evrelerinde rol ald›klar› saptanm›flt›r. Son y›llarda 

fitosterollerin LDL kolesterol düzenleyicisi özellikleri, kroner ölümleri azalt›c› etkileri bak›m›ndan do¤al önleme 

ürünü olmalar› sebebiyle önemleri artm›flt›r. Bitkilerde çok iyi tespit edilip belirlenen 40’dan fazla farkl› sterol 

bulunmufltur. Bu steroller ço¤unlukla ya¤ bitkilerinde saptanarak fitosterol olarak adland›r›lm›fllard›r. Yap›lan 

çal›flmalarda kültür bitkisine göre elde edilen 1 kg ya¤da bulunabilecek fitosterol iktar› 1,41-15,57 gr/kg arala¤›nda 

oldu¤u saptanm›flt›r. Kolza dünyada üretilen en önemli ya¤ bitkilerinden biridir. Kolzada fitosteroller miktar› 5,13 ile 

9,79 gr/kg ya¤ aras›nda de¤iflim göstermektedir. 

Anahtar Sözcükler: Sterol, fitosterol, kolza, bitki, insan 

71

72 M. Kemal Gül and Samija Amar 

Introduction 

Sterols are natural, organic compounds and they are 

widely distributed in all eukaryotic organisms. They 

present a significant part of the organism membrane 

biomass, while their functional role is evident through 

the participation in the control of membraneassociated 

metabolic processes, such as: regulations of 

membrane permeability and fluidity, signal 

transduction events and the activity of membranebound 

enzymes (Piironen et al., 2000). Sterols are the 

precursors of steroid hormones and bile acids in 

humans, brassinosteroids - phytohormones in plants 

and, as the recent identifications of sterol mutants have 

shown (Lindsey et al., 2003), they are involved in 

important growth and developmental processes in 

living organisms (Hartmann, 1998). Plants have a 

variety of more than 40 well-identified and studied 

sterols (Law, 2000), which are termed phytosterols and 

are predominantly present in oilseed plants. Cereals 

are recognised as a significant source of phytosterols 

as well, whereas phytosterol content in vegetables and 

nuts is considerably lower (Piironen et al., 2000; 

Piironen et al., 2003; Normen et al., 1999). The most 

abundant phytosterols are: sitosterol, campesterol and 

stigmasterol. Other phytosterols like avenasterol and 

cycloartenol are synthesised earlier in the biosynthetic 

pathway and as sterol precursors they usually occur in 

relatively smaller amounts (Määttä et al., 1999). 

Phytosterols are, with respect to their physiological 

function and their chemical structure, similar to the 

major and only animal produced sterol – cholesterol. 

Increased scientific interest and economic 

importance, in the past few decades, in the most 

important oil crop in Europe – rapeseed, has been 

largely due to its improved quality of oil seeds, which 

can yield between 40 and 47 percentages of oil 

(Becker et al., 1999). Brassica napus L., known as 

rapeseed, rape, or in some cultivars, low in erucic acid 

and glucosinolate content, as canola, belongs to the 

genus B r a s s i c a , which is a member of the 

Brassicaceae (Cruciferae) f a m i l y. This family, of 

about 375 genera and 3200 species, includes crops, 

condiments and ornamentals but only genus Brassica 

is well known for their admirable phenotypical 

diversity: cabbage, cauliflower, broccoli, Brussels 

sprouts, kohl-rabi, turnip, black and white mustards, 

garden cress and so forth (Gomez-Campo, 1999). Like 

other vegetable oils, the rapeseed oil is the richest 

natural source of phytosterols. Apart from phytosterols 

rapeseed oil is predominantly composed of fatty acids, 

such as oleic acid, linoleic and linolenic acid (vitamin 

F complex), of phospho- and glycolipids and of 

tocopherols (vitamin E) and carotenoids - pro-vitamin 

A (Rehm and Espig, 1991). Therefore, it became 

reasonable to increase the rapeseed oil production. 

According to “Food Outlook” (FAO, 2004) from Food 

and Agriculture Organisation of the United Nations, 

global production of rapeseed crop rose more than 

10 % from 1998 to 2002, with the estimation for 2004 

that it will reach second place after soybean. 

Encouraged with the development of improved rape 

cultivars with high quality edible oils and most recent 

utilisation of rapeseed oil for bio-diesel (biogenic fuel) 

production (UFOP, 2004), the EU farmers expanded 

rapeseed planting, exceeding those of soybean, 

sunflower, groundnut and cottonseed (Kimber and 

McGregor, 1995). 

Literature review 

Phytosterols have been isolated from a large number 

of species and according to numerous publications 

(Grunwald, 1980; Gordon and Miller, 1997; Dutta and 

Normen, 1998; Piironen et al., 2000) they probably 

exist in all angiosperm and gymnosperm species. 

Although, there are more than 40 diff e r e n t 

phytosterols found in higher plants, sitosterol, 

campesterol and stigmasterol often predominate, 

while other phytosterols are usually typical only for 

certain plant family or even species. Brassicasterol is 

for example typical only for Brassicaceae family, and 

therefore it could be used for identification 

(Benveniste, 2002). 

Chemical structure and properties 

Sterols belong to a large group of hydrocarbons, 

o rganic chemical compounds known as 

polyisoprenoids with carbon skeletons structurally 

based and derived from multiple isoprene, five carbon 

unit -CH 2=C(CH 3)CH=CH 2. Sterols are, together with 

tocopherols, carotenoids and chlorophylls, formed by 

polymerisation of isoprene unit (Grunwald, 1980). 

The structural feature, which virtually all sterols 

have in common, is that they are derivatives of a 

tetracyclic perhydro-cyclopentano-phenanthrene ring 

system with a flexible side chain at the C-17 atom 

(Figure 1) and 3β-monohydroxy compounds and 

(Hartmann, 1998).

Animal cells contain only one major sterol, i.e. 

c h o l e s t e ro l (Figure 2a). Cholesterol also occurs, 

though only in a few percentage of the whole sterol 

content, in plants (Gordon and Miller, 1997). 

Chemically, it is an analogue to the phytosterols, 

differing only in the side chain. Fungal cells, together 

with some unicellular algae and lichens synthesise 

ergosterol - provitamin D2 (Grunwald, 1980; Rehm 

and Espig, 1991). Namely, ergocalciferol (vitamin D2) 

is produced by ultraviolet irradiation of provitamin D2 

( e rgosterol), which occurs in yeast and fungi (Figure 2b). 

In contrast to animal cells and fungi, plant cells 

synthesize complex array of phytosterol mixtures with 

the sterol profiles varying between species. 

The scientific names of phytosterols are given to 

them according to the number of C atoms in the C-17 

side chain, the number and the position of the double 

Sterols and phytosterols in oilseed rape 73 

Figure 1. Chemical structure of 5 α cholestan 3β-ol (adapted from Piironen et al., 2000) 

a. b. 

bond in the ring system and the side chain. Their 

scientific names are usually very complex, so the most 

common phytosterols are referred to by their trivial 

names. The trivial and the scientific names of the most 

important phytosterols are given in Table 1. 

According to the IUPAC recommendations from 

1989, sterol molecules consist of four rings marked as 

A, B, C and D with standard carbon numbering 

(Figure 1). Three rings, A, B and C, have 6 carbons 

atom nonlinear structure and they are fused to one 5 

carbons atom ring (D). The various phytosterols found 

in plants differ in number of C atom in the side chain 

at the C-17 atom and the position and the number of 

the double bonds in the ring system. T h e 

predominating phytosterols in plants are: campesterol 

sometimes referred to as 24-methylcholesterol (Figure 

3a), sitosterol (Figure 3c) and stigmasterol (Figure 3d). 

Figure 2. Chemical structure of a. cholesterol and b. ergosterol (taken from Kyoto Encyclopedia of Genes and Genomes, 2004)


The phytosterol composition of family Brassicaceae 

to which rapeseed belongs, differ from most plant 

species for an additional brassicasterol (Figure 3e) 

while avenasterol (Figure 3b) is considered as one of 

the main phytosterol in cereals but, as it has been 

discussed (Dutta and Normen, 1998; Piironen et al., 

2002), avenasterol also occurs in Brassica napus seed. 

In addition to their vast structural variations, 

arising from different substitution in the side chain and 

number and the position of double bonds in the 

tetracyclic skeleton, different phytosterols play 

various roles in higher plants. Yet, it still remains 

unknown why do plants require a mixture of 

phytosterols instead of only one like animals and fungi 

and does each phytosterol play a specific function in 

plant metabolism? Further on, for the phytosterol 

classification, it is important whether the different side 

chains, or functional groups of rings system, are in α, 

i.e. under the plain of the cyclic system, or above the 

plain - in a β position (IUPAC, 1989). For example, 

the side chain and the two methyl groups at C-18 and 

C-19 are angular to the ring structure and above the 

plane, thus having β-stereochemistry, with additional 

3-hydroxyl group also having β- s t e r e o c h e m i s t r y 

(Figure 1). Another characteristic specific only to 

phytosterols is the alkylation of a C atom at 24 th 

position (Figure 3). Sitosterol and stigmasterol have 

an ethyl group at C-24 in α-position, whereas 

campesterol a methyl group at α- and brassicasterol a 

methyl group at β-position (Table 1). According to 

their structural and biosynthetical basis, phytosterols 

can be divided into three groups: 4-desmethyl, 4monomethyl 

and 4,4-dimethyl phytosterols (Table. 1). 

Most abundant are three 4-desmethyl sterols: 

sitosterol, campesterol and stigmasterol. Other 

phytosterols like 4-mono- and 4,4-dimethyl sterols are 

synthesised earlier in biosynthetic pathway, so they are 

mainly sterol precursors and usually occur in 

relatively smaller amounts (Määttä et al., 1999). The 

last two are mostly precursors of the sterol 

biosynthetical pathway and exist in lower level. The 4desmethyl 

sterols can also be distinguished according 

to their saturation and position of double bond on the 

C-5 and C-7 atoms in the B ring (Figure 1). The 

unsaturated sterols are marked with Δ 5 and Δ 7 , 

r e s p e c t i v e l y. Most phytosterols (e.g. stigmasterol, 

sitosterol, campesterol, brassicasterol and avenasterol) 

belong to the group of Δ 5 unsaturated phytosterols. 

Phytosterols with ethyl group at the 24 th C-atom - 24- 

ethylsterols (sitosterol, stigmasterol and avenasterol), 

mainly have only one type of configuration: 24α. 

According to Salo et al. (2003) and Hartmann (1998), 

24-methylsterols can consist of a mixture of two 

epimers. That is to say, 24-methylsterol is a mixture of 

2 4α-methylsterol and 24β-methylsterol know as 

campesterol or 22,23 dihydrobrassicasterol (Figure 3a). 

Phytosterols are largely hydrophobic having one 

polar - hydroxyl group at 3 rd C-atom, making them 

amphiphilic. According to one of the sterol 

classifications phytosterols with free 3β- hydroxyl 

group, are named free phytosterols (Figure 3) and they 

are the major end product of biosynthetic pathway of 

phytosterols. However, phytosterols also occur as 

steryl esters where 3β-hydroxyl group of free 

phytosterols is esterified with a long chain of saturated 

or unsaturated fatty acids (Figure 4a), mainly linoleic 

and oleic, or with phenolic acids (Figure 4d). Steryl 

glycosides are formed when the 3β-hydroxyl group is 

linked with monosaccharides, usually glucose, at the 

first C position (Figure 4c). 

When this monosaccharide is at the 6-C position 

esterified with fatty acid, than so-called acylated steryl 

glycosides are formed (Figure 4b). 

Biological functions in plants 

Phytosterols have both structural and metabolic 

functions. Structural role is obvious through the fact 

that they are integral membrane components. Being 

incorporated into membranes they are determining the 

characteristics of plasma membrane and, additionally, 

of endoplasmic reticulum and mitochondria 

membranes. Most likely, they also have a certain 

function in the membrane adaptation to temperature 

variations (Piironen et al., 2000). Participating in the 

control of metabolic processes, such as regulation of 

membrane permeability, fluidity, signal transduction 

events for cell division and even activity of 

membrane-bound enzymes, they fulfil their metabolic 

role (Hartmann, 1998; Lindsay et al., 2003). 

Interacting with their side chain, with the fatty acyl 

moiety of membrane phospholipids and proteins 

complexes, phytosterols restrict the motion of 

membrane bilayers (i.e. the sterol ordering effect), 

regulating membrane fluidity (Nes, 1987). 

It has been postulated that sitosterol and 

campesterol are most efficient in membrane 

permeability and fluidity regulation and there are

a. b. 

d. e. 

evidence that stigmasterol play an important role in 

cell proliferation, but has reduced ordering effect 

(Hartmann, 1998). Finally, it appears that they 

influence the plant development through the 

localisation and functionality of key regulatory 

proteins (Lindsey et al., 2003). During the seed 

germination, the phytosterol content increases, which 

is due to intensive membrane biosynthesis. 

Phytosterols that are accumulated in seeds and 

meristematic tissue are playing an important role in 

cellular proliferation and differentiation. Furthermore, 

in youngest plant tissues, the membrane biosynthesis 

is more intensive. Consequently, phytosterol synthesis 

will appear mostly during the seed formation and 

germination and phytosterols themselves will provide 

a supply for the growth of new cells and young shoots. 

By the time when seeds are already mature or tissues 

ages, the intensity of biosynthesis will decline 

(Grunwald, 1980). Besides, the high phytosterol 

amount could be also largely explained by the 

anatomical structure of different plant tissues. For 

instance, flower heads of broccoli and cauliflower 

(Brassica oleracea L. ) have higher proportion of 

membrane-rich meristematic tissue, which results in 


Figure 3. Examples of the most important phytosterols showing the difference in their chemical structure: a. campesterol, 

b. avenasterol, c. sitosterol, d. stigmasterol and e. brassicasterol (taken from Kyoto Encyclopedia of Genes and Genomes, 2004) 

c. 

higher content of total phytosterols in this species in 

comparison with other vegetables, fruits or berries 

(Piironen et al., 2003; Normen et al., 1999). 

M o r e o v e r, free phytosterols are precursors of 

bioactive steroids, growth factors and substrates for 

synthesis of numerous secondary plant metabolites 

(Willmann, 2000; Piironen et al., 2003). Campesterol 

is the precursor of brassinosteroids - phytohormones 

found in Brassica pollen (Benveniste, 2002). Plant 

steryl esters, intracellularly distributed, represent a 

storage form of phytosterols, analogously as 

cholesterol esters in mammalian cells (Piironen et al., 

2000). 

Biological functions of phytosterols in humans 

In contrast to phytosterols, cholesterol can be in 

humans, either synthesised de novo in liver, or taken 

up from the environment. During the process of 

cholesterol absorption, it is being transported from the 

lumen of intestine, across the intestinal wall and into 

the blood. Low-density lipoprotein (LDL) then 

transports cholesterol through the blood system. 

Narrowing the channels of the blood vessels, LDL-


Figure 4. Examples of steryl conjugated structures: a. oleic acid steryl ester, b. palmitic acid steryl glycosides, c. steryl glycosides 

and d. phenolic acid steryl ester (adapted from Piironen et al., 2000) 

cholesterol thus constricts the blood flow and those 

people with high cholesterol levels eventually become 

more susceptible to Cardiovascular Diseases (CVD) 

such as: coronary heart disease (CHD), also known as 

heart attack, hypertension (high blood pressure), 

cerebrovascular (stroke) and peripheral vascular 

diseases (Salo et al., 2003). According to the “World 

Health Report 2003” of United Nations World Health 

Organisation, heart attacks and strokes kill 12 million 

people around the world every year, from which, 

around 75% of CVD can be attributed to the major 

risks: high cholesterol, high blood pressure and low 

fruit and vegetable intake. By 2010 estimations are 

that CVD will be the leading cause of death in 

developing countries. Since the medical care of CVD 

is costly and prolonged, there is, consequently, an 

evident need for cholesterol suppression. 

According to many conducted experiments 

phytosterols decreases serum total and LDL 

cholesterol levels (Gylling et al., 1997; Miettinen, 

2001; Nissinen et al., 2002; Trautwein et al., 2003). It 

was suggested that phytosterols compete at the same 

time, in the micellar phase of the small intestine, for 

the limited space with cholesterol. Micelles are the 

essentially small aggregates, which are carrying a 

mixture of lipids and bile salts in intestinal lumen. 

Sitostanol esters, 5α-saturated sitosterol esters, were 

recognised as the most efficient for reducing the serum 

cholesterol concentration and the intestinal cholesterol 

absorption (Nissinen et al., 2002). As it seems they 

could be easily produced by sterol hydrogenation and 

trans-esterification with polyunsaturated fatty acids 

(Piironen et al., 2000). Sitostanol esters apparently 

result similar in prevention of cholesterol absorption 

but, in contrast to phytosterol esters, they do not 

increase their own absorption. In addition to this fact, 

it has been confirmed (Miettinen, 2001) that relatively 

high campesterol content, in some phytosterol 

complexes like soy phytosterols for example, can 

increase the campesterol proportion in serum, what 

w a s n ’t acknowledged for plant stanols, including 

campestanol (5α-saturated campesterol). Phytosterol-

ich diets may thus, result in symptoms analogue to 

phytosterolemia, hereditary metabolic disorder 

characterised by elevated phytosterol level in blood 

and tissue. Additional esterification of phytosterols 

and stanols with long chain of mono- or 

polyunsaturated fatty acids will increase their lipid 

solubility, facilitating their incorporation into the food, 

at the same time. 

A new rapeseed margarine Benecol, obtained from 

rapeseed oil by phytostanols trans-esterification 

(Miettinen, 2001) and enriched with sitostanol-esters 

was first launched in ’95 in Finland (Miettinen et al., 

1995) and by the end of ’99 already introduced in 

several other European countries and worldwide (Law, 

2000). Functional spreadable oils and fats, with 

corresponding products like: margarine, milk and 

yoghurt, first appeared in Germany in July 2002, 

under the product name “Becel pro-activ”. It was 

found that 3 g/day of phytostanol ester margarine, like 

Benecol, could actually reduce the LDL cholesterol 

level up to 14-22 %, decreasing the amount of 


Table 1. Trivial and scientific names of selected sterols from the sterol biosynthetic pathway (adapted from Grunwald, 1980) 

Trivial Name Scientific Name Sterol Class 

Cycloartenol 9beta,19-cyclo-24-lanosten-3beta-ol 4,4-dimethyl 

24-Methylene Lophenol 4-alpha-Methyl-5-alpha-ergosta-7,24-dien-3-beta-ol 4-methyl 

Avenasterol 24-ethylcholesta-5,24(28)Z-dien-3‚-ol 4-desmethyl 

Cholesterol cholest-5-en-3‚-ol 4-desmethyl 

Campesterol 24·-methyl-5-cholestern-3‚-ol 4-desmethyl 

Brassicasterol 5,22-cholestadien-24‚-methyl-3‚-ol 4-desmethyl 

Sitosterol 24·-ethylcholest-5-en-3‚-ol 4-desmethyl 

Stigmasterol 5,22-cholestadien-24·-ethyl-3‚-ol 4-desmethyl 

Table 2. Variation of phytosterol content in six different vegetable oils (g/kg of oil) (adapted from Piironen et al., 2000) 

Oil Type Brassicasterol Campesterol Stigmasterol Sitosterol Avenasterol Total Phytosterols 

Corn * 2.59 0.98 9.89 0.36 8.09-15.57 

Rapeseed 0.55-0.73 1.59-2.48 0.02-0.04 2.84-3.59 0.13-0.19 5.13-9.79 

Sunflower - 0.69 0.75 4.65 0.28 3.74-7.25 

Cottonseed * 0.26 * 4.00 0.05 4.31-5.39 

Soybean - 0.62-0.76 0.45-076 1.22-2.31 - 2.29-4.59 

Olive (Extra Virgin) - 0.05 0.01 1.18-1.21 0.17-0.18 1.41-1.50 

*found in traces 

-not available 

absorbed cholesterol up to 65 % (Law 2000; Miettinen 

et al., 1995; Miettinen, 2001; Jones et al., 1999). The 

reduction of LDL cholesterol level up to 20 % was, 

according to Gylling et al. (1997), achieved with the 

rapeseed margarine (5 %) and with the sitostanol 

esters (15 %) present in that margarine. In this study, it 

has been also proven that consumption of roughly 2 g 

a day of phytosterol-enriched margarines can decrease 

the coronary mortality, by about 25 %. Furthermore, 

latest experimental studies have shown that dietary 

phytosterols may be used also as prevention for 

several types of cancer e.g. stomach and colon cancer 

(Normen et al., 2001). 

Genetic variation and modification 

Gordon and Miller (1997) have published results of a 

steryl ester composition in 10 different oil types: corn, 

rapeseed, groundnut, olive, soybean, safflower, oleic 

sunflower, linoleic sunflower, cottonseed and palm oil. 

They have discovered that rapeseed had, after the corn


oil, second highest phytosterol proportion in oil. The 

mean content in oil of five rapeseed varieties was 6900 

mg/kg, in which the free phytosterol fraction equals 

65 % and the steryl ester fraction equals 35 %, of the 

total phytosterol content. They have published that 

their phytosterol content in oil can vary to a great 

extent from 6540 mg/kg to 8550 mg/kg of oil. 

Nevertheless, the average total sterol content of 

6900mg/kg classifies rapeseed oil, into oils with the 

highest content i.e. higher than 4000 mg/kg of oil. On 

the other hand Appelqvist et al. (1981) ascertained the 

content of free phytosterols in the total amount of 

rapeseed oil would be then 0.3 % and esterified 

phytosterols 0.6 %. Piironen et al. (2000) have 

published collected results of phytosterol content in 

crude corn, cottonseed, rapeseed, olive, soybean and 

sunflower oil (Table. 2), in which they have showed 

the majority of crude vegetable oils contain, at least 

1 g/kg to 5 g/kg of oil. However, they have found that 

the most significant exceptions are corn (up to 16 g/kg 

of oil) and rapeseed oil (up to 10 g/kg of oil). 

According to Abidi et al. (1999) the total 

phytosterol content is affected by genetic 

modifications. They have compared 10 experimental 

transgenic and non-transgenic canola genotypes 

differing in fatty acid composition and concluded that 

the phytosterol content was influenced by the genetic 

modification of the fatty acid composition. A 

significant decrease in amount of three major 

phytosterols: sitosterol, campesterol and 

brassicasterol, was observed in non-transgenic canola 

varieties grown for low-linolenic and high oleic acid. 

In addition, the amount of brassicasterol varied widely 

based on genotype and growing conditions. 

Brassicasterol content ranged from 85 to 189 mg/100 g 

of modified oil; campesterol content ranged from 205 

to 264 mg/100 g; sitosterol from 457 to 509 mg/100 g 

and finally variation of the total phytosterol contents 

was from 766 to 961 mg/100 g of modified oil. On the 

other hand, there wasn’t any systematic trend of 

phytosterol content in transgenic canola lines. In his 

paper Miettinen (2001) discussed on what plant 

breeders should focus when trying to developing new 

nutritionally interesting plant with an ideal phytosterol 

content, which could be later on used for cholesterollowering 

functional food production. He suggested 

that ideal phytosterol composition should contain 

mainly sitosterol esters with low campesterol ester 

content, because apparently campesterol esters result 

in similar changes, when reduction of serum 

cholesterol level is concerned, but at the same time, in 

contrast to sitosterol esters, they increase their own 

absorption. His second suggestion for oil, which 

would be preferable for preparation of functional food, 

was that it should be rich with stanols, especially 

sitostanol, esterified with polyunsaturated fatty acids. 

Since phytostanols are less abundant in plants than 

phytosterols, in order to produce esterified 

phytostanols, the final food price will increase. 

Result 

Plant sterols, also called phytosterols, occur as organic 

compounds and essential constituents of cell 

membranes in all plant oils. Recently increased 

interest in phytosterols lies in their potential to reduce 

plasma low-density lipoprotein cholesterol level, 

decreasing coronary mortality and therefore acting as 

naturally preventive dietary product. High 

expectations have already been put forward regarding 

phytosterol analysis and traditional plant-breeding 

applications in developing improved cultivars with 

desirable phytosterol composition and increased 

content. 

Phytosterols occur in relatively high concentration 

in the seeds of oilseed rape (Brassica napus L.). 

However, little is known about genetic variation of 

phytosterols and almost no data are available of the 

impact of geographic location and agricultural 

practices on the content and composition of 

phytosterols in rapeseed. To improve the phtosterol 

composition must be a major breeding aim for a high 

quality vegatable oil production. 

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modification on the distribution of minor constituents in 

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Sterols and steryl esters in some brassica and Sinapis 

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