The fatty acid and sterol composition of two marine dinoflagellates

The fatty acid, sterol and chlorophyll pigment compositions of the marine dinoflagellates Gymnodinium wilczeki and Prorocentrum cordatum are reported. The fatty acids of both algae show a typical dinoflagellate distribution pattern with a predominance of C₁₈, C₂₀ and C₂₂ unsaturated components. The acid 18:5ω3 is present at high concentration in these two dinoflagellates. G. wilczeki contains a high proportion (93.4%) of 4-methyl-5α-stanols including 4,23,24-trimethyl-5α-cholest-22E-en-3β-ol (dinosterol), dinostanol and 4,23,24-trimethyl-5α-cholest-7-en-3β-ol reported for the first time in dinoflagellates. The role of this sterol in the biosynthesis of 5α-stanols in dinoflagellates is discussed. P. cordatum contains high concentrations of a number of δ ²⁴⁽²⁸⁾-sterols with dinosterol, 24-methylcholesta-5,24(28)-dien-3β-ol, 23,24-dimethylcholesta-5,22E-dien-3β-ol, 4,24-dimethyl-5α-cholest-24(28)-en-3β-ol and a sterol identified as either 4,23,24-trimethyl- or 4-methyl-24-ethyl-5α-cholest-24(28)-en-3β-ol present as the five major components. The role of marine dinoflagellates in the input of both 4-methyl- and 4-desmethyl-5α-stanols to marine sediments is discussed.     

Dehydrodinosterol,dinosterone and related sterols of a non-photosynthetic dinoflagellate, Crypthecodinium cohnii

The heterotrophic dinoflagellate Crypthecodinium cohnii contained the 4α-methyl sterols, dinosterol, dehydrodinosterol (4α,23,24-trimethylcholesta-5,22-dien-3β-ol) and the tentatively identified 4α,24-dimethyl-cholestan-3β-ol and 4α,24-dimethylcholest-5-en-3β-ol. The major 4-demethyl sterol was cholesta-5,7-dien-3β-ol which was accompanied by a smaller amount of cholesterol and traces of several other C₂₇,C₂₈ and C₂₉ sterols. In addition, a 3-oxo-steroid fraction was isolated and the major component identified as dinosterone (4α,23,24-trimethylcholest-22-en-3-one). The possible biosynthetic relationships of these compounds are discussed.     

First examination of sterols in the marine dinoflagellate genus Vulcanodinium

Vulcanodinium is an ecologically relevant dinoflagellate genus due to its production of neurotoxins known as pinnatoxins. We present here the first examination of the sterols of a Vulcanodinium rugosum isolate. Sterols are ringed lipids that assist in maintaining rigidity of cellular membranes, and the Dinophyceae are well-studied for their ability to produce a diverse array of sterols, many of which have chemotaxonomic utility. We have determined that V. rugosum produces a set of major sterols, namely cholesterol, dinosterol, 4α,24-dimethyl-5α-cholest-22E-en-3β-ol, and 4α,24-dimethyl-5α-cholestan-3β-ol, common to the Dinophyceae. However, this displayed marked differences from those studied members of the genera Scrippsiella and Peridinium, the closest phylogenetic relatives. Included in these differences is production by V. rugosum of a much lower percentage of dinostanol, a saturated form of dinosterol.     

Sterols of Amphidinium species in the Operculatum Clade: Predominance of cholesterol instead of Δ8(14) sterols previously considered Amphidinium-specific biomarkers

The dinoflagellates Amphidinium carterae and Amphidinium corpulentum have been previously characterized as having Δ⁸⁽¹⁴⁾-nuclear unsaturated 4α-methyl-5α-cholest-8(14)-en-3β-ol (C_28:1) and 4α-methyl-5α-ergosta-8(14),24(28)-dien-3β-ol (amphisterol; C_29:2) as predominant sterols, where they comprise approximately 80% of the total sterol composition. These two sterols have hence been considered as possible major sterol biomarkers for the genus. Here, we have examined the sterols of four recently identified species of Amphidinium (Amphidinium fijiense, Amphidinium magnum, Amphidinium theodori, and Amphidinium tomasii) that are closely related to Amphidinium operculatum as part of what is termed the Operculatum Clade to show that each species has its sterol composition dominated by the common dinoflagellate sterol cholesterol (cholest-5-en-3β-ol; C_27:1), which is found in many other dinoflagellate genera, rather than Δ⁸⁽¹⁴⁾ sterols. While the Δ⁸⁽¹⁴⁾ sterols 4α-methyl-5α-cholest-8(14)-en-3β-ol and 4α,23,24-trimethyl-5α-cholest-8(14),22E-dien-3β-ol (C_30:2) were present as minor sterols along with another common dinoflagellate sterol, 4α,23,24-trimethyl-5α-cholest-22E-en-3β-ol (dinosterol; C_30:1), in some of these four species, amphisterol was not conclusively observed. From a chemotaxonomic perspective, while this does reinforce the genus Amphidinium's ability to produce Δ⁸⁽¹⁴⁾ sterols, albeit here as minor sterols, these results demonstrate that caution should be used when considering Δ⁸⁽¹⁴⁾ sterols, especially amphisterol, as Amphidinium-specific biomarkers within these species where cholesterol is the predominant sterol.     

STEROLS OF 14 SPECIES OF MARINE DIATOMS (BACILLARIOPHYTA)1

The sterol compositions of 14 species of marine diatoms were determined by gas chromatography and gas chromatography-mass spectrometry. A variety of sterol profiles were found. The sterols 24-methylcholesta-5,22E-dien-3β-ol, cholest-5-en-3β-ol, and 24-methylcholesta-5,24(28)-dien-3β-ol, previously described as the most common sterols found in diatoms, were major sterols in only a few of the species. In light of this and other recent data, it is clear that these three sterols are not typical constituents of many diatom species. Most of the centric species examined had 24-methylcholesta-5,24(28)-dien-3β-ol and 24-methylcholest-5-en-3β-ol as two of their major sterols. The exception was Rhizosolenia setigera, which possessed cholesta-5,24-dien-3β-ol as its single major sterol. In contrast to the centric species, the pennate diatoms examined did not have any particular sterols common to most species. Minor levels ofΔ⁷-sterols, rarely found in large amounts in diatoms, were found in four species. C₂₉sterols were found in many species; seven contained 24-ethylcholest-5-en-3β-ol and three contained 24-ethylcholesta-5,22E-dien-3β-ol, reinforcing previous suggestions that C₂₉ sterols are not restricted to higher plants and macroalgae. 24-Ethylcholesta-5,22E-dien-3β-ol may prove to be useful for taxonomy of the genus Amphora and the order Thalassiophysales. A major sterol of Fragilaria pinnata was the uncommon algal sterol 23,24-dimethylcholesta-5,22E-dien-3β-ol. Cholesta-5,24-dien-3β-ol was the only sterol found in the culture of Nitzschia closterium. This differed from previous reports of 24-methylcholesta-5,22E-dien-3β-ol as the single major sterol in N. closterium. Two C₂₈ sterols possessing an unusual side chain were found in Thalassi-onema nitzschioides, a C_28:2 sterol (16%) and a C_28:1 sterol in lower abundance (2.5%), which may be 23-methylcholesta-5,22E-dien-3β-ol and 23-methyl-5α-cholest-22E-en-3β-ol, respectively. The species Cylindrotheca fusiformis, T. nitzschioides, and Skeletonema sp. may be useful as direct sources of cholesterol in mariculture feeds due to their moderate to high content of this sterol.     

Dinoflagellate sterols IV: Isolation and structure of 4α,23ξ,24ξ-trimethylcholestanol from the dinoflagellate Glenodiniumhallii

The dinoflagellate $\text{Glenodinium}$$\text{hallii}$ was investigated for its sterol composition. Five of the six sterols were isolated and identified as cholest-5-en-3β-ol, (24ξ)-24-methylcholest-5-en-3β-ol, stigmasta-5,22-dien-3β-ol, (22E,24R)-4α,23,24-trimethyl-5α-cholest-22-en-3β-ol, and 4α,23ξ,24ξ-trimethyl-5α-cholestan-3β-ol.     

Sterols of a diatomaceous ooze from walvis bay

Almost an of the solvent-extractable sterols and their nuclearsaturated analogues in a sample of Walvis Bay surface sediment have been analysed by capillary GLC and GC-MS, and by coinjection with a variety of standards. The presence in sediments of 22-$\text{trans}$-24-nor-5α-cholest-22-en-3β-ol, 24-methylene-5α-cholestan-3β-ol, and components tentatively assigned as 23,24-dimethylcholesta-5,22-dien-3β-ol and 23,24-dimethyl-5α-cholest-22-en-3β-ol has been demonstrated for the first time. A novel sterol and its saturated analogue have also been found. The sterol distribution cannot be related solely to the reported major input of phytoplankton; the presence of 22,23-methylene-23,24-dimethylcholest-5-en-3β-ol and its saturated analogue indicates a coelenterate contribution. The analysis emphasises the necessity of glass capillary columns and coinjection of standards.     

Analysis of sterols in selected bloom-forming algae in China

Sterols, a group of stable lipid compounds, are often used as biomarkers in marine biogeochemical studies to indicate sources of organic matter. In this study, sterols in 13 species of major bloom-forming algae in China, which belong to Dinophyceae, Bacillariophyceae, Ulvophyceae, and Pelagophyceae, were analyzed with gas chromatography-mass spectrometry (GC–MS) to test their feasibility in representing different types of harmful algal blooms (HABs). It was found that (24Z)-stigmasta-5,24-dien-3β-ol (28-isofucosterol) was a major sterol component in green-tide forming macroalga Ulva prolifera. In bloom-forming dinoflagellates Alexandrium spp., Prorocentrum micans and Scrippsiella trochoidea, (22E)-4α,23-dimethyl-5α-ergost-22-en-3β-ol (dinosterol) was detected in addition to cholest-5-en-3β-ol (cholesterol), (22E)-ergosta-5,22-dien-3β-ol, (22E)-stigmasta-5,22-dien-3β-ol and other minor sterol components. In brown-tide forming pelagophyte Aureococcus anophagefferens, (24E)-24-propylcholesta-5,24-dien-3β-ol ((24E)-24-propylidenecholesterol) and (24Z)-24-propylcholesta-5,24-dien-3β-ol ((24Z)-24-propylidenecholesterol) were detected together with cholesterol, (22E)-stigmasta-5,22-dien-3β-ol, stigmast-5-en-3β-ol and campest-5-en-3β-ol. Among the selected bloom-forming diatoms, Chaetoceros sp. and Pseudo-nitzschia spp. only produced cholesterol, while Cylindrotheca closterium produced solely (22E)-ergosta-5,22-dien-3β-ol. Sterol content in four bloom-forming algal species correlates well with their biomass or abundance. It's proposed that 28-isofucosterol could serve as a promising biomarker for green algae in green-tide studies. Dinosterol and (24Z)-24-propylidenecholesterol can be used as potential biomarkers to represent bloom-forming dinoflagellates and pelagophytes, while (22E)-ergosta-5,22-dien-3β-ol is not a good indicator for diatoms.     

Steroid metabolites of the far eastern Holothurian Stichopus japonicus Selenka

• 1.1. Sulphated and etherified sterols were isolated from the far eastern holothurian Stichopus japonicus S. The sterol composition of both fractions was determined using gas-liquid chromatography and mass-spectroscopic methods. The structures of individual sterols were proved on the basis of mass-spectrometry and ¹H-NMR-spectroscopy data.
• 2.2. The structures of 29 sterols were established.
• 3.3. Sterols (22E, 24R)-23,24-dimethyl-5α-cholest-22-en-3β-ol, 23,24-dimethyl-cholesta-5,22-dien-3β-ol, 24-methyl-cholesta-5,24(28)-dien-3β-ol, (24Z)-24-ethyl-cholesta-5,24(28)-dien-3β-ol, 24-nor-cholesta-5,22-dien-3β-ol, 24-ethyl-cholesta-5,25-dien-3β-ol were described for holothurians for the first time.
• 4.4. Δ⁵-sterols were shown to be the main components of the sulphated alcohol fractions (67.61%), while the saturated and Δ⁷-sterols were there in less quantities (14.72 and 9.52%, respectively).
• 5.5. The etherified sterols were represented, mainly, by saturated and Δ⁷-sterols (37.82% and 33.95%, respectively). Δ⁵-sterols were 19%.
• 6.6. The sensitivity of liposomal membranes, containing steroid metabolites of the holothurian St. japonicus (Δ⁷-, sulphated and glycosilated sterols) to the action of endotoxin-stichoposide A, was studied.

     

Minor sterols of marine invertebrates 37. Isolation of novel coprostanols and 4α-methyl sterols from the tunicate Ascidia nigra

The complex sterol mixture isolated from $\text{A, nigra}$ was found to contain a low level of Δ⁴-3-keto steroids, 5β-stanols and 4α-methyl sterols in addition to regular (4-demethyl) sterols. The following new marine sterols were isolated and identified using MS and 360 MHz NMR: 5β-cholest-22E-en-3β-ol, 24S-methyl-5β-cholest-22E-en-3β-ol, 24-methylene-5β-cholestan-3β-ol, both epimers at C-24 of 4α-methyl-24-ethyl-5α-cholest-22E-en-3β-ol, 4α, 22ξ, 23ξ-(or 24ξ-)trimethyl-5α-cholest-8(14)-en-3β-ol and (22S, 23S, 24S)-4α-24-dimethyl-22, 23-methylene-5α-cholestan-3β-ol. The latter sterol and 23-demethylgorqosterol have opposite configurations at C-22, C-23, and C-24; the Δ⁸⁽¹⁴⁾ sterol has an unprecedented side chain.     

THE LIPID COMPOSITION OF THORACOSPHAERA HEIMII: EVIDENCE FOR INCLUSION IN THE DINOPHYCEAE1

The fatty acid, sterol and chlorophyll composition of the calcified, unicellular alga Thoracosphaera heimii (Lohmann) Kamptner are reported. The presence of 4,23,24-termethyl-5α-cholest-22E-en-3β-ol (dinosterol), 4,23,24-trimethyl-5α-cholest-22E-en-3-one (dinosterone) and the predominance of C₁₈, C₂₀ and C₂₂ unsaturated fatty acids, including the acid 18:5ω3, indicates that T. heimii is a dinoflagellate. The fatty acid: sterol ratio (1.3), is typical of dinoflagellates. The geochemical significance of dinosterone, the high relative concentration of 4-desmethyl-5α-stanols and the role of 23-methyl-5α-cholest-22E-en-3β-ol in the biosynthesis of dinosterol in T. heimii are also discussed.     

STEROL DISTRIBUTION IN THE GENUS HETEROCAPSA (PYRRHOPHYTA)1

The sterol composition of seven strains of marine peridinioid dinoflagellates comprising the four known species of Heterocapsa Stein was examined by gas chromatography-mass spectrometry to determine the utility of these compounds in systematics. Cholest-5-en-3β-ol (cholesterol), 24-methyl-cholest-5-en-3β-ol (24-methylcholesterol), 4α,24(S)-dimethyl-5α-cholestan-3β-ol (4,24-dimethylcholestanol), 4α,23,24(R)-trimethyl-5α-cholest-22-en-3β-ol (dinosterol), 4α,23ξ,24ξ-trimethyl-5α-cholestan-3β-ol (dihydrodinosterol), and an unknown sterol were detected. Sterol composition does not vary significantly from species to species within the genus Heterocapsa and thus cannot be used for species differentiation. Sterols may, however, have value in defining the properties of dinoflagellate taxa above the family level. Over the course of the growth curve for Heterocapsa niei (Loeblich) Morrill & Loeblich 4,24-dimethylcholestanol and dinosterol covaried, suggesting that 4,24-dimethylcholestanol is converted into dinosterol by a previously proposed bioalkylation scheme.     

PIGMENTS,FATTY ACIDS,AND STEROLS OF THE TOXIC DINOFLAGELLATE GYMNODINIUM CATENATUM1

Cultures and field samples of the toxic dinoflagellate Gymnodinium catenatum Graham from Tasmania, Australia, were analyzed for pigment, fatty acid, and sterol composition. Gymnodinium catenatum contained the characteristic pigments of photosynthetic dinoflagellates, including chlorophyll a, chlorophyll c₂, and the carotenoids peridinin, dinoxanthin, diadinoxanthin, diatoxanthin, and β,β-carotene. In midlogarithmic and early stationary phase cultures, the chlorophyll a content ranged 50–72 pg · cell^?1, total lipids 956–2084 pg · cell^?1, total fatty acids 426–804 pg · cell^?1, and total sterols 8–20 pg · cell^?1. The major fatty acids (in order of decreasing abundance) were 16:0, 22:6(n-3), and 20:5(n-3) (collectively 65–70% of the total fatty acids), followed by 16:1(n-7), 18:2(n-6), and 14:0. This distribution is characteristic of most dinoflagellates, except for the low abundance (<3%) of the fatty acid 18:5(n-3), considered by some authors to be a marker for dinoflagellates. The three major sterols were 4α-methyl-5α-cholest-7-en-3β-ol, 4α,23,24-trimethyl-5α-cholest-22E-en-3β-ol (the dinoflagellate sterol, dinosterol), and 4α,23,24-trimethyl-5α-cholest-7-en-3β-ol. These three sterols comprised about 75% of the total sterols in both logarithmic and early stationary phase cultures, and they were also found in high proportions (22–25%) in natural dinoflagellate bloom samples. 4-Desmethyl sterols, which are common in most microalgae, were only present in trace amounts in G. catenatum. The chemotaxonomic affinities of G. catenatum and the potential for using specific signature lipids for monitoring toxic dinoflagellate blooms are discussed.     

Sterols of the ‘dinotom’ Durinskia baltica (Dinophyceae) are of dinoflagellate origin

‘Dinotoms’ are a relatively small group of dinoflagellates with aberrant tertiary plastids of diatom origin, thus differing from the majority of photosynthetic dinoflagellates which possess the carotenoid pigment peridinin and have secondary plastids of red algal origin. As part of our laboratory's continuing efforts to examine such unusual dinoflagellates in the search for clues to the evolution of their lipid compositions, we have examined the sterol composition of the dinotom Durinskia baltica. As such, we here compared its sterols to those of the previously examined dinotom, Kryptoperidinium foliaceum, more broadly to other photosynthetic, peridinin-containing dinoflagellates, and to the diatom genus Nitzschia, which is the presumed ancestor of the D. baltica dinotom plastid. Sterols are ringed lipids, common to eukaryotes, thought to reinforce phospholipid bilayers. Many peridinin-containing dinoflagellates have sterol compositions which are enriched by the presence of cholesterol (cholest-5-en-3β-ol) and 4α-methyl-substituted sterols such as dinosterol (4α,23,24-trimethyl-5α-cholest-22E-en-3β-ol); this has also been found to be true for K. foliaceum despite its aberrant plastid ancestry. Our objective was to determine if this is also true for D. baltica as only the second dinotom to have its sterols characterized in detail, and to determine if there is any indication of prominent sterols which are uncommon to dinoflagellates, possibly originating from the diatom endosymbiont, as has been demonstrated previously with K. foliaceum and D. baltica chloroplast-associated galactolipids of clear diatom origin. Our results demonstrate that like K. foliaceum, the major sterols of D. baltica are cholesterol, dinosterol, and other 4α-methyl-substituted sterols common to dinoflagellates. Although there were a number of minor sterols, none were found with obvious origin from the diatom endosymbiont, indicating that most originated with the dinoflagellate host itself, most likely before acquisition of the diatom tertiary plastid.     

Novel dinoflagellate 4α-methylated sterols from four caribbean gorgonians

Fourteen 4α-methyl sterols have been isolated from the gorgonians Briareum asbestinum, Gorgonia mariae, Muriceopsis flavida and Pseudoplexaura wagenaari, including the following five new sterols: 4α-methyl-24-methylene-5α-cholestan-3β-ol, (24R)-4α, 24-dimethyl-5α-cholesta-7,22-dien-3,β-ol, 4α,24S(or 23ξ)-dimethyl-5α-cholest-7-en-3β-ol, (22E, 24R)-4α,23,24-trimethyl-5α-cholesta-7,22-dien-3β-ol and (24R)-4α,24-dimethyl-5α-cholesta-8(14),22-dien-3β-ol. There is strong evidence that these 4α-methyl sterols are synthesized by the algal (dinoflagellate) symbionts (zooxanthellae) of the gorgonians. It is suggested that analysis of 4Δ-methyl sterol mixtures isolated from a zooxanthellae-bearing invertebrate, collected in several different geographic locations, might give information on the specificity of the symbiotic association between a given animal species and a particular strain of zooxanthellae.     

Minor and trace sterols in marine invertebrates V. isolation,structure elucidation and synthesis of 3β-hydroxy-26,27-bisnorcholest-5-en-24-one from the sponge Psammaplysilla Purpurea

The free sterol mixture of the sponge Psammaplysilla purpurea was shown to contain aplysterol as the major constituent. In addition to other sterols such as 5,7-cholestadien-3β-ol, cholesterol, 5α-cholestan-3β-ol, 24ε-methylcholesta-5,22-dien-3β-ol, 24ε-methylcholesterol, 24ε-ethylcholesta-5,22-dien-3β-ol and 24,28-dehydroaplysterol, a new minor sterol was isolated and shown by spectral analysis as well as partial synthesis to be 3β-hydroxy-26,27-bisnorcholest-5-en-24-one. The sterol mixture contains no other short side chain or 24-keto sterols except for small amounts of 3β-hydroxypregn-5-en-20-one and 3β-hydroxy-5α-pregnan-20-one.     

Structural requirement of sterol nucleus for the silkworm growth and development

Several cholesterol analogs structurally modified in nuclear substitutions were tested for sustaining the growth of the silkworm $\text{Bombyx mori}$. 5α-Cholest-7-en-3β-ol, 5,7-cholestadien-3β-ol and cholesteryl acetate can replace cholesterol as sterol source for $\text{B. mori.}$ Considerably good growth was also obained with 5α-cholest-14-en-3β-ol and 5α-cholesta-6,8(14)-dien-3β-ol. Other sterols tested were either partially effective or ineffective as nutrients.     

Sterols and fatty acids of the marine diatom biddulphia sinensis

Nine sterols, most showing Δ⁵- or Δ^5,22-unsaturation, were identified in the marine diatom Biddulphia sinensis. One sterol, cholesta-5,22E-dien-3β-ol, comprised 70–80% of the total sterols which is the first such predominance noted in a diatom. The only Δ⁷-sterol detected was cholest-7-en-3β-ol and this was a very minor component. A sterol showing unusual side-chain alkylation,23,24-dimethylcholesta-5,22E-dien-3β-ol, was identified for the first time in a diatom. Total fatty acids exhibited a predominance of Δ⁹- 16:1, 14:0, 20:5 and 16:0, typical of diatoms, although the proportions of these acids were found to vary with culture maturity. n-Heneicosahexaene was the major hydrocarbon together with a small amount of squalene.     

Sterols with unusual nuclear unsaturation from three cultured marine dinoflagellates

Several new 4α-methyl sterols with unusual unsaturation in the Δ⁸⁽¹⁴⁾-or Δ¹⁴-positions, 4α,24S-dimethyl-5α-cholest-8 (14)-en-3β-ol, 4α-methyl-24ξ-ethyl-5α-cholest-8(14)-en-3β-ol, 4α-methyl-24(Z)-ethylidene-5α-cholest-8(14)- en-3β-ol, 4α,23 (or 22),24ξ-trimethyl-5α-cholesta-8(14),22-dien-3β-ol, 4α,24S(or 23ξ)-dimethyl-5α-cholest-14-en-3β-ol and 14-dehydrodinosterol, have been isolated from extracts of the cultured marine dinoflagellates Amphidinium carterae, A. corpulentum and Glenodinium sp. 4α-Methyl-24ξ-ethyl-5α-cholestan-3β-ol was isolated from the steryl ester fraction of Glenodinium sp. The structures of these new sterols are based upon extensive 360 MHz ¹H NMR and MS analyses.     

UNUSUAL DIHYDROXYSTEROLS AS CHEMOTAXONOMIC MARKERS FOR MICROALGAE FROM THE ORDER PAVLOVALES (HAPTOPHYCEAE)1

Recent studies have led to the identification of an unusual class of dihydroxysterols (steroidal diols termed “pavlovols”)in a few species of microalgae from the genus Pavlova (family Pavlovaceae, class Haptophyceae = Prymnesiophyceae). These compounds have an additional hydroxyl group at G-4 in the sterol A ring, which appears to be very rare in sterol biosynthetic pathways. The sterol compositions of many other haptophytes from different orders have been analyzed, but to date all have lacked pavlovols. We now report the occurrence of these compounds in Diacronema vlkianum Prauser and two strains of Pavlova pinguis Green. This is the first report of the lipid composition of these species. Both microalgae contained “24-methylpavlovol” (4α, 24-dimethyl-5α-cholestan-3β, 4β-diol), P. pinguis also contained “24-ethylpavlovol” (4α-methyl-24-ethyl-5α-cholestan-3β, 4β-diol), and D. vlkianum contained a diol identified from its mass spectrum as 4α, 24β-dimethyl-5α-cholest-22E-en-3β,4β-diol. Both species contained structurally analogous 4-desmethyl sterols and 4-methyl sterols, although there were major differences in the proportions in each series. The major 4-desmethyl sterol in both species was 24-ethylcholesta-5, 22E-dien-3β-ol and the major 4-methyl sterol was 4α-methyl-24-ethyl-5α-cholest-22E-en-3β-ol. The presence of pavlovols in P. pinguis, combined with earlier data, suggests that all Pavlova species might have this distinguishing lipid feature. However, their identtjication in D. vlkianum extends the occurrence of these compounds to another genus and shows that they are not unique to the genus Pavlova. However, they are probably restricted to species from the order Pavlov ales. The modes of biosynthesis and functions of pavlovols remain unknown.