Resorcinolic Lipids

Resorcinolic Lipids and Their Occurrence Biological Activities of Resorcinolic Lipids Ongoing Research in Author's Lab Useful practical informations

• Most of phenolic compounds are of plant origin. Their presence has been demonstrated in only one animal organism - marine sponges. This group of natural oligophenols as well as their derivatives is very heterogeneous. Plant phenolic compounds arise biogenetically from two main pathways - shikimic acid pathway, as hydroxycinnamic acids and coumarins, and the polyketide (acetate) pathway. Some other phenolics can be produced by combination of these two pathways.
• Among plant single-ring phenolics, the number of various compounds that is recently growing, are the compounds derived from polyketide (acetate) pathway, like 6-pentadecylsalicylic acid. Non-isoprenoic phenolic lipids are relatively uncommon and can be considered for simplicity as fatty acids, whereby the carboxyl group was replaced by the hydroxybenzene ring. Therefore they are derivatives of mono, and dihydric phenols, catechol, resorcinol and hydroquinone. The knowledge of the pathway of these compounds is still incomplete and is lacking convincing experimental data. Higher plant resorcinolic lipids include a simple homologs of orcinol-type (1,3-dihydroxy-5-methylbenzene) phenols and a variety of homologs with a ring or chain or both ring and chain modified. Resorcinolic lipid molecules have a dual, aromatic and acyclic character, demonstrated by the presence of the aromatic ring and straight hydrocarbon chain of a length depending on the source of these lipids. In most cases the side chain of resorcinolic lipids is odd numbered what is of relevance in the consideration of their biosynthetic pathway.
• It was supposed first that the members of phenolic lipids are limited only to the Plant Kingdom and to some plant families. The first species in which members of the title subclass of lipids, resorcinolic lipids, were found was Ginkgo biloba (Ginkgoaceae). Later, the presence of resorcinolic lipids (5-n-alk(en)ylresorcinols) was shown also in other species, first within Anacardiaceae. Substantial amounts of 5-n-alkylresorcinols have been demonstrated in wheat bran, than in rye, barley (Gramineae). Later their occurrence has been shown in other higher as well as lower plants.
• Resorcinolic lipids has been also demonstrated in the microbial organisms. Leprosols, resorcinolic lipid derivatives have been identified in Mycobacterium leprae. Later the occurrence of simple 5-alkylresorcinols has been demonstrated in strains of soil bacteria from Azotobacter and Pseudomonas families. The striking feature of microbial sources, contrary to the plant material, is exclusive occurence of 5-n-alkylresorcinol homologs with saturated chains.
• The natural sources in which occurrence of resorcinolic lipids (simple alkylresorcinols and various types (algae, mosses and fungi) and several bacterial families (3) - see Table below.

The striking observation is that, until now, resorcinolic lipids have been reported in only one simple animal organism. This strongly suggests possible similarity of the biosynthetic pathways that are present in both plant and microbial organisms responsible for synthesis of such compounds.

The most prominent homolog, demonstrated in vast majority of sources, is saturated or enoic 5-n-pentadecylresorcinol. In most cases, however, resorcinolic lipids occur as mixtures of at least several homologs, generally having one to three different chain lengths and/or degrees of unsaturation. In most cases, they occur as only a few derivatives with respect to the side-chain length that can be saturated or unsaturated side chains. However, in Graminaceous plants, the presence of numerous homologs from C13 to C27, with each of these homologs in saturated, monounsaturated and diunsaturated form, have been presented. A similar wide spectrum of homologs exists in bacterial cells of Azotobacter and Pseudomonas, but only in saturated form. Apart from simple 5-n-alk(en)ylresorcinols in plant material and bacterial cells, the occurrence of various derivatives (ring or chain modified) have also been demonstrated. The localization of double bonds (cis configuration) depends on the length of the side-chain. The most frequent position of double bonds are C8, C11, C14 carbon atoms (in case of C15 homologs) making a striking reference to the double bond location in shortened by one carbon atom fatty acids.

Over 100 various resorcinolic lipid homologs of the natural origin have been already described. In most cases, however, phenolic hydroxylic groups remain unmodified and the chain is straight.

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The role of the chain and ring substituents in the activity of resorcinolic lipids

Resorcinolic lipids-biomembrane interactions

Modulation of lipid metabolism by resorcinolic lipids

Biosynthesis of resorcinolic lipids

Laboratory articles on resorcinolic and phenolic lipids
Resorcinolic lipids registry numbers
Micromethod for quantitative determination
Determination of homologs in the mixtures according to chain unsaturation
Determination of homologs in the mixtrures according to chain length
Literature Data Bank

Recent Papers From Author's Laboratory

Latest review concerning title compounds and also other phenolic lipids has been published recently by
A. Kozubek, J. H. P. Tyman  Bioactive Phenolic Lipids 
in: Chemistry of Natural Compounds in Studies in Natural Products Chemistry vol 30 (Atta ur Rachman Ed.)
2005, 111-190

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