Synthesis of mammalian dolichols from plant polyprenols

Polyprenols in Ginkgo biloba; a review of their chemistry (synthesis of polyprenols and their derivatives), extraction, purification, and bioactivities

The Ginkgo biloba L. (GB) contains high bioactive compounds. To date, flavonoids and terpene trilactone have received the majority of attention in GB studies, and the GB has been utilized globally in functional food and pharmacological firms, with sales > $10 billion since 2017, while the other active components, for instance, polyprenols (a natural lipid) with various bioactivities have received less attention. Hence, this review focused on polyprenols' chemistry (synthesis of polyprenols and their derivatives) extraction, purification, and bioactivities from GB for the first time. The various extractions and purification methods (nano silica-based adsorbent, bulk ionic liquid membrane, etc.) were delved into, and their advantages and limitations were discussed. Besides, numerous bioactivities of the extracted Ginkgo biloba polyprenols (GBP) were reviewed. The review showed that GB contains some polyprenols in acetic esters' form. Prenylacetic esters are free of adverse effects. Besides, the polyprenols from GB have numerous bioactivities such as anti-bacterial, anti-cancer, anti-viral activity, etc. The application of GBPs in the food, cosmetics, and drugs industries such as micelles, liposomes, and nano-emulsions was delved into. Finally, the toxicity of polyprenol was reviewed, and it was concluded that GBP was not carcinogenic, teratogenic, or mutagenic, giving a theoretical justification for using GBP as a raw material for functional foods. This article will aid researchers to better understand the need to explore GBP usage.

Total Syntheses of C60- and C100-Dolichols

C60- and C100-dolichols were synthesized. A Z-selective Wittig reaction was achieved with high selectivity in a microflow system to realize the scalable supply of the Z-isoprene unit. An isoprene chain was efficiently elongated by an S_N2-type coupling between allyl sulfone and allyl chloride using t-BuOK. These key reactions enabled the efficient syntheses of dolichols. This study will pave the way for the functional studies of dolichols.

A Convenient Method for the Synthesis of (S)-Dolichol and (S)-Nordolichol

A procedure for the preparation of (S)-dolichol and (S)-nor-dolichol starting from the polyprenyl fraction extracted from Gingko Biloba integer or extracted leaves is described. Two chiral isoprenoid compounds in good yields and high degree of enantiomeric excess were obtained. The (S)-nordolichol appears to be a good chiral precursor for the preparation of 14C-labeled (S)-dolichol which is to be used in investigations aimed at gaining further information with respect to the role of dolichol in the function of living cells.

Synthesis and biological activity of polyprenols

The polyprenols and their derivatives are highlighted in this study. These lipid linear polymers of isoprenoid residues are widespread in nature from bacteria to human cells. This review primarily presents the synthesis and biological activities of polyprenyl derivatives. Attention is focused on the synthesis and biological activity of dolichols, polyprenyl ester derivatives and polyprenyl amines. Other polyprenyl derivatives, such as oxides of polyprenols, aromatic polyprenols, polyprenyl bromide and polyprenyl sulphates, are mentioned. It is noted that polyprenyl phosphates and polyprenyl-linked glycosylation have better antibacterial, gene therapy and immunomodulating performance, whereas polyprenyl amines have better for antibacterial and antithrombotic activity. Dolichols, polyprenyl acetic esters, polyprenyl phosphates and polyprenyl-linked glycosylation have pharmacological anti-tumour effects. Finally, the postulated prospect of polyprenols and their derivatives are discussed. Further in vivo studies on the above derivatives are needed. The compatibility of polyprenols and their derivatives with other drugs should be studied, and new preparations of polyprenyl derivatives, such as hydrogel glue and release-controlled drugs, are suggested for future research and development.

Yeast Saccharomyces cerevisiae has two cis-prenyltransferases with different properties and localizations. Implication for their distinct physiological roles in dolichol synthesis

BACKGROUND

Dolichol is a family of long-chain polyprenols, which is utilized as a sugar carrier in protein glycosylation in the endoplasmic reticulum (ER). We have identified a key enzyme of the dolichol synthesis, cis-prenyltransferase, as Rer2p from Saccharomyces cerevisiae. We have also isolated a multicopy suppressor of an rer2 mutant and named it SRT1. It encodes a protein similar to Rer2p but its function has not been established.

RESULTS

The cis-prenyltransferase activity of Srt1p has been proved biochemically in the lysate of yeast cells lacking Rer2p. The polyprenol product of Srt1p is longer in chain length than that of Rer2p and is not sufficiently converted to dolichol and dolichyl phosphate, unlike that of Rer2p. The subcellular localization of these two isozymes has been examined by immunofluorescence microscopy and by the use of GFP fusion proteins. Whereas GFP-Rer2p is localized to the continuous ER and some dots associated with the ER, GFP-Srt1p shows only punctate localization patterns. Immunofluorescence double staining with Erg6p, a marker of lipid particles in yeast, indicates that Srt1p is mainly localized to lipid particles (lipid bodies). RER2 is mainly expressed in the early logarithmic phase, while the expression of SRT1 is induced in the stationary phase.

CONCLUSIONS

We have shown that yeast has two active cis-prenyltransferases with different properties. This result implies that the two isozymes have different physiological roles during the life cycle of the yeast.