Sunday, October 07, 2007

Royal Jelly Contains Complex Steroidal Composition

Compositions of Royal Jelly II. Organic Acid Glycosides and Sterols of the Royal Jelly of Honeybees (Apis mellifera)
Chem. Pharm. Bull.,55(10) 1528—1531 (10/1/2007)

Royal jelly is a secretion from the hypopharyngeal and mandibular glands of worker bees, and it is the exclusive food of the queen bee for the entire span of both her larval and adult lives.

With regard to the constituents of this material, it contains remarkably high amounts of organic acids in the total lipid fraction.1) Many organic acids mainly consisting of 8 to 11 carbon atoms such as 10-hydroxy-2-decenoic2,3) and 10-hydroxydecanoic acids have been isolated.

Among them, a minor component, 9-hydroxy-2-decenoic acid,4) is known to be a queen honeybee pheromone with swarm-stabilizing activity,5) and it is also regarded as a precursor of the so-called queen substance, 9-keto-2-decenoic acid, which controls the caste of honeybee colonies.6) Recently,
we have isolated mono- or diesters of 10-hydroxy-2-decenoic acid in which the hydroxyl group was esterified by another organic acid residue from the total lipid fraction of the royal jelly of the honeybees (Apis mellifera).7)

In view of these findings, it seems that other unknown compounds including pheromones or their precursors exist in royal jelly.

The present study was undertaken to examine the constituents of royal jelly in the hope of discovering the biologically active compounds that control the hierarchy of honeybee colonies. By application of the recycling HPLC technique for the isolation of minor constituents from a complex mixture, two glycosides (1, 2) together with 16 compounds (3—18) were obtained in the pure state. The former two were
fatty acid monoglucosides and the latter were sterols mainlycomposed of 28 or 29 carbons.

This paper deals with the isolation and structural elucidation of these compounds…

In conclusion, two organic acid glucosides (1, 2) and 16 sterols (3—18) were isolated in pure form. Both of the formers are the first glycosides isolated from royal jelly, although 1 has already been synthesized by Takimoto and Motoyoshi.18) It is noteworthy that the main organic acids, 10-hydroxy-2E-decenoic and 10-hydroxydecanoic acids, also exist as glucosides in royal jelly.

Concerning sterols, only eight compounds have been identified so far.19) This study showed that royal jelly contains a very complex steroidal composition. A major sterol is 24-methylenecholesterol (7), followed by sitosterol (12) and isofucosterol (8). These compounds comprised as much as 80% of the total sterol fraction.

Except for desmosterol, all other sterols consist of 28 or 29 carbons. At present, it remains unclear whether all sterols obtained originate from pollen. To the best of our knowledge, compounds 3—6 are the first isofucosterol derivatives isolated from natural products. Further investigation will be made with the objective of finding more of the compounds that control the caste of honeybee colonies.

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