Isolation and quantitation of ecologically important phloroglucinols and other compounds from Eucalyptus jensenii

Eucalyptus jensenii has not been explored for its phytoconstituents except for its essential oil although a formylated phloroglucinol compound jensenone has been the focus of several ecological studies.

i) To optimise the extraction conditions for preparative scale isolation of jensenone and other secondary metabolites from leaves. (ii) To develop an RP-HPLC method for simultaneous determination of phloroglucinols and other compounds in Eucalyptus leaves.

Jensenone and other compounds were isolated from acetone extract using VLC over TLC grade silica. HPLC quantitation of isolated compounds was undertaken on a C₁₈-column using acetonitrile-water (2% formic acid) gradient elution.

Extraction conditions for isolation of jensenone were optimised and more than 99% pure jensenone was obtained in a yield of 2.1% from the dried leaves. Ten phloroglucinol compounds, including a new nuclear methylated phloroglucinol named 4-O-demethyl miniatone, and two triterpenoids were also isolated. A RP-HPLC method was developed for simultaneous quantitation of phloroglucinols and other compounds in different extracts of E. jensenii leaves. A total of 19 compounds reported from different species of Eucalyptus was separated by this method.

The method described for isolation of jensenone is a simple, rapid and low-cost procedure amenable to the preparative scale. A new monomeric phloroglucinol compound was isolated and characterised from the acetone extract of E. jensenii leaves. The HPLC method developed can be applied successfully to different eucalypt matrices for precise and accurate determination of 19 secondary metabolites belonging to different chemical classes.