The oleoresin of selected Copaifera species, commonly known as copaiba oil, is a traditional Brazilian remedy for the
treatment of various ailments, such as urinary tract infections, respiratory diseases,
wound healing, rheumatism, herpes and tumors [1],[2]. Due to its wide application in folk medicine, the oleoresin has been subject of
various studies examining its chemical composition and the correlation with its health
benefits.
As both, the diterpene acids and the biological activities vary between the different
Copaifera species [2], the aim of the present study was the development of analytical methods for the
quantification of diterpene acids.
The first method is an UHPLC assay using reversed-phase material and evaporative light
scattering detection. With this method precise (RSD values below 4%), accurate (mean
recovery rates of 91-105%) and sensitive quantification (LOQs of 10 and 20 µg/mL)
was achieved. For the second assay, quantitative heteronuclear single quantum correlation
spectroscopy (qHSQC) was applied. Here, calibration curves of eight different NMR
cross-peaks were established and normalized with dimethyl terephthalate, which served
as internal standard. This approach allowed the direct quantification of four major
and one minor diterpene, whereas he contents of the remaining minor compounds were
obtained with simple calculation procedures.
Comparison with the UHPLC assay showed good agreement for seven of out of eight diterpenoids.
In terms of precision, the qHSQC method was advantageous for the quantification of
the three major compounds, whereas UHPLC was superior in the determination of the
minor components.
