Quantification of AKBA in Boswellia sacra Using NIRS Coupled with PLSR as an Alternative Method and Cross-Validation...

3-O-Acetyl-11-keto-β-boswellic acid (AKBA), one of the pentacyclic triterpenoids, is the main biologically active constituent in the resin of Boswellia sacra and has received significant pharmacological interest in recent years.

It was aimed to develop a robust method to quantify the AKBA content in methanolic extracts of different parts of B. sacra plants and in various fractions of its resin exudates through near-infrared spectroscopy (NIRS) coupled with partial least squares regression (PLSR).

The near-infrared (NIR) spectra were used to measure the AKBA standards and B. sacra samples at a wavelength range between 700 and 2500 nm in absorption mode. A PLSR model was built from the obtained spectral data using 70% of the AKBA working standard solutions (training set), ranging from 0.1 ppm to 100 ppm. The final PLSR showed a R² value of 99% with a root mean square error of cross-validation (RMSECV) value of 0.39% and a R² value of 99%.

The results showed that a 50% CHCl₃ /n-hexane sub-fraction has the highest concentration of AKBA (14.8%), followed by 55% CHCl₃ /n-hexane (13.6%), and 40% CHCl₃ /n-hexane (6.1%).

As the results achieved with the proposed NIRS methodology are in close agreement to the results of AKBA analysis using HPLC, we suggest that our proposed NIRS method is a fast alternative and non-destructive method for the analysis of AKBA in different samples of B. sacra. Copyright © 2017 John Wiley & Sons, Ltd.