Quantification of Incensole in Three Boswellia Species by NIR Spectroscopy Coupled with PLSR and Cross-Validation by HPLC.

INTRODUCTION: Incensole can be considered as a biomarker for Boswellia species which is a diterpene that has received remarkable pharmacological interest recently due to its potent anti-inflammatory and anti-depressant activity.

OBJECTIVE: Near-infrared (NIR) spectroscopy coupled with PLSR (partial least squares regression) as a robust, rapid and alternative method was used to quantify the content of incensole in three species namely B. papyrifera, B. sacra and B. serrata and cross-validated by high-performance liquid chromatography (HPLC).

MATERIALS AND METHODS: NIR spectrophotometer was used for the quantification of incensole standards and Boswellia species in absorption mode in the wavelength range between 700 and 2500 nm. A PLSR model was built from the obtained spectral data using 70% of the incensole working standard solutions (training set), ranging from 0.5 to 100 ppm. The PLSR model obtained has a R2 value of 98% with a correlationship of 0.99 and a good prediction with root mean square error for prediction (RMSEP) value of 3.2%.

RESULTS: The results indicated that the methanol (MeOH) extract of B. papyrifera resin has the highest concentration of incensole (18.4%) followed by n-hexane (13.5%) and ethyl acetate (3.6%) while trace amounts was detected in the fractions of B. sacra and no incensole was detected in the fractions of B. serrata.

CONCLUSION: The findings are in total agreement with the HPLC analysis suggesting that NIR spectroscopy coupled with PLSR is a robust, rapid and non-destructive alternate method for the quantification of incensole in B. papyrifera. Copyright © 2018 John Wiley & Sons, Ltd.