Comparative Estimation of Major Iridoid Glucosides from Different Parts of Incarvillea emodi

Incarvillea emodi (Bignoniaceae) is a rich source of bioactive iridoid glucosides. This plant contains two major iridoid glucosides: plantarenaloside, a neurotropic compound, and boschnaloside, a strong antibacterial compound. Here, in this study we have developed a simple and fast HPLC-DAD method for the total comparative estimation of these two major iridoids from different parts of Incarvillea emodi. A linear calibration curve (r2=0.999) for both iridoid glucosides in varying range (15.6–500 μg/ml) is obtained. The limit of detection (LOD) and limit of quantification (LOQ) for plantarenaloside were 11.4 ng and 38 ng and for boschnaloside were 22.8 ng and 76 ng, respectively. The shoots, roots, and flowers of Incarvillea emodi have a combined presence of 7.66, 1.22, and 6.99 percent of these iridoid glucosides on dry weight basis. In shoots, plantarenaloside shows complete dominance (6.78%) over boschnaloside (0.88%), and a reversal of this trend was observed in case of flowers where boschnaloside shows complete dominance (6.12%) over plantarenaloside (0.87%). The roots contain 1.19% and 0.03% of both iridoids, respectively.