PHARMACOGNOSTIC STANDARDIZATION AND PHYTOCHEMICAL PROFILING OF ROOT BARK OF PAJANELIA LONGIFOLIA AND RADERMACHERA XYLOCARPA, TWO LESS-KNOWN ETHNOMEDICINAL TREES OF BIGNONIACEAE

Pharmacognostic evaluation becomes a simple and reliable method for the authentication of crude herbal drugs, once the morphological characters are lost during processing. This study presents a comprehensive pharmacognostic, physicochemical, and elemental characterization of the root bark of two ethnomedicinally important but underexplored trees- Pajanelia longifolia and Radermachera xylocarpa of Bignoniaceae family. The roots of both species share some common histological characters like stone cells and calcium oxalate crystals, but differ in odour, cork thickness, and crystal size.  Minor differences in ash values indicate variation in inorganic content. For the first time, this study reports the mineral and heavy metal elemental profiles of the root bark of P. longifolia and R. xylocarpa. Calcium was identified as the predominant mineral in P. longifolia (268.54 mg Kg⁻¹) and R. xylocarpa (328.43 mg Kg⁻¹), followed by magnesium, highlighting their potential nutritional and therapeutic significance. Major toxic heavy metals such as Al, Ni, Pb, Hg and Co were found to be below detectable levels in both species, while copper was detected only in R. xylocarpa. HPTLC analysis of root bark extracts showed that P. longifolia possessed 9 resolved peaks distributed mainly in the lower and mid Rf regions (0.02–0.65), on the other hand, R. xylocarpa displayed a broader phytochemical profile extending from Rf 0.02 to 0.80 with 12 resolved peaks. The dominant HPTLC peak at Rf 0.03 in both the root barks indicates the occurrence of a major common phytoconstituent. GC–MS analysis of P. longifolia root bark extracts revealed coumaran as the major phytoconstituent, represented by the highest peak at a retention time of 11.33 min, whereas the predominance of compounds such as quinic acid, guaiacol (2-methoxy phenol), isovanillic acid, β-sitosterol, and coumaran reflects the phytochemical complexity of R. xylocarpa. The generated diagnostic standards provide a scientific basis for the authentication, quality assurance, and safe medicinal use of these underexplored ethnomedicinal roots.