Chromatographic and spectrophotometric analysis of heartwood extracts of four Pterocarpus species

In this study, chromatographic and spectrophotometric analysis of methanolic extract of heartwood of Pterocarpus santalinus Linn (Red Sanders) collected from trees grown in eight different locations was carried out. Usefulness of these techniques for discrimination of some of the commonly occurring species in Pterocarpus genus was assessed. Thin layer chromatography (TLC) fingerprints of methanolic extract of P. santalinus heartwood revealed distinct spots at retention factor (R_f) 0.94 (light brown), 0.91 (purple), 0.79 (blackish brown), 0.75 (light purple), 0.60 (yellow), 0.51 (dark red) and 0.28 (brownish red) in normal phase. High-performance liquid chromatography (HPLC) analysis indicated at least 11 common peaks at retention time (tR) of 3.1, 3.5, 8.9, 11.1, 12.8, 13.5, 14.9, 15.7, 17.9, 18.3, and 26.5 (minutes). Ultraviolet visible spectrophotometric analysis of methanolic extract of heartwood exhibited a broad absorption spectrum with consistency in major absorbance peaks at ~ 280 nm, ~ 320 nm, ~ 472 nm and ~ 505 nm. Similarities in chromatographic pattern between the P. santalinus samples from different locations were evaluated using principal component analysis. The developed fingerprints of methanolic extract of P. santalinus heartwood were compared with those of Pterocarpus marsupium, Pterocarpus soyauxii, and Pterocarpus macrocarpus. The results demonstrate that HPLC and TLC fingerprints can supplement wood anatomy in accurate identification of above Pterocarpus species. UV visible absorption spectrophotometric analysis can be helpful to differentiate P. santalinus from P. macrocarpus and P. marsupium, but P. santalinus and P. soyauxii could not be distinguished using this technique.