Location: Natural Products Utilization ResearchTitle: Comparative study of three Plumbago L. species (Plumbaginaceae) by microscopy, UPLC–UV and HPTLC analyses ) Author
Submitted to: Journal of Natural Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2012
Publication Date: 11/15/2012
Citation: Galal, A.M., Raman, V., Avula, B., Wang, Y., Rumalla, C.S., Weerasooriya, A.D., Khan, I.A. 2012. Comparative study of three Plumbago L. species (Plumbaginaceae) by microscopy, UPLC–UV and HPTLC analyses. Journal of Natural Medicine. 67:554-661. Interpretive Summary: This research was done because of the importance of the plumbagin, as a substance with multiple bioactivities including anticancer and antimicrobial effects, and the need to identify and authenticate the plant sources of this important natural product. Microscopic studies of the leaves, stems, and roots of the three Plumbago species demonstrated the utility of the micromorphological differences that can be used to differentiate between the three species, both in the entire, as well as, in the powder form. The UPLC method described in the current work is simple, accurate and suitable for determination of plumbagin in different parts of the three species of Plumbago. In addition, a large number of samples can be analyzed at the same time without compromising the accuracy. HPTLC fingerprints of the leaves and roots of the three species exhibited distinguishable profiles, while those of the stems were undifferentiated. Therefore, the three Plumbago species can be discriminated by examining and comparing the HPTLC chromatograms of their respective leaves and roots, but not the stems.
Technical Abstract: This paper presents a comparative study of anatomy of leaves, stems and roots of three species of Plumbago, namely P. auriculata Lam., P. indica L. and P. zeylanica L. by light microscopy. The paper also provides qualitative and quantitative analysis of the naphthoquinone, plumbagin, a major constituent present in these species using UPLC–UV method. Microscopic examinations revealed the presence of distinctive differences in the anatomical features of the leaf, stem and root of the three species and thus can be used for identification and authentication of these species. UPLC–UV analysis showed the highest concentration of plumbagin in the roots of P. zeylanica (1.62 % w/w) followed by the roots of P. indica (0.97 % w/w) and then P. auriculata (0.33–0.53 % w/w). In contrast, plumbagin was not detected in the stems and leaves of P. indica and in the leaves of P. auriculata, whereas very low concentrations (<0.02 % w/w) of plumbagin were detected in the stems and leaves of P. zeylanica and in the stems of P. auriculata. HPTLC fingerprints of the leaf and root of the three species exhibited distinguishable profiles, while those of the stems were undifferentiated.