Inner morphological and chemical differentiation of Boehmeria species

The present study was designed to establish quality control parameters for pharmacognostic evaluation and differentiation of eight locally derived Boehmeria species, B. gracilis, B. nivea, B. pannosa, B. platanifolia, B. quelpaertensis, B. spicata, B. splitgerbera, B. tricuspis, and two varieties named B. japonica var. longispica, B. nivea var. concolor, which have been utilized as the folk medicine, 'Mo-Si-Pool' in Korea. Although the outer morphological study of these species had been reported, there is no pharmacognostical description yet. Therefore, inner morphological evaluation on leaf midrib, petiole and stem of eight Boehmeria species and two varieties was accomplished along with preliminary phytochemical analysis by HPLC-DAD profiling. The microscopic data showed discriminative inner morphological characteristics such as collenchyma cell layer, thickness of cortex and xylem, frequency of druse and hairs, and number of vascular bundles. The HPLC profiles exhibited more than four characteristic peaks. The molecular ions of the four peaks (1-4) were tentatively identified by ESI-MS, and their structures were identified by NMR spectroscopy to be the flavonoids, rutin (1), isoquercetin (2) and kaempferol-3-O-rutinoside (3), and a phenanthroquinolizidine alkaloid, (-)-cryptopleurine (4). While compounds 1 and 2 were detected in all samples, compound 4 was determined only in B. japonica var. longispica, B. pannosa and B. quelpaertensis and B. splitgerbera. These findings provide the initial scientific criteria for proper identification and establishment of standards for use of Boehmeria species in traditional medicine.