Botanical origin and identification of Krai-krue herbal plant

Abstract

Krai-krue is a crude drug commonly used in Thai traditional herbal remedies as an antipyretic, anti-inflammatory and muscle relaxant. This plant drug is a hard root with a characteristic smell and bitter taste. Despite its availability in Thai herbal drugstores, the botanical identity remains unknown. To reveal its botanical origin, the plant drug was traced back from herbal dispensaries in Bangkok to its natural habitats. Its identity was confirmed with the locals and traditional healers in the implemented areas. The collecting sites were revisited several times to collect complete specimens for botanical identification. The herbarium specimens were identified as Aristolochia pierrei Lec. and A. tagala Cham. (Aristolochiaceae). The roots were collected for comparative macroscopic and microscopic studies, with the samples purchased from three different herbal drugstores in Bangkok. The microscopic investigations employed different methods, including a technique specifically modified for cutting microscopic cross section of extremely hard root samples. All of the samples are morphologically and histologically alike, indicating that they may be all originated from the same Aristolochia genera. Statistical analysis the measured cells determined by ANOVA, however, appeared to be significantly different in corks and xylem vessels among the roots of A. pierrei Lee. and A. tagala Cham. (p<0.05). Thin-layered chromatographic data of these crude drugs also supported the botanical origin of Krai-krue to be Aristolochia pierrei Lec. as shown in the phylogenetic grouping based on their similarity coefficients (0.94≤r≤0.98) but relatively different from A. tagala Cham. (r=0.64).