Curculigo orchioides Rhizoma(COR) is the dried rhizome of C. orchioides Gaertn, which has a long history of using as herbal medicine in China. The first appearance of COR was in the ancient medical book “Lei Gong Pao Zhi Lun”, and it has been included in Pharmacopoeia of the People’s Republic of China (PPRC). COR has the traditional effects of nourishing the kidney, strengthening bones and muscles, dispelling cold and dampness . COR and its preparations are widely used in clinical practice, and have pharmacological activities such as preventing osteoporosis [2–4], anti-tumor , anti-oxidation , anti-depression , neuroprotection , and improving learning ability . In recent years, extensive research has been conducted on the chemical components of COR, including phenolic and their glycosides , triterpenoid glycosides , lignans and their glycoside s, and Cl-containing compounds, etc .
C. orchioides Gaertn is mostly wild, mainly distributed in Sichuan, Zhejiang, Guangdong and other places in China, there are no cultivation and planting bases, with limited resources and low yields. The formula of a hot-selling health care product contains COR, which is in great demand, and the wild resources of COR are gradually depleted. The imbalance between supply and demand has led to an increase of counterfeit. According to market research, C. glabrescens Rhizoma (CGR), which originated from Vietnam, is a major counterfeit. Furthermore, there are lack of pharmacological activities and clinical evidences of CGR, only a new compound crassifoside H and free radical scavenging activity have been reported . The safety and effectiveness of CGR are still controversial. Nevertheless, it is difficult to identify accurately the COR and CGR. C. orchioides Gaertn and C. glabrescens (Ridl.) Merr. belong to the same family and genus, with close plant relationships and high genetic similarity , on the other hand, the plant identification characteristics of C. glabrescens (Ridl.) Merr. are smooth and glabrous on the back of leaves. However, the appearance of the CGR is similar to the COR. Thus, it is necessary to establish a quick and accurate method to distinguish the two medicines.
The 2020 edition of the PPRC only includes COR, and stipulates that the content of curculigoside is not less than 0.10%. Preliminary research found that the existing standards of the PPRC could not accurately distinguish CGR and COR through microscopic characteristics, TLC, and curculigoside content. A chemical fingerprint/characteristic defines an unique pattern of a herb and reflects the presence of multiple chemical constituents. This approach follows the fundamental holistic theory of traditional Chinese medicines as major and minor chemical constituents are analyzed simultaneously in herbal sample [15, 16]. This method may contribute to evaluate herbal medicine, quality, safety and effectiveness. High performance liquid chromatography (HPLC) is the most popular analytical method in separation science and is regarded as one of the gold standard in the authentication of pharmaceutics and herbal medicines due to its good precision, sensitivity and reproducibility . Compared with traditional morphological and microscopic identification methods, the HPLC method is relatively faster and more accurate.
Based on that, in this study, in order to distinguish COR and CGR more accurately and conveniently, HPLC method was used to analyze their components. A characteristic component from CGR was discovered for the first time, and was systematically separated and purified. The structure was identified as 5-(3',4'-dihydroxyphenyl)-1-(4''-hydroxyphenyl) pentane-1,4-dione, it was a new neolignans and named glabrescenin (Fig. 3). Therefore, the HPLC method we used could establish a characteristic chromatography of CGR, which can distinguish between COR and CGR. The novel compound and characteristic chromatography discovered in this study could effectively identify CGR, and provided technical reference and support for the correct medication, market norms and healthy development of COR.