Introduction Molecular Identification of Traditional Medicinal Materials

3.1 Introduction

Traditional medicines have been used worldwide for centuries, and over 80% of the world population use traditional medicines to maintain health and cure diseases [ 1 ]. A fundamental prerequisite for the proper delivery of healthcare with traditional medicines is the use of authentic herbal materials. When adulterants or erroneous substitutes are dispensed instead, they could compromise treatments or even cause adverse reactions. In the early 1990s in Belgium, rapidly progressive interstitial fibrosis and end-stage renal failure were observed in some 80 women taking a slimming regimen of herbal medicinal product made from various herbs including Fangji (Stephaniae Tetrandrae Radix) and Houpo (Magnoliae officinalis Cortex) [ 2 ] . It was later revealed that the herb Fangji was adulterated by another herb Guangfangji derived from Aristolochia fangchi which contains the carcinogenic aristolochic acids [ 3 ]. Many more cases of aristolochic acid nephropathy have subsequently been reported in many Western and Asian countries [ 4– 8 ]. In addition, substitution of the traditional medicinal herb Lingxiaohua (Campsis Flos) derived from Campsis grandiflora by a toxic herb Yangjinhua (Daturae Flos) derived from Datura metel caused four cases of herbal poisoning in Hong Kong [ 4 ]. In 1996, the herb Weilingxian (Clematidis Radix et Rhizoma) derived from Clematis species was substituted by a herb derived from Podophyllum hexandrum [ 9 ]. Subsequently, several poisoning cases were reported worldwide, drawing global attention to the severe side effects and life-threatening consequences of adulteration of medicinal materials and their products [ 10, 11 ]. Adulteration is due to: (1) erroneous adulteration caused by sharing of similar features or absence of distinguishable characters, (2) intentional substitution of high-value materials by inexpensive substances, (3) misuse caused by sharing of similar common names, and (4) historical use of local substitutes. In order to ensure safety, efficacy and quality of traditional medicines and their products, identification of medicinal materials is necessary.

There are a number of effective identification methods which evolve with the improvement of technologies. In the past, identification of medicinal materials is based on the description of morphological features as stated in Shengnong Bencaojing (~200 ad ). In a later record, Bencao Gangmu (1,593 ad), morphological features were graphically illustrated. Nowadays, morphological and microscopic features provide first-line identification of medicinal materials. These methods complemented with chemical profiles obtained from thin-layer chromatography (TLC), high-pressure liquid chromatography (HPLC), or liquid chromatography/mass spectrometry (LC/MS) are applied to increase the accuracy of identification.

In 1990s, the introduction of molecular techniques was a major breakthrough in the history of identification of traditional medicines. Recently, identification of living organisms, including medicinal materials, by DNA barcodes has been proposed [ 12– 15 ]. The DNA barcode initiative provides an international standard reference for organism identification. In the Pharmacopoeia of the People’s Republic of China (2010 edition), molecular techniques have been added as standard means of identification for three medicinal materials including Beimu (Fritillariae Cirrhosae Bulbus), Wushaoshe (Zaocys) and Qishe (Agkistrodon). It is foreseeable that molecular protocols will be included for more medicinal materials in future editions.

This chapter reviews and comments on the commonly used molecular authentication techniques. An account on the strategies and examples for identifying plant and animal medicinal materials at different taxonomic levels is also included.