Pharmacognosy Journal | December 2010 | Vol 2 | Issue 17 1 ORIGINAL ARTICLE PHCOG J. *Address for correspondence: E-mail: pywgs@mahidol.ac.th DOI: **** Microscopic Characterization as a Tool for Separation of Stemona Groups Sumet Kongkiatpaiboon 1 , Vichien Keeratinijakal 2,3 and Wandee Gritsanapan 1, * 1 Department of Pharmacognosy, Faculty of Pharmacy, Mahidol University, Bangkok, 10400 2 National Center for Agricultural Biotechnology, Kasetsart University, Bangkok, 10900 3 Agronomy Department, Faculty of Agriculture, Kasetsart University, Bangkok, 10900, Thailand ABSTRACT: Introduction: Stemona plants have been traditionally used as an insecticide, scabicide and pediculocide, and for the treatment of skin and respiratory diseases. Stemona can be separated into two groups according to their morphological characters and bioactive components i.e. stichoneurine and protostemonine groups. Protostemonine group contains alkaloids that possess potent insecticidal activity while stichoneurine group accumulates alkaloids with antitussive activity. In Thailand, a vernacular name “Non Tai Yak” refers to the roots of different species of Stemona, making it confusing to discern different species. The purposes of this study are to investigate the microscopic characteristics of the roots of seven species of Stemona growing in Thailand and to distinguish and identify these groups of Stemona. Methods: Cross-sectional histology of fresh root samples and powdered drug characteristics of 7 species of Stemona were studied under a microscope. Results: The roots of Stemona in the stichoneurine group (S. tuberosa and S. phyllantha) contained a non-lignifed large pith while the roots of protostemonine group (S. burkillii, S. cochinchinensis, S. collinsiae, S. curtisii and S. kerrii) had a small lignifed one. The powder of stichoneurine group contained numerous thin-walled parenchyma, but only few thick-walled parenchyma and lignifed fbers and vessels were present. In contrast, thick-walled parenchyma and lignifed fbers and vessels were frequently found in the powdered roots of protostemonine Stemona. These characteristics could be used to discern between Stemona in the stichoneurine and protostemonine groups. Conclusions: The microscopic characterizations can be used as a primary tool to categorize and separate 2 main Stemona groups. Key words: Non Tai Yak, protostemonine, Stemona, Stemonaceae, stichoneurine INTRODUCTION Since ancient time, Stemona plants have been traditionally used as an insecticide, scabicide, pediculocide; used for treating skin and respiratory diseases, and also for killing head lice. [1-3] “Non Tai Yak” is a Thai vernacular name that refers to various species of Stemona in Thailand [4] and some other plants such as Asparagus sp. of the family Asparagaceae and Clitoria sp. of the family Leguminosae in some locations. [1] This plant has been used to protect plants against insect attack, the infection of fermented fsh “Pla Raa” or fermented shrimp “Ka Pi” from housefy larvae. The inconsistency when providing and using the proper Stemona plant materials has led to the confusion in the scientifc identifcation and in agricultural and pharmaceutical uses. [1] Recent taxonomic revision of the family Stemonaceae indicates that Stemona in Thailand comprises of 11 known species i.e. S. aphylla Craib, S. burkillii Prain, S. cochinchinensis Gagnep., S. collinsiae Craib, S. curtisii Hk. F., S. involuta Inthachub, S. kerrii Craib, S. phyllantha Gagnep., S. pierrei Gagnep., S. rupestris Inthachub and S. tuberosa Lour. [5] They can be separated into two main groups according to their morphological characters and bioactive component accumulation i.e. stichoneurine or tuberosa group and protostemonine or non-tuberosa group. [6] Stichoneurine group comprises of S. tuberosa and S. phyllantha and they are different from other Stemona plants because of their large and thick tuberous roots, large perianths and scented fowers. [5,6] However, the three dominant species of Stemona (S. tuberosa, S. collinsiae and S. curtisii) and some other species of Stemona in Thailand are still called “Non Tai Yak”, making it confusing and causing misuses of these plants. Phytochemical investigations of Stemona species revealed the presence of alkaloids, stilbenoids and chromenols. The