Thesis (M.Sc.)--Chulalongkorn University, 2012

Datura metel L. var. metel and Datura metel L. var. fastuosa (Thai name Lamphong- Khaao and Lam-Phong-Ka-Sa-Lak, respectively) are indigenous herb in genus Datura, that can be found in Southeast Asia, including Thailand. They have a long history of usage in folkloric medicine as parasympatholytic and mydriatic agents. Their pharmacological actions are due to tropane alkaloids, namely hyoscine (scopolamine) and hyoscyamine/atropine, presented in all parts of the plant. Due to the limited data in these medicinal plants, the purpose of this study is to evaluate the characteristics of D. metel L. var. metel and D. metel L. var. fastuosa by microscropic and molecular technique, including their scopolamine contents. According to the results, macroscopic and microscopic analysis of these plants revealed the different morphology and almost similar of stem and midrib cross section. The constant values of leaves (stomatal number, stomata index and palisade ratio), which are the important property for species identification showed different constant numbers. The PCR amplification of ITS region generated the PCR product approximately 670 bp in size, which indicated 99-100% homology. There are two polymorphisms within the 5.8S region, four polymorphisms within the ITS2. The two positions of single nucleotide polymorphism (SNP) were shown at positions 512 and 614 of ITS2 region could be classified these closely related plants.The PCR amplification of rbcL, and atpB region generated the PCR product approximately 1.5 kp in size, which indicated 95-100% and 94-99 % homology, respectively. In this study, the scopolamine contents of two varieties of D. metel L. were compared by TLC image and HPLC method. The comparison of two methods showed good correlation. The results of this study showed the most of scopolamine content in flower part of D. metel L. var. metel, while D. metel L.var. fastuosa showed the most of scopolamine content in fruit part, respectively. According to these evidences, the combinations of macroscopic, constant values of leaves and molecular method are able to authenticate these closely related plants and both of them have a potency to be a source of scopolamine production.