The authors are grateful to the 90th anniversary of Chulalongkorn
University Fund (Ratchadaphiseksomphot Endowment Fund) for financial support. We also thank Ms. Suttira Khumkratok,Walai Rukhavej Bo-
tanical Research Institute, Mahasarakham University, Mahasarakham
44000, Thailand for identification and deposition of the plant material.