title: Grayanane and leucothane diterpenoids from the leaves of Rhododendron micranthum.
abstract: Eleven grayanane diterpenoids, 1-epi-grayanotoxin IV, 1-epi-grayanotoxin II, 6-deoxy-1-epi-grayanotoxin XVII, 6-deoxygrayanotoxin XVII, 16-acetylgrayanotoxin II, 3-oxograyanotoxin IX, 14-deoxygrayanotoxin VIII, 14-acetylisograyanotoxin II, rhodomicranols C-E, and a leucothane diterpenoid, rhodomicranol F, together with eleven known diterpenoids were isolated from leaves of Rhododendron micranthum. Their structures were elucidated by spectroscopic analyses, with the absolute configurations of 1-epi-grayanotoxin IV and rhodomicranol C determined by single-crystal X-ray diffraction with Cu Kα radiation, and the structures of 14-acetylisograyanotoxin II and known grayanotoxins IX and X confirmed by single-crystal X-ray diffraction. All twenty-three diterpenoids were evaluated for their in vitro immunomodulatory activities, and none showed significant immunomodulatory activities in a dose-dependent manner. In addition, they are non-toxic to the murine lymphocytes in the general cytotoxicity assay.
authors.affiliation: Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China.
authors.forename: Mengke
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China.
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China.
authors.forename: Guanqun
authors.initials: G
authors.lastname: Zhan
authors.affiliation: Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China.
authors.forename: Liang
authors.initials: L
authors.lastname: Lei
authors.affiliation: Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China.
authors.forename: Penghua
authors.initials: P
authors.lastname: Shu
authors.affiliation: College of Natural and Computational Sciences, Hawaii Pacific University, Kaneohe, HI 96744, United States.
authors.forename: Yongli
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China.
authors.forename: Yongbo
authors.initials: Y
authors.lastname: Xue
authors.affiliation: Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China.
authors.forename: Zengwei
authors.initials: Z
authors.lastname: Luo
authors.affiliation: Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wan
authors.affiliation: Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China. Electronic address: gyap@mail.hust.edu.cn.
authors.forename: Guangmin
authors.initials: G
authors.lastname: Yao
authors.affiliation: Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China. Electronic address: zhangyh@mails.tjmu.edu.cn.
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray; D004224:Diterpenes / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification / Q000494:pharmacology; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification / Q000494:pharmacology; D008214:Lymphocytes / Q000187:drug effects; D051379:Mice; D008968:Molecular Conformation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D018515:Plant Leaves / Q000737:chemistry; D029793:Rhododendron / Q000737:chemistry*
chemical_list: D004224:Diterpenes; D004365:Drugs, Chinese Herbal
keywords: Absolute configuration; Ericaceae; Grayanane diterpenoids; Immunomodulatory activity; Leucothane diterpenoids; Rhododendron micranthum; Single-crystal X-ray diffraction