2189-80-2Relevant articles and documents
Cloning and characterization of oxidosqualene cyclases from Kalanchoe daigremontiana: Enzymes catalyzing up to 10 rearrangement steps yielding friedelin and other triterpenoids
Wang, Zhonghua,Yeats, Trevor,Han, Hong,Jetter, Reinhard
experimental part, p. 29703 - 29712 (2011/10/31)
The first committed step in triterpenoid biosynthesis is the cyclization of oxidosqualene to polycyclic alcohols or ketones C30H50O. It is catalyzed by single oxidosqualene cyclase (OSC) enzymes that can carry out varying numbers of carbocation rearrangements and, thus, generate triterpenoids with diverse carbon skeletons. OSCs from diverse plant species have been cloned and characterized, the large majority of them catalyzing relatively few rearrangement steps. It was recently predicted that special OSCs must exist that can form friedelin, the pentacyclic triterpenoid whose formation involves the maximum possible number of rearrangement steps. The goal of the present study, therefore, was to clone a friedelin synthase from Kalanchoe daigremontiana, a plant species known to accumulate this triterpenoid in its leaf surface waxes. Five OSC cDNAs were isolated, encoding proteins with 761-779 amino acids and sharing between 57.4 and 94.3% nucleotide sequence identity. Heterologous expression in yeast and GC-MS analyses showed that one of the OSCs generated the steroid cycloartenol together with minor side products, whereas the other four enzymes produced mixtures of pentacyclic triterpenoids dominated by lupeol (93%), taraxerol (60%), glutinol (66%), and friedelin (71%), respectively. The cycloartenol synthase was found expressed in all leaf tissues, whereas the lupeol, taraxerol, glutinol, and friedelin synthases were expressed only in the epidermis layers lining the upper and lower surfaces of the leaf blade. It is concluded that the function of these enzymes is to form respective triterpenoid aglycones destined to coat the leaf exterior, probably as defense compounds against pathogens or herbivores.
Taraxer-14-en-3β-ol, an Anti-Inflammatory Compound from Sterculia foetida L.
Naik,Mujumdar,Waghole,Misar,Annie Bligh,Bashall, Alan,Crowder, John
, p. 68 - 69 (2007/10/03)
Taraxer-14-en-3β-ol (1) was shown to be the active ingredient in the leaves of Sterculia foetida L. The alcohol 1, its acetate and ketone showed anti-inflammatory activity against TPA induced mouse ear oedema with inhibition ratios of 60.0, 58.57 and 40.57 at 0.5 mg/ear, respectively. The percentage inhibition of inflammation increased with dose for each compound.
Chemical Constituents of Stem Bark of Magnifera indica Linn. (Cultivar Desi)
Sharma, S. K.,Ali, M.
, p. 339 - 342 (2007/10/03)
The structure of mangdesisterol, mangfarnasoic acid and mangeudesmenone, isolated from the stem bark of Mangifera indica variety Desi, are reported along with characterisation of some minor constituents.
REDUCTION OF KETONES TO EPIMERIC ALCOHOLS WITH POTASSIUM HYDROXIDE-DIETHYLENE GLYCOL
Pradhan, B. P.,Hassan, A.,Ray, T.
, p. 2513 - 2516 (2007/10/02)
Triterpenoid ketones have been reduced to epimeric alcohols on boiling with potassium hydroxide in diethylene glycol. α,β-unsaturated ketone furnished saturated epimeric alcohols.
Wagner-Meerwein Rearrangement in Taraxerol
Anjaneyulu, A. S. R.,Prasad, A. V. Rama
, p. 443 - 445 (2007/10/02)
Dehydration of taraxerol (I) with POCl3 gives an anhydro product which is different from the anhydro product obtained earlier by other methods.Its structure is established as A-nor-Δ5,14-taraxadiene (VI) by a study of its physical and spectroscopic data.Solvolysis of taraxerol-3β-tosylate (Ib) affords the same anhydro compound (VI) along with taraxerol-3β-acetate (Ia).Dehydration of taraxerol (I) with PCl5 is found to give A-nor-3,4-dichloro product (VII).The reactions are rationalised on the basis of conformation and ring strain in the molecule.