C. Anhalonidine
Biological Source It is invariably obtained from the mescal buttons, the buds of Lophophora williamsii (Lemaire) Coult. (Anhalonium lewinii Henn.) belonging to the natural order Coctaceae.
Chemical Structure
1, 2, 3, 4-Tetrahydro-6, 7-dimethoxy-1-methyl-8-isoquinolinol; (C12H17NO3).
Characteristic Features
1. It is mostly obtained as small octahedral crystals from benzene having mp 160-161°C.
2. Its uvmax (ethanol) is 270 nm (log € 2.81).
3. Its aqueous solution acts as a strong base.
4. It is freely soluble in water, ethanol, chloroform and hot benzene; sparingly soluble in ether; and practically insoluble in petroleum ether.
5. It has been observed that the solutions of anhalonidine acquire a reddish colouration on standing.
Uses It may be used as a mild hallucinogen.
Biosynthesis of Anhalamine, Anhalonine and Anhalonidine Interestingly, the two additional C-atoms present in anhalonidine and anhalonine are provided by pyruvate; whereas, the C-atom for anhalamine is supplied by glyoxylate, as shown below. However, in each instance, a carboxyl group is lost from this aforesaid additional precursor. The pyruvate i.e., the keto-acid eventually reacts with an appropriate phenylethylamine, in this particular instance the dimethoxy-hydroxy derivative, thereby yielding a Schiff Base. Further, a Mannich-like mechanism helps in the cyclization to produce the heterocyclic isoquinoline nucleus, whereby the mesomeric effect of an oxygen substituent caters for the nucleophilic site on the aromatic ring. Evidently, restoration of aromaticity via proton loss yields the tetrahydroquinoline nucleus, thus representing overall a biosynthetic equivalent of the Pictet-Spengler Isoquinoline Synthesis.* Subsequently, the carboxyl group is eliminated, not by means of a simple decarboxylation process, but via an unusual oxidative decarboxylation process that essentially involves the following steps, namely:
(i) First, producing the intermediate imine,
(ii) Secondly, subjecting to reduction yielding anhalonidine,
(iii) Thirdly, subjecting to methylation giving rise to anhalonine,
(iv) Fourthly, subjecting phenylethylamine precursor employing the glyoxylic acid instead of pyruvic acid generating anhalamine.
