Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar structure may also be termed alkaloids. In addition to carbon, hydrogen and nitrogen, alkaloids may also contain oxygen or sulfur. Rarer still, they may contain elements such as phosphorus, chlorine, and bromine.
β-Carboline (9H-pyrido[3,4-b]indole) represents the basic chemical structure for more than one hundred alkaloids and synthetic compounds. The effects of these substances depend on their respective substituent. Natural β-carbolines primarily influence brain functions but can also exhibit antioxidant effects. Synthetically designed β-carboline derivatives have recently been shown to have neuroprotective, cognitive enhancing and anti-cancer properties.
Isoquinoline is an individual chemical specimen - a heterocyclic aromatic organic compound - as well as the name of a family of many thousands of natural plant alkaloids, any one of which might be referred to as "an isoquinoline". It is a structural isomer of quinoline. Isoquinoline and quinoline are benzopyridines, which are composed of a benzene ring fused to a pyridine ring. In a broader sense, the term isoquinoline is used to make reference to isoquinoline derivatives. 1-Benzylisoquinoline is the structural backbone in many naturally occurring alkaloids such as papaverine. The isoquinoline ring in these natural compound derives from the aromatic amino acid tyrosine.
The Pictet–Spengler reaction is a chemical reaction in which a β-arylethylamine undergoes condensation with an aldehyde or ketone followed by ring closure. The reaction was first discovered in 1911 by Amé Pictet and Theodor Spengler. Traditionally, an acidic catalyst in protic solvent was employed with heating; however, the reaction has been shown to work in aprotic media in superior yields and sometimes without acid catalysis. The Pictet–Spengler reaction can be considered a special case of the Mannich reaction, which follows a similar reaction pathway. The driving force for this reaction is the electrophilicity of the iminium ion generated from the condensation of the aldehyde and amine under acid conditions. This explains the need for an acid catalyst in most cases, as the imine is not electrophilic enough for ring closure but the iminium ion is capable of undergoing the reaction.
Menispermaceae is a family of flowering plants. The alkaloid tubocurarine, a neuromuscular blocker and the active ingredient in the 'tube curare' form of the dart poison curare, is derived from the South American liana Chondrodendron tomentosum. Several other South American genera belonging to the family have been used to prepare the 'pot' and 'calabash' forms of curare. The family contains 78 genera with some 440 species, which are distributed throughout low-lying tropical areas with some species present in temperate and arid regions.
Stephania tetrandra is a herbaceous perennial vine of the family Menispermaceae native to China and Taiwan. It grows from a short, woody caudex, climbing to a height of around three meters. The leaves are arranged spirally on the stem, and are peltate, i.e. with the leaf petiole attached near the centre of the leaf. Its root is used in traditional Chinese medicine (TCM).
Tetrahydropalmatine (THP) is an isoquinoline alkaloid found in several different plant species, mainly in the genus Corydalis, but also in other plants such as Stephania rotunda. These plants have traditional uses in Chinese herbal medicine. The pharmaceutical industry has synthetically produced the more potent enantiomer Levo-tetrahydropalmatine (Levo-THP), which has been marketed worldwide under different brand names as an alternative to anxiolytic and sedative drugs of the benzodiazepine group and analgesics such as opiates. It is also sold as a dietary supplement.
Substitution of the heterocycle isoquinoline at the C1 position by a benzyl group provides 1‑benzylisoquinoline, the most widely examined of the numerous benzylisoquinoline structural isomers. The 1-benzylisoquinoline moiety can be identified within numerous compounds of pharmaceutical interest, such as moxaverine; but most notably it is found within the structures of a wide variety of plant natural products, collectively referred to as benzylisoquinoline alkaloids. This class is exemplified in part by the following compounds: papaverine, noscapine, codeine, morphine, apomorphine, berberine, tubocurarine.
Bibenzyl is the organic compound with the formula (C6H5CH2)2. It can be viewed as a derivative of ethane in which one phenyl group is bonded to each carbon atom. It is a colorless solid.
Amurensine is an alkaloid found in Papaver species such as P. alpinum, P. pyrenaicum, P. suaveolens, and P. tatricum and P. nudicaule. It is a member of the isoquinoline group.
Akuammicine is a monoterpene indole alkaloid of the Vinca sub-group. It is found in the Apocynaceae family of plants including Picralima nitida, Vinca minor and the Aspidosperma.
Sibiricine is a bioactive isoquinoline alkaloid isolated from Corydalis crispa (Fumariaceae), which is a Bhutanese medicinal plant from the Himalayas.
Corydaline is an acetylcholinesterase inhibitor isolated from Corydalis yanhusuo.
Gigactonine is a naturally occurring diterpene alkaloid first isolated from Aconitum gigas. It occurs widely in the Ranunculaceae plant family. The polycyclic ring system of this chemical compound contains nineteen carbon atoms and one nitrogen atom, which is the same as in aconitine and this is reflected in its preferred IUPAC name.
(S)-Magnoflorine is a quaternary benzylisoquinoline alkaloid (BIA) of the aporphine structural subgroup which has been isolated from various species of the family Menispermaceae, such as Pachygone ovata,Sinomenium acutum, and Cissampelos pareira.
Aknadinine is an opioid alkaloid isolated from members of the genus Stephania. Structurally it is a member of the hasubanan family of alkaloids and features an isoquinoline substructure.
Erysodienone is a key precursor in the biosynthesis of many Erythrina-produced alkaloids. Early work was done by Derek Barton and co-workers to illustrate the biosynthetic pathways towards erythrina alkaloids. It was demonstrated that erysodienone could be synthesized from simple starting materials by a similar approach as its biosynthetic pathway, which led to the development of the biomimetic synthesis of erysodienone.
Tuticorin Raghavachari Govindachari FNA, FASc (1915–2001), popularly known as TRG, was an Indian natural product chemist, academic, institution builder and the principal of Presidency College, Chennai. He was known for his studies on the synthesis of isoquinolines and phenanthridines and his contributions in elucidating the structure of several plant constituents. He was an elected fellow of the Indian Academy of Sciences and the Indian National Science Academy and was the nominator of Robert Burns Woodward who won the 1965 Nobel Prize in Chemistry. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards, in 1960, for his contributions to chemical sciences, making him the first recipient of the award in the chemical sciences category.
Isoquinoline alkaloids are natural products of the group of alkaloids, which are chemically derived from isoquinoline. They form the largest group among the alkaloids.
Voacristine is a indole alkaloid occurring in Voacanga and Tabernaemontana genus. It is also an iboga type alkaloid.
