Conophylline is a

autophagy Autophagy (or autophagocytosis; from the Ancient Greek , , meaning "self-devouring" and , , meaning "hollow") is the natural, conserved degradation of the cell that removes unnecessary or dysfunctional components through a lysosome-dependent re ...

inducing

vinca alkaloid ''Vinca'' alkaloids are a set of anti-mitotic and anti-microtubule alkaloid agents originally derived from the periwinkle plant ''Catharanthus roseus'' (basionym ''Vinca rosea'') and other ''vinca'' plants. They block beta-tubulin polymerizatio ...

found in several species of ''

Tabernaemontana ''Tabernaemontana'' is a genus of flowering plants in the family Apocynaceae. It has a pan-tropical distribution, found in Asia, Africa, Australia, North America, South America, and a wide assortment of oceanic islands. These plants are evergreen ...

'' including '' Ervatamia microphylla'' and ''

Tabernaemontana divaricata ''Tabernaemontana divaricata'', commonly called pinwheel flower, crape jasmine, East India rosebay, and Nero's crown, is an evergreen shrub or small tree native to South Asia, Southeast Asia and China. In zones where it is not hardy it is grown a ...

''. Among its many

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest ...

s is an

epoxide In organic chemistry, an epoxide is a cyclic ether () with a three-atom ring. This ring approximates an equilateral triangle, which makes it strained, and hence highly reactive, more so than other ethers. They are produced on a large scale for ...

: the compound where that ring is replaced with a double bond is called conophyllidine and this co-occurs in the same plants.

History

Conophylline and conophyllidine were first reported in 1993 after isolation from the ethanol extract of leaves of ''Tabernaemontana divaricata''. Their structures were confirmed by

X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

. The class of vinca alkaloids to which these compounds belong also contains

vincristine Vincristine, also known as leurocristine and marketed under the brand name Oncovin among others, is a chemotherapy medication used to treat a number of types of cancer. This includes acute lymphocytic leukemia, acute myeloid leukemia, Hodgkin's ...

and

vinblastine Vinblastine (VBL), sold under the brand name Velban among others, is a chemotherapy medication, typically used with other medications, to treat a number of types of cancer. This includes Hodgkin's lymphoma, non-small cell lung cancer, bladder ca ...

, well-known therapeutic agents for human cancers, so they were candidates for a number of biochemical assays to see if they had useful biological activity. By 1996, conophylline it had been reported to inhibit tumours in rats by its action on Ras-expressing cells. This finding did not lead to a useful drug but the molecule continues to be investigated for its biological properties.

Synthesis

Biosynthesis

As with other

Indole alkaloids Indole alkaloids are a class of alkaloids containing a structural moiety of indole; many indole alkaloids also include isoprene groups and are thus called terpene indole or secologanin tryptamine alkaloids. Containing more than 4100 known differe ...

, the biosynthesis of conophylline and conophyllidine starts from the

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α- carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic ...

. This is converted into

strictosidine Strictosidine is a natural chemical compound and is classified as a glucoalkaloid and a vinca alkaloid. It is formed by the Pictet–Spengler condensation reaction of tryptamine with secologanin, catalyzed by the enzyme strictosidine synthase. ...

before further elaboration and dimerisation.

Chemical synthesis

Fukuyama and coworkers published a total synthesis of conophylline and conophyllidine in 2011. Their strategy was to couple two

indoline Indoline is an aromatic heterocyclic organic compound with the chemical formula C8H9N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing ring. The compound is based on the indole st ...

-containing fragments using a type of

Polonovski reaction In chemistry, an amine oxide, also known as an amine ''N''-oxide or simply ''N''-oxide, is a chemical compound that contains the functional group , a nitrogen-oxygen coordinate covalent bond with three additional hydrogen and/or substituent-grou ...

. The synthesis was challenging owing to the eleven

stereogenic center In stereochemistry, a stereocenter of a molecule is an atom (center), axis or plane that is the focus of stereoisomerism; that is, when having at least three different groups bound to the stereocenter, interchanging any two different groups cr ...

s which have to be controlled. The final products are

chiral Chirality is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable from ...

, and

laevorotary Optical rotation, also known as polarization rotation or circular birefringence, is the rotation of the orientation of the plane of polarization about the optical axis of linearly polarized light as it travels through certain materials. Circul ...

Natural occurrence

Conophylline and conophyllidine are found in species of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

'' including '' Ervatamia microphylla'' and ''

''. The latter species is known to produce many other alkaloids including

catharanthine Catharanthine is a terpene indole alkaloid produced by the medicinal plant ''Catharanthus roseus'' and '' Tabernaemontana divaricata''. Catharanthine is derived from strictosidine, but the exact mechanism by which this happens is currently unknow ...

ibogamine Ibogamine is an anti-convulsant, anti-addictive, CNS stimulant alkaloid found in ''Tabernanthe iboga'' and Crepe Jasmine (''Tabernaemontana divaricata''). Basic research related to how addiction affects the brain has used this chemical. Ibogam ...

and

voacristine Voacristine is a indole alkaloid occurring in '' Voacanga'' and ''Tabernaemontana'' genus. It is also an iboga type alkaloid. Chemistry Its structure is almost similar to voacangine, an alkaloid used in semi-synthesis of ibogaine. Compared to ...

References