Monoterpene alkaloids known

Sammes and his group (77JCS(P1)663 78JCS(P1)1293 81JCS(P1)1909) attempted the thermal intramolecular cycloaddition of the substituted pyrimidine 507 possessing an alkyne to produce a monoterpene alkaloid ( )-actinidine (511)(Scheme 64). Upon thermolysis of the pyrimidine 507 at 200°C in a sealed tube, using dimethylformamide as solvent, intramolecular cycloaddition led to the known pyridone 509 in 87% yield by the loss of the amide bridge from intermediate 508. Conversion of the pyridone 509 into the chloropyridine followed by reductive dechlorination afforded racemic actinidine 511. 

Although a variety of monoterpene alkaloids and some sesquiterpene alkaloids are known, they are of little... 

No article was found reporting anxiolytic activity of phenolic acids. However, the anxiolytic activity of the alkaloids is known. Anxiolytic properties may be a crucial feature of newer antipsychotics associated with the improvement of negative symptoms in schizophrenic patients. The indole alkaloid alstonine acts as an atypical antipsychotic in behavioral models, but differs in its dopamine and serotonin binding profile [310]. Behavioral effects of psychollatine, a glycoside indole monoterpene alkaloid isolated from Psychotria umbellate Thoim., was investigated in models of anxiety, depression, memory, tremor, and... 

Kopsia macrophylla provided two more new monoterpene alkaloids, kopsilactone (51) and kopsone (52), in addition to the known compounds 5,22-dioxokopsane, dregamine, akuammiline, tabemaemontanine, deacetylakuammiline, norpleiomutine and kopsolTine [56]. 

A new monoterpene alkaloid, kinabalurine G (330) has been obtained from the leaf extract of Kopsia dasyrachis in addition to 11 known alkaloids and the novel pentacyclic indole, danuphylline vide infra) [223]. Analysis of the spectral data allowed assignment of the gross structure as well as determination of the stereochemistry at the various centers. Kinabalurine G (330) is the AZ-oxide of 9-hydroxy-S-skytanthine, which is unknown, although a 9-hydroxy-skytanthine of unknown stereochemistry has been previously reported from Tecoma stans [224]. 

The leaves of Tecoma stans (Bignoniaceae) were studied previously (1) because of their reputed antidiabetic properties, which appear to have been traced to the monoterpene alkaloid fraction. Further studies of this plant by Lins and D arc Felicio (42) have now revealed the presence of two new alkaloids, 7-hydroxy-5,6-dehydroskytanthine (58) and 4-hydroxy-tecoman-ine (59), in the fruits of T. stans. In addition, two known alkaloids, 5/3-hydroxy-skytanthine (44) and tecomanine (55) were obtained. H and 13C NMR data for these known alkaloids were reported for the first time. 

Skaltsounis and co-workers have recently reported (27) on the isolation of several monoterpene alkaloids from the New Caledonian plant Osmanthus austrocaledonica in the family Oleaceae. Four of the alkaloids were known and two were new. All of the alkaloids were produced when either ammonia or Na2C03 was used in the extraction process. The known alkaloids were 4-methyl-5,5 -[(l-methyltrimethylene)di](methylnicotinoate) (98) (28), 4,4 -bis-methyl-5,5 -[(1 -methyltrimethylene)di] (methylnicotinoate) (99)... 

The reisolations of the known monoterpene alkaloids are given in Table II (113-165). Some comments are worthy of mention with respect to certain of these isolations, particularly the frequent use of ammonia in the isolation process. 

In the previous summary of the monoterpene alkaloids (2), many of the properties of the alkaloids then known were presented. In this chapter, some references to and examples of the various physical data for the monoterpene alkaloids were discussed as the information for the various newly isolated alkaloids was examined. Table III summarizes the more recently available information for the known alkaloids, as well as those alkaloids discussed for the first time in this review. 

The iridodial intermediate can also suffer a well known transamination reaction, followed by intramolecular Schiff base formation, giving rise to the formation of 3-azabicyclo[4.3.0]nonane-type skeleton, typical of monoterpene alkaloids. 

The parent compound of the secoiridoids is secologa-nin (see secoiridoids), the most important intermediate in the biogenesis of alkaloids that are not derived from an amino acid. This includes most indole alkaloids, the ipecac, the Cinchona, and the pyrroloquinoline alkaloids as well as simple monoterpene alkaloids The best known biological property of the I. is their bitter taste. However, bitter principles are mostly not used as pure substances, instead alcoholic extracts are preferred to stimulate appetite (increased secretion of gastric juice). Furthermore, bitter substances are used to modify the taste of pharmaceutical products. Some I. exert various effects on the central nervous system as a consequence of their volatility and lipophilicity, e.g., nepetalactone, iridodial, teucrium lactones, and valepotriates. 

Overall, however, the immensity of temperate land corresponds to a most various secondary metabolic production, different from that of tropical land. The most renowned alkaloids belong to the morphine class (Chart 6.2.A1), and, in combination with isoprenoids, to the ergot and triterpene classes (Chart 6.2. A2). Prominent in the peptides are the cyclosporins (the first of which was isolated from a fiingus collected in Norway), streptogramins, and P-lactams (Chart 6.2.P). The isoprenoids are represented by pyrethrin monoterpenes, cedrane sesquiterpenes, ginkgolide and taxane diterpenes, ophiobolane sesterterpenes, and arborane and amyrin-like triterpenes (Chart 6.2.1). In the polyketides, epothilones, recently discovered from Myxobacteria, and the long known rapamycin, are two prominent classes of macrolides (Chart 6.2.FA/PO/C). 

There is a small group of alkaloids related to the iridane monoterpenes which have the general structure (86). The synthesis of a new representative, valerianine (86 R = OMe), found in Valeriana officinalis L., has been described (Scheme 2), and an isomer (87) of the known actinidine (86 R = H) has been made from citronellonitrile (88) (Scheme 3). Thin-layer chromatography of V. officinalis extracts shows 12 zones whose constituents react with DragendorfTs reagent. ... 

Several monoterpene-indole alkaloids are known in which 3-hydroxylation of the indole system has been followed by cyclisation on to the a-position [e.g., (64)]. 

Methylcyclopentanoid monoterpenes are a group of isoprenoids characterised by the presence in their skeleton of a cyclopentanoid residue. Both hydrophilic and hydrophobic compounds are known (refs 1-3 ), which may be both volatile and non volatile. Products of alkaloidal nature (ref 4 ) are also included in this family. 

Secologanin is probably one of the best known secoiridoids, being the monoterpenic key intermediate in the biogenesis of indole and related alkaloids. 

Biosynthesis A. is formed from tryptamine and the monoterpene secologanin (see secoiridoids) via stric-tosidine, catalysed by ca. 10 known enzymes (see also figure under monoterpenoid indole alkaloids). 

Alkaloids that possess an aromatic pyridine ring often are called pyridine alkaloids (Leete, 1980 Pinder, 1993 Strunz and Findlay, 1985) approximately 250 alkaloids of this type are known (Verpoorte et al., 1991). Although many are derived from nicotinic acid (Fig. 28.18), others arise from aro-matization of piperidine alkaloids and other pathways (Waller and Nowacki, 1978). This chapter includes several of the most important compounds of this type, although others (such as a number of monoterpene-derived alkaloids, Nu-phar alkaloids, and sesquiterpene alkaloids of the Celastra-ceae) are discussed in Chapter 36. 

T.a. are biosynthesized from mevalonic acid, but the origin of the nitrogen is not known. They therefore differ from the iridoid, isoquinoline and indole alkaloids, in which a monoterpene is linked to an amino acid. 

Mono- and sesquiterpenes are the main constituents of the essential oils, while the other terpenes are constituents of balsams, resins, waxes, and rubber. Oleoresin is a roughly equal mixture of turpentine (85 % Cio-monoterpenes and 15 % C15- sesquiterpenes) and rosin (C2o-diterpene) that acts in many conifer species as a toxic material to invading insects and their pathogenic fungi [12]. A number of angiosperm species have inducible terpenoid defensive compounds (phytoalexins) [13]. These include both sesquiterpenoid and diterpenoid t)pes. Isoprenoid units are also found within the framework of other natural molecules. Thus, indole alkaloids, several quinones (vitamin K), alcohols (vitamin E, vitamin A formed from p-carotene), phenols, and isoprenoid alcohols (also known as terpenols or polyprenols) also contain terpenoid fragments. The biogenesis. 

The Madagascar periwinkle Catharanthus roseus, Apocynaceae, formerly known as Vmca rosea) is a small subshrub or herbaceous plant native to Madagascar. It contains about 130 monoterpene indole alkaloids of different subclasses (vanderHeijden et ah, 2004). Nowadays, C. roseus occurs worldwide in subtropical and tropical regions. It is cultivated as an ornamental plant, but it has also found application in the folk medicine of various countries. Because the plant was used as an antidiabetic in Jamaica, it was screened for hypoglycaemic activity by Eli-Lilly, USA, and the Cancer Research Center,... 

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