Steroidal alkaloid

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Chemical structure of solanidine, a steroidal alkaloid found in potatoes Solanidine.svg
Chemical structure of solanidine, a steroidal alkaloid found in potatoes

Steroidal alkaloids have the basic steroidal skeleton with nitrogen-based functional groups attached to the skeleton. More specifically, they are distinguished by their tetracyclic cyclopentanoperhydrophenanthrene skeleton that marks their close relationship with sterols. [1] They fall in two major categories: Solanum alkaloids and Veratrum alkaloids. [1] A Steroidal alkaloid has also been found in Chonemorpha fragrans (Frangipani vine), 'chonemorphine' was used to treat intestinal infections in Wistar rats. (Chatterjee DK et al (1987) Parasitol Res 74, 1, 30-33). [2]

Contents

Examples

Apocynaceae steroid alkaloids

The family of apocynaceae alkaloids can be categorized based on their backbone structure, which may include the 5α-pregnane, Δ5-pregnane, or conanine backbone. Typically, these alkaloids feature an amino group or an oxygen compound at the 3rd carbon atom. An illustrative example is latifolinin, which is derived from the conanine backbone. This distinctive structure is characterized by a five-membered ring formed by an amino group bonded to both the 18th and 20th carbon atoms. [3] [4] [5]

Latifolinin is a compound that is naturally present in the bark of Funtumia latifolia. Additionally, the leaves of this plant contain two other compounds, namely funtumin and funtumidin. These compounds belong to the Apocynaceae steroid alkaloids family and share the 5α-pregnan backbone structure. [4]

Batrachotoxins

Batrachotoxins are neurotoxins that are naturally occurring on the dermal surface of poison dart frogs. The photo shows the Phyllobates terribilis. [7] Batrachotoxins share a structural foundation with pregnanes, consisting of 21 carbon atoms, and are distinctive for the amino group attached to the 18th carbon atom, exemplified by batrachotoxin A (see image). [7] [3]

Bufotoxins

The bufotoxins are named after the genus of Bufo. The α-pyranones at the 17th carbon atom are specific for the bufotoxins. The bufotoxin shown here is a sterane derivative with an α-pyranone at the 17th carbon atom and an esterified succinic acid at the 3rd carbon atom with arginine attached. [9]

Buxus steroid alkaloids

Buxus steroid alkaloids are present in the leaves of the common boxwood (Buxus sempervirens). This plant primarily thrives in southern and central Europe. These alkaloids are characterized by an amino group attached to the 3rd and/or 20th carbon atom. Methylation of the amino groups can be partial, complete, or absent. Buxus steroid alkaloids constitute a substantial group of bases, most of which can be categorized into three distinct groups.

Another subgroup of Buxus steroid alkaloids possesses a tetracyclic structure. In these compounds, a bond exists between the 9th and 19th carbon atoms, forming a seven-membered ring (ring B). Buxamine E serves as an example of this group.

The third major group is distinguished by the absence of additional carbon atoms bonded to the 4th carbon atom of the A ring. Buxandonin L is an illustrative member of this category.

The largest group consists of pentacyclic Buxus steroid alkaloids, featuring a core structure based on 4,4,14-trimethyl-9,19-cyclopregnan. Cyclobuxin D is a representative of this particular group. [3]

The Buxus steroid alkaloids buxamine E, buxandoline L, and cyclobuxin D are found in the leaves of common boxwood (buxus sempervirens). [13]

Salamander alkaloids

The toxic salamander alkaloids occur naturally in organisms classified within the genus Salamandra. These alkaloids are derived from 3-aza-A-homo-5β-androstane. One notable example is samandarin (see figure), which may serve as the primary alkaloid depending on the species, although it may not be present in some other organisms at all. Samandarin possesses a distinctive oxazolidine structure within the A ring. Besides samandarin, there are several other steroid alkaloids in Salamandra organisms such as samandaridin, samandarone, and cycloneosamandione. [15] [16] [17]

Solanum alkaloids

These compounds generally appear as their corresponding glycoside in plants of the genus Solanum. [20] Solanum includes plants like potatoes, tomatoes, and various nightshades [20] Starting with cholesterol, the biosynthesis of these compounds follow a similar general mechanism including hydroxylation, oxidation, and transamination before differentiating. [21] Alkaloids found in these plants include chaconine, solanine, solasodine, tomatidine, tomatine, and solanidine. [1] The Itkin group has found several of the biosynthetic gene clusters for these. [22] [23] In Itkin et al. 2011 and Itkin et al. 2013 they find several BSGs for α-tomatine in tomato and α-solanine in potato. [22] [23] Typically they are used in plants as a protection mechanism against animals. Due to the typical anti-cholinesterase activity, they can be used as poisons against the plants' predators. They can be used as starting materials for steroidal drugs. [1] There are various tests for identifying these alkaloids. The characteristic test involves dissolving the compound in hot amyl alcohol or ethanol and watching for the formation of a jelly-like product as the mixture cools. [1]

Solanidan skeleton

Steroidal alkaloids with a solanidan backbone exhibit a distinctive bicyclic structure, which replaces the cholesterol side chain on the D-ring. A notable example is solanocapsin, as discovered in the coral shrub (Solanum pseudocapsicum). [24]

Spirosolan backbone

Another category of solanum alkaloids is based on the spirosolane skeleton. In these compounds, the E-ring is a tetrahydrofuran to which a piperidine is directly attached via a spiro compound. An example of such a steroid alkaloid is tomatidenol, which is prevalent across various species within the genus Solanum. [26]

Veratrum alkaloids

Veratrum alkaloids of white/green chervil

The veratrum alkaloids derive their name from the white and green germer plants (Veratrum album and Veratrum viride, respectively). These plants belong to the Liliaceae family. Among them, procevin is a special case, as it features a nitrogen atom from piperidine connected to the 18th carbon.

Veratramine is an example of veratrum steroid alkaloids, characterized by a 22,26-epimino-14-abeo-cholestane ring system as their basis. [29] [30]

Veratrum alkaloids of sabadill

Veracevin is a member of the veratrum alkaloids group. However, this occurs in the sabadilla (Schoenocaulon officinale), which also belongs to the Liliaceae family. The veracevin is based on the cevan skeleton, in which the C-ring is a five-membered instead of a six-membered ring and the D-ring is a six-membered ring. Furthermore, the high number of hydroxy groups is still remarkable. [29] [30]

Veratrum alkaloids

True to their name, Veratrum alkaloids come from plants of the genus Veratrum. Alkaloids are found in the roots and rhizomes of these plants. [35] They include veratridine, cyclopamine, and jervine. [20] Because of their actions on the cardiovascular, neuromuscular, and respiratory systems, Veratrum alkaloids have been used for the treatment of various conditions like myasthenia gravis, hypotension, and eclampsia. [35]

Bioactivity

Steroidal alkaloids have been investigated for a wide range of potential bioactivities including antimicrobial, anti-inflammatory, anti-estrogenic, and chemotherapeutic [36] activity. These bioactivities are the result of a wide array of mechanisms across different compounds. For example, solasodine antimicrobial bioactivity is accomplished by interfering with the synthesis of genetic substances in Saccharomyces cerevisiae and Prototheca wickerhamii . Solasodine inhibits growth signaling in Geim original algal. On the other hand, tomatidine synergistically works with aminoglycosides as antibiotics against S. aureus . [37]

Antiinflammation is similarly accomplished with a variety of mechanisms. Solasodine, for example, reduces interleukin-2 and -8 production whereas tomatidine inhibits specific nuclear translocation, JNK activation, as well as induce nitrous oxide synthase. Lastly, nine steroidal alkaloids have significant antiestrogenic activity whereas seven inhibit estrone sulfatase. [37]

However, in addition to their therapeutic benefits, steroidal alkaloids, specifically veratrum alkaloids, are potentially deadly.

Veratrum alkaloid compounds act by attaching to voltage-gated sodium ion channels, altering their permeability. [38] Veratrum alkaloids cause affected sodium channels to reactivate 1000x slower than unaffected channels. [38] Furthermore, veratrum alkaloids block inactivation of sodium channels and lower their activation threshold so they remain open even at resting potential. [38] As a result, sodium concentrations within the cell rise, leading to increased nerve and muscle excitability. [39] These biochemical channels cause muscle contractions, repetitive firing of the nerves and an irregular heart rhythm caused by stimulation of vagal nerves which control the parasympathetic functions of the heart, lungs and digestive tract. [39]

Related Research Articles

<span class="mw-page-title-main">Alkaloid</span> Class of naturally occurring chemical compounds

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. More rarely still, they may contain elements such as phosphorus, chlorine, and bromine.

<span class="mw-page-title-main">Steroid</span> Polycyclic organic compound having sterane as a core structure

A steroid is an organic compound with four fused rings arranged in a specific molecular configuration.

<span class="mw-page-title-main">Phytochemistry</span> Study of phytochemicals, which are chemicals derived from plants

Phytochemistry is the study of phytochemicals, which are chemicals derived from plants. Phytochemists strive to describe the structures of the large number of secondary metabolites found in plants, the functions of these compounds in human and plant biology, and the biosynthesis of these compounds. Plants synthesize phytochemicals for many reasons, including to protect themselves against insect attacks and plant diseases. The compounds found in plants are of many kinds, but most can be grouped into four major biosynthetic classes: alkaloids, phenylpropanoids, polyketides, and terpenoids.

<span class="mw-page-title-main">Cyclopamine</span> Chemical compound

Cyclopamine (11-deoxojervine) is a naturally occurring steroidal alkaloid. It is a teratogenic component of corn lily, which when consumed during gestation has been demonstrated to induce birth defects, including the development of a single eye (cyclopia) in offspring. The molecule was named after this effect, which was originally observed by Idaho lamb farmers in 1957 after their herds gave birth to cycloptic lambs. It then took more than a decade to identify corn lily as the culprit. Later work suggested that differing rain patterns had changed grazing behaviours, which led to a greater quantity of corn lily to be ingested by pregnant sheep. Cyclopamine interrupts the sonic hedgehog signalling pathway, instrumental in early development, ultimately causing birth defects.

<span class="mw-page-title-main">Veratridine</span> Steroidal alkaloid found in plants of the lily family

Veratridine is a steroidal alkaloid found in plants of the lily family, specifically the genera Veratrum and Schoenocaulon. Upon absorption through the skin or mucous membranes, it acts as a neurotoxin by binding to and preventing the inactivation of voltage-gated sodium ion channels in heart, nerve, and skeletal muscle cell membranes. Veratridine increases nerve excitability and intracellular Ca2+ concentrations.

<span class="mw-page-title-main">Indole alkaloid</span> Class of 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 different compounds, it is one of the largest classes of alkaloids. Many of them possess significant physiological activity and some of them are used in medicine. The amino acid tryptophan is the biochemical precursor of indole alkaloids.

<span class="mw-page-title-main">Secosteroid</span> Class of chemicals derived from steroids

A secosteroid is a type of steroid with a "broken" ring. The word secosteroid derives from the Latin verb secare meaning "to cut", and 'steroid'. Secosteroids are alternatively described as a subclass of steroids or derived from steroids.

<i>Buxus sempervirens</i> Species of flowering plants in the box family

Buxus sempervirens, the common box, European box, or boxwood, is a species of flowering plant in the genus Buxus, native to western and southern Europe, northwest Africa, and southwest Asia, from southern England south to northern Morocco, and east through the northern Mediterranean region to Turkey. Buxus colchica of western Caucasus and B. hyrcana of northern Iran and eastern Caucasus are commonly treated as synonyms of B. sempervirens.

<span class="mw-page-title-main">Berberine</span> Quaternary ammonium cation

Berberine is a quaternary ammonium salt from the protoberberine group of benzylisoquinoline alkaloids

<i>Veratrum album</i> Species of plant

Veratrum album, the false helleborine, white hellebore, European white hellebore, or white veratrum is a poisonous plant in the family Melanthiaceae. It is native to Europe and parts of western Asia.

<span class="mw-page-title-main">Solasodine</span> Chemical compound

Solasodine is a poisonous alkaloid chemical compound that occurs in plants of the family Solanaceae such as potatoes and tomatoes. Solasonine and solamargine are glycoalkaloid derivatives of solasodine. Solasodine is teratogenic to hamster fetuses in a dose of 1200 to 1600 mg/kg. Literature survey reveals that solasodine has diuretic, anticancer, antifungal, cardiotonic, antispermatogenetic, antiandrogenic, immunomodulatory, antipyretic and various effects on central nervous system.

<span class="mw-page-title-main">Gonane</span> Tetracyclic hydrocarbon parent of the steroids

Gonane (cyclopentanoperhydrophenanthrene) is a chemical compound with formula C
17
H
28
, whose structure consists of four hydrocarbon rings fused together: three cyclohexane units and one cyclopentane. It can also be viewed as the result of fusing a cyclopentane molecule with a fully hydrogenated molecule of phenanthrene, hence the more descriptive name "perhydrocyclopenta[a]phenanthrene". The non-systematic version of the above name is "cyclopentanoperhydrophenanthrene".

<span class="mw-page-title-main">Solanidine</span> Chemical compound

Solanidine is a poisonous steroidal alkaloid chemical compound that occurs in plants of the family Solanaceae, such as potato and Solanum americanum. Human ingestion of solanidine also occurs via the consumption of the glycoalkaloids, α-solanine and α-chaconine, present in potatoes. The sugar portion of these glycoalkaloids hydrolyses in the body, leaving the solanidine portion. Solanidine occurs in the blood serum of normal healthy people who eat potato, and serum solanidine levels fall markedly once potato consumption ceases. Solanidine from food is also stored in the human body for prolonged periods of time, and it has been suggested that it could be released during times of metabolic stress with the potential for deleterious consequences. Solanidine is responsible for neuromuscular syndromes via cholinesterase inhibition.

Biomimetic synthesis is an area of organic chemical synthesis that is specifically biologically inspired. The term encompasses both the testing of a "biogenetic hypothesis" through execution of a series of reactions designed to parallel the proposed biosynthesis, as well as programs of study where a synthetic reaction or reactions aimed at a desired synthetic goal are designed to mimic one or more known enzymic transformations of an established biosynthetic pathway. The earliest generally cited example of a biomimetic synthesis is Sir Robert Robinson's organic synthesis of the alkaloid tropinone.

<span class="mw-page-title-main">Cyclobuxine</span> Chemical compound

Cyclobuxine is an alkaloid, which can be found in Buxus sempervirens better known as common boxwood, and is derived from the cholesterol skeleton. Alkaloids can be found in the whole plant, but the largest amounts of alkaloids including cyclobuxine can be found in the leaves and bark.

<span class="mw-page-title-main">Apparicine</span> Chemical compound

Apparicine is a monoterpenoid indole alkaloid. It is named after Apparicio Duarte, a Brazilian botanist who studied the Aspidosperma species from which apparicine was first isolated. It was the first member of the vallesamine group of alkaloids to be isolated and have its structure established, which was first published in 1965. It has also been known by the synonyms gomezine, pericalline, and tabernoschizine.

Erythrina alkaloids, generally containing benzyl-tetrahydroisoquinoline structure, are widely distributed in Erythrina species, a genus of plants which belong to the Fabaceae family in tropical and subtropical regions. The Erythrina alkaloids can be found in several organs of Erythrina trees but are primarily found in their seeds. They display several unique properties, and are the subject of active scientific research relating to their synthesis and bioactivity.

<span class="mw-page-title-main">Benzylisoquinoline alkaloids</span>

The benzylisoquinoline alkaloids are natural products that can be classified as isoquinoline alkaloids and are derived from benzylisoquinoline. They also include the benzyl(tetrahydro)isoquinoline alkaloids.

<span class="mw-page-title-main">Indolizidine alkaloids</span>

Indolizidine alkaloids are natural products from various alkaloid groups whose structure can be derived from indolizidine.

<span class="mw-page-title-main">Corydalis Alkaloids</span>

Corydalis Alkaloids are categorized as natural products of the isoquinoline alkaloid type.

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