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Solaverbascine—a new 22,26-epiminocholestane alkaloid from Solanum verbascifolium
Abstract
Besides solasodine and tomatidine the new alkaloid solaverbascine has been obtained from the leaves of Solanum verbascifolium and identified as (22S:25R)-22,26-epiminocholest-5-ene-3β, 16β-diol by physical data and direct comparison with synthetic material.
... Solanum species have been a source of diverse steroidal saponins (Dopke et al. 1975; Verbist et al. 1977; Chakravarty et al. 1978 Chakravarty et al. , 1979 Chakravarty et al. , 1980 Chakravarty et al. , 1981 Chakravarty et al. , 1982 Adam et al. 1980). Nevertheless, there are very few reports describing antifungal activity for these compounds (Mahato et al. 1982; Okunji et al. 1990 ). Extensive ethnobotanical studies, which consider the epidemiological importance of skin infections in tropical countries like México, report that Solanum chrysotrichum Schldl. is one of the most frequently used plants in the southeast of the country for the treatment of various skin mycosis (Zurita & Zolla 1986). ...
The production of an antifungal spirostanol saponin designated SC-1 has been detected in cell suspension cultures of the Mexican
species Solanum chrysotrichum. Batch cultures of a cell suspension obtained from hypocotyl derived calluses of this species
were grown for 25 days in shake flasks containing Murashige & Skoog (MS) medium. Throughout the growth cycle, fresh and dry
weight, SC-1 yield, and uptake of sucrose, glucose and fructose were determined. The effects of inoculum size and sucrose
concentration on the biomass accumulation and synthesis of the active metabolite, were studied. The maximum SC-1 production,
above 14 mg.g−1 (which was fifty times that of field grown plants), was reached after 20 days using a 2% inoculum and complete MS medium
supplemented with 2 mgl−1 2,4-D, 2 mg l−1kinetin, and sucrose between 30 and 45 gl−1.
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The family Solanaceae is immensely important because it has many species with food and medicinal values. There are nine major Solanaceous spp. Namely S. nigrum sensu Trimen (Small Kalukenweriya) and Datura stramonium L.(Sudu aththana) collected from Uva Province, Sri Lanka, a prominent area of growing these species. Currently these species are underutilized in spite of their medicinal importance. No detailed morpho-genetic and medicinal level characterization of these species has been reported to promote their economic use. Therefore, the present study was conducted to assess the morpho-genetic diversity and the antibacterial activity of these Solanaceous spp. The plant height, canopy width and leaf and fruit morphology were highly variable among these species. DNA barcoding using locus matK revealed a total of eight haplotypes. The polymorphism in matK locus is not diverse enough to set the species limit of the genotypes within S. melongena and to distinguish Thiththathibbatu from Walthibbatu. The antibacterial activity assay using ethanol extracts of roots demonstrated that all these species have inhibitory activity against Gram positive Staphylococcus aureus (NCTC4838) and Gram negative Escherichia coli (JM109).
Botanicals have been used for treatment or prevention of various human diseases throughout history. Solanum verbascifolium L. is used in folk-medicine of East Asia. S.verbascifolium (Solanum erianthum) contains highly beneficial contents which can be exploited beneficially in healthcare services and nutritional supplement. It is rich in protein and have considerably high amounts of carbohydrate, potassium, iron, sodium, calcium and phosphorus, vitamin A and vitamin C. The plant is recommended for consumption and as a potential raw material for pharmaceutical industry. In this study, the ethanolic extract of the whole plant was subjected to evaluate its antibacterial properties using various microorganisms like by disc diffusion method.
This chapter reviews the chemistry and biochemistry of Solanum steroid alkaloids as well as the occurrence of these natural products in the plant kingdom. The chapter includes a tabulated survey of the occurrence of Solanum glycoalkaloids and alkamines in plants, two additional surveys of the well-characterized alkaloid glycosides and alkamines that have been isolated from plants, and tables of physical constants compiling all the glycosides, sugar-free alkamines, and their derivatives (together more than 500 compounds) described in the chapter. The recent interest in steroidal Solunum alkaloids has been initiated by an increasing demand for steroidal raw materials all over the world and coupled with a simultaneous shortage of diosgenin, the most important starting material to date for the steroid industry (ZI) that has sharply increased in price.
Many Solanum species that occur in Nigeria are sources of food and medicinal products. The domesticated species especially serve as sources of edible fruits and vegetables. Many of the species remain good sources of diosgenin and solasodine, chemicals of great importance in the steroid industry.
Three flavonoid glycosides including a new one, 7,4′-dimethyl-apigenin-6-C-β-glucopyranosyl-2″-O-α-l-arabinopyranoside (1) were isolated from the leaves of Solanum verbascifolium (Solanaceae) through bioassay-guided isolation. The chemical structure of 1 was established on the basis of spectroscopic analysis. TRAIL-resistance-overcoming activity of 1 was evaluated.
Starting with the known (22S,25R)-16β-acetoxy-N-acetyl-22,26-epiminocholest-5-en-3β-ol (4), which has been prepared from the Solanum steroid alkaloid solasodine (3), we synthesized the nitrogenous brassinosteroid analogues (22S,25R)-2α,3α,16β-trihydroxy-22,26-epimino-5α-cholestan-6-one (11), (25R)-2α,22α-dihydroxy-5α,22αN-spirosolan-6-one (13), (22S,25R)-2α,3α,16β-trihydroxy-22,26-epimino-6,7-seco-5α-cholestano-6,7-lactone (15), and (25R)-2α-3α-dihydroxy-6,7-seco-5α,22αN-spirosolano-6,7-lactone (18) as well as some of their derivatives.
The rare 16α-hydroxylated steroid alkaloids teinemine [(22S,25S)-22,26-epiminocholest-5-ene-3β,16α-diol, 8], 22-isoteinemine [(22R,25S)-22,26-epiminocholest-5-ene-3β,16α-diol, 10], etioline [(25S)-22,26-epiminocholesta-5,22(N)-diene-3β,16α-diol, 12], and 25-isoetioline [(25R)-22,26-epiminocholesta-5,22(N)-diene-3β,16α-diol, 21] are synthesized from the abundant spirosolane alkaloids tomatid-5-en-3β-ol [(25S)-22βN-spirosol-5-en-3β-ol, 1] and solasodine [(25R)-22αN-spirosol-5-en-3β-ol, 15], respectively. The crucial stages of these syntheses are the conversions of 1 or 15 into the N-protected (22S,25S)-, (22R,25S)-, and (22S,25R)-22,26-epimino-3β-hydroxycholest-5-en-16-ones 6, 7, and 18 as well as their reductions with sodium/ 2-propanol to the 16α-hydroxy compounds teinemine (8), 22-isoteinemine (10), and (22S,25R)-22,26-epiminocholest-5-ene-3β,16α-diol (19), respectively. By treatment with sodium methanolate the N-chloro derivatives 9 and 11 of 8 and 10 afford etioline (12). In an analogous manner, the N-chloro derivative 20 of 19 is converted into 25-isoetioline (21).
Spectral techniques have established the structure of muldamine from Veratrum californicum as (22S, 25S)-22,26-epiminocholest-5-ene-3β,16
In the search for possible new anti-cancer agents, we investigated the effects of 75 aqueous and methanol extracts from 41 Argentinean plant species. The effect in cell growth was evaluated in the LM2 mammary adenocarcinoma cells. In a second stage, the highly active selected extracts were assayed in 3 other tumour cell lines: melanoma B16, bladder MB49 and lung A549; and 3 normal cell lines: mammary Hb4a and keratinocytes PAM212 and HaCat. Eight methanol extracts were found to be highly cytotoxic: Collaea argentina leaf, Iochroma australe leaf, Ipomoea bonariensis flower, Jacaranda mimosifolia flower, Solanum amygdalifolium flower, Solanum chacoense leaf, Solanum sisymbriifolium flower and Solanum verbascifolium flower. However, extract inhibition on cell growth was highly dependent on cell type. In general, except for the highly resistant cell lines, the inhibitory concentrations 50% were in the range of 10-150 μg/ml The eight extracts highly inhibited cell growth in a concentration-dependent manner, and in general the methanol extracts were always more active than the aqueous. Murine cells appear to be more sensitive than human cells to the cytotoxic action of the plant extracts. The human melanoma B16 line was the most resistant to four of the extracts. In terms of selectivity, S. verbascifolium was the species which showed most selectivity for tumour cells. Overall, this is one of the first studies focusing on southern South American native plants and their biological effects. Since some species of 5 genera analyzed have been reported to possess different degrees of alkaloid content, we examined microtubule structures after extract treatments. The eight extracts induced destabilization, condensation and aggregation of microtubules in LM2 cells, although no depolarization, typical of Vinca alkaloids damage was observed. In a near future, antitumour activity of purified fractions of the extracts administered at non-toxic doses will be assayed in transplantable murine tumour models.
An ethnobotanical field study carried out in 200 rural communities determined that the leaves of Solanum chrysotrichum Schldl. are used in Mexican traditional medicine for the treatment of skin mycosis, being particularly recommended to cure Tinae pedis. Clinical trials were performed using a cream containing 5% of a methanolic leaf extract of this plant. Results showed that 45% of the patients were completely cured after 4 weeks of topical treatment. The rest of the cases improved notably in comparison with the control group of patients using the habitual miconazole treatment. The same plant extract inhibited the growth in vitro of the dermatophytes Trychophyton mentagrophytes, T. rubrum and Microsporum gypseum at MICs under 15 mg/ml.
Naturally-occurring 3beta-O-chacotriosides of solasodine (solamargine), of its 22S, 25S isomer tomatidenol (beta-solamarine), and of solanidine (chaconine), as well as ring E- and F-modified derivatives of solamargine were prepared and assayed in order to assess the relevance of aglycone structural features to membrane-disruption and enzyme-inhibitory activities of the related glycoalkaloids. A ring E-opened dihydro-derivative of solasodine (the chacotrioside of dihydrosolasodine A) did not bind to cholesterol, stigmasterol or ergosterol in vitro, disrupt PC/cholesterol liposomes or mammalian erythrocytes. or inhibit acetylcholinesterase in vitro. It did not synergise with the solatrioside of dihydrosolasodine A or solasonine (nor did solamargine with dihydrosolasodine A solatrioside) in haemolysis tests. The ring F modified derivative, N-nitrososolamargine, did not inhibit acetylcholinesterase in vitro, but lysed liposomes at > or = 150 microM and pH 7. Increasing the pH to 8 (but not 9) further enhanced disruption. The combination of N-nitrososolamargine and solasonine did not cause any disruption of liposomes. Beta-solamarine showed no anti-acetylcholinesterase activity in vitro at up to 100 microM, but disrupted liposomes at 75 and 150 microM, although not to the extent caused by solamargine or chaconine. In combination with both the (inactive) solatriosides, solasonine and solanine, 75 microM beta-solamarine produced synergistic effects, with liposome disruption greater than 150 microM beta-solamarine alone. Beta-solamarine, solamargine and chaconine showed similar haemolytic activity. Beta-solamarine synergised with the solatriosides solasonine and solanine in disrupting erythrocytes. Preliminary structure-activity relationships were evaluated for the active chacotriosides in an attempt to define the scope and limitations of this model study.
Concomitant extraction and hydrolysis of Solanum steroidal glycoalkaloids in a two-phase system containing an aqueous mineral acid and an organic water immiscible solvent, and having a boiling point under 100(o)C, is described. It is essentially a "one-pot" process, combining direct acid hydrolysis of the glycosides in the plant material and in situ extraction of the released aglycones after alkali treatment, in a single step, the various ingredients being added simultaneously or sequentially, as required. Application of the process to fruits, leaves, and tissue cultures of Solanum khasianum Clarke plants, either fresh or in dried, finely ground form, using a two-phase aqueous hydrochloric acid-toluene system, proved to be very suitable for continuous production of pure solasodine which is a valuable raw steroid for the preparation of steroidal drugs. Pure Solanum glycoalkaloids were also prepared and hydrolysed accordingly. The process has analytical applications too, and could be extended in a general way to glycosides in other series for preparation of their related aglycones.
Chemical and spectroscopic evidence for the constitution and stereochemistry of veralkamine, a minor alkaloid from Veratrum album subsp. lobelianum (Bernh.) Suessenguth, has been given. In alteration of a former structural suggestion veralkamine is regarded as (22S:25S)-22,26-epimino-17β-methyl-18-nor-17-iso-cholesta-5,12-diene-3β.16β-diol [(17S:22S:25S)-22,26-epimino-18(13→17)-abeo-cholesta-5m12-diene-3β, 16β-diol,I] representing a novel structural type of steroidal alkaloids.
Es werden die Elektronenanlagerungs-Massenspektren einer Reihe von 22,26-Epiminocholestanen verschiedenen Sättigungs- und Substitutionsgrades sowie unterschiedlicher Stereochemie an C-22 und C-25 vergleichend untersucht. Neben dem M-1-Peak wird als typischer Spaltprozeß bei dieser Verbindungsklasse Fragmentierung zwischen C-20 und C-22 beobachtet, die zu einem um 98 bzw. bei Acetylepiminocholestanen 140 Masseneinheiten unterhalb der Molmasse liegenden Peak führt. Eine Ausnahme bilden Δ22-ungesättigte Vertreter, bei denen eine solche Spaltung ausbleibt und die stattdessen einen charakteristischen, durch Ion-Molekül-Reaktion mit Sauerstoff resultierenden M + 14-Peak zeigen. Daneben tritt in allen Fällen Abspaltung von Wasser bzw. Acetyl auf.
Zusammenfassung Über die alkaloidchemische Untersuchung von 68Solanum-Arten der UntergattungenArchaeosolanum Bitt. undLeptostemonum (Dun.) Bitt. sowie der SektionMorella (Dun.) Bitt. (UntergattungEusolanum Bitt.) wird ausführlich berichtet. Aus 40 Arten konnten Solasodin-glykoside (Solasonin, Solamargin,β-Solamargin bzw. „β-Solanigrin“) isoliert werden (Tabelle 1), so daß in Verbindung mit weiteren Literaturbefunden (Tabelle 2) nunmehr 67 solasodinführende Pflanzen bekannt sind.
Die Massenspektren verschiedener Klassen von Steroidalkaloiden werden diskutiert. Da das Fragmentierungsverhalten in allen Fällen durch die besondere Fähigkeit des Stickstoffatoms, eine positive Ladung als Immoniumion zu stabilisieren, gelenkt wird, gerben sich für die verschiedenen Strukturtypen charakteristische Spektren, die zur Identifizierung und Klassifizierung herangezogenn werden können.
Das durch Reduktion von Solasodin mit NaBH4 in Methanol erhaltene (22S,25R)- Diol (I) läßt sich nach Oppenauer partiell zu dem Keton (IIa) oxidieren, dessen Chlorierung mit Chlorsuccinimid in CH2Cl2 bei -Sbis -10°C das N-Chlorarnin (IIb) gibt.