Steroidal saponins from the rhizomes of Hosta sieboldii and their cytostatic activity on HL-60 cells

Chemical synthesis of saponins: An update

Saponins, as secondary metabolites in terrestrial plants and marine invertebrate, constitute one of the largest families of natural products. The long history of folk medicinal applications of saponins makes them attractive candidates for innovative drug design and development. Chemical synthesis has become a practical alternative to the availability of the natural saponins and their modified analogs, so as to facilitate SAR studies and the discovery of optimal structures for clinical applications. The recent achievements in the synthesis of these complex saponins reflect the advancements of both steroid/triterpene chemistry and carbohydrate chemistry. This chapter provides an updated review on the chemical synthesis of natural saponins, covering the literature from 2014 to 2020.

Cytotoxic steroidal glycosides from the underground parts of Hosta ventricosa

A phytochemical study on the underground parts of Hosta ventricosa yielded one new spirostanol saponin (1), two new furostanol saponins (2 and 3), and one new pregnane glycoside (4), along with three known compounds (5‒7). Their structures were elucidated on the basis of chemical and spectroscopic analysis. All isolated compounds were evaluated for their cytotoxic effects against five human cancer cell lines (HL-60, A-549, SMMC-7721, MCF-7, and SW-480). Compounds 1, 2, and 5‒7 showed cytotoxic activities with IC₅₀ values of 3.21-17.06 μM.

Structure, Bioactivity and Analytical Methods for the Determination of Yucca Saponins

Yucca is one of the main sources of steroidal saponins, hence different extracts are commercialized for use as surfactant additives by beverage, animal feed, cosmetics or agricultural products. For a deeper understanding of the potential of the saponins that can be found in this genus, an exhaustive review of the structural characteristics, bioactivities and analytical methods that can be used with these compounds has been carried out, since there are no recent reviews on the matter. Thus, a total of 108 saponins from eight species of the genus Yucca have been described. Out of these, the bioactivity of 68 saponins derived from the isolation of Yucca or other genera has been evaluated. Regarding the evaluation and quality control of the saponins from this genus LC-MS technique is the most often used. Nevertheless, the development of methods for their routine analysis in commercial preparations are needed. Moreover, most of the studies found in the literature have been carried out on Y. schidigera extract, since is the most often used for commercial purposes. Only eight of the 50 species that belong to this genus have been studied, which clearly indicates that the identification of saponins present in Yucca genus is still an unresolved question.

Traditional uses, phytochemistry, pharmacology and toxicological aspects of the genus Hosta (Liliaceae): A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Hosta (Liliaceae family) represents an interesting source of natural bio-constituents, and the 50 species of this genus are widespread in the world. Five species have been used as traditional East Asian medicines for treating inflammation and pain-related diseases. However, the available data for this genus have not been comprehensively reviewed regarding their extracts and secondary metabolites.

AIM OF THE STUDY

The present review aims to provide a deeper insight, better awareness and detailed knowledge of traditional uses, phytochemistry, pharmacology along with toxicological aspects of the genus Hosta in the past decades (February 1964 to August 2020). In addition, the relevance among traditional uses, pharmacology and phytochemistry in folk medicines were extensively discussed.

MATERIALS AND METHODS

The relevant information of Hosta species was obtained from several databases. Moreover, the medical books, PhD and MSc dissertations in Chinese were also used to perform this work.

RESULTS

Comprehensive analysis of the afore-mentioned databases, medical books and dissertations confirmed that ethnomedical uses of Hosta genus plants had been recorded in China, Japan, Korea and other countries. To date, only eight species have been studied for chemical constituents, and a total of 200 secondary metabolites (not include essential oil constituents), including steroids, flavonoids, alkaloids, furan derivatives, phenylpropanoids, phenethyl derivatives, terpenoids, aliphatics, and others. The crude extracts and isolated chemical constituents exhibited anti-inflammatory and analgesic, antioxidant, anti-tumor, anti-viral, acetylcholinesterase inhibitory, antimicrobial, anti-chronic prostatitis, and other effects. Moreover, only the n-butanol fraction of H. ventricosa (Salisb.) Stearn roots showed moderate acute toxicity in mice. In addition, the relevance among traditional uses, pharmacology and phytochemistry in folk medicines were extensively discussed.

CONCLUSIONS

Hosta spp. are plants rich in steroids and flavonoids with valuable medicinal properties; though, there are several gaps in understanding the traditional uses in the current available data. More high scientific quality preclinical studies with new methodology are necessary to assess the safety, efficacy and mechanism of these plants.

Steroidal glycosides from the underground parts of Hosta ventricosa and their anti-inflammatory activities in mice

Two new pregnane glycosides, 2α, 3β-dihydroxy-5α-pregn-16-en-20-one-3-O-{α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)]-β-D-galactopyranoside} (1) and 2α, 3β-dihydroxy-5α-pregn-16-en-20-one-3-O-{β-D-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside}(2), have been isolated along with two known spirostanol saponins from the underground parts of Hosta ventricosa. Their structures were elucidated on the basis of chemical and spectral evidence. The anti-inflammatory activities of these steroidal glycosides were evaluated using a xylene-induced ear edema model. Our results indicated that the compounds exhibited promising anti-inflammatory activities.

The bioassay-guided isolation of antifungal saponins from Hosta plantaginea leaves

Four new steroidal saponins hostaside Ⅰ (1), hostaside Ⅱ (2), hostaside Ⅲ (3), and hostaside Ⅳ (4), together with five known steroidal saponins (5-9), were isolated by the bioassay-guided fractionation from the leaves of Hosta plantaginea (Lam.) Aschers, a worldwide well-known ornamental plant. Hostasides Ⅰ and Ⅱ showed significant antifungal activities, and they could inhibit the growth of Candida albicans and Fusarium oxysporium with MIC values as low as 4 μg/ml.

Fast Centrifugal Partition Chromatography Fractionation of Concentrated Agave (Agave salmiana) Sap to Obtain Saponins with Apoptotic Effect on Colon Cancer Cells

Separation of potentially bioactive components from foods and plant extracts is one of the main challenges for their study. Centrifugal partition chromatography has been a successful technique for the screening and identification of molecules with bioactive potential, such as steroidal saponins. Agave is a source of steroidal saponins with anticancer potential, though the activity of these compounds in concentrated agave sap has not been yet explored. In this study, fast centrifugal partition chromatography (FCPC) was used coupled with in vitro tests on HT-29 cells as a screening procedure to identify apoptotic saponins from an acetonic extract of concentrated agave sap. The three most bioactive fractions obtained by FCPC at partition coefficients between 0.23 and 0.4 contained steroidal saponins, predominantly magueyoside b. Flow cytometry analysis determined that the fraction rich in kammogenin and manogenin glycosides induced apoptosis, but when gentrogenin and hecogenin glycosides were also found in the fraction, a necrotic effect was observed. In conclusion, this study provides the evidence that steroidal saponins in concentrated agave sap were potential inductors of apoptosis and that it was possible to separate them using fast centrifugal partition chromatography.

Steroidal saponins from Tribulus terrestris

Sixteen steroidal saponins, including seven previously unreported compounds, were isolated from Tribulus terrestris. The structures of the saponins were established using 1D and 2D NMR spectroscopy, mass spectrometry, and chemical methods. They were identified as: 26-O-β-d-glucopyranosyl-(25R)-furost-4-en-2α,3β,22α,26-tetrol-12-one (terrestrinin C), 26-O-β-d-glucopyranosyl-(25R)-furost-4-en-22α,26-diol-3,12-dione (terrestrinin D), 26-O-β-d-glucopyranosyl-(25S)-furost-4-en-22α,26-diol-3,6,12-trione (terrestrinin E), 26-O-β-d-glucopyranosyl-(25R)-5α-furostan-3β,22α,26-triol-12-one (terrestrinin F), 26-O-β-d-glucopyranosyl-(25R)-furost-4-en-12β,22α,26-triol-3-one (terrestrinin G), 26-O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl-(25R)-furost-4-en-22α,26-diol-3,12-dione (terrestrinin H), and 24-O-β-d-glucopyranosyl-(25S)-5α-spirostan-3β,24β-diol-12-one-3-O-β-d-glucopyranosyl-(1→4)-β-d-galactopyranoside (terrestrinin I). The isolated compounds were evaluated for their platelet aggregation activities. Three of the known saponins exhibited strong effects on the induction of platelet aggregation.

Efficient one-pot synthesis of tigogenin saponins and their antitumor activities

An efficient synthesis of naturally occurring tigogenin triglycoside 1a and its three derivatives 1b-d bearing different carbohydrate moieties, as well as their antitumor activities, is described. Partially protected thiogalactosides bearing unprotected 2,4-OH or 4-OH groups were used to facilitate regioselective reactions for one-pot sequential multi-step glycosylation, which has significantly simplified the target molecule synthesis. The synthetic saponins 1a-d exhibited much higher anti-tumor activities than the positive control cisplatin against the human epithelial cervical cancer cell (HeLa) as evaluated by CCK-8 assay.

Bioactive steroidal saponins from Agave offoyana flowers

Bioguided studies of flowers of Agave offoyana allowed the isolation of five steroidal saponins never described previously, Magueyosides A-E (1-5), along with six known steroidal saponins (6-11). The structures of compounds were determined as (25R)-spirost-5-en-2α,3β-diol-12-one 3-O-{β-d-xylopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (1), (25R)-spirost-5-en-2α,3β-diol-12-one 3-O-{β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (2), (25R)-spirost-5-en-2α,3β,12β-triol 3-O-{β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (3), (25R)-5α-spirostan-2α,3β-diol-12-one 3-O-{β-d-xylopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (4), and (25R)-5α-spirostan-2α,3β-diol-9(11)-en-12-one 3-O-{β-d-xylopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (5), by comprehensive spectroscopic analysis, including one- and two-dimensional NMR techniques, mass spectrometry and chemical methods. The bioactivities of the isolated compounds on the standard target species Lactuca sativa were evaluated. A dose-dependent phytotoxicity and low dose stimulation were observed.

Optimization of a method for the profiling and quantification of saponins in different green asparagus genotypes

The main goal of this study was the optimization of a HPLC-MS method for the qualitative and quantitative analysis of asparagus saponins. The method includes extraction with aqueous ethanol, cleanup by solid phase extraction, separation by reverse phase chromatography, electrospray ionization, and detection in a single quadrupole mass analyzer. The method was used for the comparison of selected genotypes of Huétor-Tájar asparagus landrace and selected varieties of commercial diploid hybrids of green asparagus. The results showed that while protodioscin was almost the only saponin detected in the commercial hybrids, eight different saponins were detected in the Huétor-Tájar asparagus genotypes. The mass spectra indicated that HT saponins are derived from a furostan type steroidal genin having a single bond between carbons 5 and 6 of the B ring. The total concentration of saponins was found to be higher in triguero asparagus than in commercial hybrids.

Steroidal Glycosides from the Roots of Solanum Melongena L

One new cholestane glycoside, six steroidal glycosides of spirostane series and one pregnane glycoside have been isolated from the roots of Solanum melongena L. for the first time. Their structures were determined by physico-chemical methods.

Steroidal saponins from the whole plants of Agave utahensis and their cytotoxic activity

Phytochemical investigation of the whole plants of Agave utahensis Engelm. (Agavaceae) has resulted in the isolation of 15 steroidal saponins (1-15), including five spirostanol saponins (1-5) and three furostanol saponins (11-13). Structures of compounds 1-5 and 11-13 were determined by spectroscopic analysis and the results of hydrolytic cleavage. The isolated compounds were evaluated for their cytotoxic activity against HL-60 human promyelocytic leukemia cells.

Benzylphenethylamine alkaloids from Hosta plantaginea with inhibitory activity against tobacco mosaic virus and acetylcholinesterase

Five new benzylphenethylamine alkaloids, hostasine (1), 8-demethoxyhostasine, 8-demethoxy-10-O-methylhostasine, 10-O-methylhostasine, and 9-O-demethyl-7-O-methyllycorenine, along with 12 known compounds, were isolated from Hosta plantaginea by bioassay-guided fractionation. The structures of the new alkaloids were established by means of extensive spectroscopic methods, and the relative configuration of 1 was further confirmed by single-crystal X-ray diffraction. 7-Deoxy-trans-dihydronarciclasine (IC(50) = 1.80 microM), a known alkaloid, showed strong activity against tobacco mosaic virus by the half-leaf method. Some of these alkaloids were also evaluated for their inhibitory activity against acetylcholinesterase. 8-Demethoxy-10-O-methylhostasine was found to possess significant activity, with an IC(50) of 2.32 microM.

Saponins, classification and occurrence in the plant kingdom

Saponins are a structurally diverse class of compounds occurring in many plant species, which are characterized by a skeleton derived of the 30-carbon precursor oxidosqualene to which glycosyl residues are attached. Traditionally, they are subdivided into triterpenoid and steroid glycosides, or into triterpenoid, spirostanol, and furostanol saponins. In this study, the structures of saponins are reviewed and classified based on their carbon skeletons, the formation of which follows the main pathways for the biosynthesis of triterpenes and steroids. In this way, 11 main classes of saponins were distinguished: dammaranes, tirucallanes, lupanes, hopanes, oleananes, taraxasteranes, ursanes, cycloartanes, lanostanes, cucurbitanes, and steroids. The dammaranes, lupanes, hopanes, oleananes, ursanes, and steroids are further divided into 16 subclasses, because their carbon skeletons are subjected to fragmentation, homologation, and degradation reactions. With this systematic classification, the relationship between the type of skeleton and the plant origin was investigated. Up to five main classes of skeletons could exist within one plant order, but the distribution of skeletons in the plant kingdom did not seem to be order- or subclass-specific. The oleanane skeleton was the most common skeleton and is present in most orders of the plant kingdom. For oleanane type saponins, the kind of substituents (e.g. -OH, =O, monosaccharide residues, etc.) and their position of attachment to the skeleton were reviewed. Carbohydrate chains of 18 monosaccharide residues can be attached to the oleanane skeleton, most commonly at the C3 and/or C17 atom. The kind and positions of the substituents did not seem to be plant order-specific.

Biological activities and distribution of plant saponins

Plant saponins are widely distributed amongst plants and have a wide range of biological properties. The more recent investigations and findings into their biological activities were summarized. Isolation studies of saponins were examined to determine which are the more commonly studied plant families and in which families saponins have been identified.

Enzymatic liberation of lycotetraose from the Solanum glycoalkaloid α-tomatine

The branched tetrasaccharide, O-beta-d-glucopyranosyl-(1-->2)-O-[beta-d-xylopyranosyl-(1-->3)]-O-beta-d-glucopyranosyl-(1-->4)-d-galactose (lycotetraose) is a key constituent of many biologically interesting natural products. Described herein is a convenient enzymatic preparation of lycotetraose from the readily available Solanum glycoalkaloid alpha-tomatine. The preparation makes use of the recombinant endo-glycosidase, tomatinase, from the plant pathogen Fusarium oxysporum f. sp. lycopersici.

The biological action of saponins in animal systems: a review

Saponins are steroid or triterpenoid glycosides, common in a large number of plants and plant products that are important in human and animal nutrition. Several biological effects have been ascribed to saponins. Extensive research has been carried out into the membrane-permeabilising, immunostimulant, hypocholesterolaemic and anticarcinogenic properties of saponins and they have also been found to significantly affect growth, feed intake and reproduction in animals. These structurally diverse compounds have also been observed to kill protozoans and molluscs, to be antioxidants, to impair the digestion of protein and the uptake of vitamins and minerals in the gut, to cause hypoglycaemia, and to act as antifungal and antiviral agents. These compounds can thus affect animals in a host of different ways both positive and negative.

The bioactivity of saponins: triterpenoid and steroidal glycosides

Triterpenoid and steroidal glycosides, referred to collectively as saponins, are bioactive compounds present naturally in many plants. They have considerable potential as pharmaceutical and/or nutraceutical agents in natural or synthetic form. Saponins, from a variety of sources, have been shown to have hypocholesterolemic, anti-coagulant, anticarcinogenic, hepatoprotective, hypoglycemic, immunomodulatory, neuroprotective, anti-inflammatory and anti-oxidant activity. This paper reviews saponin research of the last decade, focussing on developments in understanding their mechanism of action and structure-activity relationships. Virtually all of this work has used animal and in vitro models. To date there are very few human data.