Further studies on new furostanol saponins from the bulbs of Allium macrostemon

Natural Products and Health

A natural product is an organic compound from a living organism that can be isolated from natural sources or synthesized [...].

Chemical Constituents, Biological Activities, and Proposed Biosynthetic Pathways of Steroidal Saponins from Healthy Nutritious Vegetable-Allium

Allium is a common functional vegetable with edible and medicinal value. Allium plants have a special spicy taste, so they are often used as food and seasoning in people's diets. As a functional food, Allium also has abundant biological activities, some of which are used as drugs to treat diseases. By consuming Allium on a daily basis, people can receive active compounds of natural origin, thereby improving their health status and reducing the likelihood of disease. Steroidal saponins are important secondary metabolites of Allium, which are formed by the steroidal aglycone group and sugar. Steroidal saponins have various physiological activities, such as hypoglycemic, antiplatelet aggregation, anti-inflammatory, antitumor, antimicrobial, and enzyme activity inhibition, which is one of the key reasons why Allium has such significant health benefits. The structural diversity and rich biological activities of steroidal saponins make Allium important plants for both food and medicine. In this paper, the chemical structures, biological activities, and structure-activity relationships of steroidal saponins isolated from Allium are reviewed, and the biosynthetic pathways of some key compounds are proposed as well, to provide a molecular reference basis based on secondary metabolites for the health value of Allium.

Allii Macrostemonis Bulbus: A Comprehensive Review of Ethnopharmacology, Phytochemistry and Pharmacology

The dried bulbs of Allii Macrostemonis Bulbus (AMB) are called “薤白” in China and are mainly distributed in Asia. The plant species included in the 2020 Edition of the Chinese Pharmacopoeia (ChP) are Allium macrostemon Bunge (called xiaogensuan in Chinese, A. macrostemon) and Allium chinense G. Don (called xie in Chinese, A. chinense), respectively. In the traditional Chinese medicine (TCM) theoretical system, AMB is warm in nature, acrid-bitter taste, and attributive to the heart, lung, stomach, large intestine meridian. AMB has the function of activating Yang and removing stasis, regulating Qi and eliminating stagnation. Modern pharmacological studies have shown that AMB has anti-platelet aggregation, hypolipidemic, anti-atherosclerotic, cardiomyocyte, vascular endothelial cell protection, anti-cancer, anti-bacterial, anti-asthmatic, and anti-oxidant effects. In some Asian countries, AMB is often used to treat coronary heart disease (CHD), angina pectoris (AP), asthma, and diarrhea. This review collates the botanical background, ethnopharmacology, phytochemistry, pharmacological activities, quality control, and toxicological studies of AMB, and provides an outlook on the current research deficiencies and future research priorities of AMB, intending to provide ideas for future research directions and commercial development.

The chemical and metabolite profiles of Gualou-Xiebai-Banxia decoction, a classical traditional Chinese medicine formula, by using high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and in-house software

ETHNOPHARMACOLOGICAL RELEVANCE

Gualou-Xiebai-Banxia decoction (GXBD) was a classical traditional Chinese medicine formula for the treatment of coronary heart disease. However, the current study on the chemical and metabolite profiles of GXBD did not follow the ancient prescription and extraction method, which hindered the discovery of effective compounds and quality control.

MATERIALS AND METHODS

In this study, we prepared GXBD by ancient prescription and extraction methods, and then analysed the chemical components and xenobiotics of GXBD in vivo using high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and in-house software.

RESULTS

49 chemical constituents were preliminarily identified, including 7 terpenoids, 6 flavonoids, 5 alkaloids, 17 organic acids, 8 steroids and steroidal saponins, 2 nucleosides and 4 other types of compounds, of which 10 constituents were confirmed unambiguously with authentic standards. Moreover, 129 metabolites were tentatively identified, including 83 metabolites in plasma, 39 metabolites in urine, 25 metabolites in bile and 9 metabolites in feces. Our study speculated that luteolin, adenosine, vanillic acid and curbitacin B might be possible effective components of GXBD for the treatment of coronary heart disease. Dehydration, deglycosylation, dehydrogenation, acetylation and taurine regulation were the main biotransformation reactions of GXBD.

CONCLUSION

Our results provided an important basis for the discovery of effective compounds and quality control of GXBD. In addition, in-house software was an useful tool for identifcation of metabolites.

Discovery of cardio-protective constituents of Gualou Xiebai Decoction, a classical traditional Chinese medicinal formula

BACKGROUD

Finding effective compounds of TCMs has always been the basis for achieving marker-based quality control which is currently most widely used quality control strategy. Gualou Xiebai Decoction (GLXB), a classical TCM formula, is recorded and proven as a therapy for curing coronary heart disease but the effective constituents are unidentified and the substantial basis of the therapeutic effects is not clear.

PURPOSE

The present research is an investigation on the chemistry of this formula aiming at finding and precisely identifying effective compounds.

STUDY DESIGN AND METHODS

This research started with screening for effective fractions of GLXB by rat myocardial infarction model and H9c2 cell hypoxia/reoxygenation model, then compounds in effective fractions were isolated and identified by phytochemical and spectroscopic methods. The cardio-protective activities of the compounds were tested in vitro and one of the effective compounds was taken as example to investigate the mechanisms.

RESULTS

The water-insoluble parts of GLXB were identified as effective parts in both in vitro and in vivo experiments. Systematic isolation of compounds in the effective fractions resulted in the isolation of 34 compounds including 7 new compounds, whereas 8 compounds were effective in protecting H9c2 cells against hypoxia/reoxygenation injury. One of the effective compounds, macrostemonoside P (MP) possibly exerted its effect by activating RISK pathway and attenuating apoptosis.

CONCLUSION

An array of effective constituents of GLXB were discovered, and discovery of these compounds contributed to elucidating the substantial basis for the therapeutic effects of this formula, and provides fundaments for establishing Q-markers for further reliable quality control of GLXB.

Ferulic acid esters of glucosylglucose from Allium macrostemon Bunge

Three new ferulic acid esters of glucosylglucose, 1-O-(E)-feruloyl-β-d-glucopyranosyl (1-2)-[β- d-glucopyranosyl (1-6)]-β-d-glucopyranose (allimacronoid A, 1), 1-O-(E)-feruloyl-{β-d-glucopyranosyl (1-4)-[β-d-glucopyranosyl (1-2)]}-[β- d-glucopyranosyl (1-6)]-β-d-glucopyranose (allimacronoid B, 2), and 1-O-(E)-feruloyl-{β-d-glucopyranosyl (1-6)-[β-d-glucopyranosyl (1-2)]}-[β- d-glucopyranosyl (1-6)]-β-d-glucopyranose (allimacronoid C, 3) were isolated together with tuberonoid A (4), from the leaves of Allium macrostemon Bunge. The chemical structures were elucidated based on the analyses of the spectroscopic and chemical data.

Qualitative and quantitative characterization of secondary metabolites and carbohydrates in Bai-Hu-Tang using ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and ultraperformance liquid chromatography coupled with photodiode array detector

Bai-Hu-Tang (BHT), a classic traditional Chinese medicine (TCM) formula used for clearing heat and promoting body fluid, consists of four traditional Chinese medicines, i.e., Gypsum Fibrosum (Shigao), Anemarrhenae Rhizoma (Zhimu), Glycyrrhizae Radix et Rhizoma Praeparata cum Melle (Zhigancao), and nonglutinous rice (Jingmi). The chemical composition of BHT still remains largely elusive thus far. To qualitatively and quantitatively characterize secondary metabolites and carbohydrates in BHT, here a combination of analytical approaches using ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and ultraperformance liquid chromatography coupled with photodiode array detector was developed and validated. A total of 42 secondary metabolites in BHT were tentatively or definitely identified, of which 10 major chemicals were quantified by the extracting ion mode of quadrupole time-of-flight mass spectrometry. Meanwhile, polysaccharides, oligosaccharides, and monosaccharides in BHT were also characterized via sample pretreatment followed by sugar composition analysis. The quantitative results indicated that the determined chemicals accounted for 35.76% of the total extract of BHT, which demonstrated that the study could be instrumental in chemical dissection and quality control of BHT. The research deliverables not only laid the root for further chemical and biological evaluation of BHT, but also provided a comprehensive analytical strategy for chemical characterization of secondary metabolites and carbohydrates in traditional Chinese medicine formulas.

Allimacrosides A-E, new steroidal glycosides from Allium macrostemon Bunge

A new pregnane-type steroidal glycoside (1), two new spirostane-type steroidal glycosides (2, 3), and two new furostane-type steroidal glycosides (4, 5), named allimacrosides A-E, together with four known compounds (6-9) were isolated from a 80% MeOH extract of Allium macrostemon Bunge. The identification and structural elucidation of these compounds were based on their 1D- and 2D-NMR spectra, and HR-FAB-MS data analysis. The isolated compounds were tested for cytotoxicity against four human tumor cell lines in vitro using the sulforhodamine B bioassay.

Ferulic Acid Esters of Oligo-glucose from Allium macrostemon

Two new ferulic acid esters of oligo-glucose, 1- O- (E)-feruloyl-β-D-gentiobioside (1) and 1- O-( E)-feruloyl-{β-D-glucopyranosyl (1→6)-[β-D-glucopyranosyl (1→2)]}-β-D-glucopyranoside (allimacronoid D, 2) were isolated together with 1- O-( E)-feruloyl-β-D-glucopyranoside (3) and trans-ferulic acid (4) from the leaves of Allium macrostemon Bunge. The chemical structures were elucidated based on the analyses of the spectroscopic and chemical data.

Determination of the chemical constituents of the different processed products of Anemarrhena asphodeloides Rhizomes by high-performance liquid chromatography quadrupole time-of-flight mass spectrometry

In this work, high-performance liquid chromatography (HPLC) coupled with a hybrid quadrupole time of-flight mass spectrometry (Q-TOF-MS/MS) was used to study chemical compositions of different processed products of Rhizoma Anemarrhenae (RA). A Grace Alltima(TM) C18 column (250 × 4.6 mm, 5 µm) was used for separation. Mobile phase consisted of 0.1% formic acid and acetonitrile, using gradient elution. ESI-MS data was acquired in both positive and negative mode. The experiment was established on the basis of a series of reference substances (two xanthone and seven saponins) to qualitatively identify the chemical compounds of different processed products of RA by MS analysis. There was no difference in the type of chemical constituents between different processed products of RA. A total of 25 compounds were identified, including four xanthones, 21 steroidal saponins and eight pairs of isomers.

Flavonol Glycosides from the Leaves of Allium Macrostemon

Twelve flavonoids were isolated from Allium macrostemon leaves. Five compounds were identified as kaempferol 3,7-di -O-glucoside (1), kaempferol 3,4′-di- O-glucoside (2), quercetin 3- O-glucoside (3), kaempferol 3- O-glucoside (4) and isorhamnetin 3- O-glucoside (5) by UV spectra, LC-MS, acid hydrolysis and HPLC comparisons with authentic standards. Other flavonoids were characterized as kaempferol glycosides (6–8, 10 and 11) and quercetin glycosides (9 and 12). Other compounds, such as steroidal saponins, have been already found from the bulbs of A. macrostemon. However, flavonoids were reported for the first time from the leaves.

Steroidal saponins from the genus Allium

Steroidal saponins are widely distributed among monocots, including the Amaryllidaceae family to which the Allium genus is currently classified. Apart from sulfur compounds, these are important biologically active molecules that are considered to be responsible for the observed activity of Allium species, including antifungal, cytotoxic, enzyme-inhibitory, and other. In this paper, literature data concerning chemistry and biological activity of steroidal saponins from the Allium genus has been reviewed.

Steroidal glycosides from the underground parts of Yucca glauca and their cytotoxic activities

Six steroidal glycosides and 14 known compounds were isolated from the underground parts of Yucca glauca (Agavaceae). Their structures were determined from extensive spectroscopic analysis, including analysis of two-dimensional NMR data, and from chemical transformations. The compounds were also evaluated for cytotoxic activities against HL-60 human leukemia cells and A549 human lung adenocarcinoma cells. Four spirostanol glycosides and three furostanol glycosides exhibited cytotoxic activities against both HL-60 and A549 cells. Two of the compounds induced apoptosis in HL-60 cells.

Evaluation of larvicidal activity of the essential oil of Allium macrostemon Bunge and its selected major constituent compounds against Aedes albopictus (Diptera: Culicidae)

BACKGROUND

During the screening programme for new agrochemicals from Chinese medicinal herbs and local wild plants, the essential oil of dried bulbs of Allium macrostemon Bunge (Liliaceae) was found to possess larvicidal activity against mosquitoes. The aim of this research was to determine the larvicidal activity of the essential oil and its major constituent compounds against the larvae of the Culicidae mosquito, Aedes albopictus.

METHODS

Essential oil of A. macrostemon was obtained by hydrodistillation and analyzed by gas chromatography (GC) and gas chromaotography-mass spectrometry (GC-MS). The activity of the essential oil and its two major constituents were evaluated, using World Health Organization (WHO) procedures, against the fourth instar larvae of Ae. albopictus for 24 h and larval mortalities were recorded at various essential oil/compound concentrations ranging from 9.0 - 150 μg/ml.

RESULTS

The essential oil of A. macrostemon exhibited larvicidal activity against the early fourth instar larvae of Ae. albopictus with an LC₅₀ value of 72.86 μg/ml. The two constituent compounds, dimethyl trisulfide and methyl propyl disulfide possessed strong larvicidal activity against the early fourth instar larvae of Ae. albopictus with LC50 values of 36.36 μg/ml and 86.16 μg/ml, respectively.

CONCLUSION

The results indicated that the essential oil of A. macrostemon and its major constituents have good potential as a source for natural larvicides.

Inhibition of platelet activation and aggregation by furostanol saponins isolated from the bulbs of Allium macrostemon Bunge

Three new furostanol saponins (FSs) were recently isolated from the dried bulbs of Allium macrostemon and were shown to have antiplatelet effects. This study investigated the inhibitory capabilities of these compounds on adenosine diphosphate (ADP)-induced human platelet activation. FS-1, when compared with the other 2, had a potent inhibitory effect on ADP-induced platelet aggregation and on the expression of P-selectin and integrin β-3. FS-1 also inhibited Ca mobilization and significantly decreased phosphorylated AKT expression in ADP-activated platelets. The suppression by FS-1 of ADP-induced platelet activation and aggregation shown in this study indicate its potential for therapeutic applications.

Characterization of three saponins from a fraction using 1D DOSY as a solvent signal suppression tool. Agabrittonosides E-F. Furostane saponins from Agave brittoniana Trel. spp. Brachypus

A careful NMR analysis, especially by 1D TOCSY and 1D ROESY, of a refined saponin fraction allowed us to determine the structure of three saponins from a polar extract of Agave brittoniana Trel. spp. Brachypus leaves. The use of 1D DOSY for the suppression of the solvent signal was useful to obtain the chemical shifts of anomeric signals. A full assignment of the (1)H and (13)C spectral data for the new saponins, agabrittonosides E-F (1-2) and the well-known Karatavioside C (3) and their methoxyl derivatives, is reported. The structures were established using a combination of 1D and 2D ((1)H, (1)H-COSY, TOCSY, ROESY, g-HSQC, g-HMBC and g-HSQC-TOCSY) NMR techniques and ESI-MS. In addition, the methoxylation of these furostane saponins in the presence of MeOH was studied.

Clarifying the real bioactive constituents of garlic

Compounds in garlic work synergistically to produce various effects, but, because of garlic's chemical complexity, processing methods yield preparations with differing efficacy and safety. Although thiosulfinates such as allicin have been long misunderstood to be active compounds due to their characteristic odor, it is not necessary for garlic preparations to contain such odorous compounds to be effective, and they decompose and disappear during any processing. Garlic exhibits hypolipidemic, antiplatelet, and procirculatory effects. It prevents cold and flu symptoms through immune enhancement and demonstrates anticancer and chemopreventive activities. In addition, aged garlic extract possesses hepatoprotective, neuroprotective, antioxidative activities, whereas other preparations may stimulate oxidation. Additional effects may be caused by S-allylcysteine, S-allyl mercaptocysteine), saponins, Nalpha-fructosyl arginine, and other substances formed during a long-term extraction process. Although not all of active ingredients of garlic are known, and allicin-like transient components are not directly active, ample research suggests that an allicin-free garlic preparation that is standardized with a bioavailable component such as S-allylcysteine, is active and various effects of garlic may be attributed to it. Furthermore, various chemical constituents in garlic products, including nonsulfur compounds such as saponins, may contribute to the essential biological activities of garlic. Further studies are needed to confirm their bioavailability and associated activities.

Novel furostanol saponins from the bulbs of Allium macrostemon B. and their bioactivity on [Ca2+]i increase induced by KCl

Chemical reinvestigation of the ethanol extract of the dried bulbs of Allium macrostemon B. led to the isolation of two novel furostanol saponins, named macrostemonoside M (1) and macrostemonoside N (2), together with six known saponins. The structures of new compounds were elucidated on the basis of extensive spectroscopic analysis including 1D and 2D NMR as (25R)-22-hydroxy-5beta-furostane-1beta,2beta,3beta,6alpha-tetraol-26-O-beta-D-glucopyranoside and 22-hydroxy-5beta-furost-25-(27)-ene-1beta,2beta,3beta,6alpha-tetraol-26-O-beta-D-glucopyranoside, respectively. The pharmacological activities of all the saponins on [Ca2+]i increase induced by KCl were evaluated.

The active constituents from Gualou-xiebai-baijiu-tang part I: active saponins

Two new steroidal saponins and a new triterpenoidal saponin, together with nine known steroidal saponins, were isolated from "Gualou-xiebai-baijiu-tang" consisting of Fructus trichosanthis and Bulbus allii macrostemi. The structures of the three new compounds were determined as 3-O-beta-D-galactopyranosyl-hederagenin 28-O-beta-D-xylopyranosyl (1-->6)-beta-D-galactopyranosyl ester (1), spirost 25(27)-ene-2beta,3beta-diol-3-O-beta-D-glucopyranosyl (1-->2)-beta-D-galactopyranoside (2) and 26-O-beta-D-glucopyranosyl-22alpha-hydroxy-5beta-furost-25(27)-ene-1beta,3beta,6beta,26-tetraol-3-O-beta-D-galactopyranoside (3), respectively, by means of chemical evidences and spectral analysis.

Two new steroidal saponins from "Gualou-xiebai-baijiu-tang" consisting of Fructus trichosanthis and Bulbus allii macrostemi

Two new steroidal saponins were isolated from the Chinese folk medicine called Gualou-xiebai-baijiu-tang. The structures were determined to be spirost 25(27)-ene-2beta,3beta-diol-3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranoside and 26-O-beta-D-glucopyranosyl-22alpha-hydroxy-5beta-furost-25(27)-ene-1beta,3beta,6beta,26-tetraol-3-O-beta-D-galactopyranoside, respectively, based on chemical evidences and spectral analysis.

Constituents and the antitumor principle of Allium victorialis var. platyphyllum

To search for cytotoxic components from Allium victorialis, MTT assays on each extract and an isolated component, gitogenin 3-O-lycotetroside, were performed against cancer cell lines. Cytotoxicities of most extract were shown to be comparatively weak, though IC50 values of CHCl3 fraction was found to be <31.3-368.4 microg/ml. From the incubated methanol extract at 36 degrees C, eleven kinds of organosulfuric flavours were predictable by GC-MS performance. The most abundant peak was revealed to be 2-vinyl-4H-1,3-dithiin (1) by its mass spectrum. Further, this extract showed significant cytotoxicities toward cancer cell lies. Silica gel column chromatography of the n-butanol fraction led to the isolation of gitogenin 3-O-lycotetroside (3) along with astragalin (4) and kaempferol 3, 4'-di-O-beta-D-glucoside (5). This steroidal saponin exhibited significant cytotoxic activities (IC50, 6.51-36.5 microg/ml) over several cancer cell lines. When compound 3 was incubated for 24 h with human intestinal bacteria, a major metabolite was produced and then isolated by silica gel column chromatography. By examining parent- and prominent ion peak in FAB-MS spectrum of the metabolite, the structure was speculated not to be any of prosapogenins of 3, suggesting that spiroketal ring were labile to the bacterial reaction. These suggest that disulfides produced secondarily are the antitumor principles.