Cycloartane triterpene glycosides from Astragalus trigonus

Phenolic Compound Profiles, Cytotoxic, Antioxidant, Antimicrobial Potentials and Molecular Docking Studies of Astragalus gymnolobus Methanolic Extracts

Since Astragalus is a genus with many important medicinal plant species, the present work aimed to investigate the phytochemical composition and some biological activities of Astragalus gymnolobus. The methanolic fractions of four organs (stems, flowers, leaves, root and whole plant) were quantified and identified by Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS) analysis. Hesperidin, hyperoside, p-hydroxybenzoic acid, protocatechuic acid and p-coumaric acid were identified as main compounds among the extracts. Among all cells, leaf methanol (Lm) extract had the highest cytotoxic effect on HeLa cells (IC50 = 0.069 μg/mL). Hesperidin, the most abundant compound in A. gymnolobus extract, was found to show a strong negative correlation with the cytotoxic effect observed in HeLa cells according to Pearson correlation test results and to have the best binding affinity to targeted proteins by docking studies. The antimicrobial activity results indicated that the most susceptible bacterium against all extracts was identified as Streptococcus pyogenes with 9-11 mm inhibition zone and 8192 mg/mL MIC value. As a result of the research, it was suggested that A. gymnolobus could be considered as a promising source that contributes to the fight against cancer.

Cycloartane Saponins from Astragalus glycyphyllos and Their In Vitro Neuroprotective, Antioxidant, and hMAO-B-Inhibiting Effects

Astragalus glycyphyllos (Fabaceae) is used in the traditional medicine of many countries against hepatic and cardiac disorders. The plant contains mainly flavonoids and saponins. From a defatted methanol extract from its overground parts, a new triterpenoid saponin, 3-O-[α-L-rhamnopyranosyl-(1→2)]-β-D-xylopyranosyl]-24-O-α-L-arabinopyranosyl-3β,6α,16β,24(R),25-pentahydroxy-20R-cycloartane, together with the rare saponin astrachrysoside A, were isolated using various chromatography methods. The compounds were identified via extensive high resolution electrospray ionisation mass spectrometry (HRESIMS) and NMR analyses. Both saponins were examined for their possible antioxidant and neuroprotective activity in three different in vitro models. Rat brain synaptosomes, mitochondria, and microsomes were isolated via centrifugation using Percoll gradient. They were treated with the compounds in three different concentrations alone, and in combination with 6-hydroxydopamine or tert-butyl hydroperoxide as toxic agents. It was found that the compounds had statistically significant dose-dependent in vitro protective activity on the sub-cellular fractions. The compounds exhibited a weak inhibitory effect on the enzyme activity of human recombinant monoamine oxidase type B (hMAO-B), compared to selegiline.

Potent telomerase activators from a novel sapogenin via biotransformation utilizing Camarosporium laburnicola, an endophytic fungus

BACKGROUND

Cycloartane-type triterpenoids possess important biological activities, including immunostimulant, wound healing, and telomerase activation. Biotransformation is one of the derivatization strategies of natural products to improve their bioactivities. Endophytic fungi have attracted attention in biotransformation studies because of their ability to perform modifications in complex structures with a high degree of stereospecificity.

RESULTS

This study focuses on biotransformation studies on cyclocephagenol (1), a novel cycloartane-type sapogenin from Astragalus species, and its 12-hydroxy derivatives (2 and 3) to obtain new telomerase activators. Since the hTERT protein levels of cyclocephagenol (1) and its 12-hydroxy derivatives (2 and 3) on HEKn cells were found to be notable, biotransformation studies were carried out on cyclocephagenol and its 12-hydroxy derivatives using Camarosporium laburnicola, an endophytic fungus isolated from Astragalus angustifolius. Later, immunoblotting and PCR-based ELISA assay were used to screen starting compounds and biotransformation products for their effects on hTERT protein levels and telomerase activation. All compounds showed improved telomerase activation compared to the control group.

CONCLUSIONS

As a result of biotransformation studies, seven new metabolites were obtained and characterized, verifying the potential of C. laburnicola as a biocatalyst. Additionally, the bioactivity results showed that this endophytic biocatalyst is unique in transforming the metabolites of its host to afford potent telomerase activators.

Insights into HPLC-MS/MS Analysis, Antioxidant and Cytotoxic Activity of Astragalus fruticosus against Different Types of Cancer Cell Lines

Plants from the genus Astragalus are gaining attention for their pharmacological importance. However, the information available regarding the HPLC–MS/MS chemical profile of A. fruticosus is inadequate. In this study, we performed HPLC–MS/MS analysis using electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI). We tentatively identified 11 compounds in the A. fruticosus methanolic extract, including five flavonoidal and six saponin glycosides. The extract showed moderate antioxidant activity with 21.05% reduction in DPPH UV absorption. The preliminary cytotoxic screening against seven human cancer cell lines using 100 μg/mL extract showed prominent cytotoxic potential against colorectal cancer HCT–116 with 3.368% cell viability. It also showed moderate cytotoxic potential against prostate (DU–145), ovarian (SKOV–3) and lung (A–549) cancer cell lines with cell viability of 14.25%, 16.02% and 27.24%, respectively. The IC₅₀ of the total extract against HCT–116 and DU–145 cell lines were 7.81 μg/mL and 40.79 μg/mL, respectively. The observed cytotoxicity of the total methanolic extract from the leaves against colorectal cancer might facilitate future investigations on cytotoxic agent(s) for disease management.

Alleviation of liver cirrhosis and associated portal-hypertension by Astragalus species in relation to their UPLC-MS/MS metabolic profiles: a mechanistic study

Liver cirrhosis is a late-stage liver disease characterized by excessive fibrous deposition triggering portal-hypertension (PH); the prime restrainer for cirrhosis-related complications. Remedies that can dually oppose hepatic fibrosis and lower PH, may prevent progression into decompensated-cirrhosis. Different Astragalus-species members have shown antifibrotic and diuretic actions with possible subsequent PH reduction. However, A.spinosus and A.trigonus were poorly tested for eliciting these actions. Herein, A.spinosus and A.trigonus roots and aerial parts extracts were subjected to comprehensive metabolic-fingerprinting using UHPLC-MS/MS resulting in 56 identified phytoconstituents, followed by chemometric untargeted analysis that revealed variable metabolic profiles exemplified by different species and organ types. Consequently, tested extracts were in-vivo evaluated for potential antifibrotic/anticirrhotic activity by assessing specific markers. The mechanistic prospective to induce diuresis was investigated by analyzing plasma aldosterone and renal-transporters gene-expression. Serum apelin and dimethylarginine-dimethylaminohydrolase-1 were measured to indicate the overall effect on PH. All extracts amended cirrhosis and PH to varying extents and induced diuresis via different mechanisms. Further, An OPLS model was built to generate a comprehensive metabolic-profiling of A.spinosus and A.trigonus secondary-metabolites providing a chemical-based evidence for their efficacious consistency. In conclusion, A.spinosus and A.trigonus organs comprised myriad pharmacologically-active constituents that act synergistically to ameliorate cirrhosis and associated PH.

Analysis of astragalosides I, II and IV in some Egyptian Astragalus species and Astragalus dietary supplements using high-performance liquid chromatography/evaporative light scattering detector and non-parametric regression

INTRODUCTION

GenuTs Astragalus L. is characterised by the presence of cycloartane saponins which have wide biological activities such as antioxidant, immunomodulating' hepatoprotective and anti-inflammatory activities. From these cycloartane saponins are astragalosides I, II and IV which have been regarded as the most important active constituents in Astragalus species.

OBJECTIVES

This work describes the quantitative analysis of astragalosides I, II and IV in some Egyptian Astragalus species and Astragalus dietary supplements in a single run by high-performance liquid chromatography/evaporative light scattering detector (HPLC/ELSD) using gradient elution.

METHODOLOGY

The method of quantitation adopted in this study is the standard addition method. First and second derivative treatment of the data was performed, and the study presents comparison between two statistical regression methods for handling data; parametric and non-parametric regression methods.

RESULTS

Derivative treatment of the chromatographic response data gives improved quantitation of the chromatographic signals. Non-parametric regression of the data using Theil's method is advantageous over the usual least squares method as it assumes that errors could occur in both x- and y-directions and they might not be normally distributed. In addition, it could effectively circumvent any outlier data points.

CONCLUSION

Due to the simplicity and the good accuracy and reproducibility of the suggested methods, they could be used for analysis and quality control of Astragalus species and Astragalus dietary supplements.

Comparative anti-inflammatory and hepatoprotective activities of Astragalus gummifer Labill herb and roots in rats

BACKGROUND

The Astragalus gummifer (F. Fabaceae), herb and roots were studied for anti-inflammatory and hepatoprotective activities.

MATERIALS AND METHOD

The alcoholic extracts of Astragalus gummifer (F. Fabaceae), herb (AGHE), and roots (AGRE), were used for anti-inflammatory and hepatoprotective activities in Wister rats. The effects of AGHE and AGRE were compared with the standard drugs Phenylbutazone and silymarin, for anti-inflammatory and hepatoprotective activities respectively.

RESULT

Both extracts showed significant anti-inflammatory activity (P< 0.001). AGRE showed comparatively more significant hepatoprotective activity (P< 0.001), than AGHE (P< 0.05); at doses of 250 and 500 mg/kg body weight as manifested by lowering the serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), alkaline phosphatase (ALP), and total bilirubin. The hepatoprotective activity was, also, supported by total protein (TP), malondialdehyde (MDA), nonprotein sulfhydryls (NP-SH), and histo-pathological studies of liver tissue.

DISCUSSION

To the best of our knowledge, this is the first report of the anti-inflammatory and hepatoprotective activities of Astragalus gummifer. The results of present studies indicated that both AGHE and AGRE can be used in inflammatory conditions, while investigation supports the use of AGRE in cases that hepatoprotection are required in the hepatotoxic conditions. More supportive studies are required before clinical recommendation.

Unusual secondary metabolites from Astragalus halicacabus LAM

From the whole plant of Astragalus halicacabus (Sect. Halicacabus), a new cycloartane-type glycoside, (20R,24S)-3-O-[α-L-arabinopyranosyl-(1→2)-β-D-xylopyranosyl]-20,24-epoxy-16-O-β-D-glucopyranosyl-3β,6α,16β,25-tetrahydroxycycloartane, and a new glycoside, 3-O-[β-D-apiofuranosyl-(1→2)-β-D-glucopyranosyl]maltol were isolated together with seven known cycloartane-type glycosides, i.e., cyclocanthoside D, askendosides D, F, and G, cyclosieversioside G, cyclostipuloside A, elongatoside, and a known maltol glucoside, 3-O-β-D-glucopyranosylmaltol. The structures were elucidated by means of high-resolution mass spectrometry, and extensive 1D- and 2D-NMR spectroscopic analysis. This is the first phytochemical work on A. halicacabus, and a maltol glycoside was encountered for the first time in the Leguminosae family.

Hepatoprotective effects of Astragalus kahiricus root extract against ethanol-induced liver apoptosis in rats

The hepatoprotective activity of the ethanol extract of Astragalus kahiricus (Fabaceae) roots against ethanol-induced liver apoptosis was evaluated and it showed very promising hepatoprotective actions through different mechanisms. The extract counteracted the ethanol-induced liver enzymes leakage and glutathione depletion. In addition, it demonstrated anti-apoptotic effects against caspase-3 activation and DNA fragmentation that were confirmed by liver histopathological examination. Moreover, the phytochemical study of this extract led to the isolation of four cycloartane-type triterpenes identified as astrasieversianin II (1), astramembrannin II (2), astrasieversianin XIV (3), and cycloastragenol (4). The structures of these isolates were established by HRESI-MS and 1D and 2D NMR experiments. The antimicrobial, antimalarial, and cytotoxic activities of the isolates were further evaluated, but none of them showed any activity.

Oleanane glycosides from Astragalus tauricolus: isolation and structural elucidation based on a preliminary liquid chromatography-electrospray ionization tandem mass spectrometry profiling

As a part of our ongoing research for bioactive compounds from Turkish Astragalus species, the investigation of Astragalus tauricolus has been carried out. An approach based on HPLC-ESIMS(n) experiments has been used to profile the triterpene glycosides occurring in the butanol extract of the whole plant. On the basis of the results of the online screening by HPLC-ESIMS(n), 22 oleanane-type triterpene glycosides, including ten compounds never reported before, were isolated, and their structures were established by the extensive use of 1D and 2D-NMR experiments along with ESIMS and HRMS analysis. Noteworthy, cycloartane-type triterpene glycosides, the main constituents of Astragalus spp., were not found. This peculiar feature characterizes a very limited group of Astragalus spp. The antiproliferative activity of the isolated compounds 1-12, 15, 17-19 was evaluated against a small panel of cancer cell lines. Only compound 11 showed an IC(50) of 22 μM against human leukemia cell line (U937). The other tested compounds, in a range of concentrations between 1 and 50 μM, did not cause any significant reduction of the cell number.

Cycloartane-type triterpenes from the leaves of Homonoia riparia with VEGF-induced angiogenesis inhibitory activity

Six new cycloartane-type triterpenes (1-6), 24-methylenecycloartane-3β,6β,7β-triol (1), 24-methylenecycloartane-3β,6β,7β,16β-tetraol (2), 24-methylenecycloartane-3β,6β,16β-triol (3), 24-methylenecycloartane-3β,7β,16β-triol 3-O-β-d-xylopyranoside (4), 24-methylenecycloartane-3β,6β,16β-triol 3-O-β-d-xylopyranoside (5), and 24-methylenecycloartane-3β,6β,7β-triol 3-O-β-d-xylopyranoside (6), were isolated from the leaves of Homonoia riparia, together with one known compound, 24-methylenecycloartane-3β,6β,7β,16β-tetraol 3-O-β-d-xylopyranoside (7). The structures of the new triterpenes were established by spectroscopic studies and from chemical evidence, and the inhibitory effects of compounds 1 and 3-7 on VEGF-induced vascular permeability were examined in vivo in rats using the Miles assay. In addition, the inhibitory effect of 7 on VEGF-induced tube formation by HUVECs in vitro was investigated.

Evaluation of the immunomodulatory properties in mice and in vitro anti-inflammatory activity of cycloartane type saponins from Astragalus species

ETHNOPHARMACOLOGICAL RELEVANCE

Astragalus roots are used to treat leukemia and for their wound healing properties in Southeast Anatolia-Turkey.

MATERIALS AND METHODS

In vivo studies to investigate the effects of two Astragalus saponins were carried out on the immune response cytokines by using six to eight weeks old male Swiss albino mice. The production of IL-1β, TGF-1β, TNF-α, IL-2, IL-4 and IFN-γ cytokines was determined by ELISA. The spleen and lymph nodes, isolated from the mice subjects, were analyzed to realize induction of the surface antigen productions for IL-2Rα (CD25) and CD69. In addition, their effects on the targets of inflammation such as NF κB, iNOS and NAG-1 were investigated in cell-based assays.

RESULTS

The results suggested that AST VII and Mac B had positive effect on Th1 cytokine release (IL-2 and IFN-γ), and suppression on Th2 cytokine production (IL-4). The immunohistochemical results exhibited induction of both IL-Rα (CD25) and CD69 surface receptors justifying the Th1 cytokine release. The compounds did not affect NF-κB or NAG-1 activity but iNOS activity was inhibited by Mac B with an IC(50) of 156 μg/ml.

CONCLUSIONS

The results show that Ast VII and Mac B create powerful immunoregulatory effects without the stimulation of inflammatory cytokines in mice, and have no significant effect on the inflammatory cellular targets in vitro.

Cycloartane glycosides from Astragalus aureus

Eight cycloartane-type triterpene glycosides (1-8) were isolated from Astragalus aureus Willd along with ten known cycloartane-type glycosides (9-18). Their structures were established by the extensive use of 1D and 2D-NMR experiments along with ESIMS and HRMS analyses. Compounds 1-5 are cyclocanthogenin glycosides, whereas compounds 6-8 are based on cyclocephalogenin as aglycon, more unusual in the plant kingdom, so far reported only from Astragalus spp. Moreover, for the first time monoglycosides of cyclocanthogenin (5) and cyclocephalogenin (7, 8) are reported. All of the compounds tested for their cytotoxic activities against a number of cancer cell lines. Among the compounds, only 8 exhibited activity versus human breast cancer (MCF7) at 45 μM concentration.

Triterpene glycosides from Astragalus icmadophilus

Six cycloartane-type triterpene glycosides were isolated from Astragalus icmadophilus along with two known cycloartane-type glycosides, five known oleanane-type triterpene glycosides and one known flavonol glycoside. The structures of the six compounds were established as 3-O-[alpha-L-arabinopyranosyl-(1-->2)-O-3-acetoxy-alpha-L-arabinopyranosyl]-6-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane, 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-O-alpha-L-arabinopyranosyl-(1-->2)-O-beta-D-xylopyranosyl]-6-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxy cycloartane, 3-O-[alpha-L-arabinopyranosyl-(1-->2)-O-3,4-diacetoxy-alpha-L-arabinopyranosyl]-6-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane, 3-O-[alpha-L-arabinopyranosyl-(1-->2)-O-3-acetoxy-alpha-L-arabinopyranosyl]-6-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,25-tetrahydroxy-20(R),24(S)-epoxycycloartane, 3-O-[alpha-L-arabinopyranosyl-(1-->2)-O-beta-D-xylopyranosyl]-6-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,24alpha-tetrahydroxy-20(R),25-epoxycycloartane, 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-O-alpha-L-arabinopyranosyl-(1-->2)-O-beta-D-xylopyranosyl]-6-O-beta-D-glucopyranosyl-3beta,6alpha,16beta,24alpha-tetrahydroxy-20(R),25-epoxycycloartane by the extensive use of 1D- and 2D-NMR experiments along with ESIMS and HRMS analysis. The first four compounds are cyclocanthogenin and cycloastragenol glycosides, whereas the last two are based on cyclocephalogenin as aglycone, more unusual in the plant kingdom, so far reported only from Astragalus spp.

Cycloartane-type Glycosides from Two Species of Astragalus (Fabaceae)

Three known cycloartane-type glycosides were isolated from the roots of two different species of Astragalus, A. glycyphyllos, A. sempervirens. The identification of these compounds were mainly achieved by 2D NMR spectroscopic techniques and FAB-MS. The results of our studies confirm that triterpene saponins from the cycloartane-type skeleton might be chemotaxonomically significant to the genus Astragalus.

Structure elucidation and complete NMR spectral assignments of two new sesquiterpene lactone xylosides from Lactuca triangulata

Two new sesquiterpene lactone xylosides, derivatives of the guaianolides 9alpha-hydroxyleucodin and 9alpha-hydroxy-11,13-dehydroleucodin, were isolated from roots of Lactuca triangulata. Their structures were established on the basis of (1)H and (13)C NMR spectra, 2D NMR (HMQC, HMBC, COSY, NOESY) techniques and comparison with the literature data. The compounds represent the first example of sesquiterpene lactone xylosides.

Cycloartane glycosides from Astragalus campylosema Boiss. ssp. campylosema

Four cycloartane glycosides, 3-O-[alpha-l-arabinopyranosyl-(1-->2)-beta-d-xylopyranosyl]-3beta,6alpha,16beta,23alpha,25-pentahydroxy-20(R),24(S)-epoxycycloartane (1), 3-O-[alpha-l-arabinopyranosyl-(1-->2)-beta-d-xylopyranosyl]-16-O-hydroxyacetoxy-23-O-acetoxy-3beta,6alpha,25-trihydroxy-20(R),24(S)-epoxycycloartane (2), 3-O-[alpha-l-arabinopyranosyl-(1-->2)-beta-d-xylopyranosyl]-3beta,6alpha,23alpha,25-tetrahydroxy-20(R),24(R)-16beta,24;20,24-diepoxycycloartane (3), 3-O-[alpha-l-arabinopyranosyl-(1-->2)-beta-d-xylopyranosyl]-25-O-beta-d-glucopyranosyl-3beta,6alpha,16beta,25-tetrahydroxy-20(R),24(S)-epoxycycloartane (4), along with three known cycloartane glycosides were isolated from the MeOH extract of the roots of Astragalus campylosema ssp. campylosema. Their structures were established by the extensive use of 1D- and 2D-NMR experiments along with ESIMS and HRMS analysis. The occurrence of the hydroxyl function at position 23 (1-2) and of the ketalic function at C-24 (3) are very unusual findings in the cycloartane class.

Spinocoumarin I, a New Coumarin Derivative from Astragalus spinosus Forssk

Phytochemical investigation of the roots of Astragalus spinosus Forssk (Fabaceae) resulted in the isolation of ten metabolites. The structure of spinocoumarin I (1), a new coumarin derivative, was established as 3-[( cis-2′,5′-dihydroxycinnamoyl)]-7-hydroxy-6-methoxycoumarin. The structures of the isolated compounds were determined using spectroscopic methods. All compounds exhibited weak antiproliferative activity against the A2780 ovarian cancer cell line.

Antitrypanosomal cycloartane glycosides from Astragalus baibutensis

Baibutoside (5), a new cycloartane-type triterpene glycoside, has been isolated from the roots of Astragalus baibutensis along with four known glycosides, acetylastragaloside I (1), and astragalosides I, II, and IV (2-4, resp.). The structure elucidation of the compounds were achieved by a combination of one- and two-dimensional NMR techniques (DQF-COSY, HSQC, HMBC, and ROESY), and mass spectrometry (ESI-MS), where all the compounds were shown to have cycloastragenol (=(20R,24S)-3beta,6alpha,16beta,25-tetrahydroxy-20,24-epoxy-9,19-cyclolanostane) as aglycone. All compounds were tested for in vitro antiprotozoal activity. Compounds 1-4 displayed notable activity vs. Trypanosoma brucei rhodesiense, with acetylastragaloside I (1) being the most potent (IC50 9.5 microg/ml). Acetylastragaloside I (1) was also lethal to T. cruzi (IC50 5.0 microg/ml), and it is the first cycloartane-type triterpene with remarkable trypanocidal activity against both T. brucei rhodesiense and T. cruzi. However, it exhibits some cytotoxicity on mammalian cells.

Subchronic toxicity studies of Radix Astragali extract in rats and dogs

Radix Astragali extract (RAE) is obtained from Astragalus membranaceus. It consists of Astragalus polysaccharide and Astragalus membranaceus saponins. In the study, we observed the subchronic toxicity of RAE in Sprague-Dawley rats and beagle dogs to evaluate the safety dosage range in clinical application. These subjects were daily administered of RAE by intra-peritoneum or vein for three consecutive months. General index were observed such as food-intake, behavior, body weight, hematological parameters, etc. Body weight, the weight of principal organ and hematology index are normal in experimental groups and control groups. The hematological biochemistry examination and histopathology examination of experimental groups are similar to control groups. In conclusion, our studies clearly demonstrated that RAE was safe without any distinct toxicity and side effects, the safety dosage range is 5.7-39.9g/kg for rats and 2.85-19.95g/kg for beagle dogs, which is equal to 70 or 35 times of that of human (0.57g/kg, say, average BW 70kg), respectively.

Haemolytic activities and adjuvant effect of Astragalus membranaceus saponins (AMS) on the immune responses to ovalbumin in mice

In this study, the haemolytic activities of Astragalus membranaceus saponins (AMS) and its adjuvant potentials on the cellular and humoral immune responses of ICR mice against OVA were evaluated. We determined the haemolytic activity of AMS using 0.5% rabbit red blood cell. AMS showed a slight haemolytic effect, with its haemolytic percent being 0.66% at the concentration of 500 microg/ml. Furthermore, the adjuvant potentials of AMS at three dose levels on the cellular and humoral immune responses of ICR mice against ovalbumin (OVA) were investigated. ICR mice were immunized subcutaneously with OVA 100 microg alone or with OVA 100 microg dissolved in saline containing Alum (200 microg), QuilA (10 and 20 microg) or AMS (50, 100 or 200 microg) on Day 1 and 15. Two weeks later (Day 28), concanavalin A (Con A)-, lipopolysaccharide (LPS)- and OVA-stimulated splenocyte proliferation and OVA-specific antibodies in serum were measured. AMS significantly enhanced the Con A-, LPS-, and OVA-induced splenocyte proliferation in the OVA-immunized mice especially at a dose of 100 microg (P<0.05 or P<0.001). OVA-specific IgG, IgG1 and IgG2b antibody titers in serum were also significantly enhanced by AMS compared with OVA control group (P<0.01 or P<0.001). Moreover, no significant differences (P>0.05) were observed between enhancing effect of AMS and QuilA on the OVA-specific IgG, IgG1 and IgG2b antibody responses to OVA in mice. In conclusion, the results suggest that AMS could be safely used as adjuvant with low or non-haemolytic effect.

Leishmanicidal cycloartane-type triterpene glycosides from Astragalus oleifolius

Two new cycloartane-type glycosides oleifoliosides A (1) and B (2) were isolated from the lower stem parts of Astragalus oleifolius. Their structures were identified as 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-xylopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane and 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane, respectively, by means of spectroscopic methods (IR, 1D and 2D NMR, ESI-MS). Three known cycloartane glycosides cyclocanthoside E (3), astragaloside II (4) and astragaloside IV (5) were also isolated and characterized. All five compounds were evaluated for in vitro trypanocidal, leishmanicidal and antiplasmodial activities as well as their cytotoxic potential on primary mammalian (L6) cells. Except for the compound 5, all compounds showed notable growth inhibitory activity against Leishmania donovani with IC50 values ranging from 13.2 to 21.3 microg/ml. Only weak activity against Trypanosoma brucei rhodesiense was observed with the known compounds astragaloside II (4, IC50 66.6 microg/ml) and cyclocanthoside E (3, IC50 85.2 microg/ml), while all compounds were inactive against Trypanosoma cruzi and Plasmodium falciparum. None of the compounds were toxic to mammalian cells (IC50's > 90 microg/ml). This is the first report of leishmanicidal and trypanocidal activity of cycloartane-type triterpene glycosides.

Kahiricosides II-V, cycloartane glycosides from an Egyptian collection of Astragalus kahiricus

Four cycloartane-type saponins, kahiricosides II-V (1-4), were isolated from the aerial parts of Astragalus kahiricus of Egyptian origin. Their structures were established as 9beta,19-cyclolanost-24E-ene-3beta,6alpha,16beta,27-tetraol-3-O-beta-D-glucopyranoside, 9beta,19-cyclolanost-24E-ene-3beta,6alpha,16beta,27-tetraol-3-O-(2'-O-acetyl)-beta-D-glucopyranoside, 9beta,19-cyclolanost-24E-ene-3beta,6alpha,16beta,27-tetraol-3-O-(6'-O-acetyl)-beta-D-glucopyranoside, and 9beta,19-cyclolanost-24E-ene-3beta,6alpha,16beta,27-tetraol-3-O-beta-D-glucopyranosyl-27-O-beta-D-glucopyranoside based on chemical and spectral evidences. All compounds exhibited very weak cytotoxicity against the A2780 ovarian cancer cell line.

Cycloartane saponins from Astragalus peregrinus as modulators of lymphocyte proliferation

From Astragalus peregrinus, four cycloartane-type saponins have been isolated and their structures elucidated by spectral means as 20(R),24(S)-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,25-tetrol 3-O-beta-D-glucopyranoside (1), 20(R),24(S)-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,25-tetrol 3-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranoside (2), 20(R),24(S)-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,25-tetrol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside (3) and 20(R),25-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,24(S)-tetrol (24-O-acetyl)- 3-O-alpha-L-rhamnopyranosyl-(1-->2)-(6'-O-acetyl)-beta-D-glucopyranoside (4). Compounds 2 and 3 showed to stimulate the proliferation of mouse splenocytes and were not significantly cytotoxic.

Chemical diversification trends in Astragalus caprinus (Leguminosae), based on the flavonoid pathway

Flavonoid glycosides of Astragalus caprinus (Leguminosae) were investigated; more than 30 glycosides were found in leaf material, based on the aglycones kaempferol, quercetin and their methylated derivatives. Among them 14 compounds were found in significant amounts and showed a contrasting distribution. They could be ordered into three groups: polyglycosides, acylated polyglycosides and methylated polyglycosides. The distribution of these compounds was studied within a large collection of individual plants harvested in Tunisia; the results showed a relationship between metabolic trends and ecological diversification.

Two new glycosides from Astragalus caprinus

A new glycoside of flavonol (1) and a new glycoside of a cycloartane-type triterpene (2) were isolated from the leaves and the roots of Astragalus caprinus, respectively. Their structures were elucidated in turn by spectroscopic data interpretation as 3-O-[[beta-D-xylopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->6)][beta-D-apiofuranosyl(1-->2)]]-beta-D-galactopyranosyl kaempferol (1) and 3-O-(beta-D-xylopyranosyl)-24-O-(beta-D-glucopyranosyl)-20,25-epoxycycloartane-3beta,6alpha,16beta,24alpha-tetrol (2).

Four novel cycloartane glycosides from Astragalus oleifolius

Four novel cycloartane-type triterpene glycosides, macrophyllosaponins A-D (1-4) were isolated from the roots of Astragalus oleifolius. By means of chemical (acetylation, alkaline hydrolysis) and spectroscopic methods (IR, 1D- and 2D-NMR, FABMS), their structures were established as 3-O-alpha-L-rhamnopyranosyl-24-O-(4"-O-acetyl)-beta-D-xylopyranosyl-1 alpha,3 beta,7 beta,24(S), 25-pentahydroxycycloartane (1), 3-O-alpha-L-rhamnopyranosyl-24-O-beta-D-xylopyranosyl-1 alpha,3 beta, 7 beta,24(S), 25-pentahydroxycycloartane (2), 3-O-alpha-L-rhamnopyranosyl-25-O-beta-D-glucoyranosyl-1 alpha, 3 beta,7 beta,24(S),25-pentahydroxycycloartane (3), and 3-O-alpha-L-rhamnopyranosyl-24-O-(2-O-beta-D-xylopyranosyl) -beta-D-xylopyranosyl-1 alpha,3 beta,7 beta,24(S), 25-pentahydroxycycloartane (4).