[Feasibility study for whole plant medicinal use of Tribulus terrestris]

OBJECTIVE

The content differences of leaf, plant and fruit of Tribulus terrestris was compared to study the feasibility of whole plant medicinal use.

METHOD

The samples were collected in three typical habitats and six different production areas of T. terrestris. The main medicinal ingredients saponins and flavonoids were determined in root, stem, leaf and fruit during the harvest time.

RESULT

The two ingredients were abounded in leaf and more than 2.61 times as in other parts of the plant. The results showed that there were no differences between the whole plant and the fruit.

CONCLUSION

It should pay more attentions on the collection, preservation and utilization of the leaf of T. terrestris in the harvesting and processing stage. The whole plant for medical use was feasibility based on the content of the ingredients.

Molluscicidal activity of Piper cubeba Linn., Piper longum Linn. and Tribulus terrestris Linn. and their combinations against snail Indoplanorbis exustus Desh

The toxic effect of dried berries powder of P. cubeba, dried fruit powder of P. longum and T. terrestris singly as well as in combination [binary (1:1) and tertiary (1:1:1)] were studied against snail L. exustus. Toxicity of these plant products were time and concentration dependent. Ethanol extracts of these plants were more effective than that of other organic solvents. 96 h LC50 value of column purified fraction of T. terrestris against I. exustus was 9.57 mg/l, where as 96 h LC50 values of column purified fractions of P. longum and P. cubeba were 11.57 mg/l and 10.93 mg/l, respectively. Binary (1:1) combination of P. cubeba (PC) + P. longum (PL) (41.78 mg/l) was more effective than P. cubeba (PC) + T. terrestris (TT) (42.17 mg/l) and P. longum (PL) + T. terrestris (TT) (55.84 mg/l) respectively; while tertiary (1:1:1) combinations of P. cubeba (PC) + T. terrestris (TT) + T. foenum-graecum (TF) (10.67 mg/l) was more effective than rest of the combinations. These plants can be used as potent source of molluscicides against the snail I. exustus.

Screening of some saponins and phenolic components of Tribulus terrestris and Smilax excelsa as MDR modulators

BACKGROUND

Cytotoxic activity of saponins and phenolic compounds have been described in the literature, but no reports were found on their multidrug resistance (MDR)-modulating effects on human mdr1 gene-transfected mouse lymphoma cell line.

MATERIALS AND METHODS

Methylprototribestin, structurally related compounds and a mixture of 3 acetylated isomers of methylprotodioscin were investigated for antiproliferative effect and modulation of drug accumulation.

RESULTS

The growth inhibitory dose (ID50) of the compounds ranged from 12.64 to 20.62 mug/ml. Methylprototribestin was the most effective resistance modifier. However, methylprotodioscin, pseudoprotodioscin, prosapogenin A of dioscin, tribestin and 5-O-caffeoylshikimic acid showed moderate MDR reversal activity. In a checkerboard method, methyloprototribestin and the mixture of the 3 acetylated isomers enhanced the antiproliferative effects on MDR cells in combination with doxorubicin.

CONCLUSION

Based on these results, methylprototribestin and the mixture of the 3 acetylated isomers can be recommended for further in vivo experiments in combination with anthracyclines in human MDR-cancer xenograft transplanted mice.

Two new steroidal glucosides from Tribulus terrestris L

Two new furostanol saponins, tribufurosides D (1) and E (2), were isolated from the fruits of Tribulus terrestris L. With the help of chemical and spectral analyses (IR, MS, 1D, and 2D NMR), the structures of the two new furostanol saponins were established as 26-O-beta-d-glucopyranosyl-(25S)-5alpha-furost-12-one-2alpha,3beta,22alpha,26-tetraol-3-O-beta-d-glucopyranosyl-(1 --> 4)-beta-d-galactopyranoside (1) and 26-O-beta-d-glucopyranosyl-(25R)-5alpha-furost-12-one-2alpha,3beta,22alpha,26-tetraol-3-O-beta-d-glucopyranosyl-(1 --> 4)-beta-d-galactopyranoside (2).

Steroidal saponins from Tribulus terrestris

Five new steroidal saponins were isolated from the fruits of Tribulus terrestris. Their structures were fully established by spectroscopic and chemical analysis as (23S,25S)-5alpha-spirostane-24-one-3beta,23-diol-3-O-{alpha-l-rhamnopyranosyl-(1-->2)-O-[beta-d-glucopyranosyl-(1-->4)]-beta-d-galactopyranoside} (1), (24S,25S)-5alpha-spirostane-3beta,24-diol-3-O-{alpha-l-rhamnopyranosyl-(1-->2)-O-[beta-d-glucopyranosyl-(1-->4)]-beta-d-galactopyranoside} (2), 26-O-beta-d-glucopyranosyl-(25R)-5alpha-furostan-2alpha,3beta,22alpha,26-tetraol-3-O-{beta-d-glucopyranosyl-(1-->2)-O-beta-d-glucopyranosyl-(1-->4)-beta-d-galactopyranoside} (3), 26-O-beta-d-glucopyranosyl-(25R)-5alpha-furostan-20(22)-en-2alpha,3beta,26-triol-3-O-{beta-d-glucopyranosyl-(1-->2)-O-beta-d-glucopyranosyl-(1-->4)-beta-d-galactopyranoside} (4), and 26-O-beta-d-glucopyranosyl-(25S)-5alpha-furostan-12-one-22-methoxy-3beta,26-diol-3-O-{alpha-l-rhamnopyranosyl-(1-->2)-O-[beta-d-glucopyranosyl-(1-->4)]-beta-d-galactopyranoside} (5). The isolated compounds were evaluated for cytostatic activity against HL-60 cells.

[Mechanisms of gross saponins of Tribulus terrestris via activating PKCepsilon against myocardial apoptosis induced by oxidative stress]

This study is to observe the effect of gross saponins of Tribulus terrestris (GSTT) on protein kinase Cepsilon (PKCepsilon) and apoptosis-associated protein in the apoptosis of cultured cardiocyte apoptosis induced by hydrogen peroxide (H2O2), and to explore the mechanisms of GSTT against myocardial apoptosis. Primary cardiocytes were isolated and cultured. Myocardial apoptosis was induced by H2O2 and analyzed with flow cytometry. Protein content of phospho-PKCepsilon, Bcl-2, and Bax were detected with Western blotting analysis. Cleaved caspase-3 protein content was determined with immunocytochemical technique. After the pretreatment of 100 mg x L(-1) GSTT, compared with H2O2 group, GSTT could not only decrease the apoptotic percentage in cardiocytes damaged by H2O2 (P < 0.01), but also reduce protein contents of Bax and cleaved caspase-3 (P < 0.01), and increase protein content of phospho-PKCepsilon and Bcl-2 significantly (P < 0.01). PKC inhibitor chelerythrine (Che) could prevent partly the effect of GSTT against myocardial apoptosis (P < 0.05 and P < 0.01). Mechanisms of GSTT against myocardial apoptosis might be associated with inhibition of mitochondrial apoptosis pathway after PKCepsilon activation.

The influence of the Tribulus terrestris extract on the parameters of the functional preparedness and athletes' organism homeostasis

The influence of the Tribulus terrestris extract on the parameters of the functional preparadness and athletes' organism homeostase was investigated. It was established the positive impact of dietary supplement "Tribulus" (Optimum Nutrition, U.S.A.) using per 1 capsule 3 times a day during 20 days on athletes' physical power in various energy producing zones: anaerobic alactic muscular power and anaerobic alactic glycolytic power statistically reliable increased. Tribulus terrestris extract, after 20 days of consuming it, did not have essential effect on erythrocytes, haemoglobin and thrombocytes indices. During the experimental period statistically importantly increased percentage of granulocytes and decreased percentage of leucocytes show negative impact of this food supplement on changes of leucocytes formula in athletes' blood. Creatinkinase concentration in athletes' blood statistically importantly has increased and creatinine amount has had a tendency to decline during 20 days period of consuming Tribulus terrestris extract. The declining tendency of urea, cholesterol and bilirubin concentrations has appeared. The concentration of blood testosterone increased statistically reliable during the first half (10 days) of the experiment; it did not grow during the next 10 days while consuming Tribulus still.

Two new steroidal saponins from Tribulus terrestris

Two new steroidal saponins and two known flavonoid glycosides were isolated from the fruits of Tribulus terrestris. Their structures were assigned by spectroscopic analysis and chemical reaction as 26-O-beta-D-glucopyranosyl-(25R)-5 alpha-furostan-12-one-3beta,22 alpha,26-triol-3-O-beta-D-glucopyranosyl (1 --> 2)-beta-D-glucopyranosyl(1 --> 4)-beta-D-galactopyranoside (1), 26-O-beta-D-glucopyranosyl-(25S)-5 alpha-furostan-22-methoxy-2 alpha,3beta,26-triol-3-O-beta-D-glucopyranosyl(1 --> 2)-beta-D-glucopyranosyl(1 --> 4)-beta-D-galactopyranoside (2), kaempferol-3-gentiobioside (3), and isorhamnetin-3-gentiobioside (4).

Evaluation of Tribulus terrestris Linn (Zygophyllaceae) acetone extract for larvicidal and repellence activity against mosquito vectors

Acetone extracts of leaves and seeds from the Tribulus terrestris (Zygophyllaceae) were tested against mature and immature different mosquito vectors under laboratory condition. The extract showed strong larvicidal, properties 100 per cent mortality in the 3rd-instar larvae was observed in the bioassays with An. culicifacies Giles species A, An. stephensi Liston, Culex quinquefasciatus Say and Aedes aegypti Linn, against 200 ppm of the leaf acetone extract and 100 ppm seed acetone extract. The LC50 values of leaf acetone extract estimated for 3rd-instars An. culicifacies species A, An. stephensi, Cx. quinquefasciatus and Ae. aegypti after 24 hour of exposure were 117, 124, 168 and 185 ppm respectively. The LC50 values of seed acetone extract estimated for 3rd-instars An. culicifacies species A, An. stephensi, Cx. quinquefasciatus and Ae. aegypti after 24 hour of exposure were 100, 72, 91 and 91 ppm respectively. It is confirmed from the LC50 values that the seed acetone extract of T. terrestris is more effective compared to leaf extracts. A significant (P<0.004) higher concentration of acetone extract leaf was required to kill equal number of larvae i.e. against acetone extract of seed. The seed acetone extract showed strong repellent activity against adults mosquitoes. Per cent protection obtained against Anopheles culicifacies species A 100% repellency in 1 h, 6 h; Anopheles stephensi 100% repellency in 0 h, 4 h, 6 h; and Culex quinquefasciatus 100% repellency in 0 h, 2 h, 4 h, at 10% concentration respectively. Against Deet- 2.5% An. culicifacies Giles species A has shown 100% repellency in 1 h, 2 h, 6 h, An. stephensi Liston 99% repellency in 4 h, and Culex quinquefasciatus Say has shown 100% repellency in 1 h, 2 h.

Potent inhibition of human phosphodiesterase-5 by icariin derivatives

Plant extracts traditionally used for male impotence (Tribulus terrestris, Ferula hermonis, Epimedium brevicornum, Cinnamomum cassia), and the individual compounds cinnamaldehyde, ferutinin, and icariin, were screened against phosphodiesterase-5A1 (PDE5A1) activity. Human recombinant PDE5A1 was used as the enzyme source. Only E. brevicornum extract (80% inhibition at 50 microg/mL) and its active principle icariin (1) (IC50 5.9 microM) were active. To improve its inhibitory activity, 1 was subjected to various structural modifications. Thus, 3,7-bis(2-hydroxyethyl)icaritin (5), where both sugars in 1 were replaced with hydroxyethyl residues, potently inhibited PDE5A1 with an IC50 very close to that of sildenafil (IC50 75 vs 74 nM). Thus, 5 was 80 times more potent than 1, and its selectivity versus phosphodiesterase-6 (PDE6) and cyclic adenosine monophosphate-phosphodiesterase (cAMP-PDE) was much higher in comparison with sildenafil. The improved pharmacodynamic profile and lack of cytotoxicity on human fibroblasts make compound 5 a promising candidate for further development.

[Study on fitting growth density and best harvest time of Tribulus terrestris]

OBJECTIVE

To study the suitable growth density and the optimal harvest time of Tribulus terrestris.

METHOD

Four growth densities were set with 60 cm breadth ridge and individual distance of 10, 20, 30 and 50 cm. The yield per individual and per unit area under the different growth densities were determined. Using yam saponin as a standard substance, the total saponin of T. terrestris was determined by UV spectrophotometry.

RESULT

The individual yield decreased with the density increase, but the difference between 30 cm and 50 cm individual distance was not substantial. The yield per unit area increased with density increase, and the difference between all densities was significant. The yield peak was in the last ten-day of August. The best leaves area index was 1.4 at the growth peak time. The total saponins content reached peaks respectively in the last ten-day of June and August, but the peak in last ten-day of August was consistent with the one of yield per unit area, and the total ashes content was the lowest at the same time.

CONCLUSION

The suitable growth density is 10 cm individual distance on the 60 cm breadth ridge. The optimal harvest time is in the last ten-day of August. The yield per unit area is 1 400 - 2 000 kg x hm(-2).

[A pharmacognostical study on Nitraria tangutorum]

OBJECTIVE

To study the pharmacognosy of Nitraria tangutorum Bobr. systematically.

METHODS

Macroscopic, microscopic identifications, physicochemical identification and UV spectrometry methods were carried out.

RESULTS

The macroscopical, microscopical and physicochemical characteristics of Nitraria tangutorum Bobr. were decribed in details.

CONCLUSION

The results can be taken as the reference for identifying the species, analyzing the quality and laying down quality standard of the crude drug.

A triterpene saponin from Tribulus terrestris attenuates apoptosis in cardiocyte via activating PKC signalling transduction pathway

The present study was conducted to examine the role of hecogenin-3-O-beta-D-glucopyranosyl(1-->4)-beta-D-galactopyranoside (1), which is a triterpene saponin of Tribulus terrestris in cardiocytes during chemical hypoxia-ischaemia in vitro. Neonatal rat ventricular myocytes were isolated by collagenase digestion and treated with NaCN for 12 h. Cell apoptosis was defined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) and flow cytometry. [Ca(2+)] was measured by confocal microscopy. There was a marked increase in the expression of the anti-apoptotic protein, Bcl-2, by NaCN. This change was increased by the saponin 1. PKCepsilon protein contents were increased in the cardiocyte membrane fraction in response to NaCN. PKCepsilon activation was augmented by the saponin 1. Inhibition of PKCepsilon with inhibitory peptide prevented Bcl-2 expression. Moreover, the saponin attenuated the apoptosis in cardiocyte in response to NaCN. It is therefore suggested that the saponin 1 may play a role in cardiocyte survival via PKCepsilon and Bcl-2.

Distribution of steroidal saponins in Tribulus terrestris from different geographical regions

The steroidal saponins of Tribulus terrestris L. (Zygophyllaceae) are considered to be the factor responsible for biological activity of products derived from this plant. The activity depends on the concentration and the composition of active saponins, which in turn is influenced by the geographical origin of plant material. Samples of T. terrestris collected in Bulgaria, Greece, Serbia, Macedonia, Turkey, Georgia, Iran, Vietnam and India were analyzed by LC-ESI/MS/MS for the presence and the concentration of protodioscin (1), prototribestin (2), pseudoprotodioscin (3), dioscin (4), tribestin (5) and tribulosin (6). The flavonoid rutin (7) was also included in the comparison. The results revealed distinct differences in the content of these compounds depending on region of sample collection, plant part studied and stage of plant development. The samples from Bulgaria, Turkey, Greece, Serbia, Macedonia, Georgia and Iran exhibited similar chemical profile and only some quantitative difference in the content of 1-7 with protodioscin (1) and prototribestin (2) as main components. The Vietnamese and Indian samples exhibit totally different chemical profile. They lack 2 and 5, while tribulosin (6) is present in high amounts. Compounds different from 1 to 7 are dominating in these 3 samples. The presented results suggested the existence of one chemotype common to the East South European and West Asian regions. Most probably, the Vietnamese and Indian samples belong to other chemotypes which are still to be studied and characterized. No clear correlation between the burrs morphology and the chemical composition of the samples has been found.

Hypoglycemic and hypolipidemic effects of alcoholic extract of Tribulus alatus in streptozotocin-induced diabetic rats: a comparative study with T. terrestris (Caltrop)

The extracts of both T. alatus and T. terrestris significantly decrease fasting glucose level in diabetic rats. After 4 and 6 hr, T. alatus extract showed significant reduction in glucose level as compared to T. terrestris. After 3 weeks of treatment with T. alatus extract, glucose level was significantly decreased to the normal level. Both the extracts also caused a significant decrease in the levels of glycosylated hemoglobin, total cholesterol, triglycerides and LDL-cholesterol. The percent of reduction in rats treated with T. alatus extract was significantly higher than that of the rats treated with T. terrestris. The results indicate that alcoholic extract of T. alatus possesses hypoglycemic activity in type-1 model of diabetes.

Free serum testosterone level in male rats treated with Tribulus alatus extracts

OBJECTIVE

The present study was undertaken to investigate the effect of Tribulus alatus extracts on free serum testosterone in male rats.

MATERIALS AND METHODS

Free serum testosterone level was measured in male rats treated with alcoholic extracts of the aerial part without fruits, fruits of Tribulus alatus and their fractions.

RESULTS

All tested extracts showed significant increase in the level of free serum testosterone when compared to that of corresponding control, p < 0.05. Statistical comparison of all groups revealed that the maximum level was found in groups treated with chloroformic and ethanolic fractions of fruits extract.

CONCLUSION

Tribulus alatus extract appears to possess aphrodisiac activity due to its androgen increasing property.

The effects of Gokshura, Tribulus terrestris on sex reversal of guppy, Poecilia reticulata

This study examined the effects of Tribulus terrestris (TT) on sex reversal in guppy, Poecilia reticulata. The objective of this study was to introduce a new environmentally friendly method for masculinization in P. reticulata. Since male guppy has higher commercial value than female. TT is a natural, non-toxic herb which helps enhance testosterone levels in human and animals. It was prepared in a laboratory in France. Different concentration (0.0, 0.05, 0.1 and 0.15 g L(-1)) of TT was investigated for sex reversal in the Poecilia reticulata. TT extract was administered by immersion of newly born offspring once weekly for two months. Among the dosages used in the present study 0.15 g L(-1) TT was the most effective dosage that ensured maximum male ratio (80%, p < 0.01). Although, sex ratios of 0.05 and 0.1 g L(-1) TT were not significantly different from the expected 1:1 ratio, in these two groups treatment with TT also result in higher number of males (58.25 and 59.77%, respectively), than control (p > 0.05). Total survival rates in all treatments and control were uniformly high ranging from 83 to 87% (p > 0.05). It is concluded that TT has no negative effect on survival rate of P. reticulata. All groups of TT-treated fish exhibited successful growth acceleration comparing to the control group, but only TT treatment at the concentration of 0.15 and 0.1 g L(-1) TT significantly improved growth rate of P. reticulata (p < 0.01). Histological examinations revealed that testes of fish treated with TT-extract contained all stages of spermatogenesis. Sex reversal in P. reticulata demonstrated that TT treated new-born progenies showed successful sex reversal, spermatogenesis and better growth rate than untreated progenies.

Saponins from Tribulus terrestris L are less toxic for normal human fibroblasts than for many cancer lines: influence on apoptosis and proliferation

The objective of the study was to explore the influence of saponins derived from Tribulus terrestris L. (TT) on normal human skin fibroblasts and to compare it with their anticancer properties. In this study, [3H]thymidine incorporation and MTT to assess cell proliferation and viability, respectively, and immunoblotting and HPLC analysis to explore intracellular signal transduction pathways have been used. We found that TT caused a dose-dependent decrease in [3H]thymidine incorporation into the DNA of treated fibroblast compared to the untreated controls. Viability of treated cells remained within the control levels with treatment of up to 5 micro g TT/ml medium. It was significantly depressed with incubation in > or =6 micro g TT/ml medium with an IC50 of 12.6 micro g TT/ml of cultivating media. ERK1/2 was significantly dephosphorylated at 5 mins of incubation with TT until the 48th hour, when phosphorylation slightly recovered, but was still below the control levels. In contrast, p38 and JNK phosphorylation was positively influenced, with peaks at 1 hr and 24 hrs of incubation respectively. Phosphorylation/dephosphorylation events of SAPK/MAPK clearly correlated with Mkp-1 induction. Procaspase 3 was activated after 5 mins of incubation and coincided with a rapid actin cleavage. There was a significant decrease of putrescine concentration and a concomitant increase of spermidine and spermine at 2 mins of treatment. According to our results, TT is less toxic for normal human skin fibroblasts in comparison to many cancer lines investigated in previous studies. The molecular mechanism of this cytotoxicity involves up- and downregulation of polyamines' homeostasis, suppression of proliferation, and induction of apoptosis. Further research in this field using animal models would help to explore and interpret the potential properties of TT as an anticancer supplement.

[Effect of Tribulus terrestris extract on melanocyte-stimulating hormone expression in mouse hair follicles]

OBJECTIVE

To observe the effect of Tribulus terrestris extract on melanocyte stimulating hormone (MSH) expression in C57BL/6J mouse hair follicles, and investigate the role of Tribulus terrestris extract in activation, proliferation, epidermal migration of dormant hair follicle melanocytes.

METHODS

The aqueous extract of Tribulus terrestris was administered orally in specific pathogen-free C57BL/6J mouse at the daily dose equivalent to 1 g/1 kg in adult human, and the expression and distribution of MSH in the mouse hair follicles was observed with immunohistochemistry.

RESULTS

The positivity rate of MSH expression in the hair follicle melanocytes was 75% in mice treated with the extract, significantly higher than the rate of only 18.75% in the control group (P<0.01).

CONCLUSION

The aqueous extract of Tribulus terrestris can significantly increase MSH expression in the hair follicle melanocytes by activating tyrosinase activity and promoting melanocyte proliferation, melanine synthesis, and epidermal migration of dormant melanocytes.

[Protective effects of Xinnao Shutong capsule on acute cerebral ischemic injury of multiple infarcts in rats]

OBJECTIVE

To study the effect of Xinnao Shutong capsule (XNST) on energy metabolism dysfunction, free radical injury and inflammatic factors in the course of acute cerebral ischemic damage, and try to reveal the mechanism of the protection against ischemia.

METHOD

60 male Wistar rats weighing 280 - 320 g were randomly divided into five groups: normal, sham operation, model, XNST treatment( XNST-T) , and Western medicine treatment (WM-T) group. Acute multi-infarct model in rats was induced by injecting the embolus of blood powder through the right external carotid artery (ECA) into the internal carotid artery (ICA). At 72 hours after ischemia, morphologic change and the express of tumor necrosis factor-alpha (TNF-alpha) and interleukin -1beta ( IL-1beta) in hippocampus CAl section and cortex were observed, biochemical criterions including the activity of Na+ -K+ -ATPase, lactate dehydrogenase (LDH), superoxide dismutase (SOD), and the content of malondialdehyde (MDA) in hippocampus were examined.

RESULT

The morphologic change of hippocampus and cortex in both XNST-T and WM-T groups was milder than that in model group. The activity of Na+ -K+ -ATPase, LDH and SOD in hippocampus were all significantly decreased in model group (P <0. 01), and elevated in XNST group (P <0. 01) as well as in WM-T group (P <0. 01). The content of MDA in hippocampus was significantly increased in model group (P <0. 05), and was reduced in XNST group (P <0. 05) as well as in WM-T group (P <0. 01).

CONCLUSION

The results reveal that XNST has the protective effect against cerebral ischemic injury. And its possible mechanism is that XNST can prevent the upper pathological process.

[Inhibitory effects of saponins from Tribulus terrestris on alpha-glucosidase in small intestines of rats]

OBJECTIVE

To determine the effects of saponins from Tribulus terrestris (STT) on small intestinal a-glucosidase and postprandial blood glucose levels in rats.

METHOD

The inhibitory effects of STT on a-glucosidase extracted from small intestines in rats were carried out in vitro. The blood glucose levels were measured after 60 min when sucrose (2 g x kg(-1)) or glucose (2 g x kg(-1)) was administered orally with STT (100 mg x kg(-1)). After treated with STT (100 mg x kg(-1)) for 14 d, the activities of a-glucosidase were determined daily, as well as the postprandial blood glucose levels after oraly administered sucrose (2 g x kg(-1)).

RESULT

STT at concentrations of 0.1, 1 and 10 mg x mL(-1) reduced significantly the activities of alpha-glucosidase with inhibitory rates of (20.83 +/- 1.66)%, (43.73 +/- 2.39)% and (52.62 +/- 2.69)%, respectively. In facts STT (100 mg x kg(-1)) considerably decreased the blood glucose levels which was 52.61% of that of the control in rats co-administered orally with sucrose (2 g x kg(-1)). However, it showed no such effect on the rats co-administered orally with glucose (2 g x kg(-1)). After orally administered of STT for 14 d, the activity of alpha-glucosidase was significantly reduced (P < 0.05) to (58.17 +/- 3.24)% of that those in control. Meanwhile, The rats were oral administered with sucrose, the increase of postprandial blood glucose levels were (69.50 +/- 4.28)% of that in control 60 min later ( P < 0.05).

CONCLUSION

It was through inhibiting the activity of a-glucosidase in small intestines that STT significantly retarded the increase in postprandial blood glucose levels in rats.

Steroidal saponins from the aerial parts of Tribulus alatus Del

Six steroidal glycosides (1-6) were isolated from the aerial parts of Tribulus alatus Del. (Zygophyllaceae), together with one known cholestane, one spirostane, and six flavonol glycosides. Among them, 1 and 2 possess a furostane-type aglycone, 3 and 6 a cholestane structure, and 4 and 5 a spirostane skeleton. Their structural elucidation was accomplished by extensive spectroscopic methods including 1D ((1)H, (13)C, (13)C DEPT, TOCSY, ROESY) and 2D NMR experiments (DQF-COSY, HSQC, HMBC) as well as ESI-MS analysis.

Antifungal activities and action mechanisms of compounds from Tribulus terrestris L

Antifungal activity of natural products is being studied widely. Saponins are known to be antifungal and antibacterial. We used bioassay-guided fractionation to have isolated eight steroid saponins from Tribulus terrestris L., which were identified as hecogenin-3-O-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-8), tigogenin-3-O-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-9), hecogenin-3-O-beta-D-glucopyranosyl (1-->2)-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-10), hecogenin-3-O-beta-D-xylopyranosyl (1-->3)-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-11), tigogenin-3-O-beta-D-xylopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-[alpha-L-rhamnopyranosyl (1-->2)]-beta-D-galactopyranoside (TTS-12), 3-O-[beta-D-xylopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-[alpha-L-rhamnopyranosyl (1-->2)]-beta-D-galactopyranosyl]-26-O-beta-D-glucopyranosyl-22-methoxy-(3beta,5alpha,25R)-furostan-3,26-diol (TTS-13), hecogenin-3-O-beta-D-glucopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-14), tigogenin-3-O-beta-D-glucopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-15). The in vitro antifungal activities of the eight saponins against five yeasts, Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis and Cryptococcus neoformans were studied using microbroth dilution assay. In vivo activity of TTS-12 in a Candida albicans vaginal infection model was studied in particular. The results showed that TTS-12 and TTS-15 were very effective against several pathogenic candidal species and Cryptococcus neoformans in vitro. It is noteworthy that TTS-12 and TTS-15 were very active against Candida albicans (MIC(80) = 10 and 2.3 microg/mL) and Cryptococcus neoformans (MIC(80) = 1.7 and 6.7 microg/mL). Phase contrast microscopy showed that TTS-12 inhibited hyphal formation, an important virulence factor of Candida albicans, and transmission electron microscopy showed that TTS-12 destroyed the cell membrane of Candida albicans. In conclusion, TTS-12 has significant in vitro and in vivo antifungal activity, weakening the virulence of Candida albicans and killing fungi through destroying the cell membrane.

Cytotoxic furostanol saponins and a megastigmane glucoside from tribulus parvispinus

Two new furostanol saponins, (25R)-26-O-beta-D-glucopyranosyl-5alpha-furostan-2alpha,3beta,22alpha,26-tetraol 3-O-{beta-D-galactopyranosyl-(1-->2)-O-[beta-D-xylopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->4)-beta-D-galactopyranoside} (1) and (25R)-26-O-beta-D-glucopyranosyl-5alpha-furostan-3beta,22alpha,26-triol 3-O-{beta-D-galactopyranosyl-(1-->2)-O-[beta-D-xylopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->4)-beta-D-galactopyranoside} (2), and their O-methyl derivatives (3 and 4), and a new megastigmane glucoside, (6S,7E,9xi)-6,9,10-trihydroxy-4,7-megastigmadien-3-one 10-O-beta-D-glucopyranoside (6), along with one known spirostanol saponin, gitonin (5), and four known megastigmane glucosides were isolated from the aerial parts of Tribulus parvispinus. Their structures were established by detailed spectroscopic analysis. The cytotoxic activities of 1-6 against U937, MCF7, and HepG2 cells were evaluated. Compounds 2 (IC(50) 0.5 microM) and 5 (IC(50) 0.1 microM) showed the highest activity against U937 cells.

Assigning stereodiversity of the 27-Me group of furostane-type steroidal saponins via NMR chemical shifts

Applicability of (13)C and (1)H NMR chemical shifts for the assignment of the 25R/25S configuration of the 27-methyl group in the case of furostane-type steroidal saponins has been investigated. A comparative study of (13)C NMR data suggest that chemical shift values for C-20, C-21, C-22, C-23, C-24, C-25, C-26 and C-27 resonances were not much influenced by R/S configuration of the 27-Me group, thus reflecting limited application of (13)C NMR chemical shifts for such stereochemical determinations. In contrast, (1)H NMR chemical shifts (delta(a), delta(b)) for geminal protons of glycosyloxy methylene (H(2)-26) exhibit pronounced dependence and the difference (Delta(ab)=delta(a)-delta(b)) among their chemical shifts [Delta(ab)= or <0.48 for 25R; Delta(ab)= or >0.57 for 25S] seems to be of general applicability for ascertaining 25R/25S orientation of the 27-methyl group of furostane-type steroidal saponins.