Anti-herpes virus activity of fabaceous triterpenoidal saponins')

Hemolysis by Saponin Is Accelerated at Hypertonic Conditions

Saponins are a large group of organic amphiphilic substances (surfactants) mainly extracted from herbs with biological activity, considered as one of the main ingredients in numerous remedies used in traditional medicine since ancient times. Anti-inflammatory, antifungal, antibacterial, antiviral, antiparasitic, antitumor, antioxidant and many other properties have been confirmed for some. There is increasing interest in the elucidation of the mechanisms behind the effects of saponins on different cell types at the molecular level. In this regard, erythrocytes are a very welcome model, having very simple structures with no organelles. They react to changing external conditions and substances by changing shape or volume, with damage to their membrane ultimately leading to hemolysis. Hemolysis can be followed spectrophotometrically and provides valuable information about the type and extent of membrane damage. We investigated hemolysis of erythrocytes induced by various saponin concentrations in hypotonic, isotonic and hypertonic media using measurements of real time and end-point hemolysis. The osmotic pressure was adjusted by different concentrations of NaCl, manitol or a NaCl/manitol mixture. Unexpectedly, at a fixed saponin concentration, hemolysis was accelerated at hypertonic conditions, but was much faster in NaCl compared to mannitol solutions at the same osmotic pressure. These findings confirm the colloid-osmotic mechanism behind saponin hemolysis with pore formation with increasing size in the membrane.

Oriental traditional herbal Medicine--Puerariae Flos: A systematic review

ETHNOPHARMACOLOGICAL RELEVANCE

Pueraria Flos (PF), a traditional herbal medicine, is botanically from the dried flowers of Pueraria lobate (Willd.) Ohwi. (Chinese: ) or Pueraria thomsonii Benth. (Chinese: ). It has a long history of thousands of years in China for awakening the spleen, clearing the lungs, relieving alcohol.

AIM OF THE REVIEW

This review aims to report the up-to-date research progress in ethnopharmacology, phytochemistry, pharmacology and toxicology, metabolism and therapeutic application of PF, so as to provide a strong basis for future clinical treatment and scientific research.

MATERIALS AND METHODS

Relevant information on PF was collected from scientific literature databases including PubMed, CNKI and other literature sources (Ph.D. and M.Sc. dissertations and Chinese herbal classic books) by using the keyword "Puerariae".

RESULTS

Briefly, phytochemical research report has isolated 39 flavonoids, 19 saponins and 25 volatile oils from PF. Flavonoids and saponins are the most important bioactive compounds, and most of the quality control studies focus on these two types of compounds. Modern pharmacological studies have revealed their significant biological activities in relieving alcoholism, hepatoprotective, anti-tumor, anti-inflammatory, and anti-oxidation, which provides theoretical support for the traditional use.

CONCLUSIONS

Comprehensive analysis showed that pharmacological activity of most purified compounds from PF had not been reported. Kakkalide, tectoridin and their deglycosylated metabolites (irisolidone and tectorigenin) has been focused on excessively due to their higher content and better activities. This leads to low development and resources waste. Interestingly, PF made a breakthrough in the field of food. Many kinds of fat-lowering foods such as PILLBOX Onaka have been popular in Japan market, which received extensive attention. Therefore, we suggest that future research can be paid attention on the development of the plant's function in the field of food and medicine, as well as the transformation from experimental to clinical.

Characterization and Utilization of Disulfide-Bonded SARS-CoV-2 Receptor Binding Domain of Spike Protein Synthesized by Wheat Germ Cell-Free Production System

The spike protein (SP) of SARS-CoV-2 is an important target for COVID-19 therapeutics and vaccines as it binds to the ACE2 receptor and enables viral infection. Rapid production and functional characterization of properly folded SP is of the utmost importance for studying the immunogenicity and receptor-binding activity of this protein considering the emergence of highly infectious viral variants. In this study, we attempted to express the receptor-binding region (RBD) of SARS-CoV-2 SP containing disulfide bonds using the wheat germ cell-free protein synthesis system. By adding protein disulfide isomerase (PDI) and endoplasmic reticulum oxidase (ERO1α) to the translational reaction mixture, we succeeded in synthesizing a functionally intact RBD protein that can interact with ACE2. Using this RBD protein, we have developed a high-throughput AlphaScreen assay to evaluate the RBD–ACE2 interaction, which can be applied for drug screening and mutation analysis. Thus, our method sheds new light on the structural and functional properties of SARS-CoV-2 SP and has the potential to contribute to the development of new COVID-19 therapeutics.

Bridging the Gaps between Plant and Human Health: A Systematic Review of Soyasaponins

Saponins, prominent secondary plant metabolites, are recognized for their roles in plant defense and medicinal benefits. Soyasaponins, commonly derived from legumes, are a class of triterpenoid saponins that demonstrate significant potential for plant and human health applications. Previous research and reviews largely emphasize human health effects of soyasaponins. However, the biological effects of soyasaponins and their implications for plants in the context of human health have not been well-discussed. This review provides comprehensive discussions on the biological roles of soyasaponins in plant defense and rhizosphere microbial interactions; biosynthetic regulation and compound production; immunological effects and potential for therapeutics; and soyasaponin acquisition attributed to processing effects, bioavailability, and biotransformation processes based on recent soyasaponin research. Given the multifaceted biological effects elicited by soyasaponins, further research warrants an integrated approach to understand molecular mechanisms of regulations in their production as well as their applications in plant and human health.

Effective Search of Triterpenes with Anti-HSV-1 Activity Using a Classification Model by Logistic Regression

Natural products are an excellent source of skeletons for medicinal seeds. Triterpenes and saponins are representative natural products that exhibit anti-herpes simplex virus type 1 (HSV-1) activity. However, there has been a lack of comprehensive information on the anti-HSV-1 activity of triterpenes. Therefore, expanding information on the anti-HSV-1 activity of triterpenes and improving the efficiency of their exploration are urgently required. To improve the efficiency of the development of anti-HSV-1 active compounds, we constructed a predictive model for the anti-HSV-1 activity of triterpenes by using the information obtained from previous studies using machine learning methods. In this study, we constructed a binary classification model (i.e., active or inactive) using a logistic regression algorithm. As a result of the evaluation of predictive model, the accuracy for the test data is 0.79, and the area under the curve (AUC) is 0.86. Additionally, to enrich the information on the anti-HSV-1 activity of triterpenes, a plaque reduction assay was performed on 20 triterpenes. As a result, chikusetsusaponin IVa (11: IC₅₀ = 13.06 μM) was found to have potent anti-HSV-1 with three potentially anti-HSV-1 active triterpenes. The assay result was further used for external validation of predictive model. The prediction of the test compounds in the activity test showed a high accuracy (0.83) and AUC (0.81). We also found that this predictive model was found to be able to successfully narrow down the active compounds. This study provides more information on the anti-HSV-1 activity of triterpenes. Moreover, the predictive model can improve the efficiency of the development of active triterpenes by integrating many previous studies to clarify potential relationships.

Exploring the possible use of saponin adjuvants in COVID-19 vaccine

There is an urgent need for a safe, efficacious, and cost-effective vaccine for the coronavirus disease 2019 (COVID-19) pandemic caused by novel coronavirus strain, severe acute respiratory syndrome-2 (SARS-CoV-2). The protective immunity of certain types of vaccines can be enhanced by the addition of adjuvants. Many diverse classes of compounds have been identified as adjuvants, including mineral salts, microbial products, emulsions, saponins, cytokines, polymers, microparticles, and liposomes. Several saponins have been shown to stimulate both the Th1-type immune response and the production of cytotoxic T lymphocytes against endogenous antigens, making them very useful for subunit vaccines, especially those for intracellular pathogens. In this review, we discuss the structural characteristics, mechanisms of action, structure-activity relationship of saponins, biological activities, and use of saponins in various viral vaccines and their applicability to a SARS-CoV-2 vaccine.

Biological functionality of soyasaponins and soyasapogenols

Soyasaponins are a group of structurally complex oleanane triterpenoids primarily found in soybeans and have diverse biological properties. The recent investigations and findings (since 2000) regarding the biological functions of soyasaponins and their aglycones, including their anti-inflammatory, antimutagenic, anticarcinogenic, antimicrobial, and hepato- and cardiovascular-protective activities, are herein summarized. The primary conclusion is that the use of soyasaponins and soyasapogenols in functional foods should be considered.

Cloning and Characterization of Saponin Hydrolases fromAspergillus oryzaeandEupenicillium brefeldianum

We purified saponin hydrolases from Aspergillus oryzae PF1224 and Eupenicillium brefeldianum PF1226. It was confirmed that the enzymes from A. oryzae PF1224 (Sda1) and E. brefeldianum PF1226 (Sde1) are glycoproteins with molecular masses of 82 and 90 kDa respectively. The deduced amino acid sequences of each enzyme from the cloned genes (sda1 or sde1) showed approximately 50% homology with that of the saponin hydrolase Sdn1 from Neocosmospora vasinfecta var. vasinfecta PF1225 (DDBJ accession no. AB110615). When sda1 and sde1 were expressed in the host Trichoderma viride under the control of the cellobiohydrolase I gene promoter, recombinant proteins were secreted with molecular masses of 77 and 67 kDa respectively. These recombinant enzymes hydrolyzed soyasaponin I to soyasapogenol B and triose, and its substrate specificities for glycosides were similar to that of Sdn1, but the specific activities of these enzymes were lower than that of Sdn1.

Astragaloside IV inhibits adenovirus replication and apoptosis in A549 cells in vitro

Objectives

Astragaloside IV, purified from the Chinese medical herb Astragalus membranaceus (Fisch) Bge and Astragalus caspicus Bieb, is an important natural product with multiple pharmacological actions. This study investigated the anti-ADVs effect of astragaloside IV on HAdV-3 (human adenovirus type 3) in A549 cell.

Methods

CPE, MTT, quantitative real-time PCR (qPCR), flow cytometry (FCM) and Western blot were apply to detect the cytotoxicity, the inhibition and the mechanisms of astragaloside IV on HAdV-3.

Key findings

TC0 of astragaloside IV was 116.8 µm, the virus inhibition rate from 15.98% to 65.68% positively was correlated with the concentration of astragaloside IV from 1.25 µm to 80 µm, IC50 (the medium inhibitory concentration) was 23.85 µm, LC50 (lethal dose 50% concentration) was 865.26 µm and the TI (therapeutic index) was 36.28. qPCR result showed astragaloside IV inhibited the replication of HAdV-3. Flow FCM analysis demonstrated that the anti-HAdV-3 effect was associated with apoptosis. Astragaloside IV was further detected to reduce the protein expressions of Bax and Caspase-3 and increasing the protein expressions of Bcl-2 using western blotting, which improved the anti-apoptosis mechanism of astragaloside IV on HAdV-3.

Conclusions

Our findings suggested that astragaloside IV possessed anti-HAdV-3 capabilities and the underlying mechanisms might involve inhibiting HAdV-3 replication and HAdV-3-induced apoptosis.

A review of the herbal phosphodiesterase inhibitors; future perspective of new drugs

Phosphodiesterase inhibitors (PDEIs) are a class of drugs that are widely used because of their various pharmacological properties including cardiotonic, vasodilator, smooth muscle relaxant, antidepressant, antithrombotic, bronchodilator, antiinflammatory and enhancer of cognitive function. In the recent years, interest in drugs of plant origin has been progressively increased. Some pharmacologically active substances that come from plants demonstrate PDEI activity. They mainly belong to alkaloids, flavonoids, and saponins. In this review, studies on herbal PDEI were reviewed and their possible therapeutic applications were discussed. Screening plants for PDE inhibitory activity may help to develop standardized phytotherapeutic products or find new sources for new lead structures with PDEI pharmacological activity. The studies discussed in this paper are mainly in vitro and for more reasonable and conclusive results, it is required to conduct in vivo and finally human and clinical tests.

Preparative separation of four triterpene saponins from radix astragali by high-speed counter-current chromatography coupled with evaporative light scattering detection

Four triterpene saponins, including astragaloside IV, astragaloside II, astragaloside I and acetylastragaloside I, were successfully isolated and separated by high-speed counter-current chromatography coupled with evaporative light scattering detection from Radix Astragali using stepwise elution with a pair of solvent systems composed of n-hexane:ethyl acetate:ethanol:water in volume ratios of 1:0.6:0.6:1 and 1:1:1:1 (by volume). The isolation produced 26.5 mg astragaloside IV, 28.2 mg astragaloside II, 48.7 mg astragaloside I and 17.6 mg acetylastragaloside I with purities of 97.6, 96.4, 98.8 and 96.8%, respectively, determined by high-performance liquid chromatography from 250 mg crude extract. The chemical structures of the isolated compounds were identified by UV, NMR and MS, and confirmed by authentic standards.

Sensitive and selective liquid chromatography-electrospray ionisation-mass spectrometry analysis of astragaloside-IV in rat plasma

Astragaloside-IV (3-O-beta-d-xylopyranosyl-6-O-beta-d-glucopyranosyl-cycloastragenol) is the major active constituent contained in Radix Astragali. This paper describes a rapid, sensitive and specific assay for quantitative determination of astragaloside-IV in rat plasma. After a liquid/liquid extraction (LLE) with n-butanol and high-performance liquid chromatography (HPLC) gradient separation with acetonitrile-NH4Cl solution (0.5 micromol/L) as the mobile phase, the anions adduct [M + Cl]- at m/z 819.4 of astragaloside-IV, and [M + Cl]- at m/z 815.35 of internal standard (IS) digoxin were analyzed by electrospray ionisation-mass spectrometry (LC-ESI-MS) in selected ion monitoring (SIM) mode. Chromatographic separation was achieved in less than 9 min and calibration curve was linear over a concentration range of 2-200 ng/ml. The described assay method was successfully applied to the preclinical pharmacokinetic study of astragaloside-IV. After intragastric administration of astragaloside-IV to rats, Cmax and Tmax of astragaloside-IV were 134.73 +/- 39.86 ng/ml and 1.5 h, respectively, and the elimination half-life (t1/2) was 5.45 +/- 0.39 h.

Anti-herpes virus type 1 activity of oleanane-type triterpenoids

The anti-herpes simplex virus type 1 (HSV-1) activity of 15 oleanan-type triterpenoides including glycyrrhizin and its sapogenol was examined and their structure-activity relationships were discussed. Although glycyrrhizin which exhibited in vivo efficacy against HSV-1 replication showed moderate in vitro anti-HSV-1 activity, its sapogenol, glycyrrhetic acid, showed 10 times greater action than glycyrrhizin. Therefore, the in vivo anti-HSV-1 activity of glycyrrhizin administered orally could be reasonably attributed to glycyrrhetic acid generated by hydrolysis by intestinal bacteria. Since the activity of soyasapogenol A was less than 1/20 of that of soyasapogenol B, the hydroxylation at C-21 seemed to reduce anti-HSV-1 activity. Since kudzusapogenol A, abrisapogenols B and C lacked the activity, the C-29 hydroxy group would eliminate anti-HSV-1 activity. On the other hand, since the methylesters of kudzusapogenol B and glycyrrhetic acid exhibited greater action, a methoxy carboxy group at C-20 might enhance activity.

Antiviral activities of medicinal herbs traditionally used in southern mainland China

The aqueous extracts from 21 medicinal herbs traditionally used in southern mainland China were screened for antiviral activities against human herpes simplex virus type 1 (HSV-1) and human respiratory syncytial virus (RSV) using a cytopathic effect (CPE) reduction assay. Three extracts from Agrimonia pilosa, Pithecellobium clypearia and Punica granatum, respectively, showed anti-HSV-1 activity, which was possibly contributed by the polyphenolic compounds in the herbal extracts. Six of the extracts, from Blumea laciniata, Elephantopus scaber, Laggera pterodonta, Mussaenda pubescens, Schefflera octophylla and Scutellaria indica, respectively, exhibited anti-RSV activity with 50% inhibition (IC50) concentrations ranging from 12.5 to 32 microg/mL, and selective indices (SI) ranging from 11.2 to 40. In addition to polyphenolic compounds, other constituents present in these extracts may also contribute to their anti-RSV activity.

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.

Soyasaponins: the relationship between chemical structure and colon anticarcinogenic activity

Soyasaponins are bioactive compounds found in many legumes. Although crude soyasaponins have been shown to have anti-colon carcinogenic activity, there have been no structure-activity studies. In this study, therefore, purified soyasaponins and soyasapogenins were tested for their ability to suppress the growth of HT-29 colon cancer cells, as determined by the WST-1 assay, over a concentration range of 0-50 ppm. Soyasaponin I and III, soyasapogenol B monoglucuronide, soyasapogenol B, soyasaponin A1, soyasaponin A2, and soyasapogenol A were evaluated. Also tested were mixtures comprising acetylated group A soyasaponins, deacetylated group A soyasaponins, and group B soyasaponins. The most potent compounds were the aglycones soyasapogenol A and B, which showed almost complete suppression of cell growth. The glycosidic soyasaponins by comparison were largely inactive. Soyasaponin A(1), A(2), and I, group B and deacetylated and acetylated group A fractions had no effect on cell growth. Soyasaponin III and soyasapogenol B monoglucuronide were marginally bioactive. These results suggested that the bioactivity of soyasaponins increased with increased lipophilicity. Results from in vitro fermentation suggested that colonic microflora readily hydrolyzed the soyasaponins to aglycones. These observations suggest that the soyasaponins may be an important dietary chemopreventive agent against colon cancer, after alteration by microflora.

A novel saponin hydrolase from Neocosmospora vasinfecta var. vasinfecta

We isolated a soybean saponin hydrolase from Neocosmospora vasinfecta var. vasinfecta PF1225, a filamentous fungus that can degrade soybean saponin and generate soyasapogenol B. This enzyme was found to be a monomer with a molecular mass of about 77 kDa and a glycoprotein. Nucleotide sequence analysis of the corresponding gene (sdn1) indicated that this enzyme consisted of 612 amino acids and had a molecular mass of 65,724 Da, in close agreement with that of the apoenzyme after the removal of carbohydrates. The sdn1 gene was successfully expressed in Trichoderma viride under the control of the cellobiohydrolase I gene promoter. The molecular mass of the recombinant enzyme, about 69 kDa, was smaller than that of the native enzyme due to fewer carbohydrate modifications. Examination of the degradation products obtained by treatment of soyasaponin I with the recombinant enzyme showed that the enzyme hydrolyzed soyasaponin I to soyasapogenol B and triose [alpha-L-rhamnopyranosyl (1-->2)-beta-D-galactopyranosyl (1-->2)-D-glucuronopyranoside]. Also, when soyasaponin II and soyasaponin V, which are different from soyasaponin I only in constituent saccharides, were treated with the enzyme, the ratio of the reaction velocities for soyasaponin I, soyasaponin II, and soyasaponin V was 2,680:886:1. These results indicate that this enzyme recognizes the fine structure of the carbohydrate moiety of soyasaponin in its catalytic reaction. The amino acid sequence of this enzyme predicted from the DNA sequence shows no clear homology with those of any of the enzymes involved in the hydrolysis of carbohydrates.

Antiviral activity of a hot water extract of black soybean against a human respiratory illness virus

Significant antiviral activity against respiratory illness viruses has been found in a hot-water extract of black soybean. This black soybean extract showed significant antiviral activity against human adenovirus type 1 and coxsackievirus B1 in a dose-dependent manner, while the hot-water extract from common yellowish soybean showed only weak activity. The antiviral activity could not be extracted from the black soybean by 70% aqueous ethanol, suggesting that saponin in the seed did not contribute to this activity. The antiviral activity was only recovered from cotyledons and not from seed coats with the hot water, showing that the activity was distributed in the cotyledons and that antocyanins in the black soybean seed coats did not contribute to the antiviral activity. The antiviral compound(s) in the black soybean was partially purified by up to 166 times by a combination of gel filtration, reversed phase HPLC, and ion-exchange HPLC. The partially purified antiviral compound showed hydrophilic and anionic properties, and a maximum absorption at 260 nm, suggesting that this antiviral fraction may contain a phenyl group(s). On the other hand, an amino acid analysis with the acid hydrolyzate and a neutral sugar analysis showed that the antiviral compound from black soybean might not be a polypeptide or glycoconjugate bearing neutral sugar(s).