Notoginsenoside ST-4 inhibits virus penetration of herpes simplex virus in vitro

Integration of network pharmacology with experimental validation to reveal the mechanism of action of Longdan Xiegan Decoction against HSV2 infection and determine its effective components

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese Medicine (TCM) has made enormous strides recently in the discovery of anti-herpes simplex virus (HSV) drugs under the guidance of TCM theory. Longdan Xiegan Decoction (LXD), a formulation recorded in the Pharmacopoeia of the People's Republic of China, has proved to be effective against HSV infection. However, its effective components and action mechanism remain unclear.

AIM OF THE STUDY

To investigate the effective components and mechanisms of LXD in treating HSV infection based on network pharmacology and experimental validation.

MATERIALS AND METHODS

The anti-HSV activities of key compounds predicted by network analysis were detected by antiviral tests. High-performance liquid chromatography (HPLC) was applied to identify the main components of the LXD aqueous extract. Time-of-addition assay and infectivity inhibition reversibility assay were conducted to identify the potential antiviral mechanisms of licochalcone B (LCB). Additionally, we assessed the antiviral effect of LCB in vivo by use of body weight, viral load, histological analysis, and scoring of genital lesions in an HSV2-infected mouse model.

RESULTS

Our data demonstrated that some components exhibited significant anti-HSV1/2 activity in vitro, including quercetin, kaempferol, wogonin, formononetin, naringenin, baicalein, isorhamnetin, glabridin, licochalcone A, echinatin, oroxylin A, isoliquiritigenin, pinocembrin, LCB and acacetin. HPLC analysis showed that LCB was the main component of LXD aqueous extract. In vitro experiments revealed that LCB not only inactivated HSV2 particles, but also inhibited HSV2 multiplication through the inhibition of the phosphorylation of Akt and its downstream targets. In vivo experiments confirmed that LCB could significantly reduce viral titer, delay weight loss, and alleviate pathological changes in vaginal tissue in vaginal infection mouse models.

CONCLUSION

LCB acted as the main component of LXD, with significant anti-HSV2 infection effects both in vivo and in vitro. This study provides additional evidence of the healing efficacy of LXD against HSV infection and presents an efficient analytical method for further investigation of the mechanisms of TCM in prevention and treatment of various diseases.

Rare ginsenosides: A unique perspective of ginseng research

BACKGROUND

Rare ginsenosides (Rg3, Rh2, C-K, etc.) refer to a group of dammarane triterpenoids that exist in low natural abundance, mostly produced by deglycosylation or side chain modification via physicochemical processing or metabolic transformation in gut, and last but not least, exhibited potent biological activity comparing to the primary ginsenosides, which lead to a high concern in both the research and development of ginseng and ginsenoside-related nutraceutical and natural products. Nevertheless, a comprehensive review on these promising compounds is not available yet.

AIM OF REVIEW

In this review, recent advances of Rare ginsenosides (RGs) were summarized dealing with the structurally diverse characteristics, traditional usage, drug discovery situation, clinical application, pharmacological effects and the underlying mechanisms, structure-activity relationship, toxicity, the stereochemistry properties, and production strategies.

KEY SCIENTIFIC CONCEPTS OF REVIEW

A total of 144 RGs with diverse skeletons and bioactivities were isolated from Panax species. RGs acted as natural ligands on some specific receptors, such as bile acid receptors, steroid hormone receptors, and adenosine diphosphate (ADP) receptors. The RGs showed promising bioactivities including immunoregulatory and adaptogen-like effect, anti-aging effect, anti-tumor effect, as well as their effects on cardiovascular and cerebrovascular system, central nervous system, obesity and diabetes, and interaction with gut microbiota. Clinical trials indicated the potential of RGs, while high quality data remains inadequate, and no obvious side effects was found. The stereochemistry properties induced by deglycosylation at C (20) were also addressed including pharmacodynamics behaviors, together with the state-of-art analytical strategies for the identification of saponin stereoisomers. Finally, the batch preparation of targeted RGs by designated strategies including heating or acid/ alkaline-assisted processes, and enzymatic biotransformation and biosynthesis were discussed. Hopefully, the present review can provide more clues for the extensive understanding and future in-depth research and development of RGs, originated from the worldwide well recognized ginseng plants.

Antiviral activities of ginseng and its potential and putative benefits against monkeypox virus: A mini review

Due to the Covid-19 pandemic more than 6 million people have died, and it has bought unprecedented challenges to our lives. The recent outbreak of monkeypox virus (MPXV) has brought out new tensions among the scientific community. Currently, there is no specific treatment protocol for MPXV. Several antivirals, vaccinia immune globulin (VIG) and smallpox vaccines have been used to treat MPXV. Ginseng, one of the more famous among traditional medicines, has been used for infectious disease for thousands of years. It has shown promising antiviral effects. Ginseng could be used as a potential adaptogenic agent to help prevent infection by MPXV along with other drugs and vaccines. In this mini review, we explore the possible use of ginseng in MPXV prevention based on its antiviral activity.

Identification of Therapeutic Targets in an Emerging Gastrointestinal Pathogen Campylobacter ureolyticus and Possible Intervention through Natural Products

Campylobacter ureolyticus is a Gram-negative, anaerobic, non-spore-forming bacteria that causes gastrointestinal infections. Being the most prevalent cause of bacterial enteritis globally, infection by this bacterium is linked with significant morbidity and mortality in children and immunocompromised patients. No information on pan-therapeutic drug targets for this species is available yet. In the current study, a pan-genome analysis was performed on 13 strains of C. ureolyticus to prioritize potent drug targets from the identified core genome. In total, 26 druggable proteins were identified using subtractive genomics. To the best of the authors’ knowledge, this is the first report on the mining of drug targets in C. ureolyticus. UDP-3-O-acyl-N-acetylglucosamine deacetylase (LpxC) was selected as a promiscuous pharmacological target for virtual screening of two bacterial-derived natural product libraries, i.e., postbiotics (n = 78) and streptomycin (n = 737) compounds. LpxC inhibitors from the ZINC database (n = 142 compounds) were also studied with reference to LpxC of C. ureolyticus. The top three docked compounds from each library (including ZINC26844580, ZINC13474902, ZINC13474878, Notoginsenoside St-4, Asiaticoside F, Paraherquamide E, Phytoene, Lycopene, and Sparsomycin) were selected based on their binding energies and validated using molecular dynamics simulations. To help identify potential risks associated with the selected compounds, ADMET profiling was also performed and most of the compounds were considered safe. Our findings may serve as baseline information for laboratory studies leading to the discovery of drugs for use against C. ureolyticus infections.

Panax Notoginseng Saponins Suppress Type 2 Porcine Reproductive and Respiratory Syndrome Virus Replication in vitro and Enhance the Immune Effect of the Live Vaccine JXA1-R in Piglets

Porcine reproductive and respiratory syndrome virus (PRRSV) suppresses the innate immune response in the host, reducing and delaying neutralizing antibody production against PRRSV infection and promoting viral infection. Here, we aimed to assess the potential of Panax notoginseng saponins (PNS) for improving the immune response exerted upon PRRSV-2-modified live virus (MLV) vaccine administration. Thirty piglets were randomly divided into six groups. Group 1 piglets were injected with medium 0 days post vaccination (dpv). Group 2 piglets were fed PNS 0–28 dpv. Group 3 and group 4 piglets were administered the JXA1-R vaccine 0 dpv. Group 4 piglets were also fed PNS 0–28 dpv. Group 1–4 piglets were challenged intranasally with the PRRSV JXA1 strain 28 dpv. Group 5 piglets were fed with PNS without challenge. Group 6 piglets served as controls. During the experiment, the samples were collected regularly for 49 days. Compared with group 1 piglets, group 3 piglets showed significantly reduced viremia and clinical scores, and significantly increased average daily gain (ADWG). Compared with group 3 piglets, group 4 piglets showed significantly improved neutralizing antibody titers, IFN-α and IFN-β mRNA expression, and significantly decreased viremia and viral load in the lungs and lymph nodes, but did not demonstrate any further improvement in PRRSV-specific antibody titer, rectal temperature, ADWG, or clinical scores. PNS upregulates neutralizing antibodies against PRRSV-2 and enhances the expression of IFN-α and IFN-β, which may reduce PRRSV viremia upon PRRSV-2 MLV vaccine administration. PNS may serve as an effective immunomodulator for boosting the immune defense against PRRSV.

Anaphylactic Rare Saponins Separated from Panax notoginseng Saponin and a Proteomic Approach to Their Anaphylactic Mechanism

In recent years, many traditional Chinese medicine injections based on Panax notoginseng saponin (PNS) have been reported to cause anaphylaxis. Previous studies on the anaphylactic saponins of PNS and their mechanism are inadequate. In this study, potential anaphylactic saponins were obtained by the separation of PNS and preparation of each individual component through comprehensive techniques, such as liquid chromatography, preparative chromatography, HPLC, NMR, and MS. The anaphylactic abilities of these saponins were tested using RBL-2H3 cells via a β-hexosaminidase release rate test. The results for the mechanism of anaphylaxis were obtained by a proteomic analysis using RBL-2H3 cells. The results indicate that, among all the saponins prepared, gypenoside LXXV and notoginsenoside T5 showed strong anaphylactic abilities and notoginsenoside ST-4 and ginsenoside Rk3 showed weak anaphylactic abilities. These 4 saponins can induce anaphylaxis via direct stimulation of effector cells. The gene oncology enrichment analysis results showed that, among these saponins, only gypenoside LXXV was related to organelles of the endoplasmic reticulum and Golgi apparatus and biological processes in response to organic cyclic compounds. Four proteins in RBL-2H3 cells with the accession numbers A0A0G2JWQ0, D3ZL85, D4A5G8, and Q8K3F0 were identified as crucial proteins in the anaphylactic process. This research will help traditional Chinese medicine injection manufacturers strengthen their quality control and ensure the safety of anaphylactic saponins.

Isolation, identification, and quantification of triterpene saponins in the fresh fruits of Panax notoginseng

This study is to develop a method for isolation, identification, and quantitative determination of dammarane-type triterpene saponins in the Panax notoginseng fruits (PNF). The saponins were isolated by a serious of chromatographic methods, and their structures were elucidated on the basis of spectroscopic evidence and comparison with those of literature reports. Quantitative assay was performed on an ultra-performance liquid chromatography-UV (UPLC-UV) method. As a result, 22 saponins were isolated from the extract of PNF, among them, compound 1 was a new saponin, named as malonylgypenoside IX, compounds 3-10, and 14-18 were isolated from the PNF for the first time. As to quantitative analysis, the calibration curves showed good linearity (r > 0.998) within the concentration range, and the method validation provided good reproducibility and sensitivity for the quantification of eight major saponins with precision and accuracy of less than 3.0%.

Identification of an antiviral compound isolated from Pistacia lentiscus

This study screened mastic gum (Pistacia lentiscus L.) for antiviral activity against herpes simplex virus type 2 (HSV-2), coxsackievirus type B3, and adenovirus type 5. The organs of this plant (leaves, stem, and seed) were macerated sequentially using solvents of increasing polarity (hexane, dichloromethane, ethyl acetate, and methanol). Only the methanol extract of stem exhibited significant activity against HSV-2. This extract showed anti-HSV-2 activity with a selectivity index of 51 (50% cytotoxic concentration = 186 µg/mL; 50% inhibitory concentration = 3.63 µg/mL), and demonstrated direct inhibition against this virus with a virucidal selectivity index of 620 (50% virucidal concentration = 0.30 µg/mL). A bio-guided assay involving thin-layer chromatography led to the isolation of two active compounds, which have been identified as dammaradienone and dammaradienol using high-performance liquid chromatography-diode array detection coupled with electrospray ionization mass spectrometry. P. lentiscus has been widely studied for other biological activities. However, to our knowledge, this is the first report of P. lentiscus L. exhibiting antiviral activity.

Advances in Pharmacological Activities of Terpenoids

Terpenoids, the most abundant compounds in natural products, are a set of important secondary metabolites in plants with diverse structures. Terpenoids play key roles in plant growth and development, response to the environment, and physiological processes. As raw materials, terpenoids were also widely used in pharmaceuticals, food, and cosmetics industries. Terpenoids possess antitumor, anti-inflammatory, antibacterial, antiviral, antimalarial effects, promote transdermal absorption, prevent and treat cardiovascular diseases, and have hypoglycemic activities. In addition, previous studies have also found that terpenoids have many potential applications, such as insect resistance, immunoregulation, antioxidation, antiaging, and neuroprotection. Terpenoids have a complex structure with diverse effects and different mechanisms of action. Activities and mechanisms of terpenoids were reviewed in this paper. The development and application prospect of terpenoid compounds were also prospected, which provides a useful reference for new drug discovery and drug design based on terpenoids.

Pharmacological effects of ginseng on infectious diseases

Ginseng has been traditionally used as an herbal nutritional supplement in Asian countries, including Korea, China, Japan, and Vietnam for several millennia. Most studies have focused on the role of ginseng on anti-oxidative stress, anti-inflammatory, and anti-cancer activities. Recently, modulator activities of ginseng on the immune responses during pathogenic bacterial and viral infections and beneficial effects of ginseng in infectious diseases have been elucidated. In vivo and in vitro studies revealed the potential of ginseng extracts and ginsenosides Rg1, Rg3, Rb1, Rb2, Rb3, compound K, Re, Rd, Rh2 for treatment of several infectious diseases. The molecular mechanisms of these effects mainly involve inflammatory cytokines (TNF-α, IL-6, IL-1β, IFN-γ, IL-10), apoptotic pathway (bcl-2, bcl-xL), PI3K/Akt pathway, MAPKs pathway, JAK2/STAT5, NF-κB pathway, and the inflammasome. In this review, we will summarize the current knowledge on the effects of ginseng in the immune responses during the infections and its bioactivities on the prevention of infectious diseases as well as its underlying mechanisms. Moreover, the therapeutic potential of ginseng as an anti-bacterial and anti-viral medication and vaccine adjuvant will be discussed as well.

Traditional Chinese Medicine as a Potential Source for HSV-1 Therapy by Acting on Virus or the Susceptibility of Host

Herpes simplex virus type 1 (HSV-1) is the most common virus, with an estimated infection rate of 60–95% among the adult population. Once infected, HSV-1 can remain latent in the host for a lifetime and be reactivated in patients with a compromised immune system. Reactivation of latent HSV-1 can also be achieved by other stimuli. Though acyclovir (ACV) is a classic drug for HSV-1 infection, ACV-resistant strains have been found in immune-compromised patients and drug toxicity has also been commonly reported. Therefore, there is an urge to search for new anti-HSV-1 agents. Natural products with potential anti-HSV-1 activity have the advantages of minimal side effects, reduced toxicity, and they exert their effect by various mechanisms. This paper will not only provide a reference for the safe dose of these agents if they are to be used in humans, referring to the interrelated data obtained from in vitro experiments, but also introduce the main pharmacodynamic mechanisms of traditional Chinese medicine (TCM) against HSV-1. Taken together, TCM functions as a potential source for HSV-1 therapy by direct (blocking viral attachment/absorption/penetration/replication) or indirect (reducing the susceptibility to HSV-1 or regulating autophagy) antiviral activities. The potential of these active components in the development of anti-HSV-1 drugs will also be described.

New triterpenoid saponins from the steaming treated roots of Panax notoginseng

Further phytochemical investigation of the steaming treated roots of Panax notoginseng (Araliaceae) led to the identification of two new dammarane-type triterpenoid saponins, notoginsenoside SP20 (1) and SP21 (2). In addition, a pair of new phenolic glycosides (3a and 3b) was also isolated together with two known compounds. Their structures were elucidated by HRESIMS, 1D- and 2D-NMR spectra. Compounds 1 and 2 showed no in vitro cytotoxicity against five human cancer cell lines (HL-60, SMMC-7712, A-549, MCF-9 and SW480).

Dammarane-type saponins from the leaves of Panax notoginseng and their neuroprotective effects on damaged SH-SY5Y cells

Seven dammarane-type saponins previously undescribed (notoginsenosides Fh1-Fh7) were isolated from the aqueous extract leaves of Panax notoginseng (Burk.) F.H.Chen (Araliaceae), together with eleven known saponins. Their structures of were elucidated by spectroscopic analysis (NMR, UV, IR, ect.), HR-ESI-MS techniques and chemical methods. Screening results indicated that compounds 4, 5, 12, 13 showed moderate neuroprotective effects on H2O2-induced cellular damage in human neuroblastoma SH-SY5Y cells (10 μM).

Protective Effect of Panax notoginseng Root Water Extract against Influenza A Virus Infection by Enhancing Antiviral Interferon-Mediated Immune Responses and Natural Killer Cell Activity

Influenza is an acute respiratory illness caused by the influenza A virus, which causes economic losses and social disruption mainly by increasing hospitalization and mortality rates among the elderly and people with chronic diseases. Influenza vaccines are the most effective means of preventing seasonal influenza, but can be completely ineffective if there is an antigenic mismatch between the seasonal vaccine virus and the virus circulating in the community. In addition, influenza viruses resistant to antiviral drugs are emerging worldwide. Thus, there is an urgent need to develop new vaccines and antiviral drugs against these viruses. In this study, we conducted in vitro and in vivo analyses of the antiviral effect of Panax notoginseng root (PNR), which is used as an herbal medicine and nutritional supplement in Korea and China. We confirmed that PNR significantly prevented influenza virus infection in a concentration-dependent manner in mouse macrophages. In addition, PNR pretreatment inhibited viral protein (PB1, PB2, HA, NA, M1, PA, M2, and NP) and viral mRNA (NS1, HA, PB2, PA, NP, M1, and M2) expression. PNR pretreatment also increased the secretion of pro-inflammatory cytokines [tumor necrosis factor alpha and interleukin 6] and interferon (IFN)-beta and the phosphorylation of type-I IFN-related proteins (TANK-binding kinase 1, STAT1, and IRF3) in vitro. In mice exposed to the influenza A H1N1 virus, PNR treatment decreased mortality by 90% and prevented weight loss (by approximately 10%) compared with the findings in untreated animals. In addition, splenocytes from PNR-administered mice displayed significantly enhanced natural killer (NK) cell activity against YAC-1 cells. Taking these findings together, PNR stimulates an antiviral response in murine macrophages and mice that protects against viral infection, which may be attributable to its ability to stimulate NK cell activity. Further investigations are needed to reveal the molecular mechanisms underlying the protective effects of PNR and its components against influenza virus A infection.

Chemical transformation and target preparation of saponins in stems and leaves of Panax notoginseng

Background

Notoginsenoside Ft1 is a promising potential candidate for cardiovascular and cancer disease therapy owing to its positive pharmacological activities. However, the yield of Ft1 is ultralow utilizing reported methods. Herein, an acid hydrolyzing strategy was implemented in the acquirement of rare notoginsenoside Ft1.

Methods

Chemical profiles were identified by ultraperformance liquid chromatography coupled with quadruple-time-of-flight and electrospray ionization mass spectrometry (UPLC-Q/TOF-ESI-MS). The acid hydrolyzing dynamic changes of chemical compositions and the possible transformation pathways of saponins were monitored by ultrahigh-performance LC coupled with tandem MS (UHPLC-MS/MS).

Results and conclusion

Notoginsenoside Ft1 was epimerized from notoginsenoside ST4, which was generated through cleaving the carbohydrate side chains at C-20 of notoginsenosides Fa and Fc, and vina-ginsenoside R7, and further converted to other compounds via hydroxylation at C-25 or hydrolysis of the carbohydrate side chains at C-3 under the acid conditions. High temperature contributed to the hydroxylation reaction at C-25 and 25% acetic acid concentration was conducive to the preparation of notoginsenoside Ft1. C-20 epimers of notoginsenoside Ft1 and ST4 were successfully separated utilizing solvent method of acetic acid solution. The theoretical preparation yield rate of notoginsenoside Ft1 was about 1.8%, which would be beneficial to further study on its bioactivities and clinical application.

Traditional uses, botany, phytochemistry, pharmacology and toxicology of Panax notoginseng (Burk.) F.H. Chen: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Panax notoginseng (Burk.) F.H. Chen is a widely used traditional Chinese medicine known as Sanqi or Tianqi in China. This plant, which is distributed primarily in the southwest of China, has wide-ranging pharmacological effects and can be used to treat cardiovascular diseases, pain, inflammation and trauma as well as internal and external bleeding due to injury.

AIMS OF THE REVIEW

This paper provides up-to-date information on investigations of this plant, including its botany, ethnopharmacology, phytochemistry, pharmacology and toxicology. The possible uses and perspectives for future investigation of this plant are also discussed.

MATERIALS AND METHODS

The relevant information on Panax notoginseng (Burk.) F.H. Chen was collected from numerous resources, including classic books about Chinese herbal medicine, and scientific databases, including Pubmed, SciFinder, ACS, Ebsco, Elsevier, Taylor, Wiley and CNKI.

RESULTS

More than 200 chemical compounds have been isolated from Panax notoginseng (Burk.) F.H. Chen, including saponins, flavonoids and cyclopeptides. The plant has pharmacological effects on the cardiovascular system, immune system as well as anti-inflammatory, anti-atherosclerotic, haemostatic and anti-tumour activities, etc.

CONCLUSIONS

Panax notoginseng is a valuable traditional Chinese medical herb with multiple pharmacological effects. This review summarizes the botany, ethnopharmacology, phytochemistry, pharmacology and toxicology of P. notoginseng, and presents the constituents and their corresponding chemical structures found in P. notoginseng comprehensively for the first time. Future research into its phytochemistry of bio-active components should be performed by using bioactivity-guided isolation strategies. Further work on elucidation of the structure-function relationship among saponins, understanding of multi-target network pharmacology of P. notoginseng, as well as developing its new clinical usage and comprehensive utilize will enhance the therapeutic potentials of P. notoginseng.

New strategies against drug resistance to herpes simplex virus

Herpes simplex virus (HSV), a member of the Herpesviridae family, is a significant human pathogen that results in mucocutaneous lesions in the oral cavity or genital infections. Acyclovir (ACV) and related nucleoside analogues can successfully treat HSV infections, but the emergence of drug resistance to ACV has created a barrier for the treatment of HSV infections, especially in immunocompromised patients. There is an urgent need to explore new and effective tactics to circumvent drug resistance to HSV. This review summarises the current strategies in the development of new targets (the DNA helicase/primase (H/P) complex), new types of molecules (nature products) and new antiviral mechanisms (lethal mutagenesis of Janus-type nucleosides) to fight the drug resistance of HSV.

Ginseng, the natural effectual antiviral: Protective effects of Korean Red Ginseng against viral infection

Korean Red Ginseng (KRG) is a heat-processed ginseng developed by the repeated steaming and air-drying of fresh ginseng. Compared with fresh ginseng, KRG has been shown to possess greater pharmacological activities and stability because of changes that occur in its chemical constituents during the steaming process. In addition to anticancer, anti-inflammatory, and immune-modulatory activities, KRG and its purified components have also been shown to possess protective effects against microbial infections. Here, we summarize the current knowledge on the properties of KRG and its components on infections with human pathogenic viruses such as respiratory syncytial virus, rhinovirus, influenza virus, human immunodeficiency virus, human herpes virus, hepatitis virus, norovirus, rotavirus, enterovirus, and coxsackievirus. Additionally, the therapeutic potential of KRG as an antiviral and vaccine adjuvant is discussed.

Triterpenoids with Promoting Effects on the Differentiation of PC12 Cells from the Steamed Roots of Panax notoginseng

The roots of Panax notoginseng, an important Chinese medicinal plant, have been used traditionally in both the raw and processed forms, due to the different chemical constituents and bioactivities found. Thirty-eight dammarane-type triterpenoid saponins were isolated from the steam-processed roots of P. notoginseng, including 18 new substances, namely, notoginsenosides SP1-SP18 (1-18). The structures of 1-18 were determined on the basis of spectroscopic analysis and acidic hydrolysis. The absolute configuration of the hydroxy group at C-24 in 1-4, 19, and 20 was determined in each case by Mo2(AcO)4-induced circular dichroism. The new compounds were found to feature a diversity of highly oxygenated side chains, formed by hydrolysis of the C-20 sugar moiety followed by dehydration, dehydrogenation, epoxidation, hydroxylation, or methoxylation of the main saponins in the raw roots. The new saponins 1, 2, 6-8, 14, and 17 and the known compounds 20-27 showed promoting effects on the differentiation of PC12 cells, at a concentration of 10 μM.

Bioactive natural products with anti-herpes simplex virus properties

Objectives

In this review, we highlight and summarise the most promising extracts, fractions and pure compounds as potential anti-herpes simplex virus (HSV) agents derived from microorganisms, marine organisms, fungi, animals and plants. The role of natural products in the development of anti-HSV drugs will be discussed.

Key findings

Herpes simplex viruses (HSV-1 and -2) are common human pathogens that remain a serious threat to human health. In recent years, a great interest has been devoted to the search for integrated management of HSV infections. Acyclovir and related nucleoside analogues have been licensed for the therapy that target viral DNA polymerase. Although these drugs are currently effective against HSV infections, the intensive use of these drugs has led to the problem of drug-resistant strains. Therefore, the search for new sources to develop new antiherpetic agents has gained major priority to overcome the problem.

Summary

Natural products as potential, new anti-HSV drugs provide several advantages such as reduced side effects, less resistance, low toxicity and various mechanisms of action. This paper aims to provide an overview of natural products that possess antiviral activity against HSV.

Minor dehydrogenated and cleavaged dammarane-type saponins from the steamed roots of Panax notoginseng

Nine new minor dehydrogenated and cleavaged dammarane-type triterpenoid saponins, namely notoginsenosides ST6-ST14 (1-9) were isolated from the steamed roots of Panax notoginseng, together with 14 known ones. Among them, 5-7 and 21-22 were protopanaxadiol type and the left 18 compounds, including 1-4, 8-20, and 23 were protopanaxatriol type saponins. Their structures were identified by extensive analysis of MS, 1D and 2D NMR spectra, and acidic hydrolysis. Resulted from the side chain cleavage, the new saponins 1 and 2 featured in a ketone group at C-25, and 3-5 had an aldehyde unit at C-23. The known saponins 12, 16 and 18 displayed the enhancing potential of neurite outgrowth of NGF-mediated PC12 cells at a concentration of 10 μM, while 20 exhibited acetyl cholinesterase inhibitory activity, with IC50 value of 13.97 μM.

Enzymatic transformation of vina-ginsenoside R₇ to rare notoginsenoside ST-4 using a new recombinant glycoside hydrolase from Herpetosiphon aurantiacus

An eco-friendly and convenient preparation method for notoginsenoside ST-4 has been established by completely transforming vina-ginsenoside R7 using a recombinant glycosidase hydrolyzing enzyme (HaGH03) from Herpetosiphon aurantiacus. This enzyme specifically hydrolyzed the glucose at the C-20 position but not the external xylose or two inner glucoses at position C-3. Protein sequence BLAST revealed that HaGH03, composed of 749 amino acids and presumptively listed as a member of the family 3 glycoside hydrolases, has highest identity (48 %) identity with a thermostable β-glucosidase B, which was not known of any functions for ginsenoside transformation. The steady state kinetic parameters for purified HaGH03 measured against p-nitrophenyl β-D-glucopyranoside and vina-ginsenoside R7 were K M = 5.67 ± 0.24 μM and 0.59 ± 0.23 mM, and k cat = 69.2 ± 0.31/s and 2.15 ± 0.46/min, respectively. HaGH03 converted 2.5 mg/mL of vina-ginsenoside R7 to ST-4 with a molar yield of 100 % and a space-time yield of 104 mg/L/h in optimized conditions. These results underscore that HaGH03 has much potential for the effective preparation of target ginsenosides possessing valuable pharmacological activities. This is the first report identifying an enzyme that has the ability to transform vina-ginsenoside R7 and provides an approach to preparing rare notoginsenoside ST-4.

Quantitative comparison and metabolite profiling of saponins in different parts of the root of Panax notoginseng

Although both rhizome and root of Panax notoginseng are officially utilized as notoginseng in "Chinese Pharmacopoeia", individual parts of the root were differently used in practice. To provide chemical evidence for the differentiated usage, quantitative comparison and metabolite profiling of different portions derived from the whole root, as well as commercial samples, were carried out, showing an overall higher content of saponins in rhizome, followed by main root, branch root, and fibrous root. Ginsenoside Rb2 was proposed as a potential marker with a content of 0.5 mg/g as a threshold value for differentiating rhizome from other parts. Multivariate analysis of the metabolite profile further suggested 32 saponins as potential markers for the discrimination of different parts of notoginseng. Collectively, the study provided comprehensive chemical evidence for the distinct usage of different parts of notoginseng and, hence, is of great importance for the rational application and exploitation of individual parts of notoginseng.