Anti-HIV-1 activities of extracts from the medicinal plant Rhus chinensis

Synthesis of silver nanoparticles assisted by aqueous root and leaf extracts of Rhus chinensis Mill and its antibacterial activity

In the present study, silver nanoparticles were synthesized using aqueous root and leaf extracts of Rhus chinensis Mill. This study aimed to undertake the green synthesis of silver nanoparticles utilizing plant extracts in an eco-friendly, cost-effective, and more efficient manner with its antibacterial application. The prepared silver nanoparticles (AgNPs) were characterized by using different techniques. Such as ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), x-ray diffraction spectroscopy (XRD), field emission-scanning electron microscopy (FE-SEM), and energy dispersive X-ray (EDX). The color changes from yellowish to reddish brown can be visualized and it indicates the formation of silver nanoparticles. The UV-Vis absorption peak shown by the synthesized AgNPs assisted by root and leaf extract was at 443 nm and 440 nm respectively. The functional group present in plants' secondary metabolites may act as capping and stabilizing agents, indicated by the shifting and disappearing of the peak in the plant extracts and the extracts-assisted synthetic nanoparticles. The crystallite size of synthesized AgNPs assisted by the root and leaf extracts of Rhus cinensis was found to be 11.01 nm and 13.39 nm respectively, while with the help of FE-SEM image the shape and particle size of synthesized AgNPs root and leaf extract was found spherical with particle diameter of 54.40 nm and 30.89 nm respectively. The presence of an intense silver component was confirmed by EDX analysis which showed an intense peak at around 3 Kev and other elements like Cl, O, C, and N were also reported in synthesized AgNPs. Both the plant extracts assisted synthesized AgNPs showed higher zones of inhibition (ZOI) against both the Gram-positive and Gram-negative bacteria. The results of the study indicate the potential benefit of synthesized silver nanoparticles using Rhus chinensis root and leaf extracts for biomedical purposes.

The Importance of Traditional Chinese Medicine in the Intervention and Treatment of HIV while Considering its Safety and Efficacy

Natural products have been considered a potential resource for the development of novel therapeutic agents, since time immemorial. It is an opportunity to discover cost-effective and safe drugs at the earliest, with the goal to hit specific targets in the HIV life cycle. Natural products with inhibitory activity against human immunodeficiency virus are terpenes, coumarins, flavonoids, curcumin, proteins, such as lectins, laccases, bromotyrosines, and ribosome-inactivating proteins. Terpenes inhibit virus fusion, lectins and flavonoids have an inhibitory impact on viral binding, curcumin and flavonoids inhibit viral DNA integration. The most important medicinal plants which have been used in traditional Chinese medicinal sciences with anti-HIV properties are Convallaria majalis, Digitalis lanata, Cassia fistula, Croton macrostachyus, Dodonaea angustifolia, Ganoderma lucidum, Trametes versicolor, Coriolus versicolor, Cordyceps sinensis, Gardenia jasminoides, Morus alba, Scutellaria baicalensis, Ophiopogon japonicus, Platycodon grandiflorus, Fritillaria thunbergii, Anemarrhena asphodeloides, Trichosanthes kirilowii, Citrus reticulata, Glycyrrhiza uralensis, Rheum officinale, Poria cocos, Rheum palmatum, Astragalus membranaceus, Morinda citrifolia, Potentilla kleiniana, Artemisia capillaris, Sargassum fusiforme, Piperis longi fructus, Stellera chamaejasme, Curcumae rhizoma, Dalbergia odorifera lignum, Arisaematis Rhizoma preparatum, and Phellodendron amurense. The information provided is gathered from randomized control experiments, review articles, and analytical studies and observations, which are obtained from different literature sources, such as Scopus, Google Scholar, PubMed, and Science Direct from July 2000 to August 2023. The aim of this review article is to survey and introduce important medicinal plants and herbs that have been used for the treatment of HIV, especially the medicinal plants that are common in traditional Chinese medicine, as research to date is limited, and more evidence is required to confirm TCM,s efficacy.

A comprehensive review on ethnobotanical, phytochemical and pharmacological aspects of Rhus chinensis Mill

ETHNOPHARMACOLOGICAL RELEVANCE

Rhus chinensis Mill., firstly recorded as herbal medicine in Shan Hai Jing, have been used for thousands of years to treat various diseases.

AIM OF THIS REVIEW

This review targets on the ethnomedicinal applications of R. chinensis and to gather the phytochemical, pharmacological and toxicological data which support the therapeutic potential of R. chinensis in treatment on different diseases, with emphasis on the naturally occurring compounds and detailed pharmacological developments.

MATERIALS AND METHODS

The information of R. chinensis was collected based on a variety of popular databases such as Scifinder, PubMed, Web of Science, ScienceDirect, Springer, Wiley, ACS, CNKI, Baidu Scholar, Google Scholar and other published materials (books and Ph.D. and M. Sc. Dissertations). The keywords "Rhus chinensis", "Rhus amela", "Rhus javanica", "Rhus osbeckii", "Rhus semialata", and "Schinus indicus" were applied to search the literature related in this review.

RESULTS

152 natural compounds of R. chinensis belong to different classes are presented in this review, including flavonoids, lignans, coumarins, simple phenolics, urushiols, tannins, triterpenoids, steroids and other types of constituents. Among them, flavonoids, lignans, and triterpenoids are most frequently reported components. The pharmacological effects of R. chinensis were numerous and complicated, including anti-viral, anti-bacterial, anti-diarrheal, hepatoprotective, anti-proliferation, enzyme-inhibiting, anti-oxidants and so on.

CONCLUSION

In order to discover more compounds with novel structures to both enrich chemical context of genus Rhus and expand the variety of constituents, the phytochemical research is urgent and indispensable. Anti-diarrhea, the most widely application of R. chinensis traditionally, is insufficient in underlying mechanism exploration. And for other activities, in-depth studies on the mechanism of pharmacological effects in vivo and in vitro are both needed. Meanwhile, pharmacokinetics, toxicology, quality control and preclinical and clinical data are urgent to assess the rationale and safety of the medicinal and food application of R. chinensis.

Computational Prospecting for the Pharmacological Mechanism of Activity: HIV-1 Inhibition by Ixoratannin A-2

BACKGROUND

Ixora coccinea is a tropical ornamental shrub employed in ethnomedicine for the treatment of a number of diseases none of which include the Human Immunodeficiency Virus (HIV) infection. Ixoratannin A-2, one of the constituents, was previously identified via virtual-screening and experimentally confirmed to possess significant anti-HIV-1 activity in an in vitro CD4+ replication assay. This activity was observed to be significantly reduced in degree in viruses lacking the protein Vpu. This suggests the involvement of Vpu as well as other extra-Vpu macromolecules in its antiviral activity.

METHODS

In the present computational search for the identity of the other macromolecules that could possibly explain the observed activity, a panel of fourteen established HIV-1 macromolecular targets was assembled against which ixoratannin A-2 and other major phytoconstituents of I. coccinea were virtually screened.

RESULTS

Structural analyses of the computed ligand-bound complexes, as well as the careful investigation of the thermodynamic attributes of the predicted binding, revealed subtle selectivity patterns at the atomistic level that suggest the likely involvement of multiple macromolecular processes. Some of the binding interactions were found to be thermodynamically favourable, including the multidrug-resistant HIV protease enzyme, CXCR4 and the human elongin C protein all of which formed reasonably strong interactions with ixoratannin A-2 and other constituents of I. coccinea.

CONCLUSION

Ixoratannin A-2's ability to favourably interact with multiple HIV-1 and human targets could explain its observed extra-Vpu antiviral activity. This, however, does not imply uncontrolled binding with all available targets; on the other hand, molecular size of ixoratannin A-2 and combination of functional groups confer on it a decent level of selectivity against many of the investigated HIV/AIDS targets.

Phytochemicals of Rhus spp. as Potential Inhibitors of the SARS-CoV-2 Main Protease: Molecular Docking and Drug-Likeness Study

Background

The outbreak of coronavirus disease 2019 (COVID-19) induced by the novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) originated in China and spread to cover the entire world with an ongoing pandemic. The magnitude of the situation and the fast spread of the new and deadly virus, as well as the lack of specific treatment, led to a focus on research to discover new therapeutic agents.

Aim

In this study, we explore the potential inhibitory effects of some active polyphenolic constituents of Rhus spp. (sumac) against the SARS-CoV-2 main protease enzyme (M^pro; 6LU7).

Methods

26 active polyphenolic compounds of Rhus spp. were studied for their antiviral activity by molecular docking, drug likeness, and synthetic accessibility score (SAS) as inhibitors against the SARS-CoV-2 M^pro.

Results

The results show that all tested compounds of sumac provided good interaction with the main active site of SARS-CoV-2 M^pro, with better, lower molecular docking energy (kcal/mol) compared to the well-known drugs chloroquine and favipiravir (Avigan). Only six active polyphenolic compounds of Rhus spp. (sumac), methyl 3,4,5-trihydroxybenzoate, (Z)-1-(2,4-dihydroxyphenyl)-3-(3,4-dihydroxyphenyl)-2-hydroxyprop-2-en-1-one, (Z)-2-(3,4-dihydroxybenzylidene)-6-hydroxybenzofuran-3(2H)-one, 3,5,7-trihydroxy-2-(4-hydroxyphenyl)chroman-4-one, 2-(3,4-dihydroxyphenyl)-3,5-dihydroxy-7-methoxy-4H-chroman-4-one, and 3,7-dihydroxy-2-(4-hydroxyphenyl)chroman-4-one, were proposed by drug likeness, solubility in water, and SAS analysis as potential inhibitors of M^pro that may be used for the treatment of COVID-19.

Conclusion

Six phenolic compounds of Rhus spp. are proposed for synthesis as potential inhibitors against M^pro and have potential for the treatment of COVID-19. These results encourage further in vitro and in vivo investigations of the proposed ligands and research on the preventive use of Rhus spp. against SARS-CoV-2.

Rhus semialata M. extract ameliorate para-phenylenediamine-induced toxicity in keratinocytes

para-Phenylediamine (PPD), a major component of hair dyeing ingredients, can induce allergenic sensitization and exert mutagenic, tumorigenic and cytotoxic effect. In this study, we determined the cytotoxic effect of PPD on human keratinocytes and evaluated the protective effect of Rhus semialata M. extracts (RSE) on PPD induced cytotoxicity for the first time. We observed that RSE is a strong inhibitory agent against PPD-induced toxicity in human keratinocytes. The results indicated that RSE pretreatment significantly could suppress PPD induced cytotoxic effects, including decrease of cell viability, accumulation in subG1 phase of cells, and relocation of phosphatidylserine on keratinocytes. Also, we found that PPD caused cytotoxicity was associated with mitochondrial membrane potential loss and subsequent activation of caspase and PARP degradation. However, pretreatment of RSE showed preventive activities against PPD induced mitochondrial membrane potential loss and ROS production in keratinocytes. In conclusion, the results of present study suggest that RSE was able to protect the skin from several cytotoxic effects of PPD and could be a meaningful material in many industries using PPD.

Daphnane Diterpenoids from Trigonostemon lii and Inhibition Activities Against HIV-1

Natural products are the important source for the discovery of more potent anti-HIV agents. In this study, six daphnane diterpenoids including three unreported structures were isolated from Trigonostemon lii, which showed significant activities against HIV-1 strains replication in the nanomolar/picomolar range. Meanwhile, these diterpenoids significantly inhibited the fusion of H9/HIV-1 IIIB cells with uninfected C8166 cells, with the EC_50s from 1.06 to 8.73 ng/mL, and did not show any inhibition activities against HIV-1 reverse transcriptase. Moreover, all of the diterpenoids shows significant inhibitions against T20-resistan HIV-1 strains, PNL4-3gp41(36G)V38E, N42S and pNL4-3gp41(36G)V38A, N42T. The results revealed that the six diterpenoids could be a new type of potential lead candidate as an HIV entry inhibitor, particularly for those infected by T20-resistant variants.

Dimeric Pyranonaphthoquinone Glycosides with Anti-HIV and Cytotoxic Activities from a Soil-Derived Streptomyces

Eight new sulfur-bridged pyranonaphthoquinone (PNQ) dimers, naquihexcins C-J (1-8), a new PNQ monomer, naquihexcin K (10), and three known analogues (9, 11, and 12) were isolated from Streptomyces sp. KIB3133. The new structures were elucidated by interpretation of spectroscopic data. Dimer 4 was synthesized via a cascade S_N2 reactions between two monomers and sodium sulfide, an approach motivated by the proposed biosynthetic pathway of dimeric pyranonaphthoquinones. Naquihexcin E (3) exhibited moderate HIV-1 inhibitory activity. Naquihexcins C (1), E (3), and I (7) showed inhibitory effects against two tumor cell lines (HL-60 and MCF-7) with IC₅₀ values ranging from 1.4 to 16.1 μM.

Medicinal Plants Used in the Treatment of Human Immunodeficiency Virus

Since the beginning of the epidemic, human immunodeficiency virus (HIV) has infected around 70 million people worldwide, most of whom reside is sub-Saharan Africa. There have been very promising developments in the treatment of HIV with anti-retroviral drug cocktails. However, drug resistance to anti-HIV drugs is emerging, and many people infected with HIV have adverse reactions or do not have ready access to currently available HIV chemotherapies. Thus, there is a need to discover new anti-HIV agents to supplement our current arsenal of anti-HIV drugs and to provide therapeutic options for populations with limited resources or access to currently efficacious chemotherapies. Plant-derived natural products continue to serve as a reservoir for the discovery of new medicines, including anti-HIV agents. This review presents a survey of plants that have shown anti-HIV activity, both in vitro and in vivo.

Anti-human immunodeficiency virus-1 activities of pratensein and pratensein glycoside from Alhaji maurorum and its parasite Cuscuta kotchiana

OBJECTIVE

To test the anti-human immunodeficiency virus (HIV) activity of pure compounds isolated from aerial part extracts of Alhaji maurorum and its parasite Cuscuta kotchiana.

METHODS

The anti-HIV-1 and anti-HIV-2 activities of these extracts were performed by use of quantitative polymerase chain reaction assay and high pure viral nucleic acid kit. The most active fractions against HIV-1 were detected by nuclear magnetic resonance as pratensein and pratensein glycoside respectively in A. maurorum and C. campestris.

RESULTS

These two extracts have low toxicity on HIV-2 replication. The 50% effective concentration for HIV-1 replication of pratensein and pratensein glycoside were 100 and 22 μg/mL, respectively. The time of addition assay showed that pratensein and pratensein glycoside were most effective when added at the early stage (0-4 h) of virus replication.

CONCLUSION

The pratensein glycoside inhibits HIV-1 replication in host cells more than pratensein and both extracts are potent inhibitors of HIV-1 entry.

Wikstroelide M potently inhibits HIV replication by targeting reverse transcriptase and integrase nuclear translocation

AIM

To evaluate the anti-HIV activity and mechanism of action of wikstroelide M, a daphnane diterpene from Daphne acutiloba Rehder (Thymelaeaceae).

METHODS

The anti-HIV activities of wikstroelide M against different HIV strains were evaluated by cytopathic effect assay and p24 quantification assay with ELISA. The inhibitory effect of wikstroelide M on HIV reverse transcription was analyzed by real-time PCR and ELISA. The effect of wikstroelide M on HIV-1 integrase nuclear translocation was observed with a cell-based imaging assay. The effect of wikstroelide M on LEDGF/p75-IN interaction was assayed by molecular docking.

RESULTS

Wikstroelide M potently inhibited different HIV-1 strains, including HIV-1IIIB, HIV-1A17, and HIV-19495, induced a cytopathic effect, with EC50 values ranging from 3.81 to 15.65 ng·mL⁻¹. Wikstroelide M also had high inhibitory activities against HIV-2ROD and HIV-2CBL-20-induced cytopathic effects with EC50 values of 18.88 and 31.90 ng·mL⁻¹. The inhibitory activities of wikstroelide M on the three HIV-1 strains were further confirmed by p24 quantification assay, with EC50 values ranging from 15.16 to 35.57 ng·mL⁻¹. Wikstroelide M also potently inhibited HIV-1IIIB induced cytolysis in MT-4 cells, with an EC50 value of 9.60 ng·mL⁻¹. The mechanistic assay showed that wikstroelide M targeted HIV-1 reverse transcriptase and nuclear translocation of integrase through disrupting the interaction between integrase and LEDGF/p75.

CONCLUSION

Wikstroelide M may be a potent HIV-1 and HIV-2 inhibitor, the mechanisms of action may include inhibition of reverse trascriptase activity and inhibition of integrase nuclear translocation through disrupting the interaction between integrase and LEDGF/p75.

Anti-HIV-1 activity, protease inhibition and safety profile of extracts prepared from Rhus parviflora

Background

In the present study, extracts prepared from the leaves of Rhus parviflora Roxb. (Anacardiaceae) were evaluated for their anti-HIV activity, which have been traditionally used for the treatment of neurological disorders such as anxiety, insomnia and epilepsy.

Methods

Aqueous and 50% ethanolic extracts prepared from leaves of the plant were tested for their cytotoxicity and anti-HIV property using reporter gene based assays as well as human peripheral blood lymphocytes (PBLs). Further these extracts were evaluated for their ability to inhibit HIV-1 reverse transcriptase (RT) and protease activity. Safety profile of the extracts was determined on viability of Lactobacillus sp., secretion of pro-inflammatory cytokines by vaginal keratinocytes and transepithelial resistance.

Results

Both aqueous (IC₅₀ = 15 μg/ml) and 50% ethanolic (IC₅₀ = 26 μg/ml) extracts prepared from leaves of R. parviflora showed anti-HIV activity in TZM-bl cells wherein the virus was treated with the extracts prior to infection. Further, both the extracts also inhibited virus load in HIV infected CEM-GFP cells and human PBLs. The anti-HIV activity is mediated through inhibition of HIV-1 protease activity. Both the extracts did not disturb the integrity of monolayer formed by intestinal epithelial Caco-2 cells. The extracts when tested up to 100 μg/ml did not significantly reduce the viability of L. plantarum, L. fermentum, L. rhamnosus and L. casei. The extracts (100 μg/ml) did not reveal any cytotoxic effect on vaginal keratinocytes (Vk2/E6E7). Levels of pro-inflammatory cytokines secreted by Vk2/E6E7 cells treated with both the plant extracts were within the non-inflammatory range.

Conclusions

The studies reported herein showed in vitro anti-HIV activity and preliminary safety profile of the extracts prepared from the leaves of R. parviflora.

Potent anti-HIV activities and mechanisms of action of a pine cone extract from Pinus yunnanensis

The anti-HIV activities of a pine cone extract (YNS-PY-F) from Pinus yunnanensis have been evaluated, and its mechanisms of action were also explored. The pine cone extract, YNS-PY-F, potently inhibited HIV-1_IIIB, HIV-1_RF, HIV-1_A17, HIV-1_AO18 and HIV-2_ROD and induced cytopathic effect in C8166 cells with EC₅₀ values of 0.96 μg/mL, 1.53 μg/mL, 0.88 μg/mL, 7.20 μg/mL and 6.17 μg/mL, respectively. The quantification of a p24 production assay showed that YNS-PY-F significantly inhibited the acute replication of HIV-1_IIIB, HIV-1_RF, HIV-1_A17 and HIV-1_AO18 in C8166 cells. An MTT assay showed that YNS-PY-F also significantly inhibited the HIV-1_IIIB induced cytolysis in MT-4 cells with an EC₅₀ value of 2.22 μg/mL. The mechanism assays showed that YNS-PY-F had potent inhibitory effects on the fusion between infected cells and uninfected cells, and the activity of HIV-1 reverse transcriptase, with EC₅₀ values of 7.60 μg/mL and 4.60 μg/mL, respectively. Overall, these data suggest that the pine cone extract from Pinus yunnanensis has potent inhibitory activities against HIV-1_IIIB, HIV-1_RF, RT inhibitor-resistant strains HIV-1_A17 and HIV-1_AO18, and HIV-2_ROD, and its anti-HIV mechanisms include inhibition of HIV entry and inhibition of reverse transcriptase activity.

Inhibitory effect of aqueous Dandelion extract on HIV-1 replication and reverse transcriptase activity

BACKGROUND

Acquired immunodeficiency syndrome (AIDS), which is caused by the human immunodeficiency virus (HIV), is an immunosuppressive disease that results in life-threatening opportunistic infections. The general problems in current therapy include the constant emergence of drug-resistant HIV strains, adverse side effects and the unavailability of treatments in developing countries. Natural products from herbs with the abilities to inhibit HIV-1 life cycle at different stages, have served as excellent sources of new anti-HIV-1 drugs. In this study, we aimed to investigate the anti-HIV-1 activity of aqueous dandelion extract.

METHODS

The pseudotyped HIV-1 virus has been utilized to explore the anti-HIV-1 activity of dandelion, the level of HIV-1 replication was assessed by the percentage of GFP-positive cells. The inhibitory effect of the dandelion extract on reverse transcriptase activity was assessed by the reverse transcriptase assay kit.

RESULTS

Compared to control values obtained from cells infected without treatment, the level of HIV-1 replication and reverse transcriptase activity were decreased in a dose-dependent manner. The data suggest that dandelion extract has a potent inhibitory activity against HIV-1 replication and reverse transcriptase activity. The identification of HIV-1 antiviral compounds from Taraxacum officinale should be pursued.

CONCLUSIONS

The dandelion extract showed strong activity against HIV-1 RT and inhibited both the HIV-1 vector and the hybrid-MoMuLV/MoMuSV retrovirus replication. These findings provide additional support for the potential therapeutic efficacy of Taraxacum officinale. Extracts from this plant may be regarded as another starting point for the development of an antiretroviral therapy with fewer side effects.

Advances of research on anti-HIV agents from traditional Chinese herbs

The current approach for dealing with the global pandemic of AIDS focuses on pharmaceuticals. The classic treatment of AIDS is highly active antiretroviral therapy, but most people living with HIV/AIDS-especially those in developing countries-have little or no access to the treatment because of the high cost of the therapy. Such treatment is associated with toxic side effects and drug resistance. As such, the search for better anti-HIV agents continues, with much attention focused on natural sources-particularly, plant species. Thousands of herbs have been screened for anti-HIV activity, and new compounds have been discovered from the extracts, many of which demonstrate inhibitory activity against HIV. Their mechanisms of action include inhibiting the activities of reverse transcriptase, protease, and integrase; weakening infection at the level of viral entry; and downregulating related gene expression. This provides researchers with new clues to synthesize drugs for the anti-HIV battle. Some synthetic derivatives of the anti-HIV natural products have stronger inhibitory effects in vitro than do their natural counterparts. Various mixed preparations of these anti-HIV herbs are in clinical trials or are applied in the treatment of people living with HIV/AIDS-some of which yield lower plasma viral load, enhance immune function, relieve related symptoms and signs, improve the quality of life, or, in combination with highly active antiretroviral therapy, alleviate the side effects of biomedical drugs. This article reviews current laboratory findings and clinical trials of anti-HIV agents from traditional herbs-particularly, herbs in traditional Chinese medicine. Drug interactions with highly active antiretroviral therapy and criteria for clinical evaluation of traditional Chinese medicine treatment are also discussed.

Rhus chinensis and Galla Chinensis--folklore to modern evidence: review

The species Rhus chinensis Mill. (Anacardiaceae) is an important representative of the genus Rhus, which contains over 250 individual species found in temperate and tropical regions worldwide. Rhus chinensis has long been used by folk medicine practitioners in Asia. Leaves, roots, stem, bark, fruit and particularly the galls on Rhus chinensis leaves, Galla chinensis, are recognized to have preventative and therapeutic effects on different ailments (such as diarrhea, dysentery, rectal and intestinal cancer, diabetes mellitus, sepsis, oral diseases and inflammation). However, it is critical to separate evidence from anecdote. Fortunately, recent scientific research has revealed that Rhus chinensis compounds possess strong antiviral, antibacterial, anticancer, hepatoprotective, antidiarrheal and antioxidant activities. Moreover, compounds isolated from the stem of Rhus chinensis significantly suppressed HIV-1 activity in vitro. Compounds from this plant were also found to inhibit enamel demineralization in vitro and enhance remineralization of dental enamel with fluoride. This review highlights claims from traditional and tribal medicinal lore and makes a contemporary summary of phytochemical, biological and pharmacological findings on this plant material. It aims to show that the pharmaceutical potential of this plant deserves closer attention.

Anti-HIV-1 efficacy of extracts from medicinal plants

The anti-HIV-1 activities of butanol, hexane, chloroform and water extracts from four widely used folk medicinal plants (Sophora flavescens, Tulipa edulis, Herba ephedra, and Pachyma hoelen Rumph) were evaluated in this study. The hexane extract of Pachyma hoelen Rumph, PH-4, showed effective inhibition against HIV-1. The 50% effective concentration (EC(50)) of PH-4 was 37.3 microg/ml in the p24 antigen assay and 36.8% in the HIV-1 recombinant RT activity test (at 200 microg/ml). In addition, the PH-4 showed the protective effect on the infected MT-4 cells, with a 58.2% rate of protection. The 50% cytotoxic concentration (CC(50)) of PH-4 was 100.6 microg/ml. These results suggest that PH-4 from Pachyma hoelen Rumph might be the candidate for the chemotherapy agent against HIV-1 infection with further study.

In vitro anti-viral activity of the total alkaloids from Tripterygium hypoglaucum against herpes simplex virus type 1

Herpes simplex virus type 1 (HSV-1) is a commonly occurring human pathogen worldwide. There is an urgent need to discover and develop new alternative agents for the management of HSV-1 infection. Tripterygium hypoglaucum (level) Hutch (Celastraceae) is a traditional Chinese medicine plant with many pharmacological activities such as anti-inflammation, anti-tumor and antifertility. The usual medicinal part is the roots which contain about a 1% yield of alkaloids. A crude total alkaloids extract was prepared from the roots of T. hypoglaucum amd its antiviral activity against HSV-1 in Vero cells was evaluated by cytopathic effect (CPE) assay, plaque reduction assay and by RT-PCR analysis. The alkaloids extract presented low cytotoxicity (CC(50) = 46.6 μg/mL) and potent CPE inhibition activity, the 50% inhibitory concentration (IC(50)) was 6.5 μg/mL, noticeably lower than that of Acyclovir (15.4 μg /mL). Plaque formation was significantly reduced by the alkaloids extract at concentrations of 6.25 μg/mL to 12.5 μg/mL, the plaque reduction ratio reached 55% to 75 which was 35% higher than that of Acyclovir at the same concentration. RT-PCR analysis showed that, the transcription of two important delayed early genes UL30 and UL39, and a late gene US6 of HSV-1 genome all were suppressed by the alkaloids extract, the expression inhibiting efficacy compared to the control was 74.6% (UL30), 70.9% (UL39) and 62.6% (US6) respectively at the working concentration of 12.5 μg/mL. The above results suggest a potent anti-HSV-1 activity of the alkaloids extract in vitro.

Anti-HIV-1 activities of compounds isolated from the medicinal plant Rhus chinensis

AIM OF THE STUDY

Previously, we reported that the petroleum ether fraction, RC-1, and EtOAc fraction, RC-2, of the medicinal plant Rhus chinensis showed potent anti-HIV-1 activities. To address anti-HIV-1 constituents of RC-1 and RC-2, 17 compounds were isolated. Anti-HIV-1 activities and possible action mechanisms of these compounds were investigated.

METHODS

The syncytial formation induced by HIV-1 was determined under the inverted microscope, cellular toxicity and protection assay were assessed by MTT method, reduction of p24 antigen expression level and RT activity were measured by ELISA, and inhibition of recombinant HIV-1 PR was monitored by the fluorescent signal.

RESULTS

The compounds 1 and 13 inhibited HIV-1-induced syncytium formation potently with TI value of 42.31 and 19.07, respectively. Compounds 4, 5, 6, 9 and 10 were less potent with TI value of 8.94, 8.22, 4.14, 5.11 and 5.34, respectively. Compound 1, a benzofuranone-type compound, previously reported as a novel anti-HIV-1 agent, might target late-steps of HIV-1 life cycle. Compound 13 inhibited HIV-1 replication with EC(50) of 7.16mug/ml and might target at/before integration step.

CONCLUSION

These compounds might contribute to anti-HIV-1 activities extracts of the medicinal plant Rhus chinensis.