Ergosterol promotes neurite outgrowth, inhibits amyloid-beta synthesis, and extends longevity: In vitro neuroblastoma and in vivo Caenorhabditis elegans evidence

AIMS

Alzheimer's disease (AD), the most common neurodegenerative disorder associated with aging, is characterized by amyloid-β (Aβ) plaques in the hippocampus. Ergosterol, a mushroom sterol, exhibits neuroprotective activities; however, the underlying mechanisms of ergosterol in promoting neurite outgrowth and preventing Aβ-associated aging have never been investigated. We aim to determine the beneficial activities of ergosterol in neuronal cells and Caenorhabditis elegans (C. elegans).

MATERIALS AND METHODS

The neuritogenesis and molecular mechanisms of ergosterol were investigated in wild-type and Aβ precursor protein (APP)-overexpressing Neuro2a cells. The anti-amyloidosis properties of ergosterol were determined by evaluating in vitro Aβ production and the potential inhibition of Aβ-producing enzymes. Additionally, AD-associated transgenic C. elegans was utilized to investigate the in vivo attenuating effects of ergosterol.

KEY FINDINGS

Ergosterol promoted neurite outgrowth in Neuro2a cells through the upregulation of the transmembrane protein Teneurin-4 (Ten-4) mRNA and protein expressions, phosphorylation of the extracellular signal-regulated kinases (ERKs), activity of cAMP response element (CRE), and growth-associated protein-43 (GAP-43). Furthermore, ergosterol enhanced neurite outgrowth in transgenic Neuro2A cells overexpressing either the wild-type APP (Neuro2a-APPwt) or the Swedish mutant APP (Neuro2a-APPswe) through the Ten-4/ERK/CREB/GAP-43 signaling pathway. Interestingly, ergosterol inhibited Aβ synthesis in Neuro2a-APPwt cells. In silico analysis indicated that ergosterol can interact with the catalytic sites of β- and γ-secretases. In Aβ-overexpressing C. elegans, ergosterol decreased Aβ accumulation, increased chemotaxis behavior, and prolonged lifespan.

SIGNIFICANCE

Ergosterol is a potential candidate compound that might benefit AD patients by promoting neurite outgrowth, inhibiting Aβ synthesis, and enhancing longevity.

M1 macrophages polarized by crude polysaccharides isolated from Auricularia polytricha exhibit anti-tumor effect on human breast cancer cells

Breast cancer has been reported to correlate with the infiltration of tumor-associated macrophages (TAMs) or M2-like macrophages in tumor microenvironment (TME) that could promote breast cancer progression. In contrast, M1-like macrophages displayed anti-tumor activity toward cancer. This study was focused on Auricularia polytricha (AP), a cloud ear mushroom, which has been reported for anti-tumor activity and immunomodulation. AP extracts were screened on differentiated THP-1 macrophages (M0). Results demonstrated that water extract (APW) and crude polysaccharides (APW-CP) could upregulate M1-related genes and cytokines production (IL-6, IL-1 β and TNF-α) significantly. Moreover, APW and APW-CP showed a high expression of CD86 (M1 marker) compared to M0. The NF-κB signaling pathway is crucial for pro-inflammatory gene regulation. The APW and APW-CP treatment showed the induction of the NF-κB pathway in a dose-dependent manner, which related to the β-glucan content in the extracts. Furthermore, APW-CP polarized macrophages were investigated for anti-tumor activity on human breast cancer cells (MCF-7 and MDA-MB-231). Results showed that APW-CP could inhibit the invasion of breast cancer cells and induce apoptosis. Therefore, M1 macrophages polarized by APW-CP showed anti-tumor activity against the breast cancer cells and β-glucan may be the potential M1-phenotype inducer.

Potential Beneficial Effects and Pharmacological Properties of Ergosterol, a Common Bioactive Compound in Edible Mushrooms

Ergosterol is an important sterol commonly found in edible mushrooms, and it has important nutritional value and pharmacological activity. Ergosterol is a provitamin. It has been well established that edible mushrooms are an excellent food source of vitamin D2 because ergosterol is a precursor that is converted to vitamin D2 under ultraviolet radiation. The pharmacological effects of ergosterol, which include antimicrobial, antioxidant, antimicrobial, anticancer, antidiabetic, anti-neurodegenerative, and other activities, have also been reported. This review aims to provide an overview of the available evidence regarding the pharmacological effects of ergosterol and its underlying mechanisms of action. Their potential benefits and applications are also discussed.

Stigmasterol isolated from Azadirachta indica flowers attenuated glutamate-induced neurotoxicity via downregulation of the Cdk5/p35/p25 signaling pathway in the HT-22 cells

BACKGROUND

Glutamate, an excitatory neurotransmitter, was elevated in the brain of neurodegenerative disease (ND) patients. The excessive glutamate induces Ca²⁺ influx and reactive oxygen species (ROS) production which exacerbates mitochondrial function, leading to mitophagy aberration, and hyperactivates Cdk5/p35/p25 signaling leading to neurotoxicity in ND. Stigmasterol, a phytosterol, has been reported for its neuroprotective effects; however, the underlying mechanism of stigmasterol on restoring glutamate-induced neurotoxicity is not fully investigated.

PURPOSE

We investigated the effect of stigmasterol, a compound isolated from Azadirachta indica (AI) flowers, on ameliorating glutamate-induced neuronal apoptosis in the HT-22 cells.

STUDY DESIGN

To further understand the underlying molecular mechanisms of stigmasterol, we investigated the effect of stigmasterol on Cdk5 expression, which was aberrantly expressed in glutamate-treated cells. Cell viability, Western blot analysis, and immunofluorescence are employed.

RESULTS

Stigmasterol significantly inhibited glutamate-induced neuronal cell death via attenuating ROS production, recovering mitochondrial membrane depolarization, and ameliorating mitophagy aberration by decreasing mitochondria/lysosome fusion and the ratio of LC3-II/LC3-I. In addition, stigmasterol treatment downregulated glutamate-induced Cdk5, p35, and p25 expression via enhancement of Cdk5 degradation and Akt phosphorylation. Although stigmasterol demonstrated neuroprotective effects on inhibiting glutamate-induced neurotoxicity, the efficiency of stigmasterol is limited due to its poor water solubility. We conjugated stigmasterol to soluble soybean polysaccharides with chitosan nanoparticles to overcome the limitations. We found that the encapsulated stigmasterol increased water solubility and enhanced the protective effect on attenuating the Cdk5/p35/p25 signaling pathway compared with free stigmasterol.

CONCLUSION

Our findings illustrate the neuroprotective effect and the improved utility of stigmasterol in inhibiting glutamate-induced neurotoxicity.

Cleistocalyx nervosum var. paniala Berry Seed Protects against TNF-α-Stimulated Neuroinflammation by Inducing HO-1 and Suppressing NF-κB Mechanism in BV-2 Microglial Cells

Sustained inflammatory responses have been implicated in various neurodegenerative diseases (NDDs). Cleistocalyx nervosum var. paniala (CN), an indigenous berry, has been reported to exhibit several health-beneficial properties. However, investigation of CN seeds is still limited. The objective of this study was to evaluate the protective effects of ethanolic seed extract (CNSE) and mechanisms in BV-2 mouse microglial cells using an inflammatory stimulus, TNF-α. Using LC-MS, ferulic acid, aurentiacin, brassitin, ellagic acid, and alpinetin were found in CNSE. Firstly, we examined molecular docking to elucidate its bioactive components on inflammation-related mechanisms. The results revealed that alpinetin, aurentiacin, and ellagic acid inhibited the NF-κB activation and iNOS function, while alpinetin and aurentiacin only suppressed the COX-2 function. Our cell-based investigation exhibited that cells pretreated with CNSE (5, 10, and 25 μg/mL) reduced the number of spindle cells, which was highly observed in TNF-α treatment (10 ng/mL). CNSE also obstructed TNF-α, IL-1β, and IL-6 mRNA levels and repressed the TNF-α and IL-6 releases in a culture medium of BV-2 cells. Remarkably, CNSE decreased the phosphorylated forms of ERK, p38MAPK, p65, and IκB-α related to the inhibition of NF-κB binding activity. CNSE obviously induced HO-1 protein expression. Our findings suggest that CNSE offers good potential for preventing inflammatory-related NDDs.

Effect of cold atmospheric microwave plasma (CAMP) on wound healing in canine keratinocytes

Cutaneous wound healing is a biological process that occurs upon skin injury and involves different mechanisms to repair tissue damage. Improper healing or prolonged curation period of wound lesions may induce unpleasant complications. Cold atmospheric microwave plasma (CAMP) is an upcoming medical therapeutic option for skin infection and wound treatment. However, the molecular mechanisms of CAMP-mediated canine wound healing are not well characterized. Wound-healing activity was examined to elucidate the biological effects and molecular mechanisms of CAMP. Canine keratinocytes (CPEKs) were treated using CAMP, and their wound-healing activities were evaluated. The molecular mechanisms of that effect were examined, based on RNA-Seq analysis data, and verified using immunoblotting and polymerase chain reaction. It was found that the CAMP-treated cells exhibited a significant increase in cell migration evaluated by scratch assay in human keratinocytes (HaCaT) and canine keratinocytes (CPEK). Additionally, CAMP-treated CPEK cells showed a significant positive effect on cell invasion. The RNA-Seq data revealed that CAMP alters different genes and pathways in CPEK cells. Gene expression involved in the cell cycle, cell proliferation, angiogenesis, cell adhesion, and wound healing was upregulated in CAMP-treated cells compared with gas-activated media used as a control. The Hippo pathway was also analyzed, and the protein and mRNA levels of YAP were significantly increased in CAMP-treated cells. CAMP-treated CPEK cells indicated the downregulation of E-cadherin and upregulation of vimentin, Snail, and Slug at transcription and translation levels, contributing to a favorable effect on cell migration. Our findings suggested that CAMP treatment provided beneficial effects on the curative wound process through the induction of genes involved in wound healing, promotion of EMT, and increase in the molecular targets in the Hippo signaling pathway.

Antioxidant and Anti-Skin Aging Potential of Selected Thai Plants: In Vitro Evaluation and In Silico Target Prediction

The skin is the largest organ that performs a variety of the body's essential functions. Impairment of skin structure and functions during the aging process might severely impact our health and well-being. Extensive evidence suggests that reactive oxygen species play a fundamental role in skin aging through the activation of the related degradative enzymes. Here, the 16 Thai medicinal plant species were screened for their potential anti-skin aging properties. All extracts were investigated for total phenolic and flavonoid contents, antioxidant, anti-elastase, and anti-tyrosinase activities, as well as the binding ability of compounds with target enzymes by molecular docking. Among all the plants screened, the leaves of A. occidentale and G. zeylanicum exhibited strong antioxidants and inhibition against elastase and tyrosinase. Other potential plants include S. alata leaf and A. catechu fruit, with relatively high anti-elastase and anti-tyrosinase activities, respectively. These results are also consistent with docking studies of compounds derived from these plants. The inhibitory actions were found to be more highly positively correlated with phenolics than flavonoids. Taken together, our findings reveal some Thai plants, along with candidate compounds as natural sources of antioxidants and potent inhibitors of elastase and tyrosinase, could be developed as promising and effective agents for skin aging therapy.

Aquilaria crassna Leaf Extract Ameliorates Glucose-Induced Neurotoxicity In Vitro and Improves Lifespan in Caenorhabditis elegans

Hyperglycemia is one of the important causes of neurodegenerative disorders and aging. Aquilaria crassna Pierre ex Lec (AC) has been widely used to relieve various health ailments. However, the neuroprotective and anti-aging effects against high glucose induction have not been investigated. This study aimed to investigate the effects of hexane extract of AC leaves (ACH) in vitro using human neuroblastoma SH-SY5Y cells and in vivo using nematode Caenorhabditis elegans. SH-SY5Y cells and C. elegans were pre-exposed with high glucose, followed by ACH treatment. To investigate neuroprotective activities, neurite outgrowth and cell cycle progression were determined in SH-SY5Y cells. In addition, C. elegans was used to determine ACH effects on antioxidant activity, longevity, and healthspan. In addition, ACH phytochemicals were analyzed and the possible active compounds were identified using a molecular docking study. ACH exerted neuroprotective effects by inducing neurite outgrowth via upregulating growth-associated protein 43 and teneurin-4 expression and normalizing cell cycle progression through the regulation of cyclin D1 and SIRT1 expression. Furthermore, ACH prolonged lifespan, improved body size, body length, and brood size, and reduced intracellular ROS accumulation in high glucose-induced C. elegans via the activation of gene expression in the DAF-16/FoxO pathway. Finally, phytochemicals of ACH were analyzed and revealed that β-sitosterol and stigmasterol were the possible active constituents in inhibiting insulin-like growth factor 1 receptor (IGFR). The results of this study establish ACH as an alternative medicine to defend against high glucose effects on neurotoxicity and aging.

Neuroprotective effects of ergosterol against TNF-α-induced HT-22 hippocampal cell injury

Neuroinflammation is a brain pathology that involves the expression of high levels of pro-inflammatory mediators, including tumor necrosis factor-alpha (TNF-α). An excessive TNF-α expression could result in neuronal cell death and subsequently lead to neurodegeneration. Auricularia polytricha (AP; an edible mushroom) has been reported as a rich source of ergosterol with several medicinal benefits. The current study reports on the neuroprotective effects of AP extracts and ergosterol against the TNF-α-induced HT-22 hippocampal cell injury. The hexane extract of AP (APH) demonstrated a neuroprotective effect against the TNF-α-induced HT-22 cell toxicity, taking place through the activation of the antioxidant pathway. Ergosterol, a major component of APH, could attenuate the toxicity of TNF-α on HT-22 cells, by increasing the expression of a major antioxidant enzyme (superoxide dismutase-1) and by facilitating the scavenging of reactive oxygen species through antioxidant signaling. Moreover, an antibody array was performed to screen the possible molecular targets of ergosterol in HT-22 cells exposed to TNF-α. Based on the antibody array, the phospho-Akt was activated in the presence of ergosterol, and this finding was also supported by Western blotting analysis. Furthermore, ergosterol inhibited the transcriptional expressions of the glutamate ionotropic receptor N-methyl-D-aspartate (NMDA) type subunit 2B gene (Grin2b) through an early growth response-1 (EGR-1) overexpression in TNF-α-treated HT-22 cells. Our findings suggest that a novel therapeutic effect of AP and ergosterol against neuroinflammation, that it is mediated by an NMDA gene modulation occurring through the overexpression of the EGR-1 transcription factor.

Auricularia polytricha ethanol crude extract from sequential maceration induces lipid accumulation and inflammatory suppression in RAW264.7 macrophages

Auricularia polytricha (AP), an edible mushroom, is continuously being studied due to the medicinal properties. In this study, AP crude extracts from three sequential extraction, starting from hexane (APH), ethanol (APE) and water (APW), were examined for their anti-inflammatory activity and lipid accumulation property in macrophages. APE treatment was found to increase lipid droplet accumulation in both RAW264.7 and LPS-stimulated RAW264.7 cells in a dose dependent manner. Furthermore, nitric oxide production upon LPS stimulation was suppressed on APE pre-treatment. LC-MS analysis was performed to identify the potential bioactive compounds in APE. The PPARγ agonist, 15-Deoxy-Δ12,14-prostaglandin J2-2-glycerol ester (15d-PGJ2-G), was uniquely presented in APE, which was previously described to bind with PPARγ and induces lipid uptake via the upregulation of Cd36. We found that pre-treatment with APE also showed an increase in Cd36 mRNA in RAW264.7 cells, indicating that 15d-PGJ2-G is the potential active compound found in AP. In conclusion, APE exhibited the induction of lipid uptake via CD36, resulting in lipid accumulation.

HIV-1 Protease and Reverse Transcriptase Inhibitory Activities of Curcuma aeruginosa Roxb. Rhizome Extracts and the Phytochemical Profile Analysis: In Vitro and In Silico Screening

Human immunodeficiency virus type-1 (HIV-1) infection causes acquired immunodeficiency syndrome (AIDS). Currently, several anti-retroviral drugs are available, but adverse effects of these drugs have been reported. Herein, we focused on the anti-HIV-1 activity of Curcuma aeruginosa Roxb. (CA) extracted by hexane (CA-H), ethyl acetate (CA-EA), and methanol (CA-M). The in vitro HIV-1 protease (PR) and HIV-1 reverse transcriptase (RT) inhibitory activities of CA extracts were screened. CA-M potentially inhibited HIV-1 PR (82.44%) comparable to Pepstatin A (81.48%), followed by CA-EA (67.05%) and CA-H (47.6%), respectively. All extracts exhibited moderate inhibition of HIV-1 RT (64.97 to 76.93%). Besides, phytochemical constituents of CA extracts were identified by GC-MS and UPLC-HRMS. Fatty acids, amino acids, and terpenoids were the major compounds found in the extracts. Furthermore, drug-likeness parameters and the ability of CA-identified compounds on blocking of the HIV-1 PR and RT active sites were in silico investigated. Dihydroergocornine, 3β,6α,7α-trihydroxy-5β-cholan-24-oic acid, and 6β,11β,16α,17α,21-Pentahydroxypregna-1,4-diene-3,20-dione-16,17-acetonide showed strong binding affinities at the active residues of both HIV-1 PR and RT. Moreover, antioxidant activity of CA extracts was determined. CA-EA exhibited the highest antioxidant activity, which positively related to the amount of total phenolic content. This study provided beneficial data for anti-HIV-1 drug discovery from CA extracts.

Thunbergia laurifolia Leaf Extract Inhibits Glutamate-Induced Neurotoxicity and Cell Death through Mitophagy Signaling

Oxidative stress plays a crucial role in neurodegeneration. Therefore, reducing oxidative stress in the brain is an important strategy to prevent neurodegenerative disorders. Thunbergia laurifolia (Rang-jued) is well known as an herbal tea in Thailand. Here, we aimed to determine the protective effects of T. laurifolia leaf extract (TLE) on glutamate-induced oxidative stress toxicity and mitophagy-mediated cell death in mouse hippocampal cells (HT-22). Our results reveal that TLE possesses a high level of bioactive antioxidants by LC–MS technique. We found that the pre-treatment of cells with TLE prevented glutamate-induced neuronal death in a concentration-dependent manner. TLE reduced the intracellular ROS and maintained the mitochondrial membrane potential caused by glutamate. Moreover, TLE upregulated the gene expression of antioxidant enzymes (SOD1, SOD2, CAT, and GPx). Interestingly, glutamate also induced the activation of the mitophagy process. However, TLE could reverse this activity by inhibiting autophagic protein (LC3B-II/LC3B-I) activation and increasing a specific mitochondrial protein (TOM20). Our results suggest that excessive glutamate can cause neuronal death through mitophagy-mediated cell death signaling in HT-22 cells. Our findings indicate that TLE protects cells from neuronal death by stimulating the endogenous antioxidant enzymes and inhibiting glutamate-induced oxidative toxicity via the mitophagy–autophagy pathway. TLE might have potential as an alternative or therapeutic approach in neurodegenerative diseases.

Caesalpinia mimosoides Leaf Extract Promotes Neurite Outgrowth and Inhibits BACE1 Activity in Mutant APP-Overexpressing Neuronal Neuro2a Cells

Alzheimer’s disease (AD) is implicated in the imbalance of several proteins, including Amyloid-β (Aβ), amyloid precursor protein (APP), and BACE1. APP overexpression interferes with neurite outgrowth, while BACE1 plays a role in Aβ generation. Medicinal herbs with effects on neurite outgrowth stimulation and BACE1 inhibition may benefit AD. This study aimed to investigate the neurite outgrowth stimulatory effect, along with BACE1 inhibition of Caesalpinia mimosoides (CM), using wild-type (Neuro2a) and APP (Swedish mutant)-overexpressing (Neuro2a/APPSwe) neurons. The methanol extract of CM leaves stimulated neurite outgrowth in wild-type and APP-overexpressing cells. After exposure to the extract, the mRNA expression of the neurite outgrowth activation genes growth-associated protein-43 (GAP-43) and teneurin-4 (Ten-4) was increased in both Neuro2a and Neuro2a/APPSwe cells, while the mRNA expression of neurite outgrowth negative regulators Nogo receptor (NgR) and Lingo-1 was reduced. Additionally, the extract suppressed BACE1 activity in the APP-overexpressing neurons. Virtual screening demonstrated that quercetin-3′-glucuronide, quercetin-3-O-glucoside, clausarinol, and theogallin were possible inhibitors of BACE1. ADMET was analyzed to predict drug-likeness properties of CM-constituents. These results suggest that CM extract promotes neurite outgrowth and inhibits BACE1 activity in APP-overexpressing neurons. Thus, CM may serve as a source of drugs for AD treatment. Additional studies for full identification of bioactive constituents and to confirm the neuritogenesis in vivo are needed for translation into clinic of the present findings.

Anti-COVID-19 drug candidates: A review on potential biological activities of natural products in the management of new coronavirus infection

Background and aim

The novel coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is now become a worldwide pandemic bringing over 71 million confirmed cases, while the specific drugs and vaccines approved for this disease are still limited regarding their effectiveness and adverse events. Since virus incidences are still on rise, infectivity and mortality may also rise in the near future, natural products are highly considered to be valuable sources for the discovery of new antiviral drugs against SARS-CoV-2. This present review aims to comprehensively summarize the up-to-date scientific literatures on biological activities of plant- and mushroom-derived compounds relevant to mechanistic targets involved in SARS-CoV-2 infection and inflammatory-associated pathogenesis, including viral entry, replication and release, and the renin-angiotensin-aldosterone system (RAAS).

Experimental procedure

Data were retrieved from a literature search available on PubMed, Scopus and Google Scholar databases and collected until the end of May 2020. The findings from in vitro cell and non-cell based studies were considered, while the results of in silico studies were excluded.

Results and conclusion

Based on the previous findings in SARS-CoV studies, except in silico molecular docking analysis, herein, we provide a total of 150 natural compounds as potential candidates for development of new anti-COVID-19 drugs with higher efficacy and lower toxicity than the existing therapeutic agents. Several natural compounds have showed their promising actions on multiple therapeutic targets, which should be further explored. Among them, quercetin, one of the most abundant of plant flavonoids, is proposed as a lead candidate with its ability on the virus side to inhibit SARS-CoV spike protein-angiotensin-converting enzyme 2 (ACE2) interaction, viral protease and helicase activities, as well as on the host cell side to inhibit ACE activity and increase intracellular zinc level.

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Relevant and up-to-date publications in natural products with anti-COVID-19 potential.

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Emphasis on the potential of anti-COVID-19 plant/mushroom-based medicine.

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Twenty four proposed natural compounds for the anti-COVID-19 drug candidates.

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Quercetin emerged as the most promising compound acting on multiple therapeutic targets.

Anti-HIV-1 protease activity of the crude extracts and isolated compounds from Auricularia polytricha

BACKGROUND

Acquired immunodeficiency syndrome (AIDS) is caused by the Human immunodeficiency virus type-1 (HIV-1). HIV-1 protease (HIV-1 PR) is an essential enzyme for the HIV replication, and therefore, it is an important target for antiretroviral drugs development, particularly from natural products. Auricularia polytricha (AP) is an edible mushroom with several important therapeutic properties. These properties will be investigated as HIV-1 PR inhibitors.

METHODS

The sequential hexane (APH), ethanol (APE) and water (APW) extracts from AP were screened for inhibitory activity against HIV-1 PR. The extract that consistently showed the strong HIV-1 PR inhibition was further investigated for its phytochemical constituents. The compounds were purified by column chromatography. The isolated compounds were structurally elucidated using 1D and 2D NMR, HRMS, FTIR, and GC/MS techniques. Each compound was screened against HIV-1 PR to determine its inhibitory activity and to provide an explanation for the activity found in the extract.

RESULTS

Hexane crude extract of AP (APH) exhibited significant inhibition on HIV-1 PR activity. Four major compounds isolated from APH fraction were identified to be two triacylglycerols, linoleic acid and ergosterol. Moreover, all four compounds showed significant inhibition of HIV-1 PR activity.

CONCLUSION

The findings from this study suggest that AP is a good source of fatty esters, fatty acids and ergosterol. These natural products exhibit anti-HIV-1 properties by blocking HIV-1 PR. These important biological results warrant further development of AP as an alternative antiretroviral drug.

HIV-1 protease and reverse transcriptase inhibition by tiger milk mushroom (Lignosus rhinocerus) sclerotium extracts: In vitro and in silico studies

Background and aim

Lignosus rhinocerus (LR) is an edible mushroom with a variety of medicinal properties such as neurostimulation, immunomodulation, anti-inflammation, anti-oxidation, anti-proliferation, anti-diabetes and especially antiviral activity. Human immunodeficiency virus type-1 (HIV-1) needs the HIV-1 protease (PR) and reverse transcriptase (RT) for its replication. Therefore, both HIV-1 PR and RT are important targets for antiretroviral drug development.

Experimental procedure

The crude hexane (LRH), ethanol (LRE) and water (LRW) extracts of LR were in vitro screened for inhibitory activity against HIV-1 PR and RT, then anti-HIV-1 activity on the infected MOLT-4 cells were determined. Chemical constituents of the extracts were identified by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography (LC)-MS. The identified compounds were in silico analysed for drug-likeness property and molecular modelling.

Results and conclusion

According to our screening assays, LRE and LRW significantly inhibited both enzymes (25–55%), while LRH suppressed only the HIV-1 PR activity (88.97%). At 0.5 mg/ml of LRW showed significant inhibition of HIV-1 induced syncytial formation and p24 production in the infected MOLT-4 cells. Investigation of chemical analysis revealed that major groups of identified constituents found in the extracts were fatty acids, peptides and terpenoids. In silico analysis showed that heliantriol F and 6 alpha-fluoroprogesterone displayed great binding energies with HIV-1 PR and HIV-1 RT, respectively. These findings suggest that LR could be a potential source of compounds to inhibit HIV-1 PR and/or RT activities in vitro. Furthermore, our results provide beneficial data for the development of novel HIV-1 PR and RT inhibitors.

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The hexane extract of L. rhinocerus strongly inhibited HIV-1 PR activity.

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The ethanol and water extracts of L. rhinocerus showed HIV-1 PR and RT inhibitions.

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Chemical constituents of L. rhinocerus could block HIV-1 PR and RT in silico studies.

Polygonumins A, a newly isolated compound from the stem of Polygonum minus Huds with potential medicinal activities

Polygonumins A, a new compound, was isolated from the stem of Polygonum minus. Based on NMR results, the compound’s structure is identical to that of vanicoside A, comprising four phenylpropanoid ester units and a sucrose unit. The structure differences were located at C-3″″′. The cytotoxic activity of polygonumins A was evaluated on several cancer cell lines by a cell viability assay using tetrazolium dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The compound showed the highest antiproliferative (p < 0.05) activities against K562 (Human Leukaemia Cell Line), MCF7 (Human breast adenocarcinoma cell line), and HCT116 (Colorectal cancer cells) cells. Cytotoxic studies against V79–4 cells were carried out and showed that polygonumins A was toxic at 50 µg/ml, suggesting that this compound may be used as an anticancer drug without affecting normal cells. Polygonumins A also showed promising activity as an HIV-1 protease inhibitor with 56% relative inhibition. Molecular docking results indicated that the compound possesses high binding affinity towards the HIV protease over the low binding free energy range of -10.5 to -11.3 kcal/mol. P. minus is used in Malaysian traditional medicine for the treatment of tumour cells. This is the first report on the use of P. minus as an HIV-1 protease inhibitor.