Hyperforin is a modulator of inducible nitric oxide synthase and phagocytosis in microglia and macrophages

Targeting autophagy to counteract neuroinflammation: A novel antidepressant strategy

Depression is a common disease that affects physical and mental health and imposes a considerable burden on afflicted individuals and their families worldwide. Depression is associated with a high rate of disability and suicide. It causes a severe decline in productivity and quality of life. Unfortunately, the pathophysiological mechanisms underlying depression have not been fully elucidated, and the risk of its treatment is still presented. Studies have shown that the expression of autophagic markers in the brain and peripheral inflammatory mediators are dysregulated in depression. Autophagy-related genes regulate the level of autophagy and change the inflammatory response in depression. Depression is related to several aspects of immunity. The regulation of the immune system and inflammation by autophagy may lead to the development or deterioration of mental disorders. This review highlights the role of autophagy and neuroinflammation in the pathophysiology of depression, sumaries the autophagy-targeting small moleculars, and discusses a novel therapeutic strategy based on anti-inflammatory mechanisms that target autophagy to treat the disease.

Hyperforin ameliorates neuroinflammation and white matter lesions by regulating microglial VEGFR2 /SRC pathway in vascular cognitive impairment mice

AIM

To explore the neuroprotective potential of hyperforin and elucidate its underlying molecular mechanisms involved in its therapeutic effects against vascular cognitive impairment (VCI).

METHODS

The active compounds and possible targets of Hypericum perforatum L. that may be effective against VCI were found by network pharmacology in this research. We utilized bilateral common carotid artery occlusion (BCCAO) surgery to induce a VCI mouse model. Morris water maze (MWM) and Y-maze tests were used to assess VCI mice's cognitive abilities following treatment with hyperforin. To evaluate white matter lesions (WMLs), we utilized Luxol fast blue (LFB) stain and immunofluorescence (IF). Neuroinflammation was assessed using IF, western blot (WB), and enzyme-linked immunosorbent assay (ELISA). The effects of hyperforin on microglia were investigated by subjecting the BV2 microglial cell line to oxygen-glucose deprivation/reperfusion (OGD/R) stimulation. The expressions of VEGFR2 , p-SRC, SRC, VEGFA, and inflammatory markers including IL-10, IL-1β, TNF-α, and IL-6 were subsequently assessed.

RESULTS

The VEGFR2 /SRC signaling pathway is essential for mediating the protective properties of hyperforin against VCI according to network pharmacology analysis. In vivo findings demonstrated that hyperforin effectively improved BCCAO-induced cognitive impairment. Furthermore, staining results showed that hyperforin attenuated WMLs and reduced microglial activation in VCI mice. The hyperforin treatment group's ELISA results revealed a substantial decrease in IL-1β, IL-6, and TNF-α levels. According to the results of in vitro experiments, hyperforin decreased the release of pro-inflammatory mediators (TNF-α, IL-6, and IL-1β) and blocked microglial M1-polarization by modulating the VEGFR2 /SRC signaling pathway.

CONCLUSION

Hyperforin effectively modulated microglial M1 polarization and neuroinflammation by inhibiting the VEGFR2 /SRC signaling pathways, thereby ameliorating WMLs and cognitive impairment in VCI mice.

Effect of Plant Extracts Combinations on TNF-α, IL-6 and IL-10 Levels in Serum of Rats Exposed to Acute and Chronic Stress

Oxydative stress, anxiety and depression are associated with changes in cytokine levels. Natural products, including individual and combined plant extracts, have the potential to be used in the treatment of neuropsychiatric disorders. The goal of this study is to investigate the effects of two combined plant extracts, rich in flavonoids, on the levels of the cytokines TNF-α, IL-6, and IL-10 in rats subjected to models of acute cold stress and chronic unpredictable stress. The study utilized common medicinal plants such as Valeriana officinalis, Melissa officinalis, Crataegus monogyna, Hypericum perforatum, and Serratula coronata, which were combined in two unique combinations-Antistress I and Antistress II. The compositions of the used extracts were determined by HPLC methods. Pro- and anti-inflammatory cytokines in rats' serum were measured with Enzyme-linked immunosorbent assay. The results from the acute stress model revealed that the individual extract of Crataegus monogyna decreased levels of TNF-α, while Serratula coronata, Hypericum perforatum, and Valeriana officinalis effectively reduced IL-6 levels. Both combinations, Antistress I and Antistress II, were effective in reducing TNF-α and IL-6 levels, with Antistress II also increasing IL-10 levels. In the chronic stress model, Hypericum perforatum extract decreased the levels of the pro-inflammatory cytokines TNF-α and IL-6, whereas extracts of Serratula coronata and Valeriana officinalis only reduced TNF-α levels. The two combined extracts, Antistress I and Antistress II, decreased TNF-α and IL-6 levels, while Antistress I also reduced the levels of the anti-inflammatory cytokine IL-10. The combinations of plant extracts used in our experiment have not been previously studied or documented in the available literature. However, based on our own experimental results, we can draw the conclusion that the combinations exhibit a more pronounced effect in reducing cytokine levels compared to the individual plant extracts.

Hyperforin: A natural lead compound with multiple pharmacological activities

Hypericum perforatum L. (Clusiaceae), commonly known as St. John's wort, has a rich historical background as one of the oldest and most widely studied herbal medicines. Hyperforin is the main antidepressant active ingredient of St. John's wort. In recent years, hyperforin has attached increasing attention due to its multiple pharmacological activities. In this review, the information on hyperforin was systematically summarized. Hyperforin is considered to be a lead compound with diverse pharmacological activities including anti-depression, anti-tumor, anti-dementia, anti-diabetes and others. It can be obtained by extraction and synthesis. Further pharmacological studies and more precise detection methods will help develop a value for hyperforin. In addition, structural modification and pharmaceutical preparation technology will be beneficial to promoting the research progress of hyperforin based innovative drugs. Although these works are full of known and unknown challenges, researchers are still expected to make hyperforin play a greater value.

Targeting autophagy and neuroinflammation pathways with plant-derived natural compounds as potential antidepressant agents

Major depressive disorder (MDD) is a life-threatening disease that presents several characteristics. The pathogenesis of depression still remains poorly understood. Moreover, the mechanistic interactions of natural components in treating depression to target autophagy and neuroinflammation are yet to be evaluated. This study overviewed the effects of plant-derived natural components in regulating critical pathways, particularly neuroinflammation and autophagy, associated with depression. A list of natural components, including luteolin, apigenin, hyperforin, resveratrol, salvianolic acid b, isoliquiritin, nobiletin, andrographolide, and oridonin, have been investigated. All peer-reviewed journal articles were searched by Scopus, MEDLINE, PubMed, Web of Science, and Google Scholar using the appropriated keywords, including depression, neuroinflammation, autophagy, plant, natural components, etc. The neuroinflammation and autophagy dysfunction are critically associated with the pathophysiology of depression. Natural components with higher efficiency and lower complications can be used for targeting neuroinflammation and autophagy. These components with different doses showed the beneficial antidepressant properties in rodents. These can modulate autophagy markers, mainly AMPK, LC3II/LC3I ratio, Beclin-1. Moreover, they can regulate the NLRP3 inflammasome, resulting in the suppression of proinflammatory cytokines (e.g., IL-1β and IL-18). Future in vitro and in vivo studies are required to develop novel therapeutic approaches based on plant-derived active components to treat MDD.

In Vitro Effects of St. John's Wort Extract Against Inflammatory and Oxidative Stress and in the Phagocytic and Migratory Activity of Mouse SIM-A9 Microglia

Introduction: Herbal medicinal plants as Hypericum perforatum L., known as St. John’s wort (SJW) have been in use for a long time. SJW that is specifically used for the treatment of depressive disorders. Inflammatory cytokines derived from microglia play an important role in the regulation of the synthesis and reuptake of glutamate and influence synaptic function, morphology and neuronal plasticity. The present study was performed to investigate, whether STW3-VI, a special SJW extract has protective effects on mouse SIM-A9 microglia against cytotoxic and proinflammatory effects of ROS, glutamate, NMDA or cortisol. Additionally, we investigated the effects of SJW on migratory and phagocytic properties of microglia.

Results: Pre-treatment (48 h) of microglia with STW3-VI (5 or 10 μg/ml)—in contrast to desipramine—inhibited the H₂O₂-induced TNF-α release by 20–40%. Pre-treatment (48 h) of microglia with STW3-VI (5 or 10 μg/ml) delayed the 3 or 4 mM H₂O₂-induced intracellular ROS level by 26.9 and 44.4%, respectively. Furthermore, pre-treatment (48 h) of microglia with STW3-VI (5 μg/ml) - in contrast to desipramine - lowered the glutamate-induced cytotoxicity by 13.2%. Besides, pre-treatment (48 h) of microglia with STW3-VI (5 or 10 μg/ml) or desipramine (5 µM) inhibited the NMDA-induced decrease of the viability by 16.5–28.8% or 12%, respectively. Finally, pre-treatment (48 h) of microglia with STW3-VI (5 or 10 μg/ml)—in contrast to desipramine - reduced the cortisol-induced cytotoxicity by 15.5 and 12.9%. Treatment of microglia with STW3-VI (10 or 100 μg/ml) increased the migratory and the phagocytic capacities by 100 and 40%.

Conclusion: Our data provide evidence that STW3-VI—in contrast to desipramine - protects microglia from oxidative stress, NMDA- or glutamate-induced cytotoxicity, and has anti-inflammatory properties that are accompanied by improvement of their migratory and phagocytic capacity. These protective (particularly the anti-inflammatory) properties may be beneficial in the treatment of depressive disorders.

Anti-Tumor Activity of Hypericum perforatum L. and Hyperforin through Modulation of Inflammatory Signaling, ROS Generation and Proton Dynamics

In this paper we review the mechanisms of the antitumor effects of Hypericum perforatum L. (St. John's wort, SJW) and its main active component hyperforin (HPF). SJW extract is commonly employed as antidepressant due to its ability to inhibit monoamine neurotransmitters re-uptake. Moreover, further biological properties make this vegetal extract very suitable for both prevention and treatment of several diseases, including cancer. Regular use of SJW reduces colorectal cancer risk in humans and prevents genotoxic effects of carcinogens in animal models. In established cancer, SJW and HPF can still exert therapeutic effects by their ability to downregulate inflammatory mediators and inhibit pro-survival kinases, angiogenic factors and extracellular matrix proteases, thereby counteracting tumor growth and spread. Remarkably, the mechanisms of action of SJW and HPF include their ability to decrease ROS production and restore pH imbalance in tumor cells. The SJW component HPF, due to its high lipophilicity and mild acidity, accumulates in membranes and acts as a protonophore that hinders inner mitochondrial membrane hyperpolarization, inhibiting mitochondrial ROS generation and consequently tumor cell proliferation. At the plasma membrane level, HPF prevents cytosol alkalization and extracellular acidification by allowing protons to re-enter the cells. These effects can revert or at least attenuate cancer cell phenotype, contributing to hamper proliferation, neo-angiogenesis and metastatic dissemination. Furthermore, several studies report that in tumor cells SJW and HPF, mainly at high concentrations, induce the mitochondrial apoptosis pathway, likely by collapsing the mitochondrial membrane potential. Based on these mechanisms, we highlight the SJW/HPF remarkable potentiality in cancer prevention and treatment.

Protective Role of St. John's Wort and Its Components Hyperforin and Hypericin against Diabetes through Inhibition of Inflammatory Signaling: Evidence from In Vitro and In Vivo Studies

Diabetes mellitus is a very common chronic disease with progressively increasing prevalence. Besides the well-known autoimmune and inflammatory pathogenesis of type 1 diabetes, in many people, metabolic changes and inappropriate lifestyle favor a subtle chronic inflammatory state that contributes to development of insulin resistance and progressive loss of β-cell function and mass, eventually resulting in metabolic syndrome or overt type 2 diabetes. In this paper, we review the anti-inflammatory effects of the extract of Hypericum perforatum L. (St. John's wort, SJW) and its main active ingredients firstly in representative pathological situations on inflammatory basis and then in pancreatic β cells and in obese or diabetic animal models. The simultaneous and long-lasting inhibition of signal transducer and activator of transcription (STAT)-1, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinases (MAPKs)/c-jun N-terminal kinase (JNK) signaling pathways involved in pro-inflammatory cytokine-induced β-cell dysfunction/death and insulin resistance make SJW particularly suitable for both preventive and therapeutic use in metabolic diseases. Hindrance of inflammatory cytokine signaling is likely dependent on the hyperforin content of SJW extract, but recent data reveal that hypericin can also exert relevant protective effects, mediated by activation of the cyclic adenosine monophosphate (cAMP)/protein kinase cAMP-dependent (PKA)/adenosine monophosphate activated protein kinase (AMPK) pathway, against high-fat-diet-induced metabolic abnormalities. Actually, the mechanisms of action of the two main components of SJW appear complementary, strengthening the efficacy of the plant extract. Careful quantitative analysis of SJW components and suitable dosage, with monitoring of possible drug-drug interaction in a context of remarkable tolerability, are easily achievable pre-requisites for forthcoming clinical applications.

Bicyclic polyprenylated acylphloroglucinols and their derivatives: structural modification, structure-activity relationship, biological activity and mechanism of action

Bicyclic polyprenylated acylphloroglucinols (BPAPs), the principal bioactive benzophenone products isolated from plants of genera Garcinia and Hypericum, have attracted noticeable attention from the synthetic and biological communities due to their fascinating chemical structures and promising biological activities. However, the potential drug interaction, undesired physiochemical properties and toxicity have limited their potential use and development. In the last decade, pharmaceutical research on the structural modifications, structure-activity relationships (SARs) and mechanisms of action of BPAPs has been greatly developed to overcome the challenges. A comprehensive review of these scientific literature is extremely needed to give an overview of the rapidly emerging area and facilitate research related to BPAPs. This review, containing over 226 references, covers the progress made in the chemical synthesis-based structure modifications, SARs and the mechanism of action of BPAPs in vivo and vitro. The most relevant articles will focus on the discovery of lead compounds via synthetic modifications and the important BPAPs for which the direct targets have been deciphered. From this review, several key points of the SARs and mode of actions of this novel class of compounds have been summarized. The perspective and future direction of the research on BPAPs are concluded. This review would be helpful to get a better grasp of medicinal research of BPAPs and become a compelling guide for chemists dedicated to the synthesis of these compounds.

Nitric oxide signaling inhibits microglia proliferation by activation of protein kinase-G

Microglia population is primarily determined by a finely-regulated proliferation process during early development of the central nervous system (CNS). Nitric oxide (NO) is known to inhibit proliferation in numerous cell types. However, how NO signaling regulates microglia proliferation remains elusive. Using wildtype (WT) and inducible nitric oxide synthase knockout (iNOS^-/-) mice, this study investigated the role and underlying mechanisms of iNOS/NO signaling in microglia proliferation. Here we reported that iNOS^-/- mice displayed significantly more BrdU-labeled proliferating microglia in the cortex than that in WT mice at postnatal day 10. Compared to microglia isolated from WT mouse cortex, significantly more iNOS^-/- microglia displayed the specific cell-cycle markers Ki67 and phospho-histone H3 (pH3) in their nuclei. In addition, treating WT microglia with the NOS inhibitor LNAME drastically increased the percentage of cells expressing Ki67 and pH3, whereas treating iNOS^-/- microglia with NOC18, a slow-release NO-donor, significantly decreased the percentage of microglia expressing the two cell-cycle markers. Moreover, inhibition of protein kinase-G (PKG) in WT microglia increased the proportion of microglia expressing Ki67 and pH3, whereas activation of PKG signaling using 8Br-cGMP in iNOS^-/- microglia significantly decreased the fraction of microglia displaying Ki67 and pH3. Interestingly, in the presence of a PKG inhibitor, NOC18 increased the quantity of iNOS^-/- microglia expressing Ki67 and pH3. Together, these results indicate that basal activity of iNOS/NO signaling impedes microglial cell-cycle progression and attenuates proliferation through activation of the cGMP-PKG pathway. However, NO increases microglia cell-cycle progression in the absence of cGMP-PKG signaling.

Hypericum perforatum chronic treatment affects cognitive parameters and brain neurotrophic factor levels

Objective:

To evaluate the effects of Hypericum perforatum (hypericum) on cognitive behavior and neurotrophic factor levels in the brain of male and female rats.

Methods:

Male and female Wistar rats were treated with hypericum or water during 28 days by gavage. The animals were then subjected to the open-field test, novel object recognition and step-down inhibitory avoidance test. Nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and glial cell-line derived neurotrophic factor (GDNF) levels were evaluated in the hippocampus and frontal cortex.

Results:

Hypericum impaired the acquisition of short- and long-term aversive memory in male rats, evaluated in the inhibitory avoidance test. Female rats had no immediate memory acquisition and decreased short-term memory acquisition in the inhibitory avoidance test. Hypericum also decreased the recognition index of male rats in the object recognition test. Female rats did not recognize the new object in either the short-term or the long-term memory tasks. Hypericum decreased BDNF in the hippocampus of male and female rats. Hypericum also decreased NGF in the hippocampus of female rats.

Conclusions:

The long-term administration of hypericum appears to cause significant cognitive impairment in rats, possibly through a reduction in the levels of neurotrophic factors. This effect was more expressive in females than in males.

Research Progress of Polycyclic Polyprenylated Acylphloroglucinols

Polycyclic polyprenylated acylphloroglucinols (PPAPs) are a class of hybrid natural products sharing the mevalonate/methylerythritol phosphate and polyketide biosynthetic pathways and showing considerable structure and bioactivity diversity. This review discusses the progress of research into the chemistry and biological activity of 421 natural PPAPs in the past 11 years as well as in-depth studies of biological activities and total synthesis of some PPAPs isolated before 2006. We created an online database of all PPAPs known to date at http://www.chem.uky.edu/research/grossman/PPAPs . Two subclasses of biosynthetically related metabolites, spirocyclic PPAPs with octahydrospiro[cyclohexan-1,5'-indene]-2,4,6-trione core and complicated PPAPs produced by intramolecular [4 + 2] cycloadditions of MPAPs, are brought into the PPAP family. Some PPAPs' relative or absolute configurations are reassigned or critically discussed, and the confusing trivial names in PPAPs investigations are clarified. Pharmacologic studies have revealed a new molecular mechanism whereby hyperforin and its derivatives regulate neurotransmitter levels by activating TRPC6 as well as the antitumor mechanism of garcinol and its analogues. The antineoplastic potential of some type B PPAPs such as oblongifolin C and guttiferone K has increased significantly. As a result of the recent appearances of innovative synthetic methods and strategies, the total syntheses of 22 natural PPAPs including hyperforin, garcinol, and plukenetione A have been accomplished.

Enhancing the anti-inflammatory activity of chalcones by tuning the Michael acceptor site

Inflammatory signaling pathways orchestrate the cellular response to infection and injury. These pathways are known to be modulated by compounds that alkylate cysteinyl thiols. One class of phytochemicals with strong thiol alkylating activity is the chalcones. In this study we tested fourteen chalcone derivatives, α-X-substituted 2',3,4,4'-tetramethoxychalcones (α-X-TMCs, X = H, F, Cl, Br, I, CN, Me, p-NO2-C6H4, Ph, p-OMe-C6H4, NO2, CF3, COOEt, COOH), for their ability to modulate inflammatory responses, as monitored by their influence on heme oxygenase-1 (HO-1) activity, inducible nitric oxide synthase (iNOS) activity, and cytokine expression levels. We confirmed that the transcriptional activity of Nrf2 was activated by α-X-TMCs while for NF-κB it was inhibited. For most α-X-TMCs, anti-inflammatory activity was positively correlated with thiol alkylating activity, i.e. stronger electrophiles (X = CF3, Br and Cl) being more potent. Notably, this correlation did not hold true for the strongest electrophiles (X = CN and NO2) which were found to be ineffective as anti-inflammatory compounds. These results emphasize the idea that chemical fine-tuning of electrophilicity is needed to achieve and optimize desired therapeutic effects.

Natural phenolic metabolites with anti-angiogenic properties - a review from the chemical point of view

Considering the many secondary natural metabolites available from plants, phenolic compounds play a particularly important role in human health as they occur in significant amounts in many fruits, vegetables and medicinal plants. In this review natural phenolic compounds of plant origin with significant anti-angiogenic properties are discussed. Thirteen representatives from eight different natural or natural-like phenolic subclasses are presented with an emphasis on their synthesis and methods to modify the parent compounds. When available, the consequence of structural variation on the pharmacological activity of the molecules is described.

Hyperforin attenuates microglia activation and inhibits p65-Ser276 NFκB phosphorylation in the rat piriform cortex following status epilepticus

Hyperforin, a lipophilic constituent of medicinal herb St. John's Wort, has neurobiological effects including antidepressant activity, antibiotic potency, anti-inflammatory activity and anti-tumoral properties. Furthermore, hyperforin activates transient receptor potential conical channel-6 (TRPC6), a nonselective cation channel. To elucidate the roles of hyperforin and TRPC6 in neuroinflammation in vivo, we investigated the effect of hyperforin on neuroinflammatory responses and its related events in the rat piriform cortex (PC) following status epilepticus (SE). Hyperforin attenuated microglial activation, p65-serine 276 NFκB phosphorylation, and suppressed TNF-α expression in the PC following SE. Hyperforin also effectively alleviated SE-induced vasogenic edema formation, neuronal damage, microglial TRPC6 induction and blood-derived monocyte infiltration. Our findings suggest that hyperforin may effectively attenuate microglia-mediated neuroinflammation in the TRPC6-independent manner.

Phloroglucinol derivatives from Hypericum empetrifolium with antiproliferative activity on endothelial cells

Five acylphloroglucinols substituted with monoterpenoids (empetrifelixin A-D and empetrikajaforin), three known monocyclic acylphloroglucinols and one monocyclic acylphloroglucinol were isolated from a petrol ether extract of Hypericum empetrifolium after fractionation by flash chromatography on silica gel, RP-18 and subsequent purification by preparative HPLC (RP-18). Their structures were elucidated by 1D, 2D NMR techniques and HREIMS. To determine a possible anti-angiogenic activity, inhibition of cell proliferation was measured using a human microvascular endothelial cell line (HMEC-1). Subconfluent grown HMEC-1 cells were treated with all compounds isolated in sufficient amounts and stained with crystal violet. Highest activity was observed for empetrifelixin A and empetrifelixin D showing a concentration dependent inhibition of cell proliferation with IC(50) values of 6.5 ± 0.1 and 7.3 ± 0.4 μM, respectively. Empetrifelixin A also showed activity in a cell migration assay with HMEC-1 cells in low micromolar concentrations.

The effect of Hypericum perforatum on isolated rat aorta

CONTEXT

Different Hypericum species such as Hypericum perforatum (HP) L. and Hypericum triquetrifolium Turra are well known and widely used traditional medicine in Turkey.

OBJECTIVES

We investigated the effect of standardized HP extract on endothelium and vascular function.

MATERIALS AND METHODS

After suspending the aortas with endothelium in organ baths containing Krebs solution, contractile and relaxant responses were assessed in the absence and presence of HP (0.05 mg/ml).

RESULTS

Although there were significant reductions in the contractile responses to phenylephrine (1113.73 ± 164.11; 477.40 ± 39.94; p < 0.05) and potassium chloride (745.58 ± 66.73; 112.58 ± 26.58; p < 0.05), no differences in the relaxant responses to acetylcholine (94.61 ± 2.65; 87.79 ± 9.40) and sodium nitroprusside (108.82 ± 5.06; 106.43 ± 7.45) were observed.

DISCUSSION AND CONCLUSION

These data suggest that even the high dose of HP intervention does not bring any harmful effect on endothelium and smooth muscle function; meanwhile it might be beneficial on some of diseases accompanied with increased vascular contraction.