Evaluation of the light-sensitive cytotoxicity of Hypericum perforatum extracts, fractions, and pure compounds

Potent Virucidal Activity In Vitro of Photodynamic Therapy with Hypericum Extract as Photosensitizer and White Light against Human Coronavirus HCoV-229E

The emergent human coronavirus SARS-CoV-2 and its high infectivity rate has highlighted the strong need for new virucidal treatments. In this sense, the use of photodynamic therapy (PDT) with white light, to take advantage of the sunlight, is a potent strategy for decreasing the virulence and pathogenicity of the virus. Here, we report the virucidal effect of PDT based on Hypericum extract (HE) in combination with white light, which exhibits an inhibitory activity of the human coronavirus HCoV-229E on hepatocarcinoma Huh-7 cells. Moreover, despite continuous exposure to white light, HE has long durability, being able to maintain the prevention of viral infection. Given its potent in vitro virucidal capacity, we propose HE in combination with white light as a promising candidate to fight against SARS-CoV-2 as a virucidal compound.

On the Sensitivity of the Virion Envelope to Lipid Peroxidation

Emerging viruses are a public health threat best managed with broad spectrum antivirals. Common viral structures, like capsids or virion envelopes, have been proposed as targets for broadly active antiviral drugs. For example, a number of lipoperoxidators have been proposed to preferentially affect viral infectivity by targeting metabolically inactive enveloped virions while sparing metabolically active cells. However, this presumed preferential virion sensitivity to lipoperoxidation remains untested. To test whether virions are indeed more sensitive to lipoperoxidation than are cells, we analyzed the effects of two classic generic lipoperoxidators: lipophilic 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN) and hydrophilic 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH) on Vero and human foreskin fibroblasts (HFF) cell viability, HSV-1 plaquing efficiency, and virion and cell lipoperoxidation. Cells or virions were incubated with the lipoperoxidators at 37°C for 2 h or incubated in atmospheric O₂, and dose responses (half maximal cytotoxic and effective concentration [CC₅₀ and EC₅₀]) were evaluated by three or four parameter regression. The HSV-1 virions were slightly more sensitive to lipoperoxidators than were the cells (selectivity index [SI], 3.3 to 7.4). The effects of the lipophilic AMVN on both cell and virion viability directly correlated with the extent of membrane lipoperoxidation as evaluated by two different probes, C11-Bodipy and liperfluo. Moreover, the hydrophilic AAPH-induced virion inactivation at lower concentrations than did lipoperoxidation. Known lipoperoxidators inhibit infectivity via lipoperoxidation-independent mechanisms. Antioxidants protected against a loss of viral infectivity by less than 5-fold. Carrier bovine serum albumin (BSA) protected against both peroxidators to a similar extent when present together with the lipoperoxidating agents, suggesting that BSA quenches them as expected. Virions incubated in atmospheric oxidative conditions suffered losses of infectivity that were similar to those of chemically peroxidated virions, and they were protected by water soluble vitamin C and BSA with no evident lipoperoxidation, indicating predominant peroxidative damage to nonlipid virion components. Thus, lipoperoxidation is not a mechanism by which to specifically inhibit the infectivity of enveloped viruses, and the effects of known lipoperoxidators on virion infectivity are not solely mediated by lipoperoxidation. IMPORTANCE Small molecules that induce lipoperoxidation have been proposed repeatedly as potential antiviral drugs based on a presumed unique sensitivity of virions to this type of damage. Several small molecules that inactivate virions without affecting cells have been proposed to act primarily by inducing lipoperoxidation. However, the preferential sensitivity of virions to lipoperoxidators had not been experimentally evaluated. Using two of the best characterized small molecule lipoperoxidators, which are widely considered to be the prototypical water soluble and liposoluble lipoperoxidators, we show that lipoperoxidators have no preference for virions over cells. Moreover, they also inactivate virions by mechanisms other than the induction of lipoperoxidation. Therefore, the general induction of lipoperoxidation is not a path by which to develop antivirals. Moreover, molecules with specific antiviral activity which are not cytotoxic and have no preference to localize to virions over cells are unlikely to act primarily by inducing lipoperoxidation.

Cytotoxic activities of Hypericum perforatum L. extracts against 2D and 3D cancer cell models

Six extracts were obtained from plant species Hypericum perforatum L., collected at Samsun in Turkey. The aim of this study was to examine the mechanisms of the anticancer activity of these extracts. Methanol, ethyl-acetate and hexane were used as a solvents for extraction from both branch-body part of the plant (extracts 1, 2 and 3) and from plant flowers (extracts 4, 5 and 6). The cytotoxic effects of the extracts were determined against 2D and 3D cancer cell models. Cell cycle changes of treated HeLa cells were analyzed by flow cytometry. Measurements of gene and microRNA expression levels in treated HeLa cells were done by quantitative real time PCR. Five examined extracts (2-6) exerted selective concentration-dependent cytotoxic effects on HeLa, K562, and A549 cancer cells, while the extract 1 exhibited very weak cytotoxicity. The extract 6 showed the highest intensity of cytotoxic activity. All tested extracts (2-6) demonstrated the ability to induce apoptosis in HeLa cells through activation of caspase-3. These extracts remarkably decreased gene expression levels of MMP2, MMP9, TIMP3, and VEGFA in HeLa cells. Flower extracts might have stronger effects on miR128/193a-5p/335 level changes than branch-body extracts. Hypericum perforatum extracts exerted weaker cytotoxic effects on 3D HeLa spheroids when compared with their effects on 2D monolayer HeLa cells. Taken together, results of our research may suggest the promising anticancer properties of the Hypericum perforatum extracts.

Phytochemical profiles, phototoxic and antioxidant properties of eleven Hypericum species - A comparative study

Hypericum is one out of the nine genera belonging to the botanical family Clusiaceae Lindl (syn. Hypericaceae Juss.; APG III, 2009). The genus contains 484 species spread worldwide, one of which, Hypericum perforatum, is largely used in folk medicine. The aim of this study was to evaluate the chemical composition, along with the antioxidant and phototoxic activity, of 11 Hypericum species grown in Sicily (H. perforatum L., H. aegypticum L., H. androsaemum L., H. calycinum L., H. hircinum L., H. hirsutum L., H. montanum L., H. patulum Thunb., H. perfoliatum L., H. pubescens Boiss., H. tetrapterum Fr.). Samples of flowering tops collected from these Hypericum species were extracted and analysed by high performance liquid chromatography with diode-array detection and mass spectrometry (HPLC-DAD-MS) to determine their content of main polyphenols, acylphloroglucinols, and naphthodianthrones. The extracts were also subjected to a photocytotoxic assay using murine fibroblast (NIH/3T3), and their antioxidant activity evaluated by means of Folin-Ciocalteau, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, and oxygen radical antioxidant capacity assays. Phytochemical analysis allowed us to identify and quantify 20 metabolites, each of them possessing a well-known biological activity. Furthermore, all examined species showed a good cytotoxic and antioxidant/radical scavenging activity. These results indicate that in addition to the well-known H. perforatum, at least other three species (H. tetrapterum, H. pubescens, and H. montanum) represent potential sources of biologically active compounds, and at least other two species (H. perfoliatum and H. tetrapterum), due to their phototoxicity are candidates for application in photodynamic therapy.

Tricyclic Polyprenylated Acylphloroglucinols from St John's Wort, Hypericum perforatum

The new polyprenylated acylphloroglucinol derivatives 1-15 and the known furohyperforin (16) were isolated from the stems and leaves of Hypericum perforatum. Their structures were determined by analyses of NMR and HRESIMS data. Their absolute configurations were elucidated by a combination of electronic circular dichroism (ECD) and Rh₂(OCOCF₃)₄-induced ECD, as well as X-ray diffraction crystallography. The new hyperforatin F (9) contains a unique acetyl functionality at C-1 of the bicyclo[3.3.1]nonane core. Hyperforatins G (10) and H (11) are similarly the first examples of naturally occurring [3.3.1]-type polycyclic prenylated acylphloroglucinols possessing a carbonyl functionality at C-32. The compounds were tested for their acetylcholinesterase (AChE) inhibitory activities and cytotoxic activities against a panel of human tumor cell lines. Compounds 3, 5, 6, 8, and 9 exerted moderate inhibitory activities (IC₅₀ 3.98-9.13 μM) against AChE.

Computed Regioselectivity and Conjectured Biological Activity of Ene Reactions of Singlet Oxygen with the Natural Product Hyperforin

Hyperforin is a constituent of St. John's wort and coexists with the singlet oxygen sensitizer hypericin. Density functional theory, molecular mechanics and Connolly surface calculations show that accessibility in the singlet oxygen "ene" reaction favors the hyperforin "southwest" and "southeast" prenyl (2-methyl-2-butenyl) groups over the northern prenyl groups. While the southern part of hyperforin is initially more susceptible to oxidation, up to 4 "ene" reactions of singlet oxygen can take place. Computational results assist in predicting the fate of adjacent hydroperoxides in hyperforin, where the loss of hydrogen atoms may lead to the formation of a hydrotrioxide and a carbonyl instead of a Russell reaction.

Evaluation of the cytotoxic activity of Hypericum spp. on human glioblastoma A1235 and breast cancer MDA MB-231 cells

Cytotoxic activity of 16 Hypericum ethanolic extracts was evaluated by MTT assay on two human cancer cell lines: glioblastoma A1235 and breast cancer MDA MB-231. Morphology and the type of induced cell death were determined using light and fluorescence microscopy. The majority of Hypericum extracts had no significant cytotoxic effect on MDA MB-231 cells. Eight extracts exhibited mild cytotoxic effect on A1235 cells after 24 h incubation, ranging from 8.0% (H. patulum) to 21.7% (H. oblongifolium). After 72 h of treatment, the strongest inhibition of A1235 viability was observed for extracts of H. androsaemum (26.4-43.9%), H. balearicum (25.8-36.3%), H. delphicum (14.8-27.4%) and H. densiflorum (11.2-24.1%). Micro-scopic examination of cells showed apoptosis as the dominant type of cell death. Due to observed high viability of treated cells, we propose that cytotoxic effects of Hypericum extracts could be related to alternations/interruptions in the cell cycle.

Evidence for contributions of interactions of constituents to the anti-inflammatory activity of Hypericum perforatum

Hypericum perforatum (Hp) extracts contain many different classes of constituents including flavonoids and biflavonoids, phloroglucinols, naphthodianthrones, caffeic acid derivatives, and unknown and/or unidentified compounds. Many constituents may be responsible for the anti-inflammatory activity of Hp including quercetin and derivatives, hyperforin, pseudohypericin, and amentoflavone. In line with antidepressant data, it appears that the interactions of constituents may be important for the anti-inflammatory activity of Hp. Interactions of constituents, tested in bioavailability models, may explain why synergistic mechanisms have been found to be important for antidepressant and antiproliferative bioactivities. This review highlights the relationship among individual constituents and the anti-inflammatory activity of Hp extracts and proposes that interactions of constituents may be important for the anti-inflammatory activity of botanical extracts, although the exact mechanisms of the interactions are still unclear.

Identification and biosynthesis of acylphloroglucinols in Hypericum gentianoides

Species of the genus Hypericum contain a rich array of unusual polyketides, however, only a small proportion of the over 450 Hypericum species, other than the popular medicinal supplement St. John's Wort (Hypericum perforatum), have even been chemically characterized. Hypericum gentianoides, a small annual used medicinally by Cherokee Americans, contains bioactive acylphloroglucinols. Here, we identify acylphloroglucinol constituents of H. gentianoides and determine a potential pathway to their synthesis. Liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS) and HPLC-UV indicate that the level of accumulation and profile of acylphloroglucinols in H. gentianoides vary little seasonally when grown in a greenhouse, but do vary with development and are highly dependent on the accession, highlighting the importance of the selection of plant material for study. We identify the chemical structures of the nine prevalent polyketides, based on LC/ESI-MS and hybrid quadrupole orthogonal time-of-flight (Q-TOF) mass spectrometry; these metabolites include one monomeric phlorisobutyrophenone (PIB) derivative and eight dimeric acylphloroglucinols. Q-TOF spectrometry was used to identify eight additional PIB derivatives that were not detected by LC/ESI-MS. These data lead us to propose that diacylphloroglucinols are synthesized via modification of PIB to yield diverse phloroglucinol and filicinic acids moieties, followed by dimerization of a phloroglucinol and a filicinic acid monomer to yield the observed complement of diacylphloroglucinols. The metabolomics data from H. gentianoides are accessible in plant metabolomics resource (PMR) (http://www.metnetdb.org/pmr), a public metabolomics database with analysis software for plants and microbial organisms.

HILIC quantification of oenotheralanosterol A and B from Oenothera biennis and their suppression of IL-6 and TNF-α expression in mouse macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Evening primrose (Oenothera biennis L.) is a wild medicinal herb of Central American origin that is now globally widespread. Its traditional uses include treatment of rheumatoid arthritis and premenopausal pain both of which have an inflammatory component. The present study demonstrates the in vitro anti-inflammatory activity of three Oenothera biennis compounds.

MATERIALS AND METHODS

Oenotheralanosterol A and B (Oen-A & Oen-B) along with gallic acid (GA) were isolated and characterized using column chromatography and NMR. The compounds were tested with LPS stimulated peritoneal mouse macrophages assaying for suppression of IL-6, TNF-α and NO synthesis. An HILIC method for the simultaneous quantitation of GA, Oen-A, and Oen-B in Oenothera biennis plant material was also developed as a means of monitoring quality of plant material.

RESULTS

Significant inhibition of TNF-α and IL-6 by GA, Oen-A and Oen-B was observed (p<0.05). Inhibition was concentration dependent and no synergistic or antagonistic effect on pro-inflammatory cytokines was found when used in combination (1:1) (p>0.05). The HILIC analysis method was validated using Oenothera biennis root.

CONCLUSION

The study demonstrates the anti-inflammatory activity of Oenothera biennis root compounds and supports its traditional use in arthritis management. Active anti-inflammatory compounds were identified and quantified by the HILIC method.

The inhibition of lipopolysaccharide-induced macrophage inflammation by 4 compounds in Hypericum perforatum extract is partially dependent on the activation of SOCS3

Our previous studies found that 4 compounds, namely pseudohypericin, amentoflavone, quercetin, and chlorogenic acid, in Hypericum perforatum ethanol extract synergistically inhibited lipopolysaccharide (LPS)-induced macrophage production of prostaglandin E2 (PGE2). Microarray studies led us to hypothesize that these compounds inhibited PGE2 production by activating suppressor of cytokine signaling 3 (SOCS3). In the current study, siRNA was used to knockdown expression of SOCS3 in RAW 264.7 macrophages and investigated the impact of H. perforatum extract and the 4 compounds on inflammatory mediators and cytokines. It was found that the SOCS3 knockdown significantly compromised the inhibition of PGE2 and nitric oxide (NO) by the 4 compounds, but not by the extract. The 4 compounds, but not the extract, decreased interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), while both lowered interleukine-1β. SOCS3 knockdown further decreased IL-6 and TNF-α. Pseudohypericin was the major contributor to the PGE2 and NO inhibition in cells treated with the 4 compounds, and its activity was lost with the SOCS3 knockdown. Cyclooxygenase-2 (COX-2) and inducible NO synthase protein expression were not altered by the treatments, while COX-2 activity was decreased by the extract and the 4 compounds and increased by SOCS3 knockdown. In summary, it was demonstrated that the 4 compounds inhibited LPS-induced PGE2 and NO through SOCS3 activation. The reduction of PGE2 can be partially attributed to COX-2 enzyme activity, which was significantly elevated with SOCS3 knockdown. At the same time, these results also suggest that constituents in H. perforatum extract were alleviating LPS-induced macrophage response through SOCS3 independent mechanisms.

Plasma caffeic acid is associated with statistical clustering of the anticolitic efficacy of caffeic acid in dextran sulfate sodium-treated mice

We hypothesized that interindividual variability in the bioavailability of caffeic acid (CA) would influence its anticolitic efficacy and that mice may be appropriate for modeling human gut microbial metabolism of CA, which is thought to influence CA bioavailability. Anaerobic human fecal and mouse cecal sample mixtures were incubated with CA derivatives from Echinacea purpurea and compound disappearance rates were measured, which were similar in both sample types. CA metabolism, including formation of its main metabolite, m-hydroxyphenylpropionate, in the mouse cecum may usefully model human gut metabolism of this compound. Ten-week-old CD-1/IGS female mice were fed 120 mg CA/kg (n = 36) or control diet for 7 d (n = 12); one-half of each group then drank 1.25% dextran sulfate sodium (DSS) in water for 5 d. DSS-treated mice fed CA showed lessened colitic damage than did mice given DSS alone, with longer colons, greater body weight, and colonic Cyp4b1 expression. Cluster analysis of the cecal histopathological score showed that mice with severe cecal damage (mean cecal score = 8.5; n = 11) also had greater myeloperoxidase (MPO) activity and lower plasma CA compared with mice showing mild cecal damage (mean cecal score = 4.5; n = 4) (P < 0.05). Cecal score was positively correlated with colonic MPO activity (r = 0.72; P < 0.05) and negatively correlated with plasma CA (r = -0.57; P < 0.05). These studies indicated that the anticolitic efficacy of CA was related to variability in CA bioavailability, which may be influenced by gut microbial metabolism of this compound.

Identification of anti-inflammatory constituents in Hypericum perforatum and Hypericum gentianoides extracts using RAW 264.7 mouse macrophages

Hypericum perforatum (St. John's wort) is an herb widely used as supplement for mild to moderate depression. Our prior studies established synergistic anti-inflammatory activity associated with 4 bioactive compounds in a fraction of a H. perforatum ethanol extract. Whether these 4 compounds also contributed to the ethanol extract activity was addressed in the research reported here. Despite the popularity of H. perforatum, other Hypericum species with different phytochemical profiles could have their anti-inflammatory potentials attributed to these or other compounds. In the current study, ethanol extracts of different Hypericum species were compared for their inhibitory effect on LPS-induced prostaglandin E2 (PGE2) and nitric oxide (NO) production in RAW 264.7 mouse macrophages. Among these extracts, those made from H. perforatum and H. gentianoides demonstrated stronger overall efficacy. LC-MS analysis established the 4 compounds were present in the H. perforatum extract and pseudohypericin in all active fractions. The 4 compounds accounted for a significant part of the extract's inhibitory activity on PGE2, NO, tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) in RAW 264.7 as well as peritoneal macrophages. Pseudohypericin was the most important contributor of the anti-inflammatory potential among the 4 compounds. The lipophilic fractions of H. gentianoides extract, which did not contain the previously identified active constituents, decreased PGE2 and NO potently. These fractions were rich in acylphloroglucinols, including uliginosin A that accounted for a proportion of the anti-inflammatory activity observed with the active fractions. Overall, the current study established that a different group of major anti-inflammatory constituents were present in H. gentianoides, while showing that the previously identified 4 compound combination was important for H. perforatum's anti-inflammatory potential.

Identification of JAK-STAT pathways as important for the anti-inflammatory activity of a Hypericum perforatum fraction and bioactive constituents in RAW 264.7 mouse macrophages

Hypericum perforatum extracts have been used to treat diseases, including mild-to-moderate depression and inflammatory conditions. It is particularly important to identify which constituents present in the H. perforatum extracts are responsible for its anti-inflammatory activity since consumers are taking H. perforatum preparations to treat inflammation. We used a combination of four putative bioactive constituents, called the 4-component-system that interacted synergistically to explain the light-activated anti-inflammatory activity of an H. perforatum fraction in RAW 264.7 mouse macrophages. We also combined the constituents at concentrations detected in the fraction to identify key molecular targets. LPS was used to model an inflammatory response, and the 4-component-system and H. perforatum fraction were used as treatments that inhibited LPS-induced prostaglandin E(2) (PGE(2)) production in RAW 264.7 mouse macrophages in the studies of gene expression profiles. We used Affymetrix genechips, statistical analysis, and quantitative real-time PCR to identify key gene targets of the 4-component-system and the sub-fraction from an H. perforatum ethanol extract. The H. perforatum sub-fraction, with or without LPS stimulation, affected far more genes than the 4-component-system with and without LPS. Genes involved in Janus kinase, as well as a signal transducer and activator of transcription (JAK-STAT) and eicosanoid pathways were identified that could account for the reduction in PGE(2) observed with both treatments in LPS-stimulated macrophages. Ten genes may be particularly important targets for activity of the 4-component-system and the fraction with LPS stimulation and these genes were involved in inflammatory signaling pathways, namely the JAK-STAT and eicosanoid pathways.

Rosmarinic acid in Prunella vulgaris ethanol extract inhibits lipopolysaccharide-induced prostaglandin E2 and nitric oxide in RAW 264.7 mouse macrophages

Prunella vulgaris has been used therapeutically for inflammation-related conditions for centuries, but systematic studies of its anti-inflammatory activity are lacking and no specific active components have been identified. In this study, water and ethanol extracts of four P. vulgaris accessions were applied to RAW 264.7 mouse macrophages, and the ethanol extracts significantly inhibited lipopolysaccharide (LPS)-stimulated prostaglandin E2 (PGE2) and nitric oxide (NO) production at 30 microg/mL without affecting cell viability. Extracts from different accessions of P. vulgaris were screened for anti-inflammatory activity to identify accessions with the greatest activity. The inhibition of PGE2 and NO production by selected extracts was dose-dependent, with significant effects seen at concentrations as low as 10 microg/mL. Fractionation of ethanol extracts from the active accession, Ames 27664, suggested fractions 3 and 5 as possible major contributors to the overall activity. Rosmarinic acid (RA) content in P. vulgaris was found to independently inhibit inflammatory response, but it only partially explained the extracts' activity. LPS-induced cyclooxygenase-2 (COX-2) and nitric oxide synthase (iNOS) protein expression were both attenuated by P. vulgaris ethanol extracts, whereas RA inhibited only COX-2 expression.

Pseudohypericin is necessary for the light-activated inhibition of prostaglandin E2 pathways by a 4 component system mimicking an Hypericum perforatum fraction

Hypericum perforatum (Hp) has been used medicinally to treat a variety of conditions including mild-to-moderate depression. Recently, several anti-inflammatory activities of Hp have been reported. An ethanol extract of Hp was fractionated with the guidance of an anti-inflammatory bioassay (lipopolysaccharide (LPS)-induced prostaglandin E2 production (PGE2)), and four constituents were identified. When combined together at concentrations detected in the Hp fraction to make a 4 component system, these constituents (0.1microM chlorogenic acid (compound 1), 0.08microM amentoflavone (compound 2), 0.07microM quercetin (compound 3), and 0.03microM pseudohypericin (compound 4)) explained the majority of the activity of the fraction when activated by light, but only partially explained the activity of this Hp fraction in dark conditions. One of the constituents, light-activated pseudohypericin, was necessary, but not sufficient to explain the reduction in LPS-induced PGE2 of the 4 component system. The Hp fraction and the 4 component system inhibited lipoxygenase and cytosolic phospholipase A2, two enzymes in the PGE2-mediated inflammatory response. The 4 component system inhibited the production of the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha), and the Hp fraction inhibited the anti-inflammatory cytokine interleukin-10 (IL-10). Thus, the Hp fraction and selected constituents from this fraction showed evidence of blocking pro-inflammatory mediators but not enhancing inflammation-suppressing mediators.

Characterizing the metabolic fingerprint and anti-inflammatory activity of Hypericum gentianoides

In this paper we characterize the metabolic fingerprint and first reported anti-inflammatory activity of Hypericum gentianoides. H. gentianoides has a history of medical use by Native Americans, but it has been studied very little for biological activity. High-performance liquid chromatography (HPLC) and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) analyses of a methanol extract show that H. gentianoides contains a family of over nine related compounds that have retention times, mass spectra, and a distinctive UV absorption spectra characteristic of certain acyl-phloroglucinols. These metabolites are abundant relative to other secondary products present in H. gentianoides, accounting for approximately 0.2 g per gram of dry plant tissue. H. gentianoides methanol extracts and a specific semipreparative HPLC fraction from these extracts containing the putative acyl-phloroglucinols reduce prostaglandin E 2 synthesis in mammalian macrophages.

Echinacea species and alkamides inhibit prostaglandin E(2) production in RAW264.7 mouse macrophage cells

Inhibition of prostaglandin E(2) (PGE(2)) production in lipopolysaccharide-stimulated RAW264.7 mouse macrophage cells was assessed with an enzyme immunoassay following treatments with Echinacea extracts or synthesized alkamides. Results indicated that ethanol extracts diluted in media to a concentration of 15 microg/mL from E. angustifolia, E. pallida, E. simulata, and E. sanguinea significantly inhibited PGE2 production. In further studies, PGE2 production was significantly reduced by all synthesized alkamides assayed at 50 microM, by Bauer alkamides 8, 12A analogue, and 14, Chen alkamide 2, and Chen alkamide 2 analogue at 25 microM and by Bauer alkamide 14 at 10 microM. Cytotoxicity did not play a role in the noted reduction of PGE2 production in either the Echinacea extracts or synthesized alkamides. High-performance liquid chromatography analysis identified individual alkamides present at concentrations below 2.8 microM in the extracts from the six Echinacea species (15 microg/mL crude extract). Because active extracts contained <2.8 microM of specific alkamide and the results showed that synthetic alkamides must have a minimum concentration of 10 microM to inhibit PGE2, it is likely that alkamides may contribute toward the anti-inflammatory activity of Echinacea in a synergistic or additive manner.

Inhibition of prostaglandin E(2) production by anti-inflammatory hypericum perforatum extracts and constituents in RAW264.7 Mouse Macrophage Cells

Hypericum perforatum (Hp) is commonly known for its antiviral, antidepressant, and cytotoxic properties, but traditionally Hp was also used to treat inflammation. In this study, the anti-inflammatory activity and cytotoxicity of different Hp extractions and accessions and constituents present within Hp extracts were characterized. In contrast to the antiviral activity of Hp, the anti-inflammatory activity observed with all Hp extracts was light-independent. When pure constituents were tested, the flavonoids, amentoflavone, hyperforin, and light-activated pseudohypericin, displayed anti-inflammatory activity, albeit at concentrations generally higher than the amount present in the Hp extracts. Constituents that were present in the Hp extracts at concentrations that inhibited the production of prostaglandin E(2) (PGE(2)) were pseudohypericin and hyperforin, suggesting that they are the primary anti-inflammatory constituents along with the flavonoids, and perhaps the interactions of these constituents and other unidentified compounds are important for the anti-inflammatory activity of the Hp extracts.

Reduction in hypericin-induced phototoxicity by Hypericum perforatum extracts and pure compounds

Clinical evidence suggests that administration of Hypericum perforatum (Hp) extracts containing the photo-activated hypericin compounds may cause fewer skin photosensitization reactions than administration of pure hypericin. This study was conducted to determine whether the phototoxicity of hypericin in HaCaT keratinocytes could be attenuated by H. perforatum extracts and constituents. Two extracts, when supplemented with 20 microM hypericin: (1) an ethanol re-extraction of residue following a chloroform extraction (denoted ethanol(-chloroform)) (3.35 microM hypericin and 124.0 microM total flavonoids); and (2) a chloroform extract (hypericin and flavonoids not detected), showed 25% and 50% (p<0.0001) less phototoxicity than 20 microM hypericin alone. Two H. perforatum constituents, when supplemented with 20 microM hypericin: (1) 10 microM chlorogenic acid; and (2) 0.25 microM pyropheophorbide, exhibited 24% (p<0.05) and 40% (p<0.05) less phototoxicity than 20 microM hypericin alone. The peroxidation of arachidonic acid was assessed as a measure of oxidative damage by photo-activated hypericin, but this parameter of lipid peroxidation was not influenced by the extracts or constituents. However alpha-tocopherol, a known antioxidant also did not influence the amount of lipid peroxidation induced in this system. These observations indicate that hypericin combined with H. perforatum extracts or constituents may exert less phototoxicity than pure hypericin, but possibly not through a reduction in arachidonic acid peroxidation.