Identification of tyrosinase inhibitors in defatted seeds of evening primrose (Oenothera biennis L.) by affinity-labeled molecular networking.

The defatted seeds of evening primrose (DE), a by-product of evening primrose oil extraction, are currently underutilized. This study aimed to valorize DE by examining its effects on melanogenesis and tyrosinase activity in zebrafish embryos and in vitro, and an innovative affinity-labeled molecular networking workflow was proposed for the rapid identification of tyrosinase inhibitors in DE. Our results indicated DE significantly reduced melanin content (53.3 % at 100 µg/mL) and tyrosinse activity (80.05 % for monophenolase and 70.40 % for diphenolase at 100 µg/mL). Furthermore, through the affinity-labeled molecular networking approach, 20 compounds were identified as potential tyrosinase inhibitors within DE, predominantly flavonoids and tannins characterized by catechin and galloyl substructures. Seven of these compounds were isolated and their inhibitory effects on tyrosinase were validated using functional assays. This study not only underscores the potential of DE as a rich source of natural tyrosinase inhibitors but also establishes the effectiveness of affinity-labeled molecular networking in pinpointing bioactive compounds in complex biological matrices.

Evening primrose oil enriched with gamma linolenic acid and D/L-alpha tocopherol acetate attenuated carbon tetrachloride-induced hepatic injury model in male rats via TNF-α, IL-1ß, and IL-6 pathway.

The modulatory role of primrose oil (PO) supplementation enriched with γ-linolenic acid and D/L-alpha tocopherol acetate against a carbon tetrachloride (CCl4)-induced liver damage model was assessed in this study. Twenty male Albino rats were divided into four groups. The control group received corn oil orally. The PO group received 10 mg/kg P O orally. The CCl4 group received 2 mL/kg CCl4 orally and PO/CCl4 group; received PO and 2 mL/kg CCl4 orally. The relative liver weight was recorded. Serum liver enzymes, hepatic malondialdehyde (MDA), hepatic reduced glutathione (GSH) and the expression of hepatic tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1ß), and interleukin 6 (IL-6) were assessed. The binding affinities of γ-linolenic acid and D/L-alpha tocopherol constituents with IL-1ß, IL-6 and TNF-α were investigated using molecular docking simulations. Histopathological and electron microscopic examinations of the liver were performed. The results indicated that CCl4 elevated serum liver enzyme and hepatic MDA levels, whereas GSH levels were diminished. The upregulation of IL-1ß, IL-6, and TNF-α gene expressions were induced by CCl4 treatment. The PO/CCl4-treated group showed amelioration of hepatic injury biomarkers and oxidative stress. Restoration of histopathological and ultrastructural alterations while downregulations the gene expressions of TNF-α, IL1-ß and IL-6 were observed. In conclusion, evening primrose oil enriched with γ-linolenic acid and D/L-alpha tocopherol acetate elicited a potential amelioration of CCl4-induced hepatic toxicity.

Evening Primrose Oil Enhances Tamoxifen's Anticancer Activity against Breast Cancer Cells by Inducing Apoptosis, Inhibiting Angiogenesis, and Arresting the Cell Cycle.

BACKGROUND: Despite advancements in cancer treatment, breast cancer (BC) is still one of the leading causes of death among women. The majority of anti-breast-cancer medications induce serious side effects and multidrug resistance. Although several natural compounds, such as evening primrose oil (EPO), have been shown to have anticancer properties when used alone, their combination with the anticancer medicine tamoxifen (TAM) has yet to be investigated. The present study aimed to investigate the anticancer efficacy of EPO, alone or in combination with TAM, in the BC cell lines MCF-7 and MDA-MB-231, as well as to elucidate the mechanism of action. METHODS: The MTT assay was used to investigate the cytotoxic effect of EPO on the two cell lines, and we discovered an acceptable IC50 that was comparable to TAM. The ELISA, qRT-PCR, flow cytometry and colorimetric techniques were used. RESULTS: The combination of EPO and TAM suppressed the VEGF level, VEGF gene expression and Cyclin D1 signaling pathways, arrested the cell cycle, and induced the apoptotic signaling pathways by increasing the Bax/Bcl-2 ratio and caspase 3 activity; this revealed significant anti-tumor activity. CONCLUSIONS: The most significant finding of this study was the confirmation of the anticancer activity of the natural product EPO, which potentiated the activity of the anticancer drug TAM against MCF-7 and MDA-MB-231 BC cell lines through the induction of apoptosis, inhibiting angiogenesis and halting cell proliferation.

Effect of Evening Primrose (Oenothera biennis) Oil Cake on the Properties of Polyurethane/Polyisocyanurate Bio-Composites.

Rigid polyurethane/polyisocyanurate (RPU/PIR) foam formulations were modified by evening primrose (Oenothera biennis) oil cake as a bio-filler in the amount of 5 to 50 wt.%. The obtained foams were tested in terms of processing parameters, cellular structure (SEM analysis), physico-mechanical properties (apparent density, compressive strength, brittleness, accelerated aging tests), thermal insulation properties (thermal conductivity coefficient, closed cells content, absorbability and water absorption), flammability, smoke emission, and thermal properties. The obtained results showed that the amount of bio-filler had a significant influence on the morphology of the modified foams. Thorough mixing of the polyurethane premix allowed better homogenization of the bio-filler in the polyurethane matrix, resulting in a regular cellular structure. This resulted in an improvement in the physico-mechanical and thermal insulation properties as well as a reduction in the flammability of the obtained materials. This research provided important information on the management of the waste product from the edible oil industry and the production process of fire-safe RPU/PIR foams with improved performance properties. Due to these beneficial effects, it was found that the use of evening primrose oil cake as a bio-filler for RPU/PIR foams opens a new way of waste management to obtain new "green" materials.

Development and Validation of a Method for Determining the Quercetin-3-O-glucuronide and Ellagic Acid Content of Common Evening Primrose (Oenothera biennis) by HPLC-UVD.

Toward the standardization of common evening primrose (Oenothera biennis) sprout extract (OBS-E), we aimed to obtain indicator compounds and use a validated method. HPLC-UVD allowed simultaneous quantification of the indicator compounds quercetin-3-O-glucuronide and ellagic acid. The method was validated in terms of specificity, linearity, precision, accuracy, and limit of detection/limit of quantification (LOD/LOQ). High specificity and linearity was demonstrated, with correlation coefficients of 1.0000 for quercetin-3-O-glucuronide and 0.9998 for ellagic acid. The LOD/LOQ values were 0.486/1.472 µg/mL for quercetin-3-O-glucuronide and 1.003/3.039 µg/mL for ellagic acid. Intra-day and inter-day variability tests produced relative standard deviation for each compound of <2%, a generally accepted precision criterion. High recovery rate were also obtained, indicating accuracy validation. The OBS-E prepared using various concentrations of ethanol were then analyzed. The 50% ethanol extract had highest content of quercetin-3-O-glucuronide, whereas the 70% ethanol extract possessed the lowest. However, the ellagic acid content was highest in the 70% ethanol extract and lowest in the 90% ethanol extract. Thus, quercetin-3-O-glucuronide and ellagic acid can be used industrially as indicator compounds for O. biennis sprout products, and our validated method can be used to establish indicator compounds for other natural products.

Optimization of extraction and deamidation of edible protein from evening primrose (Oenothera biennis L.) oil processing by-products and its effect on structural and techno-functional properties.

The optimization of ultrasound-assisted alkaline extraction and enzymatic deamidation by protein-glutaminase (PG) on evening primrose seed cake (EPSC) protein and its effect on structure (amino acid composition, secondary structure and electrophoresis pattern) and techno-functional properties (water-holding and oil-binding capacities, solubility, emulsifying and foaming properties) of EPSC protein were evaluated. The optimum conditions of the both processes were measured using response surface methodology (RSM). The maximum yield (26.4%) and protein content (86.1%) were reached at the optimized extraction conditions. Optimal conditions of PG deamidation based on reaching a high degree of deamidation (DD) with a simultaneously low degree of hydrolysis (DH). Under these conditions, DD and DH were 39.40 and 2.11%, respectively. Ultrasound-assisted alkaline extraction and enzymatic deamidation by PG have great potential to produce edible EPSC protein with modified techno-functional characteristics that can be used for several aims in the food and pharmaceutical applications.

Endotoxin Contamination and Reaction Interfering Substances in the Plant Extract Library.

Endotoxin is an unintentional contaminant that has numerous activities and can affect various biological experiments using cells. In this study, we measured the endotoxin activity of samples from a plant extract library (PEL) and determined their degrees of contamination. Endotoxin was detected in approx. 48% (n = 139) and approx. 4% (n = 5) of field-collected and crude drug samples, respectively, and in concentrations >5.0 EU/mL in some samples. The concentrations of endotoxin that affect cells in vitro vary depending on the target cell type. Although the degree of contamination varied in the present study, it was considered to have little effect on the cell experiments. More than 150 PEL samples had problems with reaction courses or recovery rates of Limulus amoebocyte lysate (LAL) tests. In the LAL tests, using three plant extracts [Sanguisorba officinalis L. (Rosaceae), Oenothera biennis L. (Onagraceae), and Lythrum salicaria L. (Lythraceae)], the polyphenolic compounds in the plant extracts affected LAL test and their effects differed depending on the plant species. When the 16 single polyphenol compounds were added to the LAL tests, the compounds with caffeoyl and pyrogallol moieties were found to affect the LAL reaction course and recovery rate. Furthermore, none of the compounds had any effects at concentrations of 1 µM. Because the plant extracts contained analogs of various polyphenolic compounds, they were presumed to actually act synergistically. Our findings demonstrated that attention must be paid to the recovery rate and reaction process of LAL tests with samples containing polyphenolic compounds.

Phytochemical and Biological Screening of Oenothera Biennis L. Hydroalcoholic Extract.

Oenothera biennis L. (OB), also commonly known as evening primrose, belongs to the Onagraceae family and has the best studied biological activity of all the members in the family. In therapy, the most frequently used type of extracts are from the aerial part, which are the fatty oils obtained from the seeds and have a wide range of medicinal properties. The aim of this study was to evaluate the phytochemical composition and biological activity of OB hydroalcoholic extract and to provide directions for the antimicrobial effect, antiproliferative and pro-apoptotic potential against A375 melanoma cell line, and anti-angiogenic and anti-inflammatory capacity. The main polyphenols and flavonoids identified were gallic acid, caffeic acid, epicatechin, coumaric acid, ferulic acid, rutin and rosmarinic acid. The total phenolic content was 631.496 µgGAE/mL of extract and the antioxidant activity was 7258.67 µmolTrolox/g of extract. The tested extract had a mild bacteriostatic effect on the tested bacterial strains. It was bactericidal only against Candida spp. and S. aureus. In the set of experimental conditions, the OB extract only manifested significant antiproliferative and pro-apoptotic activity against the A375 human melanoma cell line at the highest tested concentration, namely 60 µg/mL. The migration potential of A375 cells was hampered by the OB extract in a concentration-dependent manner. Furthermore, at the highest tested concentration, the OB extract altered the mitochondrial function in vitro, while reducing the angiogenic reaction, hindering compact tumor formation in the chorioallantoic membrane assay. Moreover, the OB extract elicited an anti-inflammatory effect on the experimental animal model of ear inflammation.

Extract of Oenothera biennis L. stem inhibits LPS-induced inflammation by regulating MAPK and NF-κB signaling pathways.

Oenothera biennis L. is a perennial herb distributed across America, Asia, and Europe. The pharmacological effect of Oenothera biennis L. stem is poorly understood. We demonstrated that lipopolysaccharide (LPS)-induced the high production of inflammatory mediators nitric oxide (NO) and prostaglandin E2 (PGE2) and the pro-inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1ß in peritoneal macrophages (PMs) were significantly inhibited by the crude extract The inflammation related signaling extra cellular signal-regulated ERK, P38 of MAPK and NF-kappaB (NF-κB) activated by LPS dramatically inhibited. In conclusion, our results suggested that the stems of Oenothera biennis L. possess a high anti-inflammatory property, thus, can be used in the industrial production of medicinal products as the raw material in the future.

An investigation into the effect of evening primrose in dilatation of cervix and pain during and after hysterosalpingography.

Hysterosalpingography is one of the essential diagnostic methods for examining women who have difficulty becoming pregnant. This procedure is somehow invasive and is associated with numerous complications such as allergic sensitivity, pain, abdominal cramps and shock. Therefore, this study aimed to investigate the effect of evening primrose on cervical length and pain during and after hysterosalpingography. In this double-blind clinical trial, 66 candidates for hysterosalpingography were randomly divided into two groups. A group received 1000 mg of evening primrose orally for two days prior to hysterosalpingography, while the control group received a placebo drug similar in size to evening primrose three days prior to hysterosalpingography. The pain level was recorded based on the Visual Analogue Scale (VAS), during tenaculum placement but also immediately and four hours after hysterosalpingography. Finally, the data were analyzed using SPSS (version 20). There was a significant difference between the two groups in terms of pain during insertion of speculum and injection of the contrast medium (p <0.05). Less pain was reported in the evening primrose group compared to placebo. There was no significant difference between the two groups in terms of the length and diameter of the cervix (p <0.05). Given the fact that it is a medicinal plant with no complications and can reduce pain during speculum insertion and during contrast medium injection, evening primrose seems to be a good drug for managing pain during hysterosalpingography.

Fatty Acid, Triacylglycerol and Unsaponifiable Matters Profiles and Physicochemical Properties of Chinese Evening Primrose Oil.

This work focused on physicochemical property assaying, fatty acid composition, triacylglycerol (TAG) profiles, and unsaponifiable matters composition of the Chinese evening primrose oil. The cold press oil possessed very low acid value and peroxide value, and relatively high iodine value. Fatty acid composition results indicated that this oil was especially high in linoleic acid and linolenic acid. Characterization of TAG composition was achieved by a two-dimensional HPLC coupling of nonaqueous reverse-phase and silver ion HPLC with atmospheric pressure chemical ionization MS method. There was a total of 38 TAGs including 27 regioisomers which had been determined. Unsaponifiable matters composition results revealed that this oil possessed a number of phytosterols, in which ß-sitosterol and stigmasterol were most predominant.

Screening and Isolating Major Aldose Reductase Inhibitors from the Seeds of Evening Primrose (Oenothera biennis).

Aldose reductase (AR) is a drug target for therapies to treat complications caused by diabetes mellitus, and the development of effective AR inhibitors (ARIs) of natural origin is considered to be an attractive option for reducing these complications. In this research, the rat lens AR (RLAR) inhibitory activity of evening primrose (Oenothera biennis) seeds was investigated for the first time. In our results, the 50% (v/v) methanol extract of evening primrose seeds exhibits excellent RLAR inhibitory activity (IC50 value of 7.53 µg/mL). Moreover, after enrichment of its bioactive components, the ARIs are more likely to be present in the ethyl acetate fraction of 50% (v/v) methanol extract (EME) of evening primrose seeds, which exhibits superior RLAR inhibitory activity (IC50 value of 3.08 µg/mL). Finally, gallic acid (1), procyanidin B3 (2), catechin (3), and methyl gallate (4) were identified as the major ARIs from the EME by affinity-based ultrafiltration-high-performance liquid chromatography and were isolated by high speed countercurrent chromatography, with gallic acid (11.46 µmol/L) and catechin (14.78 µmol/L) being the more potent inhibitors of the four ARIs identified. The results demonstrated that evening primrose seeds may be a potent ingredient of ARIs.

Antiproliferative and antimicrobial efficacy of the compounds isolated from the roots of Oenothera biennis L.

BACKGROUND: Oenothera biennis L., commonly known as evening primrose, harbours the flavonoids, steroids, tannins, fatty acids and terpenoids responsible for a diverse range of biological activity, such as antitumour, anti-arthritic and anti-inflammatory effects. In addition to the previous reports from aerial parts of this plant, studies related to antiproliferative or antimicrobial activity from the roots are warranted. OBJECTIVE: To investigate antiproliferative and antimicrobial activity of compounds/mixture (1-8) isolated and characterized from the roots of O. biennis L. A possible mechanism of antiproliferative activity was also studied by targeting ornithine decarboxylase (ODC) and cathepsin D (CATD). STUDY DESIGN: Antiproliferative efficacy of the compounds/mixture was examined in selected cancer cell lines along with their probable mechanism of action. The antimicrobial activity was also studied against selected microbes (bacteria and fungi). METHODS: Antiproliferative potential was evaluated by MTT assay against selected cell lines. The mechanism of action was studied spectrophotometrically by targeting ODC and CATD using both an in-vitro and an in-silico approach. The antimicrobial efficiency was analysed using the disc diffusion and broth dilution methods. KEY FINDINGS: Oenotheralanosterol B (3) and the mixture of oenotheralanosterol A and oenotheralanosterol B (4) exhibited antiproliferative activity against breast, hepatic, prostate and leukaemia cancer cell lines as well as in mouse macrophages (IC50 8.35-49.69 µg/ml). Oenotheralanosterol B (3) and the mixture of oenotheralanosterol A and oenotheralanosterol B (4) displayed a strong molecular interaction with succinate dehydrogenase (binding energy -6.23 and -6.84 kcal/mol and Ki 27.03 and 9.6 µm, respectively). Oenotheralanosterol A (1), oenotheralanosterol B (3) and mixture of oenotheralanosterol A and oenotheralanosterol B (4) potently inhibited the ODC activity with IC50 ranging from 4.65 ± 0.35 to 19.06 ± 4.16 µg/ml and also showed a strong interaction with ODC (BE -4.17 to -4.46 kcal/mol). Oenotheralanosterol A (1), cetoleilyl diglucoside (2), oenotheralanosterol B (3), dihydroxyprenylxanthone acetylated (6) and dihydroxyprenylxanthone (7) inhibited CATD activity (IC50 3.95 ± 0.49 to 24.35 ± 2.89 µg/ml). The in-silico molecular interaction analysis of compounds with CATD revealed the non-specific interaction. A moderate antimicrobial activity was observed against selected microbes with a growth inhibition ranging from 6 to 14 mm and minimum inhibitory concentration between 125 and 500 µg/ml. Oenotheralanosterol B (3) and dihydroxyprenylxanthone acetylated (6) exhibited better antimicrobial activity with an MIC range from 62.50 to 500 µg/ml. CONCLUSION: Oenotheralanosterol B (3) exhibited stronger antiproliferative and antimicrobial potential with respect to the other compounds tested, whereas oenotheralanosterol A (1) was a potent inhibitor of ODC and CATD. Hence, it is suggested that these in-vitro findings could be studied further in vivo for biological activity, safety evaluation and derivatization to enhance potency and efficacy.

Evaluation of the effects of different supplementation on oxidative status in patients with rheumatoid arthritis.

Rheumatoid arthritis is a chronic inflammatory disease. Reactive oxygen species have been considered as aggravating factors for autoimmune diseases. Fatty acids had been linked in reduction of various diseases by augment of their antioxidant potential and antiinflammatory mechanisms. The aim of this study was to assess the oxidative status in patients with rheumatoid arthritis who used concentrated fish oil only or concentrated fish oil in combination with evening primrose oil in a period of 3 months. Subjects were divided into three groups. The group I consists of patients who had been taking only their regular rheumatologic therapy; group II, patients who had been taking concentrated fish oil; and group III, patients who had been taking concentrated fish oil and evening primrose oil. Peripheral blood samples were used for all the assays. We assessed the following oxidative stress markers: index of lipid peroxidation (thiobarbituric acid-reactive substances (TBARS)), hydrogen peroxide (H2O2), superoxide anion radical (O2 (-)), nitric oxide (NO), superoxide dismutase activity (SOD), catalase activity (CAT), and glutathione levels (GSH) in erythrocytes. There were no statistically significant changes for any of the oxidative stress parameters in group I. In group II, levels of TBARS, NO2 (-), and GSH were increased, while levels of H2O2 decreased. Increased values of TBARS, NO2 (-), and SOD were found in group III. Our findings indicate that intakes of fish oil and evening primrose oil may be of importance in mitigation of inflammation, disease activity, and oxidative stress biomarkers, through increased activities of antioxidant enzymes.

[Preparation of Oenothera biennis Oil Solid Lipid Nanoparticles Based on Microemulsion Technique].

OBJECTIVE: To study the preparation of Oenothera biennis oil solid lipid nanoparticles and its quality evaluation. METHODS: The solid lipid nanoparticles were prepared by microemulsion technique. The optimum condition was performed based on the orthogonal design to examine the entrapment efficiency, the mean diameter of the particles and so on. RESULTS: The optimal preparation of Oenothera biennis oil solid lipid nanoparticles was as follows: Oenothera biennis dosage 300 mg, glycerol monostearate-Oenothera biennis (2: 3), Oenothera biennis -RH/40/PEG-400 (1: 2), RH-40/PEG-400 (1: 2). The resulting nanoparticles average encapsulation efficiency was (89.89 ± 0.71)%, the average particle size was 44.43 ± 0.08 nm, and the Zeta potential was 64.72 ± 1.24 mV. CONCLUSION: The preparation process is simple, stable and feasible.

Polyphenol extract from evening primrose pomace alleviates experimental colitis after intracolonic and oral administration in mice.

Oenothera paradoxa (EP) preparations are commonly used in folk medicine to treat skin diseases, neuralgia, and gastrointestinal (GI) disorders. Several reports suggested that EP preparations exhibit potent anti-inflammatory and antioxidant activities both in vitro and in vivo. Here, we aimed to characterize the action of EP pomace polyphenol extract in mouse model of colitis. We analyzed the composition of EP pomace polyphenol extract using reversed phase HPLC system and ultra-performance liquid chromatography (UPLC) system coupled with a quadrupole-time of flight (Q-TOF) MS instrument. Then, we used a well-established animal model of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis to determine the anti-inflammatory action of EP pomace polyphenol extract. We also investigated the effect of the EP pomace polyphenol extract on pro-inflammatory (IL-1ß and TNF-α) cytokine mRNA levels and hydrogen peroxide concentration in the inflamed colon. Administration of EP pomace polyphenol extract significantly improved macroscopic and microscopic damage scores, as well as myeloperoxidase (MPO) activity in TNBS-treated mice. The anti-inflammatory effect of the extract was observed after intracolonic and oral administration and was dose-dependent. Significant reduction of tissue hydrogen peroxide level after treatment with EP pomace polyphenol extract suggests that its therapeutic effect is a result of free radical scavenging. This novel finding indicates that the application of the EP pomace polyphenol extract in patients with inflammatory bowel diseases (IBDs) may become an attractive supplementary treatment for conventional anti-inflammatory therapy.

Chemical composition, antioxidative and anti-inflammatory activity of extracts prepared from aerial parts of Oenothera biennis L. and Oenothera paradoxa Hudziok obtained after seeds cultivation.

In the present study we investigated the chemical composition of extracts prepared from aerial parts of Oenothera paradoxa Hudziok and Oenothera biennis L. and their antioxidative and anti-inflammatory activities. Ultra high pressure liquid chromatography (UHPLC)-DAD-MS/MS studies showed that both extracts contain a wide variety of polyphenols (39 identified constituents) among which macrocyclic ellagitannin turned out to be the main constituent. During the in vitro studies, using noncellular models, both extracts scavenged reactive oxygen species (ROS) in a concentration-dependent manner, and the lowest SC(50) values were obtained for O(2)(-) and H(2)O(2). Both extracts inhibited ROS production by stimulated human neutrophils. The stronger activity in the case of formyl-met-leu-phenylalanine stimulation suggests that both extracts may act through the receptor-dependent pathway. O. paradoxa extract and O. biennis extract exhibited anti-inflammatory activity by the inhibition of hyaluronidase and lipoxygenase in a concentration-dependent manner. The stronger activity of O.biennis extract toward lipoxygenase may be explained by its higher oenothein B content.

The sterols isolated from Evening Primrose oil modulate the release of proinflammatory mediators.

Evening Primrose oil is a natural product extracted by cold-pressed from Oenothera biennis L. seeds. The unsaponifiable matter of this oil is an important source of interesting minor compounds, like long-chain fatty alcohols, sterols and tocopherols. In the present study, sterols were isolated from the unsaponifiable matter of Evening Primrose oil, and the composition was identified and quantified by GC and GC-MS. The major components of sterols fraction were ß-Sitosterol and campesterol. We investigated the ability of sterols from Evening Primrose oil to inhibit the release of different proinflammatory mediators in vitro by murine peritoneal macrophages stimulated with lipopolysaccharide. Sterols significantly and dose-dependently decreased nitric oxide production. Western blot analysis showed that nitric oxide reduction was a consequence of the inhibition of inducible nitric oxide synthetase expression. Sterols also reduced tumor necrosis factor-α, interleukine 1ß and tromboxane B2. However, sterols did not reduce prostaglandin E2. The reduction of eicosanoid release was related to the inhibition of cyclooxygenase-2 expression. These results showed that sterols may have a protective effect on some mediators involved in inflammatory damage development, suggesting its potential value as a putative functional component of Evening Primrose oil.

Histopathological study of evening primrose oil effects on experimental diabetic neuropathy.

UNLABELLED: Diabetic polyneuropathy is a serious complication of diabetes mellitus and the most frequent neuropathy worldwide. AIM: This study was designed to investigate the possible beneficial effects of evening primrose oil (EPO) on histopathological changes of sciatic nerves in streptozotocin-induced diabetic rats. MATERIALS AND METHODS: The rats were randomly allotted into three experimental groups: A (control), B (diabetic untreated), and C (diabetic treated with EPO); each group contained 10 animals. Groups B and C received streptozotocin (STZ) to induce diabetes. The rats in group C were given EPO for 2 weeks after 6 weeks of STZ injection. Blood and tissue samples were obtained for biochemical and histopathological investigation. RESULTS: STZ-treated diabetic rats showed reduction of the size of islets of Langerhans, fatty degeneration in the pancreatic acini with dilation, irregularity, and increased thickness of blood vessels. Electron micrography of sciatic nerves of diabetic rats showed multiple vaculations and partial separation of myelinated nerve fibers with axonal atrophy, endoneural edema, and increased collagen fibers. Compared with diabetic rats, EPO induced partial recovery from diabetes-induced pancreatic and nerve damage. CONCLUSIONS: Histologic evaluation of the tissues in diabetic animals treated with EPO showed fewer morphologic alterations with significant decrease of myelin breakdown. Furthermore, the ultrastructural features of axons showed partial improvement. It is believed that further preclinical research into the utility of EPO may indicate its usefulness as a potential treatment on peripheral neuropathy in STZ-induced diabetic rats.

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.