Protective effect of hydroalcoholic olive leaf extract on experimental model of colitis in rat: involvement of nitrergic and opioidergic systems

Exploring the Nutritional and Bioactive Potential of Olive Leaf Residues: A Focus on Minerals and Polyphenols in the Context of Spain's Olive Oil Production

Lyophilized plant-origin extracts are rich in highly potent antioxidant polyphenols. In order to incorporate them into food products, it is necessary to protect these phytochemicals from atmospheric factors such as heat, light, moisture, or pH, and to enhance their bioavailability due to their low solubility. To address these challenges, recent studies have focused on the development of encapsulation techniques for antioxidant compounds within polymeric structures. In this study, lyophilized olive leaf extracts were microencapsulated with the aim of overcoming the aforementioned challenges. The method used for the preparation of the studied microparticles involves external ionic gelation carried out within a water-oil (W/O) emulsion at room temperature. HPLC analysis demonstrates a high content of polyphenols, with 90% of the bioactive compounds encapsulated. Meanwhile, quantification by inductively coupled plasma optical emission spectroscopy (ICP-OES) reveals that the dried leaves, lyophilized extract, and microencapsulated form contain satisfactory levels of macro- and micro-minerals (calcium, potassium, sodium). The microencapsulation technique could be a novel strategy to harness the polyphenols and minerals of olive leaves, thus enriching food products and leveraging the antioxidant properties of the polyphenolic compounds found in the lyophilized extract.

Olea europaea L-derived secoiridoids: Beneficial health effects and potential therapeutic approaches

Over the years, health challenges have become increasingly complex and global and, at the beginning of the 21st century, chronic diseases, including cardiovascular, neurological, and chronic respiratory diseases, as well as cancer and diabetes, have been identified by World Health Organization as one of the biggest threats to human health. Recently, antimicrobial resistance has also emerged as a growing problem of public health for the management of infectious diseases. In this scenario, the exploration of natural products as supplementation or alternative therapeutic options is acquiring great importance, and, among them, the olive tree, Olea europaea L, specifically leaves, fruits, and oil, has been increasingly investigated for its health promoting properties. Traditionally, these properties have been largely attributed to the high concentration of monounsaturated fatty acids, although, in recent years, beneficial effects have also been associated to other components, particularly polyphenols. Among them, the most interesting group is represented by Olea europaea L secoiridoids, comprising oleuropein, oleocanthal, oleacein, and ligstroside, which display anti-inflammatory, antioxidant, cardioprotective, neuroprotective and anticancer activities. This review provides an overview of the multiple health beneficial effects, the molecular mechanisms, and the potential applications of secoiridoids from Olea europaea L.

Cinnamic Acid Ameliorates Acetic Acid-induced Inflammatory Response through Inhibition of TLR-4 in Colitis Rat Model

BACKGROUND

Cinnamic acid, an active compound in cinnamon spp., has anti-inflammatory and antioxidant characteristics and is favorable in managing inflammatory bowel diseases.

OBJECTIVES

Evaluate cinnamic acid's effects on colitis in rats.

METHODS

To induce colitis in experimental rats, excluding the sham group, a 4% intrarectal solution of acetic acid was administered. The rats were then given oral doses of cinnamic acid at 30, 45, and 90 mg/kg for two days. The animals were assessed for macroscopic and microscopic changes, and the levels of inflammatory mediators such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and myeloperoxidase (MPO) were measured using Eliza kits. Additionally, real-time PCR was performed to examine the gene level of toll-like receptor 4 (TLR-4) in the colon.

RESULTS

Effective reduction of inflammation in acetic acid-induced colitis was achieved through Cinnamic acid administration at doses of 45 and 90 mg/kg. The decrease was achieved by inhibiting the activities of TNF-α, IL-6, and MPO while downregulating the expression of TLR-4. It is important to note that macroscopic and microscopic evaluations were significant in determining the effectiveness of cinnamic acid in reducing inflammation.

CONCLUSION

Downregulation of inflammatory cytokines and TLR-4 expression may contribute to cinnamic acid's anti-inflammatory effect.

Evaluation of Olive Leaf Phenolic Compounds' Gastrointestinal Stability Based on Co-Administration and Microencapsulation with Non-Digestible Carbohydrates

The large generation of olive by-products has motivated their revalorization into high-added-value products. In this regard, olive leaves pose as an interesting source of bioactive compounds, due to their phenolic content with commonly known antioxidant, anti-inflammatory, and immunomodulatory properties, with potential application in non-communicable diseases. However, their effectiveness and applicability into functional foods is limited by their instability under gastrointestinal conditions. Thus, the development of protective formulations is essential. In this study, the spray-drying encapsulation of a phenolic-rich olive leaf extract with inulin as the encapsulating agent was optimized. Then, the behavior of the free extract under gastrointestinal conditions, its co-administration with the encapsulating agent, and the optimized microencapsulated formulation were studied through an in vitro gastrointestinal digestion process following the INFOGEST protocol. Digestion of the free extract resulted in the degradation of most compounds, whereas this was minimized in the co-administration of the non-encapsulated extract with the encapsulating agent. This protective effect, related to its interaction with inulin, was similar to the microencapsulated formulation. Thus, both approaches, co-administration and microencapsulation with inulin, could be promising strategies for the improvement of the stability of these anti-inflammatory and immunomodulatory compounds under gastrointestinal conditions, enhancing their beneficial effect.

Nocellara Del Belice (Olea europaea L. Cultivar): Leaf Extract Concentrated in Phenolic Compounds and Its Anti-Inflammatory and Radical Scavenging Activity

Olea europaea L. is a plant belonging to the Oleaceae family, widely grown around the Mediterranean Basin and its leaves are a source of phenolic compounds with antioxidant and anti-inflammatory capacity. Among these, oleuropein and luteolin-7-O-glucoside represent two major polyphenolic compounds in olive-leaf extract. Herein, a polystyrene resin was used to recover the polyphenolic fraction from the acetone-water leaf extract from Nocellara del Belice cultivar, which showed the higher level of analysed bioactive compounds, compared to Carolea cultivar. The antioxidant activity of the extract concentrated in phenolic compounds (OLECp) was evaluated through a classical assay and electron paramagnetic resonance (EPR) for DPPH and hydroxyl radicals scavenging. Thus, the anti-inflammatory activity and the potential beneficial effects in reducing lipid accumulation in an in vitro model of NAFLD using McA-RH7777 cells exposed to oleic acid (OA) were evaluated. Nile Red and Oil Red O have been used to stain the lipid accumulation, while the inflammatory status was assessed by Cytokines Bioplex Assay. OLECp (TPC: 92.93 ± 9.35 mg GAE/g, TFC: 728.12 ± 16.04 mg RE/g; 1 g of extract contains 315.250 mg of oleuropein and 17.44 mg of luteolin-7-O-glucoside) exerted a good radical scavenging capability (IC₅₀: 2.30 ± 0.18 mg/mL) with a neutralizing power against DPPH and hydroxyl radicals, as confirmed by the decreased signal area of the EPR spectra. Moreover, OLECp at concentration of 25, 50 and 100 μg/mL counteracted the intracellular inflammatory status, as result of decreased intracellular lipid content. Our results highlighted the multiple properties and applications of an O. europaea extract concentrated in polyphenols, and the possibility to formulate novel nutraceuticals with antioxidant properties, destined to ameliorate human health.

Budesonide-Loaded Hyaluronic Acid Nanoparticles for Targeted Delivery to the Inflamed Intestinal Mucosa in a Rodent Model of Colitis

The aim of the present study was to investigate the therapeutic potential of budesonide- (BDS-) loaded hyaluronic acid nanoparticles (HANPs) for treatment of inflammatory bowel disease (IBD) using an acute model of colitis in rats. The therapeutic efficacy of BDS-loaded HANPs in comparison with an aqueous suspension of the drug with the same dose (30 μg/kg) was investigated 48 h following induction of colitis by intrarectal administration of acetic acid 4% in rats. Microscopic and histopathologic examinations were conducted in inflamed colonic tissue. Tissue concentration of tumor necrosis factor (TNF)-α was assessed by ELISA assay kit, while the activity of myeloperoxidase (MPO) was measured spectrophotometrically. Results from in vivo evaluations demonstrated that administrations of BDS-HANPs ameliorated the general endoscopic appearance, quite close to the healthy animals with no signs of inflammation and reduced the cellular infiltration, as well as the TNF-α level, and the MPO activity. It was found that delivery by BDS-loaded HANPSs alleviated the induced colitis significantly better than the same dose of the free drug. These data further suggest the potential of HANPs as a targeted drug delivery system to the inflamed colon mucosa.

Effect of sumatriptan on acetic acid-induced experimental colitis in rats: a possible role for the 5-HT1B/1D receptors

Mucosal inflammation in colitis is associated with changes in the intestinal serotonin (5-HT) level. Sumatriptan, a 5-HT_1B/1D receptor agonist, has demonstrated anti-inflammatory characteristics. The purpose of this study was to determine the effects of sumatriptan in a rat model of acute experimental colitis and to elucidate the probable participation of presynaptic 5-HT_1B/1D receptors. To induce colitis, acetic acid (4%) was injected intrarectally. Treatments were given intraperitoneally (IP) once daily over 3 consecutive days starting 1-h post-induction. Sumatriptan was given at 0.5, 1, 2, and 5 mg/kg. GR-127935, a 5-HT_1B/1D receptor antagonist, was injected (0.1 and 0.3 mg/kg) 30 min prior to the most effective dose of sumatriptan (1 mg/kg). On day 4, the colon samples were isolated. Significant enhancements of the tissue tumor necrosis factor-alpha (TNF-α), myeloperoxidase (MPO), microscopic and macroscopic damages, body weight losses, and also reductions in tissue superoxide dismutase (SOD) and 5-HT were observed in colitis rats. On the other hand, sumatriptan at doses 0.5, 1, and 2 mg/kg could diminish pathologic changes in the measured biomarkers, histopathologic damages, and body weight losses. Although GR-127935 at dose 0.3 mg/kg could markedly improve the pathologic indexes, its sub-effective dose (0.1 mg/kg) reversed the protective effect of sumatriptan (1 mg/kg). Moreover, sumatriptan (1 and 5 mg/kg) and GR-127935 (0.3 mg/kg) increased the serotonin level. Post-treatment with low-dose sumatriptan demonstrated a protective impact on this peripheral inflammatory condition. Notably, this protective effect may be mediated, at least in part, through 5-HT_1B/1D receptors, as well as anti-inflammatory and anti-oxidative characteristics.

Olea europea L. Leaves and Hibiscus sabdariffa L. Petals Extracts: Herbal Mix from Cardiovascular Network Target to Gut Motility Dysfunction Application

It is well known that diet and nutrition play a critical role in the etiopathogenesis of many disorders. On the other hand, nutrients or bioactive compounds can specifically target and control various aspects of the mechanism underlying the pathology itself, and, in this context, diseases related to intestinal motility disorders stand out. The Herbal Mix (HM) consisting of Olea europea L. leaf (OEE) and Hibiscus sabdariffa L. (HSE) extracts (13:2) has been proven to be a promising nutraceutical option for many diseases, but its potential in inflammatory-driven gastrointestinal disorders is still unexplored. In this study, HM effects on guinea-pig ileum and colon contractility (induced or spontaneous) and on human iNOS activity, as well as on human colorectal adenocarcinoma Caco-2 cells, were studied. Results showed that the HM can control the ileum and colon contractility without blocking the progression of the food bolus, can selectively inhibit iNOS and possesses a strong pro-apoptotic activity towards Caco-2 cells. In conclusion, the present results suggest that, in some diseases, such as those related to motility disorders, an appropriate nutritional approach can be accompanied by a correct use of nutraceuticals that could help not only in ameliorating the symptoms but also in preventing more severe, cancer-related conditions.

Olive-Leaf Extracts Modulate Inflammation and Oxidative Stress Associated with Human H. pylori Infection

Helicobacter pylori (H. pylori) is one of the major human pathogens and the main cause of pathological damages that can progress from chronic gastritis to gastric cancer. During the colonization of gastric mucosa, this bacterium provokes a strong inflammatory response and subsequent oxidative process, which are associated with tissue damage. Therefore, the objective of this research was to evaluate the ability of two olive-leaf extracts (E1 and E2) to modulate the inflammatory response and oxidative stress in H. pylori-infected human gastric AGS cells. The obtained results showed that both extracts significantly decreased interleukin-8 (IL-8) secretion and reactive oxygen species (ROS) production in human gastric AGS cells. Both extracts also showed antibacterial activity against different H. pylori strains. HPLC-PAD-MS characterization demonstrated that extract E1 was mainly composed of highly hydrophilic compounds, such as hydroxytyrosol (HT) and its glucosides, and it was the most effective extract as an antibacterial agent. In contrast, extract E2 was composed mostly of moderately hydrophilic compounds, such as oleuropein (OLE), and it was more effective than extract E1 as an anti-inflammatory agent. Both extracts exhibited similar potential to decrease ROS production. These results show the importance of standardizing the extract composition according to the bioactive properties that should be potentiated.

Hydroxytyrosol alleviate intestinal inflammation, oxidative stress and apoptosis resulted in ulcerative colitis

Hydroxytyrosol (HYT) is one of the main alcoholic compounds of the olive leaves extract (OLE), which is known for its beneficial effects. This study aimed to investigate the effectiveness of olive leaves extract standardized with 25% hydroxytyrosol (OLES-25%HYT) in treatment of induced ulcerative colitis. Three groups of albino rats, were divided as following, group 1 (normal control), group 2 (induced ulcerative colitis and untreated) and group 3 (induced ulcerative colitis and treated with OLES-25%HYT). Colonic tissue samples were collected from all studied groups, the antioxidant activity for malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), myeloperoxidase (MPO) and nitric oxide (NO) were performed. The expression of pro-inflammatory cytokines, the apoptotic gene Bax and the anti-apoptotic gene Bcl2 was obtained in colon tissue to evaluate the OLES-25%HYT effect on ulcerative colitis. OLES-25%HYT showed effectiveness on reduction of mortality rate and disease activity index (DAI). Also, reduced oxidative stress and inflammation in colon tissue, OLES-25%HYT showed a significant reduction in colon MDA, MPO and NO levels and a significant elevation in SOD, CAT and GPX levels and cause down regulation of pro-inflammatory cytokines. Also, the apoptotic gene Bax downregulated and the anti-apoptotic gene Bcl2 upregulated as a result of the treatment compared to untreated induced ulcerative colitis group. OLES-25%HYT showed intestinal anti-inflammatory, antioxidants and anti-apoptotic effects in experimental models of ulcerative colitis.

Current overview of opioids in progression of inflammatory bowel disease; pharmacological and clinical considerations

Inflammatory bowel diseases (IBD) belong to a subgroup of persistent, long-term, progressive, and relapsing inflammatory conditions. IBD may spontaneously develop in the colon, resulting in tumor lesions in inflamed regions of the intestine, such as invasive carcinoma. The benefit of opioids for IBD treatment is still questionable, thereby we investigated databases to provide an overview in this context. This review demonstrates the controversial role of opioids in IBD therapy, their physiological and pharmacological functions in attenuating the IBD symptoms, and in improving inflammatory, oxidative stress, and the quality of life factors in IBD subjects. Data were extracted from clinical, in vitro, and in vivo studies in English, between 1995 and 2019, from PubMed, Google Scholar, Scopus, and Cochrane library. Based on recent reports, there are promising opportunities to target the opioid system and control the IBD symptoms. This study suggests a novel approach for future treatment of functional and inflammatory disorders such as IBD.

Microbiological and Antioxidant Activity of Phenolic Compounds in Olive Leaf Extract

According to many reports, phenolic compounds isolated from olive leaves have very good biological activities, especially antimicrobial. Presently, the resistance of microorganisms to antibiotics is greater than ever. Therefore, there are numerous recent papers about alternative solutions for inhibiting their influence on human health. Olive leaf is studied as an important source of antimicrobials with low cost and used in medicine. Numerous publications on involving green technologies for isolation of active compounds from olive leaves have appeared over the past few decades. The present review reports on current knowledge of the most isolated phenolic compounds from olive leaf extract as well as methods for their isolation and characterization. This paper uses recent research findings with a wide range of study models to describe the antimicrobial potential of phenolic compounds. It also describes the vast range of information about methods for determination of antimicrobial potential focusing on effects on different microbes. Additionally, it serves to highlight the role of olive leaf extract as an antioxidants and presents methods for determination of antioxidant potential. Furthermore, it provides an overview of presence of enzymes. The significance of olive leaves as industrial and agricultural waste is emphasized by means of explaining their availability, therapeutic and nutritional effects, and research conducted on this field.

Interventions of natural and synthetic agents in inflammatory bowel disease, modulation of nitric oxide pathways

Inflammatory bowel disease (IBD) refers to a group of disorders characterized by chronic inflammation of the gastrointestinal (GI) tract. The elevated levels of nitric oxide (NO) in serum and affected tissues; mainly synthesized by the inducible nitric oxide synthase (iNOS) enzyme; can exacerbate GI inflammation and is one of the major biomarkers of GI inflammation. Various natural and synthetic agents are able to ameliorate GI inflammation and decrease iNOS expression to the extent comparable with some IBD drugs. Thereby, the purpose of this study was to gather a list of natural or synthetic mediators capable of modulating IBD through the NO pathway. Electronic databases including Google Scholar and PubMed were searched from 1980 to May 2018. We found that polyphenols and particularly flavonoids are able to markedly attenuate NO production and iNOS expression through the nuclear factor κB (NF-κB) and JAK/STAT signaling pathways. Prebiotics and probiotics can also alter the GI microbiota and reduce NO expression in IBD models through a broad array of mechanisms. A number of synthetic molecules have been found to suppress NO expression either dependent on the NF-κB signaling pathway (i.e., dexamethasone, pioglitazone, tropisetron) or independent from this pathway (i.e., nicotine, prednisolone, celecoxib, β-adrenoceptor antagonists). Co-administration of natural and synthetic agents can affect the tissue level of NO and may improve IBD symptoms mainly by modulating the Toll like receptor-4 and NF-κB signaling pathways.

Biochemical and histopathological evidence for the beneficial effects of modafinil on the rat model of inflammatory bowel disease: involvement of nitric oxide pathway

BACKGROUND

Inflammatory bowel disease is an intestinal disorder presented by recurrent inflammation in the gastrointestinal tract. It has been reported that modafinil, also known as an awakening drug, has anti-inflammatory characteristics. The objective of this experiment is to investigate the protective effects of modafinil on colitis induced by acetic acid in rat and the involvement of nitric oxide pathway.

METHODS

Colitis was induced by intra-rectal instillation of 1 ml acetic acid (4%). After one h of colitis induction (first day), intraperitoneal injection of dexamethasone (1 mg/kg), modafinil (50, 100, and 150 mg/kg), nitric oxide synthase inhibitors (NOS)-N (G)-nitro-L-arginine methyl ester (L-NAME) 10 mg/kg, 7-nitroindazole 40 mg/kg, and aminoguanidine 50 mg/kg-was performed and continued for 2 consecutive days. Ultimately, macroscopic, microscopic, and biochemical assessments were performed.

RESULTS

While induction of colitis caused severe macroscopic lesions, administration of dexamethasone and modafinil (100 and 150 mg/kg) significantly improved macroscopic ulcers. Interestingly, the combination of modafinil with NOS inhibitors reversed the beneficial effects of modafinil on macroscopic destructions. In addition, the elevated level of interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) was decreased by modafinil. However, treatment with NOS inhibitors before modafinil neutralized the anti-inflammatory influence of modafinil. Additionally, histological disorders emerged by acetic acid in colon tissue remarkably were disappeared after treatment with modafinil.

CONCLUSIONS

In conclusion, modafinil has a protective effect on injuries induced by acetic acid in the colon of rat, which is presumably via the inhibition of inflammatory cascade and mediation of NO pathway.

Extraction of oleuropein and luteolin-7-O-glucoside from olive leaves: Optimization of technique and operating conditions

Olive leaves have become a promising source of phenolic compounds and flavonoids with high added value. Phenolic compounds and flavonoids are important sources of antioxidants and bioactives, and one of the processes used to effectively produce them is extraction via solvents, using aqueous ethanol solutions. To obtain the highest extraction yield per kg of biomass, olive leaves were extracted using a conventional technique (dynamic maceration) and an emerging technology, such as pressurized liquid extraction. Studies of the factors that influence these processes were performed: temperature, leaf moisture content, solvent/solid, and aqueous ethanol concentration were optimized using the central composite and Box-Behnken experiment designs. Pressurized liquid extraction resulted in more efficient oleuropein and luteolin-7-O-glucoside extraction than dynamic maceration. The operational conditions for maximizing the recovery of phenolic compounds and flavonoids and antioxidant capacity were determined to be 190 °C, leaf moisture content of 5%, and aqueous ethanol concentration of 80%.

Olive Tree Biophenols in Inflammatory Bowel Disease: When Bitter is Better

The current therapeutic scenario for inflammatory bowel diseases (IBD) involves aminosalicylates, corticosteroids, and immunomodulators, but concerns regarding their safety profiles and high costs heavily impact their widespread use. In recent years, the beneficial effects thatbiophenols—from fruit and vegetables—have on human health have been investigated. The antioxidant and anti-inflammatory properties of phenolic fraction, from olive leaves and fruits, have been suggested, and a potential application in gut inflammation has been supported by in vitro and IBD-animal models studies. In the present review, we first introduced the potential therapeutic role of olive tree biophenolsin chronic inflammatory disease. Then, we aimed to describe their most interesting application for gut inflammation, as the results of basic science studies and animal experimental models. Finally, the potential role of olive tree biophenols in the setting of human IBD is discussed.

Involvement of central opioid receptors in protective effects of methadone on experimental colitis in rats

PURPOSE

There are several lines of evidence on the protective roles of opioids in gastrointestinal inflammatory conditions. This study aims to distinguish the central and peripheral roles of methadone, a non-selective opioid receptor agonist, in an acute model of ulcerative colitis in male rats.

METHODS

Ulcerative colitis was induced by intrarectal administration of acetic acid 4%. Methadone was injected subcutaneously (s.c.), 5 and 10 mg/kg, and intracerebroventricular (i.c.v.), 50 and 300 ng/rat. Opioid antagonists were employed. Methylnaltrexone (MNTX; 5 mg/kg, i.p.), a peripherally acting opioid receptor antagonist, and naltrexone (NTX; 5 mg/kg, i.p. and 10 ng/rat, i.c.v.), a peripherally and centrally acting opioid receptor antagonist were injected before methadone (10 mg/kg, s.c. and or 300 ng/rat, i.c.v.) administration. NTX (5 mg/kg, i.p. and 10 ng/rat, i.c.v.) were administered 30 min prior to administration of methadone (10 mg/kg, s.c. and 300 ng/rat, i.c.v.), respectively. MNTX (5 mg/kg, i.p.) was injected 30 min prior to methadone (10 mg/kg, s.c.). Seventy-two hours following colitis induction, macroscopic and microscopic mucosal lesions, and the colonic levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) were determined.

RESULTS

Methadone (300 ng/rat, i.c.v.) and Methadone (5 and 10 mg/kg, s.c.) improved the macroscopic and microscopic scores through opioid receptors. Also, a significant reduction in TNF-α and IL-1β was observed. Peripherally and centrally injected NTX significantly reversed methadone 10 mg/kg s.c. anti-inflammatory effects while MNTX could not completely reverse this effect. Moreover, centrally administered methadone (300 ng/rat) showed the anti-inflammatory effect which was reversed by central administration of NTX (10 ng/rat).

CONCLUSIONS

The opioid receptors mainly the central opioid receptors may mediate the protective actions of methadone on the experimental model of inflammatory bowel disease in rat.

Olive tree (Olea europaea L.) leaf as a waste by-product of table olive and olive oil industry: a review

Research into finding new uses for by-products of table olive and olive oil industry are of great value not only to the economy but also to the environment where olives are grown and to the human health. Since leaves represent around 10% of the total weight of olives arriving at the mill, it is worth obtaining high added-value compounds from those materials for the preparation of dietary supplements, nutraceuticals, functional food ingredients or cosmeceuticals. In this review article, olive tree (Olea europaea L.) leaf is reviewed as being a potential inexpensive, renewable and abundant source of biophenols. The importance of this agricultural and industrial waste is emphasised by means of describing its availability, nutritional and therapeutic effects and studies conducted on this field. © 2017 Society of Chemical Industry.

Immunomodulatory properties of Olea europaea leaf extract in intestinal inflammation

SCOPE

Extracts from olive (Olea europaea) leaves are used in Mediterranean traditional medicine as anti-inflammatory agents. They contain antioxidant phenolic compounds, such as oleuropeoside, which could be interesting for the treatment of inflammatory conditions associated with oxidative stress in humans, including inflammatory bowel disease.

METHODS AND RESULTS

The anti-inflammatory effects of olive leaf extract (0.5-25 mg/kg) were studied in two mice models of colitis (DSS and DNBS). Olive leaf extract (0.1-100 μg/mL) immunomodulatory effects were also investigated in different cell types and in ex vivo organ cultures of mucosal explants of healthy donors and Crohn's disease (CD) patients. The extract showed effect in both colitis models reducing the expression of proinflammatory mediators (IL-1β, TNF-α, and iNOS), and improving the intestinal epithelial barrier integrity restoring the expression of ZO-1, MUC-2, and TFF-3. These effects were confirmed in vitro. Furthermore, it reduced the production of proinflammatory mediators (IL-1β, IL-6, IL-8, and TNF-α) in intestinal mucosal samples from CD patients.

CONCLUSION

Olive leaf extract presented intestinal anti-inflammatory activity in colitis mouse models, maybe be related to its immunomodulatory properties and the capacity to restore the intestinal epithelial barrier. Besides, the extract could also regulate the activity of cells involved in the inflammatory response.

A mechanistic review on plant-derived natural compounds as dietary supplements for prevention of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a recurrent idiopathic inflammatory condition, characterized by disruption of the gut mucosal barrier. This mechanistic review aims to highlight the significance of plant-derived natural compounds as dietary supplements, which can be used in addition to restricted conventional options for the prevention of IBD and induction of remission. Various clinical trials confirmed the effectiveness and tolerability of natural supplements in patients with IBD. Mounting evidence suggests that these natural compounds perform their protective and therapeutic effect on IBD through numerous molecular mechanisms, including anti-inflammatory and immunoregulatory, anti-oxidative stress, modulation of intracellular signaling transduction pathways, as well as improving gut microbiota. In conclusion, natural products can be considered as dietary supplements with therapeutic potential for IBD, provided that their safety and efficacy is confirmed in future well-designed clinical trials with adequate sample size.

Bioavailability of Bioactive Molecules from Olive Leaf Extracts and its Functional Value

Olive leaves are an important low-cost source of bioactive compounds. The present study aimed to examine the effect of in vitro digestibility of an olive leaf aqueous extract so as to prove the availability of its phenolic compounds as well as its antioxidant, antimicrobial, and anticancer activity after a simulated digestion process. The total phenolic content was significantly higher in the pure lyophilized extract. Phenolic compounds, however, decreased by 60% and 90% in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF), respectively. Regarding antioxidant activity, it was reduced by 10% and 50% after gastric and intestinal digestion, respectively; despite this fact, high antioxidant capacity was found in both SGF and SIF. Moreover, the olive leaf extract showed an unusual combined antimicrobial action at low concentration, which suggested their great potential as nutraceuticals, particularly as a source of phenolic compounds. Finally, olive leaf extracts produced a general dose-dependent cytotoxic effect against U937 cells. To sum up, these findings suggest that the olive leaf aqueous extract maintains its beneficial properties after a simulated digestion process, and therefore its regular consumption could be helpful in the management and the prevention of oxidative stress-related chronic disease, bacterial infection, or even cancer. Copyright © 2016 John Wiley & Sons, Ltd.

Favorable results from the use of herbal and plant products in inflammatory bowel disease: evidence from experimental animal studies

The use of herbal therapy for inflammatory bowel disease is increasing worldwide. The aim of this study was to review the available literature on the efficacy of herbal therapy in experimental colitis. All relevant studies published in Medline and Embase up to June 2015 have been reviewed. The results of bowel histology and serum parameters have been recorded. A satisfactory number of published experimental studies, and a quite large one of both herbal and plant products tested in different studies have been reported. The results showed that in the majority of the studies, herbal therapy reduced the inflammatory activity of experimental colitis and diminished the levels of many inflammatory indices, including serum cytokines and indices of oxidative stress. The most promising plant and herbal products were tormentil extracts, wormwoodherb, Aloe vera, germinated barley foodstuff, curcumin, Boswellia serrata, Panax notoginseng, Ixeris dentata, green tea, Cordia dichotoma, Plantago lanceolata, Iridoidglycosides, and mastic gum. Herbal therapies exert their therapeutic benefit via various mechanisms, including immune regulation, anti-oxidant activity, inhibition of leukotriene B4 and nuclear factor-κB, and antiplatelet activity. Large, double-blind clinical studies assessing these natural substances should be urgently conducted.

The ameliorative effects of virgin olive oil and olive leaf extract on amikacin-induced nephrotoxicity in the rat

Amikacin is an important antibiotic, and its use is limited because of the induced nephrotoxicity. Thus, search for natural and synthetic agents that can moderate amikacin toxicity never stopped. The present study aims to investigate the possible ameliorative effects of virgin olive oil and olive leaf extract against the amikacin-induced nephrotoxicity in rat.

Methods

48 rats were distributed into 6 groups: 1-Animals of control (C) group were injected intraperitoneally (ip) with saline, 2-(AK); injected ip with amikacin {300 mg/kg/day for 12days}, 3-(OO) group: given olive oil {7 ml/kg/day for 16days}, 4-(OOAK) group: given olive oil as in OO and amikacin for 12days, 5-(OL) group: given olive leaf extract {50 mg/kg/day for 16days}, 6-(OLAK) group: given leaf extract as in OL and amikacin for 12days. Animals were fasted and sacrificed. Serum was used for biochemical analysis and kidneys for histopathology.

Results

Serum urea and creatinine were significantly (P < 0.001) elevated in AK, and significantly dropped in the OOAK and OLAK groups. Serum uric acid was reduced in AK by 45.29%. Kidneys from AK showed necrosis, whereas, those from OOAK and OLAK showed mild histology. The serum triglyceride was decreased by 17.8% in OL, by 37.02% in OOAK and by 31.48% in OLAK. The calculated amikacin effect showed a significant positive correlation with urea (r = 0.521, P = 0.0004), and a negative correlation with uric acid (r = ⿿ 0.58, P < 0.0001).

Conclusion

The study confirmed nephrotoxicity of amikacin in rat which was ameliorated by virgin olive oil and by olive leaf extract. Amikacin did not cause dyslipidemia but reduced serum uric acid.

Phytochemicals and their potential usefulness in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract with unclear etiology, namely ulcerative colitis and Crohn's disease. Various drug therapies including aminosalicylates and immunomodulators have been approved for use; they have shown to produce diverse side effects. To overcome these limitations of the current therapeutics for IBD, extensive research is underway to identify drugs that are effective and free of undesirable side effects. Recently, various naturally occurring phytochemicals that cover a wide range of chemical entities such as polyphenols, terpeniods, flavonoids, and alkaloids have received attention as alternative candidates for IBD therapy. These phytochemicals act by modulating the immune response, various transcription factors, or reduce cytokine secretion. This review summarizes the findings of recent studies on phytochemicals as therapeutic agents in the management of IBD.