Mohamed T. Khayyal

A clinical pharmacological study of the potential beneficial effects of a propolis food product as an adjuvant in asthmatic patients

The aqueous extract of propolis has been formulated as a nutritional food product and administered, as an adjuvant to therapy, to patients with mild to moderate asthma daily for 2 months in the framework of a comparative clinical study in parallel with a placebo preparation. The diagnosis of asthma was made according to the criteria of patient classification of the National Institutes of Health and Global Initiative for Asthma Management. At inclusion, the pulmonary forced expiratory volume in the first second (FEV1) as a percentage of the forced vital capacity (FVC) was more than 80% in mild persistent cases, and between 60 and 80% in moderate persistent cases, showing an increase in the degree of reversibility of > 15% in FEV1. All patients were on oral theophylline as controller therapy, none was receiving oral or inhaled corticosteroids, none had other comorbidities necessitating medical treatment, and all were from a middle‐class community and had suffered from asthma for the last 2–5 years. Twenty‐four patients received the placebo, with one drop‐out during the study, while 22 received the propolis extract, with no drop‐outs. The age range of the patients was 19–52 years; 36 were male and 10 female. The number of nocturnal attacks was recorded on a weekly basis, while pulmonary function tests were performed on all patients at the beginning of the trial, 1 month later and at the termination of the trial. Immunological parameters, including various cytokines and eicosanoids known to play a role in asthma, were measured in all patients at the beginning of the trial and 2 months later. Analysis of the results at the end of the clinical study revealed that patients receiving propolis showed a marked reduction in the incidence and severity of nocturnal attacks and improvement of ventilatory functions. The number of nocturnal attacks dropped from an average of 2.5 attacks per week to only 1. The improvement in pulmonary functions was manifested as a nearly 19% increase in FVC, a 29.5% increase in FEV1, a 30% increase in peak expiratory flow rate (PEFR), and a 41% increase in the forced expiratory flow rate between 25 and 75% of the vital capacity (FEF25‐75). The clinical improvement was associated with decreases by 52, 65, 44 and 30%, respectively, of initial values for the pro‐inflammatory cytokines tumor necrosis factor (TNF)‐α, ICAM‐1, interleukin (IL)‐6 and IL‐8, and a 3‐fold increase in the ‘protective’ cytokine IL‐10. The levels of prostaglandins E2 and F2α and leukotriene D4 were decreased significantly to 36, 39, and 28%, respectively, of initial values. Patients on the placebo preparation showed no significant improvement in ventilatory functions or in the levels of mediators. The findings suggest that the aqueous propolis extract tested is potentially effective as an adjuvant to therapy in asthmatic patients. The benefits may be related to the presence in the extract of caffeic acid derivatives and other active constituents.

Ginkgo biloba extract (EGb 761) normalizes hypertension in 2K, 1C hypertensive rats: role of antioxidant mechanisms, ACE inhibiting activity and improvement of endothelial dysfunction.

The 2 kidney, 1-clip (2K, 1C) model of hypertension was used to investigate the potential antihypertensive effect of a standardized leaf extract of Ginkgo biloba (EGb 761). Clipping of the renal artery resulted in gradual elevation of the systolic blood pressure (SBP) reaching a plateau after 4 weeks of surgery. Treatment of hypertensive rats with EGb 761 (60, 90, 180 mg/kg/day orally) was therefore started 4 weeks after surgery and continued for 3 weeks. This led to a dose-dependent reduction in SBP with no significant change in heart rate. Control hypertensive rats showed a significant elevation of total protein thiols (Pr-SHs level) in both clipped and non-clipped kidneys as well as in the serum. However, glutathione peroxidase (GSH-Px) activity was decreased in the clipped kidneys but elevated in the non-clipped ones and in the blood. The malondialdehyde (MDA) level was raised in clipped kidneys but not in non-clipped ones nor in the serum. Nitric oxide (NO level) and angiotensin converting enzyme (ACE) activity were increased in both clipped and non-clipped kidneys but not in the serum. Endothelium-dependent and -independent relaxation of aortic rings towards acetylcholine (Ach) and sodium nitroprusside (SNP) were impaired. Treatment with EGb 761 (180 mg/kg/day for 3 weeks) was associated with recovery of GSH-Px activity in clipped kidneys, inhibition of ACE activity in both kidneys and a reduction in the elevated NO level of the non-clipped kidneys, decreased responsiveness to the vasoconstrictor NE and improvement of endothelial function as evidenced by restoration of endothelium-dependent vasorelaxation induced by Ach. The observed beneficial effects of the EGb 761 may be attributed to different factors, including ACE inhibition and maintenance of cellular antioxidant capacity as well as preserving vascular reactivity towards endothelium-dependent and -independent vasodilators while inhibiting responses to vasoconstrictors.

Willow bark extract: The contribution of polyphenols to the overall effect

ZusammenfassungDie Wirksamkeit von Weidenrindenextrakten in der Behandlung schmerzhafter Erkrankungen des Bewegungsapparates, wie Rückenschmerzen und Arthritis, wurde dem Gehalt an Salicinderivaten als Prodrugs für Salicylate zugeschrieben. Aus der Erfahrung klinischer Studien und pharmakologischer Testmodelle heraus kann jedoch die Gesamtsalicinfraktion nicht als zufriedenstellende Erklärung für die Wirksamkeit der Weidenrinde herangezogen werden. Darüber hinaus fehlt den Salicinen und ihren Metaboliten das Acetylierungspotenzial der ASS, so dass hier ein anderer Wirkmechanismus vorliegen muss. Ein detailliertes pharmakologisches Screening des wässrigen Weidenrindenextraktes STW 33-I zielte auf die Frage nach der Identifizierung von Fraktionen mit einem Anteil am Gesamteffekt ab. Alle angewandten in vitro- und in vivo-Modelle ließen auf einen relevanten Beitrag der Fraktion der Polyphenole und Flavonoide schließen. Die Aufklärung der für diesen Effekt verantwortlichen Einzelsubstanzen bzw. ihrer Kombinationen wird Thema zukünftiger Untersuchungen sein.SummaryThe efficacy of willow bark extract in the treatment of painful mobility disorders, such as back pain and arthritis, has been attributed to the content of salicin and its derivatives as pro-drugs of salicylates. However, based on clinical experience and the evidence of experimental pharmacological studies, the fraction of total salicin cannot satisfactorily explain the clinical efficacy of willow bark. In addition, salicins and their metabolites lack the acetylating potential of ASA and must therefore possess a different mechanism of action. A detailed pharmacological screening of the aqueous willow bark extract STW 33-I addressed the question of the identification of fractions contributing to the overall effect. All in vivo and in vitro models studied pointed to relevant contributions of the fraction of polyphenols and flavonoids. The single compounds or their combinations responsible for the effect remain to be elucidated.

Rice bran extract protects from mitochondrial dysfunction in guinea pig brains

Mitochondrial dysfunction plays a major role in the development of age-related neurodegenerative diseases and recent evidence suggests that food ingredients can improve mitochondrial function. In the current study we investigated the effects of feeding a stabilized rice bran extract (RBE) on mitochondrial function in the brain of guinea pigs. Key components of the rice bran are oryzanols, tocopherols and tocotrienols, which are supposed to have beneficial effects on mitochondrial function. Concentrations of α-tocotrienol and γ-carboxyethyl hydroxychroman (CEHC) but not γ-tocotrienol were significantly elevated in brains of RBE fed animals and thus may have provided protective properties. Overall respiration and mitochondrial coupling were significantly enhanced in isolated mitochondria, which suggests improved mitochondrial function in brains of RBE fed animals. Cells isolated from brains of RBE fed animals showed significantly higher mitochondrial membrane potential and ATP levels after sodium nitroprusside (SNP) challenge indicating resistance against mitochondrial dysfunction. Experimental evidence indicated increased mitochondrial mass in guinea pig brains, e.g. enhanced citrate synthase activity, increased cardiolipin as well as respiratory chain complex I and II and TIMM levels. In addition levels of Drp1 and fis1 were also increased in brains of guinea pigs fed RBE, indicating enhanced fission events. Thus, RBE represents a potential nutraceutical for the prevention of mitochondrial dysfunction and oxidative stress in brain aging and neurodegenerative diseases.

Effect of methimazole treatment on doxorubicin-induced cardiotoxicity in mice

The major limiting factor in long-term administration of doxorubicin is the development of cumulative dose-dependent cardiomyopathy and congestive heart failure that limit the use of this drug. The present study was undertaken to find out the chemo protective role of methimazole against doxorubicin-induced cardiotoxicity in experimental animals. In the present study, doxorubicin treatment in a dose of 3mg/kg, i.p., every other day for six doses showed a significant 2.6-, 3- and 10.5-fold increase in the cardiac enzyme activities CK-MB and LDH and troponin-I, respectively, in the serum of the animals. Histopathological investigation of heart tissues showed swollen muscle fibers with interstitial edema and inflammatory exudate. Pretreatment of the animals with methimazole at a dose level of 40 mg/kg, i.p., 30 min before doxorubicin, returned the cardiac enzyme levels to nearly normal value with partial reversal of the inflammatory lesions and the swollen muscle fibers induced by doxorubicin. Moreover, methimazole pretreatment, decreased the doxorubicin level in the heart tissues with a significant increase in plasma level and non significant effect on doxorubicin level in tumor cells. At the same time, methimazole pretreatment did not significantly interfere with the antitumor activity of doxorubicin.

Rice Bran Extract Compensates Mitochondrial Dysfunction in a Cellular Model of Early Alzheimer's Disease

Mitochondrial dysfunction plays an important role in brain aging and has emerged to be an early event in Alzheimers disease (AD), contributing to neurodegeneration and the loss of physical abilities seen in patients suffering from this disease. We examined mitochondrial dysfunction in a cell culture model of AD (PC12APPsw cells) releasing very low amyloid-β (Aβ40) levels and thus mimicking early AD stages. Our data show that these cells have impaired energy metabolism, low ATP levels, and decreased endogenous mitochondrial respiration. Furthermore, protein levels of PGC1α as well as of Mitofusin 1 were decreased. PC12APPsw cells also showed increased mitochondrial content, probably due to an attempt to compensate the impaired mitochondrial function. Recent data showed that stabilized rice bran extract (RBE) protects from mitochondrial dysfunction in vivo Pharmacol Res. (2013) 76C, 17-27. To assess the effect of RBE on mitochondrial function, we treated PC12APPsw cells for 24 h with RBE. Key components of RBE are oryzanols, tocopherols, and tocotrienols, all substances that have been found to exert beneficial effects on mitochondrial function. RBE incubation elevated ATP production and respiratory rates as well as PGC1α protein levels in PC12APPsw cells, thus improving the impaired mitochondrial function assessed in our cell culture AD model. Therefore, RBE represents to be a promising nutraceutical for the prevention of AD.

Solanum indicum ssp. distichum extract is effective against l‐NAME‐induced hypertension in rats

Solanum indicum ssp. distichum is used as a vegetable in some parts of Africa and claimed in folk medicine to guard against cardiovascular disorders. It was of interest to study the potential blood pressure lowering effects of a standardized extract of the fruit. An ethanolic extract of the fruit, standardized to contain > 0.15% chlorogenic acids, was tested orally in both normotensive rats and in those rendered hypertensive by twice daily intraperitoneal injection of NW‐nitro‐l‐arginine methylester (l‐NAME) for 1 week. The extract was either given at the same time as l‐NAME or after the establishment of hypertension. The systolic blood pressure (SBP) was measured non‐invasively using a tail cuff computer‐aided monitoring device. Treatment of normotensive rats with the extract (30–300 mg/kg) for 4 weeks showed no hypotensive effect. Giving the extract (100 and 300 mg/kg) orally once daily during the 1 week hypertension induction period with l‐NAME prevented the development of hypertension. Administration of the extract orally for 1 week after the establishment of hypertension tended to normalize the blood pressure. Pharmacological evidence for the antihypertensive activity of S. distichum is hereby reported for the first time. The extract showed good prophylactic as well as curative effect against l‐NAME‐induced hypertension, whereby its content of chlorogenic acids may play a minor role. Other constituents may be responsible for the antihypertensive action. The findings support further development of the extract as a potential therapeutically useful antihypertensive agent.

Antidiabetic Effects of a Standardized Egyptian Rice Bran Extract

An extract was prepared from Egyptian stabilized rice bran and standardized to contain 2% γ‐oryzanol in addition to its content of other bioactives, notably tocotrienol and policosanol. The standardized extract was found to have a concentration‐dependent effect on insulin release in vitro, which, however, is not mediated by γ‐tocotrienol in rice bran (detected by HPLC) as could have been expected. Policosanol and γ‐oryzanol have insulinotropic effects. The in vitro data of rice bran directly translate into in vivo data of rats by using a glucose tolerance test (increase in plasma insulin). Tocotrienols are well known for their apoptotic effect on tumor cells; nevertheless, an attempt was made to study glucose uptake in HEP‐G2 cells, which needs to induce an insulin‐resistant state by TNF‐α. The Egyptian rice bran extract has an antidiabetic effect. γ‐Oryzanol, which is a possible precursor of the insulinotropic compound ferulic acid, is a candidate for this effect. Therefore, it is reasonable to assume that the prevalence of diabetes or at least a prediabetic (type 2) situation can be ameliorated by the investigated rice bran extract. The potential usefulness of the extract as a nutraceutical is currently undergoing more thorough investigations. Copyright

Prophylactic effect of aqueous propolis extract against acute experimental hepatotoxicity in vivo

Propolis has been extensively used in folk medicine for the management of a wide spectrum of disorders. In a previous study, we demonstrated the protective effect of the aqueous propolis extract (APE) against the injurious effects of carbon tetrachloride (CCl4) on hepatocytes in vitro. The present investigation was carried out to show whether the hepatoprotective effect of the extract could also be manifested in vivo. Rats were given APE orally for 14 consecutive days, before being subjected to a single intraperitoneal injection of CCl4. One day after the CCl4 injection, the animals were sacrificed, hepatocytes were isolated and liver homogenates were prepared for the assessment of liver injury. In isolated hepatocytes, APE afforded protection against CCl4-induced injury as manifested by a decrease in the leakage of the cytosolic enzyme lactate dehydrogenase (LDH), decreased generation of lipid peroxide and maintenance of cellular reduced glutathione (GSH) content. In principle, similar findings were observed in liver homogenates. The present findings show that APE has in vivo hepatoprotective potential which could be attributed at least in part to the maintenance of cellular GSH content. The latter effect seems to play an important role in conserving the integrity of biomembranes as it was associated with a decrease in lipid peroxidation and reduced leakage of cytosolic LDH

Effect of selective COX-2 inhibitor, celecoxib on adjuvant-induced arthritis model in irradiated rats

Purpose: The potential value of celecoxib was compared to a standard non-steroidal anti-inflammatory drug (NSAID), diclofenac in the adjuvant-induced arthritis (AIA) model in rats as a model of chronic inflammation under the influence of ionising radiation. Material and methods: Various inflammatory mediators and biochemical parameters were measured in the arthritic rats under the influence of ionising radiation. Results: Exposure of the animals to a radiation dose of 2 Gy before inoculation of the adjuvant led to a marked increase in the paw volume reaching ca. 70% more than that in non-irradiated ones as well as a significant increase in the levels of interleukin-6 (IL-6), interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α), prostaglandin E2 (PGE2) as an index of cyclooxygenase-2 (COX-2) activity, thromboxane B2 (TXB2) as an index of cyclooxygenase-1 (COX-1) activity and plasma level of malondialdehyde (MDA). The blood glutathione (GSH) level was not affected by the dose of irradiation used while superoxidedismutase (SOD) activity was reduced. Treatment with celecoxib in a dose of 5 mg/kg was effective in decreasing the elevated levels of IL-6, IL-1β, TNF-α, PGE2 whereas it lacked any effect on TXB2 level since it had hardly any effect on COX-1 enzyme. Both drugs at the selected dose levels showed no effect on level of MDA, GSH and SOD activity. Conclusion: Irradiation of animals caused a marked change in the inflammatory response in AIA model of inflammation. Both celecoxib and diclofenac were nearly equipotent in suppressing the inflammatory response in both normal and irradiated rats. Accordingly, since the inhibition of COX-1 by traditional NSAID is thought to have undesirable side-effects on proliferating tissues, it would seem preferable to use selective COX-2 inhibitors to limit such deleterious effect.