Ashraf B. Abdel-Naim

PROTECTIVE EFFECTS OF CURCUMIN AGAINST ISCHAEMIA/REPERFUSION INSULT IN RAT FOREBRAIN

Oxidative stress is believed to be implicated in the pathogenesis of postischaemic cerebral injury. Many antioxidants were shown to be neuroprotective in experimental models of cerebral ischaemia/reperfusion (I/R). The present study was designed to investigate the potential protective effects of curcumin (CUR) against I/R insult in rat forebrain. The model adopted was that of surgically-induced forebrain ischaemia, performed by means of bilateral common carotid artery occlusion (BCCAO) for 1 h, followed by reperfusion for another 1h. The effects of a single i.p. dose of CUR (50, 100 or 200 mg kg(-1)), administered 0.5 h after the onset of ischaemia, were investigated by assessing oxidative stress-related biochemical parameters in rat forebrain. CUR, at the highest dose level (200 mg kg(-1)), decreased the I/R-induced elevated xanthine oxidase (XO) activity, superoxide anion (O(2)*(-)) production, malondialdehyde (MDA) level and glutathione peroxidase (GPx), superoxide dismutase (SOD), and lactate dehydrogenase (LDH) activities. On the other hand, CUR did not affect the declined reduced glutathione (GSH) content due to I/R insult. Worth mentioning is that the activity of catalase (CAT) did not change in response to either I/R insult or drug treatment. In conclusion, CUR was found to protect rat forebrain against I/R insult. These protective effects may be attributed to its antioxidant properties and/or its inhibitory effects on xanthine dehydrogenase/xanthine oxidase (XD/XO) conversion and resultant O(2)*(-) production.

Aroclor 1254 impairs spermatogenesis and induces oxidative stress in rat testicular mitochondria.

Aroclor 1254 (A1254) has been shown to have potential testicular toxicity. The mechanism of action of A1254 on male reproduction is not clear. The present study was designed to investigate the potential toxicity of A1254 on rat spermatogenesis. Oxidative stress was also assessed in testicular mitochondria as an underlying mechanism. Adult male Wistar rats were injected with A1254 (0, 0.75, 1.5 or 3mg/kg/day i.p.) or with vehicle (corn oil) for 20 consecutive days. A1254 at doses of 1.5 and 3mg/kg/day resulted in a significant decrease in body weight, testes weight, epididymal and relative epididymal weight. Similarly, the relative testis weight was significantly decreased at 3mg/kg/day. Sperm count, motility and daily sperm production were significantly decreased at 1.5 and 3mg/kg/day. The same two doses significantly inhibited the activities of testicular mitochondrial CAT, GPx and GR while the activity of SOD was significantly decreased by 0.75, 1.5 and 3mg/kg/day. The levels of H(2)O(2) generation and LPO were significantly increased in mitochondria in a dose-related pattern. GSH and Vit C were significantly decreased at 0.75, 1.5 and 3mg/kg/day. In conclusion, A1254 impairs spermatogenesis as evidenced, at least partly, by induction of oxidative stress in testicular mitochondria.

Neuroprotective effect of taurine in 3-nitropropionic acid-induced experimental animal model of Huntington's disease phenotype

An experimental animal model of Huntingtons disease (HD) phenotype was induced using the mycotoxin 3-nitropropionic acid (3-NP) and was well characterized behaviorally, neurochemically, morphometrically and histologically. Administration of 3-NP caused a reduction in prepulse inhibition (PPI) of acoustic startle response, locomotor hyper- and/or hypoactivity, bilateral striatal lesions, brain oxidative stress, and decreased striatal gamma-aminobutyric acid (GABA) levels. Taurine is a semi-essential beta-amino acid that was demonstrated to have both antioxidant and GABA-A agonistic activity. In this study, treatment with taurine (200 mg/kg daily for 3 days) prior to 3-NP administration reversed both reduced PPI response and locomotor hypoactivity caused by 3-NP injection. Taurine pretreatment also caused about 2-fold increase in GABA concentration compared to 3-NP-treated animals. In addition, taurine demonstrated antioxidant activity against oxidative stress induced by 3-NP administration as evidenced by the reduced striatal malondialdehyde (MDA) and elevated striatal glutathione (GSH) levels. Histochemical examination of striatal tissue showed that prior administration of taurine ahead of 3-NP challenge significantly increased succinate dehydrogenase (SDH) activity compared to 3-NP-treated animals. Histopathological examination further affirmed the neuroprotective effect of taurine in 3-NP-induced HD in rats. Taken together, one may conclude that taurine has neuroprotective role in the current HD paradigm due, at least partly, to its indirect antioxidant effect and GABA agonistic action.

Caffeic acid phenethyl ester, a promising component of propolis with a plethora of biological activities: A review on its anti‐inflammatory, neuroprotective, hepatoprotective, and cardioprotective effects

Caffeic acid phenethyl ester (CAPE) is an important active component of honey bee propolis that possesses a plethora of biological activities. Propolis is used safely in traditional medicine as a dietary supplement for its therapeutic benefits. This review highlights the recently published data about CAPE bioavailability, anti‐inflammatory, neuroprotective; hepatoprotective and cardioprotective activities. CAPE showed promising efficacy both in vitro and in vivo studies in animal models with minimum adverse effects. Its effectiveness was demonstrated in multiple target organs. Despite this fact, it has not been yet investigated as a protective agent or a potential therapy in humans. Investigation of CAPE efficacy in clinical trials is strongly encouraged to elucidate its therapeutic benefit for different human diseases after performing full preclinical toxicological studies and gaining more insights into its pharmacokinetics.

Caffeic acid phenethyl ester protects against tamoxifen-induced hepatotoxicity in rats

Tamoxifen (TAM) is widely used in the treatment and prevention of breast cancer. Adverse effects of TAM include hepatotoxicity. Caffeic acid phenethyl ester (CAPE), an active component of propolis, has been used in folk medicine for diverse ailments. In the current study, the protective effects of CAPE against TAM-induced hepatotoxicity in female rats were evaluated. TAM (45 mg/kg/day, i.p., for 10 consecutive days) resulted in an elevation of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP), depletion of liver reduced glutathione (GSH) and accumulation of oxidized glutathione (GSSG) and lipid peroxidation (LPO). Also, TAM treatment resulted in inhibition of hepatic activity of glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT). Further, it raised liver tumor necrosis factor-alpha (TNF-alpha) level and induced histopathological changes. Pretreatment with CAPE (2.84 mg/kg/day; i.p., for 20 consecutive days, starting 10 days before TAM injection) significantly prevented the elevation in serum activity of the assessed enzymes. CAPE significantly inhibited TAM-induced hepatic GSH depletion and GSSG and LPO accumulation. Consistently, CAPE normalized the activity of GR, GPx, SOD and CAT, inhibited the rise in TNF-alpha and ameliorated the histopathological changes. In conclusion, CAPE protects against TAM-induced hepatotoxicity.

Caffeic acid phenethyl ester synergistically enhances docetaxel and paclitaxel cytotoxicity in prostate cancer cells

Evidence is growing for the beneficial role of selective estrogen receptor modulators (SERM) in prostate diseases. Caffeic acid phenethyl ester (CAPE) is a promising component of propolis that possesses SERM activity. This study aimed at investigating the modulatory impact of CAPE on docetaxel (DOC) and paclitaxel (PTX) cytotoxicity in prostate cancer cells and exploring the possible underlying mechanisms for this chemomodulation. CAPE significantly increased DOC and PTX potency in PC‐3, DU‐145 and LNCaP prostate cancer cells. Combination index calculations showed synergistic interaction of CAPE/DOC and CAPE/PTX cotreatments in all the tested cell lines. Subsequent mechanistic studies in PC‐3 cells indicated that cyclin D1 and c‐myc were significantly reduced in the combined treatment groups with concurrent increase in p27kip. DNA‐ploidy analysis indicated a significant increase in the percentage of cells in pre‐G1 in CAPE/DOC and CAPE/PTX cotreatments. Decreased Bcl‐2/Bax ratio together with increased caspase‐3 activity and protein abundance were observed in the same groups. Estrogen receptor‐β (ER‐β) and its downstream tumor suppressor forkhead box O1 levels were significantly elevated in CAPE and combination groups compared to DOC or PTX‐alone. ER‐α and insulin‐like growth factor‐1 receptor protein abundance were reduced in the same groups. CAPE significantly reduced AKT, ERK and ER‐α (Ser‐167) phosphorylation in PC‐3 cells. CAPE‐induced inhibition of AKT phosphorylation was more prominent (1.7‐folds higher) in cells expressing ER‐α such as PC‐3 compared to LNCaP. In conclusion, CAPE enhances the antiproliferative and cytotoxic effects of DOC and PTX in prostate cancer cells. This can be, at least partly, attributed to CAPE augmentation of DOC and PTX proapoptotic effects in addition to CAPE‐induced alterations in ER‐α and ER‐β abundance.

Chloroquine synergizes sunitinib cytotoxicity via modulating autophagic, apoptotic and angiogenic machineries

Tyrosine kinases play a pivotal role in oncogenesis. Although tyrosine kinase inhibitors as sunitinib malate are used in cancer therapy, emerging studies report compromised cytotoxicity when used as monotherapy and thus combinations with other anti-cancer agents is recommended. Chloroquine is a clinically available anti-malarial agent which has been shown to exhibit anti-cancer activity. In the current study, we questioned whether chloroquine can modulate sunitinib cytotoxicity. We found that chloroquine synergistically augmented sunitinib cytotoxicity on human breast (MCF-7 and T-47D), cervical (Hela), colorectal (Caco-2 and HCT116), hepatocellular (HepG2), laryngeal (HEp-2) and prostate (PC3) cancer cell lines as indicated by combination and concentration reduction indices. These results were also consistent with that of Ehrlich ascites carcinoma (EAC) Swiss albino mice models as confirmed by tumor volume, weight, histopathological examination and PCNA expression. Sunitinib induced autophagy via upregulating beclin-1 expression which was blocked by chloroquine as evidenced by accumulated SQTSM1/p62 level. Furthermore, chloroquine augmented sunitinib-induced apoptosis by decreasing survivin level and increasing caspase 3 activity. Chloroquine also enhanced the antiangiogenic capacity of sunitinib as indicated by decreased CD34 expression and peritoneal/skin angiogenesis. Sunitinib when combined with chloroquine also increased reactive nitrogen species production via increasing inducible nitric oxide synthase expression and nitric oxide level whilst reduced reactive oxygen species production by increasing GSH level, activities of glutathione peroxidase and catalase and reducing lipid peroxides compared to sunitinib-only treated group. Taken together, these findings suggest that chloroquine enhanced sunitinib cytotoxicity in a synergistic manner via inducing apoptosis while switching off autophagic and angiogenic machineries. Nevertheless, further studies are required to elucidate the efficacy and safety profile of such combination.

Role of the phytoestrogenic, pro-apoptotic and anti-oxidative properties of silymarin in inhibiting experimental benign prostatic hyperplasia in rats.

Androgen and estrogen play an important role in the pathogenesis of benign prostatic hyperplasia (BPH). Estrogen exerts its action through two distinct estrogen receptors (ERs) either ER-α or ER-β. The phytoestrogenic property of silymarin (SIL) has been previously characterized. Thus, this study examined the protective effect of SIL against testosterone-induced BPH in rats. In an initial dose-response study, SIL in a dose of 50mg/kg was the most effective in preventing the rise in prostate weight, prostate weight/body weight ratio and histopathologic changes induced by testosterone. Testosterone significantly decreased ER-β and increased ER-α and AR expressions as compared to the control group and these effects were significantly ameliorated by SIL. Furthermore, SIL significantly protected against testosterone-provoked decline in mRNA expression of P21(WAF1/Cip1) and Bax/Bcl-xl ratio as well as caspase-3 activity. SIL minimized the number of proliferating cell nuclear antigen (PCNA) positive cells as compared to testosterone-treated group. Moreover, SIL significantly blunted the inducible NF-κB expression and restored the oxidative status to within normal values in the prostatic tissues. Collectively these findings elucidate the effectiveness of SIL in preventing testosterone-induced BPH in rats. This could be attributed, at least partly, to its phytoestrogenic, pro-apoptotic and anti-oxidative properties.

Genistein improves 3-NPA-induced memory impairment in ovariectomized rats: impact of its antioxidant, anti-inflammatory and acetylcholinesterase modulatory properties.

Huntington’s disease (HD) is a progressive neurodegenerative disorder. The pre-motor symptomatic stages of the disease are commonly characterized by cognitive problems including memory loss. 3-Nitropropionic acid (3-NPA) is a mitochondrial toxin that produces selective lesions in the brain similar to that of HD and was proven to cause memory impairment in rodents. Phytoestrogens have well-established neuroprotective and memory enhancing effects with fewer side effects in comparison to estrogens. This study investigated the potential neuroprotective and memory enhancing effect of genistein (5, 10 and 20 mg/kg), a phytoestrogen, in ovariectomized rats challenged with 3-NPA (20 mg/kg). These potential effects were compared to those of 17β-estradiol (2.5 mg/kg). Systemic administration of 3-NPA for 4 consecutive days impaired locomotor activity, decreased retention latencies in the passive avoidance task, decreased striatal, cortical and hippocampal ATP levels, increased oxidative stress, acetylcholinesterase (AChE) activity, cycloxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expressions. Pretreatment with genistein and 17β-estradiol attenuated locomotor hypoactivity, increased retention latencies in the passive avoidance task, increased ATP levels, improved the oxidative stress profile, attenuated the increase in AChE activity and decreased the expression of COX-2 and iNOS. Overall, the higher genistein dose (20 mg/kg) was the most effective. In conclusion, this study suggests neuroprotective and memory enhancing effects for genistein in a rat model of HD. These effects might be attributed to its antioxidant, anti-inflammatory and cholinesterase inhibitory activities.

Anti-inflammatory activity of methyl palmitate and ethyl palmitate in different experimental rat models

Methyl palmitate (MP) and ethyl palmitate (EP) are naturally occurring fatty acid esters reported as inflammatory cell inhibitors. In the current study, the potential anti-inflammatory activity of MP and EP was evaluated in different experimental rat models. Results showed that MP and EP caused reduction of carrageenan-induced rat paw edema in addition to diminishing prostaglandin E2 (PGE2) level in the inflammatory exudates. In lipopolysaccharide (LPS)-induced endotoxemia in rats, MP and EP reduced plasma levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). MP and EP decreased NF-κB expression in liver and lung tissues and ameliorated histopathological changes caused by LPS. Topical application of MP and EP reduced ear edema induced by croton oil in rats. In the same animal model, MP and EP reduced neutrophil infiltration, as indicated by decreased myeloperoxidase (MPO) activity. In conclusion, this study demonstrates the effectiveness of MP and EP in combating inflammation in several experimental models.