Neuroprotection by Brazilian Green Propolis against In vitro and In vivo Ischemic Neuronal Damage

Brazilian green propolis prevent Alzheimer's disease-like cognitive impairment induced by amyloid beta in mice

BACKGROUND

The increasing incidence of cognitive impairment has become a health problem in the aging society. Owing to its antioxidant and anti-inflammatory properties, Brazilian green propolis-derived from Baccharis dracunculifolia-is anticipated to possess anticognitive properties. However, the preventive effect of Brazilian green propolis on cognitive impairment remains unexplained. This study aimed to investigate the effect of Brazilian green propolis on cognitive impairment using a mouse model of Alzheimer's disease (AD) induced by intracerebroventricular injection of amyloid beta (Aβ)25‒35.

METHODS

Five-week-old male Slc:ddY mice were randomly divided into five groups (n = 8). The groups were pretreated with vehicle and propolis at a dose of 100, 300 and 900 mg/kg body weight for 8 days, then AD-like phenotypes were induced by intracerebroventricular (ICV) injection of Aβ25‒35. A sham operation group was set as the control. Memory and learning ability were measured at 7 to 8 days after ICV injection. Gene expression and histological studies were performed at the endpoint of the study.

RESULTS

In a passive avoidance test, the administration of Brazilian green propolis prevented the impairment of learning and memory function. Furthermore, comprehensive gene expression analysis in the hippocampus and forebrain cortex revealed that Brazilian green propolis suppressed Aβ25-35-induced inflammatory and immune responses. In particular, Brazilian green propolis prevented alterations in gene expressions of microglial and astrocytic markers such as Trem2 and Lcn2 induced by Aβ25‒35 injection, suggesting the suppression of excessive activation of glial cells in the brain. In addition, Brazilian green propolis suppressed the elevation of plasma interleukin (IL)-6 levels induced by Aβ25‒35 injection.

CONCLUSIONS

The results suggest that the prophylactic administration of Brazilian green propolis has a preventive effect against AD by suppressing excessive inflammation and immune response in glial cells. To our knowledge, this study is the first to demonstrate that Brazilian green propolis may inhibit the hyperactivation of microglia and astrocytes as a mechanism of action to prevent AD. Thus, it is a promising ingredient for preventing AD-type dementia.

Propolis ameliorates ischemia/reperfusion-induced testicular damage by reducing oxidative stress

PURPOSE

This study was performed to evaluate the effect of ethanolic extract of Turkish propolis (EEP) on testicular ischemia/reperfusion (I/R) damage in rats in terms of biochemistry and histopathology, for the first time.

METHODS

A total of 18 male Sprague-Dawley rats were divided into three groups with six rats in each group: control, torsion/detorsion (T/D), and T/D+EEP (100mg/kg). Testicular torsion was performed by 720° rotating the left testicle in a clockwise direction. The duration of ischemia was 4h and orchiectomy was performed after 2h of detorsion. EEP was applied only once 30min before detorsion. Tissue malondialdehyde (MDA), total oxidant status (TOS) and total antioxidant status (TAS) levels were determined using colorimetric methods. Oxidative stress index (OSI) was calculated by proportioning tissue TOS and TAS values to each other. Tissue glutathione (GSH) and glutathione peroxidase (GPx) levels were determined using enzyme-linked immunosorbent assay (ELISA) kits. Johnsen's testicle scoring system was used for histological evaluation.

RESULTS

In the T/D group, it was determined that statistically significant decreasing in TAS, GSH, GPx levels and Johnsen score, and increasing in TOS, OSI and MDA levels (p<0.05) compared with control group. EEP administration statistically significantly restored this I/R damage (p<0.05).

CONCLUSION

This is the first study to show that propolis prevent I/R-induced testicular damage through its antioxidant activity. More comprehensive studies are needed to see the underlying mechanisms.

Effect of propolis on mood, quality of life, and metabolic profiles in subjects with metabolic syndrome: a randomized clinical trial

Metabolic syndrome (MeS) is a common multifaceted disorder. Plants contain antioxidant bioactive compounds, which are beneficial to improve the health condition of patients with MeS. Propolis is a hive natural product that is composed of various constituent. We aimed to assess the effects of Iranian propolis as a natural and safe agent on indicators of MeS, quality of life and mood status in individuals with MeS. In total, 66 interested eligible patients recruited to the present study. Participants were randomly assigned to consume a tablet at dose of 250 mg of propolis extract, twice daily for 12 weeks or placebo. Propolis supplementation could lead to a significant reduction in waist circumference (WC), increase in physical functioning, general health and the overall score of SF-36 compared with placebo group (P-value < 0.05). However, no significant differences were observed regarding other anthropometric indices and biochemical parameters between two groups (P-value > 0.05). The current study indicated that propolis can be effective in decreasing WC and improving physical health and quality of life, while had no significant effects on other components of MeS among subjects with this syndrome. Clinical trials registration Iran Registry of Clinical Trials.ir IRCT20121216011763N49, registration date 23/12/2020.

Baccharin from Brazilian green propolis induces neurotrophic signaling pathways in PC12 cells: potential for axonal and synaptic regeneration

Neurodegenerative diseases are characterized by progressive loss of the structure and function of specific neuronal populations, and have been associated with reduced neurotrophic support. Neurotrophins, like NGF (nerve growth factor), are endogenous proteins that induce neuritogenesis and modulate axonal growth, branching, and synapsis; however, their therapeutic application is limited mainly by low stability, short half-life, and inability to cross the blood-brain barrier (BBB). Small neurotrophic molecules that have suitable pharmacokinetics and are able to cross the BBB are potential candidates for neuroprotection. Baccharin is a bioactive small molecule isolated from Brazilian green propolis. In the present study, we investigated the neurotrophic and neuroprotective potential of baccharin in the PC12 cell neuronal model. We used pharmacological inhibitors (K252a, LY294002, and U0126), and ELISA (phospho-trkA, phospho-Akt, and phospho-MEK) to investigate the involvement of trkA receptor, PI3k/Akt pathway, and MAPK/Erk pathway, respectively. Additionally, we evaluated the expression of axonal (GAP-43) and synaptic (synapsin I) proteins by western blot. The results showed that baccharin induces neuritogenesis in NGF-deprived PC12 cells, through activation of trkA receptor and the downstream signaling cascades (PI3K/Akt and MAPK/ERK), which is the same neurotrophic pathway activated by NGF in PC12 cells and neurons. Baccharin also induced the expression of GAP-43 and synapsin I, which mediate axonal and synaptic plasticity, respectively. Additionally, in silico predictions of baccharin showed favorable physicochemical properties, pharmacokinetics, drug-likeness, and medicinal chemistry friendliness. Altogether, these findings suggest that baccharin is a promising neurotrophic agent whose therapeutic application in neurodegeneration should be further investigated.

Propolis Promotes Memantine-Dependent Rescue of Cognitive Deficits in APP-KI Mice

Propolis is a complex resinous substance that is relevant as a therapeutic target for Alzheimer's disease (AD) and other neurodegenerative diseases. In this study, we confirmed that propolis (Brazilian green propolis) further enhances the rescue of cognitive deficits by the novel AD drug memantine in APP-KI mice. In memory-related behavior tasks, administration of a single dose of propolis at 1-100 mg/kg p.o. significantly enhanced the rescue of cognitive deficits by memantine at 1 mg/kg p.o. in APP-KI mice. In in vitro studies, propolis significantly increased intracellular Ca²⁺ concentration and calcium/calmodulin-dependent protein kinase II (CaMKII) autophosphorylation in Kir6.2-overexpressed N2A cells treated with memantine. Propolis also significantly increased adenosine 5'-triphosphate (ATP) contents and CaMKII autophosphorylation, which was impaired in Aβ-treated Kir6.2-overexpressed N2A cells. Similarly, repeated administration of propolis at 100 mg/kg p.o. for 8 weeks further enhanced the rescue of cognitive deficits by memantine in APP-KI mice. Consistent with the rescued cognitive deficits in APP-KI mice, repeated administration of propolis markedly ameliorated memantine-dependent rescue of injured long-term potentiation (LTP) in APP-KI mice, concomitant with increased CaMKII autophosphorylation and calcium/calmodulin-dependent protein kinase IV (CaMKIV) phosphorylation in the hippocampal CA1 region. Furthermore, repeated administration of both memantine and propolis significantly restored the decreased ATP contents in the CA1 region of APP-KI mice. Finally, we confirmed that repeated administration of memantine at 1 mg/kg p.o. and propolis at 100 mg/kg p.o. for 8 weeks failed to restore the cognitive deficits in Kir6.2-/- mice. Our study demonstrates that propolis increases ATP contents and promotes the amelioration of cognitive deficits rescued by memantine via Kir6.2 channel inhibition in the CA1 region.

Artepillin C, a major component of Brazilian green propolis, inhibits endoplasmic reticulum stress and protein aggregation

Propolis, a compound produced by honeybees, has long been used in food and beverages to improve health and prevent diseases. We previously reported that the ethanol extracts of Brazilian green propolis and its constituents artepillin C, kaempferide, and kaempferol mitigate oxidative stress-induced cell death via oxytosis/ferroptosis. Here, we investigated the potential of Brazilian green propolis and its constituents to protect against endoplasmic reticulum stress in the mouse hippocampal cell line HT22. Ethanol extracts of Brazilian green propolis, artepillin C, and kaempferol attenuated tunicamycin-induced unfolded protein response and cell death. Interestingly, artepillin C inhibited both tunicamycin-induced protein aggregation in HT22 cells and the spontaneous protein aggregation of mutant canine superoxide dismutase 1 (E40K-SOD1-EGFP) in Neuro2a cells. These findings indicate that in addition to oxidative stress, the ethanol extracts of Brazilian green propolis help prevent endoplasmic reticulum stress-related neuronal cell death, which is proposedly involved in several neurodegenerative diseases. Moreover, artepillin C, a major constituent of Brazilian green propolis, may exhibit chemical chaperone-like properties.

In vitro transcriptome response to propolis in differentiated SH-SY5Y neurons

Propolis is the extract of a resinous compound that protects plants from both cold and microorganism attack and has gained a strong and sticky property because it is transformed after being collected by honey bees. Up to date, many studies have shown that propolis exhibited various beneficial biological activities, such as antifungal, antibacterial, antiviral, antioxidant, antimutagenic, and antitumor effects. Recent reports propounded the in vitro and in vivo neuroprotective effect of propolis; however, the exact molecular genetic mechanisms are still unclear. Therefore, we aimed to investigate the toxicogenomic and beneficial properties, including cytotoxic, antioxidant, apoptotic/necrotic as well as genotoxic effects of propolis (1.56-200 µg/ml) on differentiated SH-SY5Y neuronal cells. Additionally, microarray analysis was conducted on cell cultures following propolis application to explore gene differentiation. Differentially expressed genes were further analyzed using string software to characterize protein-protein interactions between gene pathways. Our results revealed that propolis applications could not have a prominent effect on cell viability even at concentrations up to 200 µg/ml. The highest propolis concentration induced apoptotic rather than necrotic cell death. The alterations in gene expression profiles, including CYP26A1, DHRS2, DHRS3, DYNC1I1, IGF2, ITGA4, SVIL, TGFβ1, and TGM2 could participate in the neuroprotective effects of propolis. In conclusion, propolis supplementation exerted remarkable advantageous; thus, it may offer great potential as a natural component in the prevention and treatment of neurodegenerative disorders. Whole-genome gene expression pattern following propolis application was investigated for the first time in neuronal cell culture to fill a gap in the literature about propolis toxicogenomics. PRACTICAL APPLICATIONS: Propolis is a very rich product in terms of benefits. In addition to its antibacterial, antiviral, antifungal, and anti-inflammatory content, it is known to have preventive and therapeutic properties for many different ailments. On the other hand, molecular mechanisms of propolis on gene expression differentiations haven't been investigated until now. Moreover, gene expression pattern is vital for all living organisms to maintain homeostasis. Thus, we conduct an experiment series for analyzing gene expression differentiation effects on neuronal cells to understand beneficial properties of propolis. Hence, it could be possible to comment on the use of propolis as a nutritional factor and beneficial diet.

Cognitive Improvement and Safety Assessment of a Dietary Supplement Containing Propolis Extract in Elderly Japanese: A Placebo-Controlled, Randomized, Parallel-Group, Double-Blind Human Clinical Study

Objectives. This study aimed to evaluate the effect of propolis on cognitive function in elderly Japanese with a placebo-controlled design. Material and Methods. This study was performed on 79 elderly Japanese. Participants orally received either a placebo or dietary supplement containing propolis extract for 24 weeks. Cognitive function assessed by Cognitrax and various blood or urine markers were measured at pre- and postadministration. Results and Conclusion. Eligible data from 68 subjects (placebo: 33, propolis: 35) who completed the study were analyzed. Compared to the placebo group, the propolis group showed significant improvement in verbal memory in Cognitrax (P=0.028). Total cholesterol, LDL cholesterol, urea nitrogen, creatinine, and uric acid were significantly improved in the propolis group compared to the placebo group (P = 0.011, P = 0.004, P = 0.048, P = 0.045, and P = 0.005, respectively). However, urea nitrogen, creatinine, and uric acid fluctuated within the normal level. Furthermore, a subgroup analysis was performed on those with higher than 100 of the standardized score of the neurocognitive index indicated by the overall Cognitrax score. Significant improvements in the propolis group compared to placebo were confirmed in verbal memory (P = 0.007) and processing speed as indications for information processing ability, complex attention, and concentration (P = 0.029). No side effects were observed in any of the groups. This study demonstrates that propolis is effective in improving cognitive functions such as memory, information processing, complex attention, and concentration in elderly Japanese.

Iranian brown propolis possesses neuroprotective effect against ischemic neuronal damage in mice

Introduction: Stroke is one of the leading causes of death and disability worldwide. Propolis, a polyphenol-rich resinous product processed by honeybees from a variety of plant sources, has a set of biological activities. We investigated the neuroprotective effect of Iranian brown propolis (IBP) in a mouse model of permanent middle cerebral artery occlusion (MCAO). Methods: Experimentally, water extracts of propolis (WEPs) were obtained from Kerman (KeWEP) and Khorasan Razavi (KhWEP) provinces, Iran. The chemical characterization and total polyphenol content of WEPs were determined using the Folin–Ciocalteu assay and gas chromatography-mass spectrometry (GC-MS). Animals were divided into eight experimental groups including: sham, control, and three groups each of which KeWEP- and KhWEP-treated mice. The drugs were administered at doses of 30, 100 and 200 mg/kg, intraperitoneally (IP), during four different time points. Infarct volume and brain edema were measured at 48 h. Behavioral tests were evaluated at 4, 24 and 48-hour post stroke. Results: The total polyphenol content was 1100 and 1400 mg/L in KhWEP and KeWEP respectively. Compared to the control group, the doses of 100 and 200 mg/kg in both samples decreased infarct volume. Brain edema was also reduced in all treatment groups. The dose of 200 mg/kg in both samples and 100 mg/kg in the KeWEP-treated group significantly increased grasping ability. Sensory-motor function was improved in all groups, too. Conclusion: These results suggest that IBP may reduce ischemic brain injury by its neuroprotective effect on focal cerebral ischemia.

Neuroprotective Effect of Brazilian Green Propolis on Retinal Ganglion Cells in Ischemic Mouse Retina

PURPOSE

The current study was undertaken to investigate whether Brazilian green propolis (BGP) can increase the viability of retinal ganglion cells (RGCs) in ischemic mouse retina, and examined the possible mechanisms underlying this neuroprotection.

MATERIALS AND METHODS

C57BL/6J mice were subjected to constant elevation of intraocular pressure for 60 min to establish retinal ischemia-reperfusion injury. Mice then received saline or BGP (200 mg/kg) intraperitoneally once daily until sacrifice. The expression of hypoxia-inducing factor (HIF)-1α and glial fibrillary acidic protein (GFAP) and the level of histone acetylation were assessed at 1, 3, and 7 days after injury. The expression of Bax, Bcl-2, p53, NF-κB, Nrf2, and HO-1 were also analyzed at 3 days after injury. The neuroprotective effect of BGP treatment on RGC survival was evaluated using Brn3a immunohistochemical staining.

RESULTS

The expression of HIF-1α and GFAP was increased and the level of histone acetylation decreased in saline-treated ischemic retinas within 7 days. BGP treatment effectively attenuated the elevated expression of HIF-1α, GFAP, Bax, NF-κB and p53. The expression of Bcl-2, Nrf2, HO-1 and the level of histone acetylation increased by BGP treatment, resulting in a significant difference between BGP-treated and saline-treated retinas. Immunohistochemical staining for Brn3a also revealed that BGP treatment protected against RGC loss in ischemic retina.

CONCLUSIONS

Our results suggest that BGP has a neuroprotective effect on RGCs through the upregulation of histone acetylation, downregulation of apoptotic stimuli, and suppression of NF-κB mediated inflammatory pathway in ischemic retina. These findings suggest that BGP is a potential neuroprotective agent against RGC loss under oxidative stress.

Evidence on the Health Benefits of Supplemental Propolis

Propolis is a honey-related product with reported health benefits such as improved immunity, lowered blood pressure, treated allergies and skin conditions. A literature review and narrative synthesis were conducted to investigate the evidence on the reported health benefits and future direction of propolis products. Using a predefined search strategy we searched Medline (OvidSP), Embase and Central for quantitative and qualitative studies (1990-2018). Citation, reference, hand searches and expert consultation were also undertaken. Studies of randomised control trials and observational data on humans with health-related outcomes were included. Collected data were entered into NVivo software (Version 12, QRS International) and analysed using a thematic framework and a narrative synthesis of emergent themes. A total of 63 publications were discussed. The majority were cell-based and animal studies, with a few key human trials conducted. There is significant promise for propolis as an effective antioxidant and anti-inflammatory agent with particular promise in cardiometabolic health.

Neuroprotective effects of Brazilian green propolis on oxytosis/ferroptosis in mouse hippocampal HT22 cells

Propolis is a sticky dark-colored substance produced by honey bees and comprises resin, balsam, wax, essential and aromatic oils, pollen, and several other substances; it is used in food and beverages to improve health and prevent diseases. We studied the neuroprotective effects of extracts of Brazilian green propolis in the mouse hippocampal cell line HT22. Ethanol extracts of Brazilian green propolis had a more potent preventive effect on oxidative stress-induced cell death, oxytosis/ferroptosis, in HT22 cells than water extracts of Brazilian green propolis, whereas it did not protect against anticancer drug-induced apoptotic cell death. Among the primary constituents of ethanol extracts of Brazilian green propolis, only artepillin C, kaempferide, and kaempferol demonstrated neuroprotective effects against oxytosis/ferroptosis. The flavonoid derivatives kaempferide and kaempferol are antioxidants with radical-scavenging abilities that additionally induce antioxidant response element-mediated transcriptional activity, suggesting that upregulation of endogenous antioxidant defense protects against oxidative stress. In contrast, artepillin C attenuated reactive oxygen species production; however, it did not induce antioxidant response element activation. These findings indicate that the ethanol extracts of Brazilian green propolis help to prevent oxidative stress-related neuronal cell death that is involved in the pathogenesis of several neurodegenerative diseases.

Impacts of Egyptian propolis extract on rat cerebellum intoxicated by aluminum silicate: histopathological studies

Human is exposed to traces of aluminum silicate (AlS), i.e., cosmetics, pesticides. Accumulation of aluminum compounds including AlS is associated with neuropathological diseases, e.g., Alzheimer's disease. The aim of the current study is to investigate the neuroprotective effects of propolis extracts in AlS-induced cerebellum intoxication in rats. Forty adult rats were randomly divided into four groups (n = 10). The first group served as a control; the second group treated with 200 ml propolis/kg bwt. every other day by stomach gavage tube, third group was intraperitoneally injected with AIS (20 mg/kg) twice a week for 8 weeks, and the fourth group received propolis extract and AIS. At the end of 8 weeks, the cerebellum was harvested for further ultrastructure, histological, and histochemical investigations. Using electron microscopy, the ultrastructure of the cerebellar cortex of AlS intoxicated rats showed Purkinje cells with an irregular euchromatic nucleus and extremely increased invagination of the nuclear envelope. In addition, the cytoplasm revealed numerous damaged mitochondria (> 20%) as well as swollen lysosomes (> 40%) compared to controls. These AlS-related ultrastructure changes were to some extent normalized to < 10% and < 30% in case of mitochondria and lysosomes, respectively, if rats were co-treated with propolis extract. Further, histopathological examination showed that AlS-exposed rats revealed abnormal Purkinje cells with irregular size and shrank shape, evidence of pre-necrotic stage in the form of nuclear pyknosis, and condensed and frequent darkly stained cells in cerebellar layers. However, propolis extract co-administration reversed from 35 to 25% (p < 0.05) these alterations. The carbohydrate and protein contents were reduced in case of AlS treatment and surprisingly propolis co-treatment was able to rescue these neurotoxic effects. Propolis extract might have neuroprotective effects against AIS-induced toxicity. Further studies are required to identify the mechanism of the pharmacological action and optimal settings for medical testing of propolis extract.

Neurotoxic Effect of Ethanolic Extract of Propolis in the Presence of Copper Ions is Mediated through Enhanced Production of ROS and Stimulation of caspase-3/7 Activity

Elevated amounts of copper are considered to be contributing factor in the progression of neurodegenerative diseases as they promote oxidative stress conditions. The aim of our study was to examine the effects of ethanolic extract of propolis (EEP) against copper-induced neuronal damage. In cultured P19 neuronal cells, EEP exacerbated copper-provoked neuronal cell death by increasing the generation of reactive oxygen species (ROS) and through the activation of caspase-3/7 activity. EEP augmented copper-induced up-regulation of p53 and Bax mRNA expressions. Neurotoxic effects of EEP were accompanied by a strong induction of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) expression and decrease in the expression of c-fos mRNA. SB203580, an inhibitor of p38 mitogen-activated protein kinase (MAPK) prevented detrimental effects of EEP, whereas SP600125, an inhibitor of c-Jun N-terminal kinase (JNK), exacerbated EEP-induced neuronal cell death. Quercetin, a polyphenolic nutraceutical, which is usually present in propolis, was also able to exacerbate copper-induced neuronal death. Our data indicates a pro-oxidative and apoptotic mode of EEP action in the presence of excess copper, wherein ROS/p53/p38 interactions play an important role in death cascades. Our study also pointed out that detailed pharmacological and toxicological studies must be carried out for propolis and other dietary supplements in order to fully recognize the potential adverse effects in specific conditions.

Mechanisms underlying the wound healing potential of propolis based on its in vitro antioxidant activity

BACKGROUND

Propolis is a resinous substance collected by honeybees, Apis mellifera, from various plant sources. Having various pharmacological and biological activities, it has been used in folk medicine and complementary therapies since ancient times.

PURPOSE

To evaluate the effects and underlying mechanism of the protective effects of the ethanol extract of Chinese propolis (EECP) on L929 cells injured by hydrogen peroxide (H₂O₂).

STUDY DESIGN

The wound healing activities of EECP in L929 cells with H₂O₂-induced damage were investigated.

METHODS

The main components of EECP were analyzed by RP-HPLC, and the free radical scavenging capacity and reducing power were also measured. The effects of EECP on the expression of antioxidant-related genes in fibroblast L929 cells were determined using qRT-PCR and western blotting.

RESULTS

EECP had significant protective effects against cell death induced by H₂O₂ and significantly inhibited the decline of collagen mRNA expression caused by H₂O₂ in L929 cells.

CONCLUSION

EECP induced the expression of antioxidant-related genes, such as HO-1, GCLM, and GCLC, which has great implications for the potential of propolis to alleviate oxidative stress in wound tissues. The protective effects of propolis have great implications for using propolis as a wound healing regent.

Anti-Inflammatory and Neuroprotective Role of Natural Product Securinine in Activated Glial Cells: Implications for Parkinson's Disease

Glial activation and subsequent release of neurotoxic proinflammatory factors are believed to play an important role in the pathogenesis of several neurological disorders including Parkinson's disease (PD). Inhibition of glial activation and inflammatory processes may represent a therapeutic target to alleviate neurodegeneration. Securinine, a major natural alkaloid product from the root of the plant Securinega suffruticosa, has been reported to have potent biological activity and is used in the treatment of neurological conditions such as amyotrophic lateral sclerosis, poliomyelitis, and multiple sclerosis. In this study, we explored the underlying mechanisms of neuroprotection elicited by securinine, particularly its anti-inflammatory effects in glial cells. Our results demonstrate that securinine significantly and dose-dependently suppressed the nitric oxide production in microglia and astrocytic cultures. In addition, securinine inhibited the activation of the inflammatory mediator NF-κB, as well as mitogen-activated protein kinases in lipopolysaccharide- (LPS-) stimulated BV2 cells. Additionally, securinine also inhibited interferon-γ- (IFN-γ-) induced nitric oxide levels and iNOS mRNA expression. Furthermore, conditioned media (CM) from securinine pretreated BV2 cells significantly reduced mesencephalic dopaminergic neurotoxicity compared with CM from LPS stimulated microglia. These findings suggest that securinine may be a potential candidate for the treatment of neurodegenerative diseases related to neuroinflammation.

Brown propolis attenuates cerebral ischemia-induced oxidative damage via affecting antioxidant enzyme system in mice

Oxidative stress plays a critical role in ischemic brain injury. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) are the enzymes underlying the endogenous antioxidant mechanisms affected by stroke and are considered as oxidative stress biomarkers. Brown propolis (BP) is a bioactive natural product with a set of biological activities that in turn may differ depending on the area from which the substance is originated. The aim of this study was to investigate the effect of water-extracted brown propolis (WEBPs), from two regions of Iran, against cerebral ischemia-induced oxidative injury in a mouse model of stroke. Experimentally, the chemical characterization and total polyphenol content were determined using GC/MS and Folin-Ciocalteu assay respectively. Seventy-two adult male mice were randomly divided into the surgical sham group, control group (treated with vehicle), and four groups of WEBPs-treated animals. The WEBPs were administered at the doses of 100 and 200mg/kg IP, during four different time points. Oxidative stress biomarkers (SOD and GPx activity, SOD/GPx ratio), lipid peroxidation (LPO) index (malondialdehyde content) and infarct volume were measured 48h post stroke. Behavioral tests were evaluated 24 and 48h after stroke. WEBPs treatment resulted in significant restoration of antioxidant enzymes activity and a subsequent decrease in LPO as well as the infarct volume compared to the control group. Sensory-motor impairment and neurological deficits were improved significantly as well. These results indicate that Iranian BP confers neuroprotection on the stroke-induced neuronal damage via an antioxidant mechanism which seems to be mediated by the endogenous antioxidant system.

Neurobehavioral and Antioxidant Effects of Ethanolic Extract of Yellow Propolis

Propolis is a resin produced by bees from raw material collected from plants, salivary secretions, and beeswax. New therapeutic properties for the Central Nervous System have emerged. We explored the neurobehavioral and antioxidant effects of an ethanolic extract of yellow propolis (EEYP) rich in triterpenoids, primarily lupeol and β-amyrin. Male Wistar rats, 3 months old, were intraperitoneally treated with Tween 5% (control), EEYP (1, 3, 10, and 30 mg/kg), or diazepam, fluoxetine, and caffeine (positive controls) 30 min before the assays. Animals were submitted to open field, elevated plus maze, forced swimming, and inhibitory avoidance tests. After behavioral tasks, blood samples were collected through intracardiac pathway, to evaluate the oxidative balance. The results obtained in the open field and in the elevated plus maze assay showed spontaneous locomotion preserved and anxiolytic-like activity. In the forced swimming test, EEYP demonstrated antidepressant-like activity. In the inhibitory avoidance test, EEYP showed mnemonic activity at 30 mg/kg. In the evaluation of oxidative biochemistry, the extract reduced the production of nitric oxide and malondialdehyde without changing level of total antioxidant, catalase, and superoxide dismutase, induced by behavioral stress. Our results highlight that EEYP emerges as a promising anxiolytic, antidepressant, mnemonic, and antioxidant natural product.

Online Measurement of Real-Time Cytotoxic Responses Induced by Multi-Component Matrices, such as Natural Products, through Electric Cell-Substrate Impedance Sensing (ECIS)

Natural products are complex matrices of compounds that are prone to interfere with the label-dependent methods that are typically used for cytotoxicity screenings. Here, we developed a label-free Electric Cell-substrate Impedance Sensing (ECIS)-based cytotoxicity assay that can be applied in the assessment of the cytotoxicity of natural extracts. The conditions to measure the impedance using ECIS were first optimized in mice immortalized hypothalamic neurons GT1-7 cells. The performance of four natural extracts when tested using three conventional cytotoxicity assays in GT1-7 cells, was studied. Betula pendula (silver birch tree) was found to interfere with all of the cytotoxicity assays in which labels were applied. The silver birch extract was also proven to be cytotoxic and, thus, served as a proof-of-concept for the use of ECIS. The extract was fractionated and the ECIS method permitted the distinction of specific kinetic patterns of cytotoxicity on the fractions as well as the extract’s pure constituents. This study offers evidence that ECIS is an excellent tool for real-time monitoring of the cytotoxicity of complex extracts that are difficult to work with using conventional (label-based) assays. Altogether, it offers a very suitable cytotoxicity-screening assay making the work with natural products less challenging within the drug discovery workflow.

Preserving neural retina through re-emerging herbal interventions

Eye related diseases such as glaucoma, diabetic retinopathy, cataract, conjunctivitis are very common worldwide. With the current scenario India will be among the top five countries in the number of glaucoma cases. Limited discovery of successful drugs for the treatment of such diseases led scientists to look towards the use of conventional sources for treatment. Herbal extracts from Ayurveda have remained an important part of treatment regime in many parts of world even today. For this reason, local herbs possessing curative properties are still being used by local inhabitants due to its anti-inflammatory and antioxidant properties. Because retinal damage involves alterations in oxidative enzymes, blood flow changes and increase in apoptotic signals, herbal extracts are being tested for their ability to moderate antioxidant machinery and trigger neuroprotective pathways. The present review summarizes some of such herbal extracts which have been tested for their neuroprotective role in eye related diseases. The active components that exert neuroprotective effects have also been discussed along with possible mechanisms of action.

Comparisons of ethanol extracts of chinese propolis (poplar type) and poplar gums based on the antioxidant activities and molecular mechanism

The biological activities of propolis are varied from plant sources and the prominent antioxidant effects of Chinese propolis (poplar type) have been extensively reported. Oxidative stress is associated with inflammation and induces many diseases. In the study, to evaluate antioxidant capacities and clarify the underlying molecular mechanisms of ethanol extracts of Chinese propolis (EECP) and ethanol extracts of poplar gums (EEPG), we analyzed their compositions by HPLC, evaluating their free radical scavenging activities and reducing power by chemical analysis methods. Moreover, we studied the roles of EECP and EEPG on the elimination of ROS and expressions of antioxidant genes (HO-1, TrxR1, GCLM, and GCLC) in RAW264.7 cells. We further investigated the effects of MAPKs on the antioxidant genes expression by specific inhibitors. The nucleus translocation effects of Nrf2 were also measured by confocal microscopy analysis. The results indicated that EECP had higher TPC and FDC values but regarding TFC values were not significant. EECP also possessed more contents of 11 compounds than EEPG. Both phytochemical analysis and cell experiment reflected that EECP exerted stronger antioxidant activities than EEPG. EECP and EEPG enhanced endogenous antioxidant defenses by eliminating reactive oxygen species directly and activating Erk-Nrf2-HO1, GCLM, and TrxR1 signal pathways.

Antidepressant- and anxiolytic-like activities of an oil extract of propolis in rats

PURPOSE

Propolis biological effects are mainly attributed to its polyphenolic constituents such as flavonoids and phenolic acids that were recently described in the chemical composition of an extract of propolis obtained with edible vegetal oil (OEP) by our group. The aim of this study was to evaluate the effect of OEP on the behavior of rats.

MATERIALS AND METHODS

An in vivo open field (OF), elevated Plus-maze (EPM), and forced swimming (FS) tests were performed to evaluate locomotor activity, anxiolytic- and antidepressant effects of the extract. Besides, oxidative stress levels were measured in rat blood samples after the behavioral assays by evaluation of the Trolox equivalent antioxidant capacity (TEAC) and nitric oxide levels.

RESULTS

OEP increased locomotion in the OF test (50mg/kg) and central locomotion and open arm entries in the OF and EPM tests (10-50mg/kg) and decreased the immobility time in the FS test (10-50mg/kg). Moreover, OEP reduced nitric oxide levels in response to swim stress induced in rats.

CONCLUSION

OEP exerted stimulant, anxiolytic and antidepressant effects on the Central Nervous System and antioxidant activity in rats, highlighting propolis as a potential therapeutic compound for behavior impairment of anxiety and depression.

Topical Brazilian propolis improves corneal wound healing and inflammation in rats following alkali burns

Background

The objective of this study was to investigate the effects of the Brazilian Scaptotrigona sp propolis, a widely used folk medicine, in corneal wound healing and inflammation.

Methods

Corneal epithelial defects of 1 mm in diameter were made in the right eyes of Wistar male adult rats by cauterization with silver nitrate sticks. Subsequently, they were divided in two groups (n = 40 rats/group): Brazilian propolis (BP) group was topically treated with a microemulsion containing 1% Brazilian propolis; vehicle (VH) group received the same formulation without propolis. The epithelial defect area was photographed and measured at t = 0 (wound induction), and after 12, 24, 48 and 120 h of treatment. The inflammatory response was evaluated based on counting of neutrophils. Epithelial regeneration rates were determined based on Ki-67 expression in basal epithelial cells. Comparisons were made using the Kruskal-Wallis and the Mann–Whitney U test.

Results

The BP group presented both smaller epithelial defect areas at 12, 24 and 48 h and fewer corneal infiltrating neutrophils at 24 and 48 h (P < 0.01) than the VH group. These effects were associated with more pervasive Ki-67 staining in the BP group at 12 and 24 h (P < 0.05).

Conclusions

Topically applied BP accelerated wound healing and reduced the inflammatory response to silver nitrate-induced corneal alkali burns in rats.

Neuroprotective effect of Danshensu derivatives as anti-ischaemia agents on SH-SY5Y cells and rat brain

Novel Danshensu derivatives (3–8) were designed and synthesized to improve bioactivity based on the strategy of ‘medicinal chemical hybridization’. Our previous studies indicated that these compounds exhibited noticeable cardioprotective activities. Here, we investigate whether these novel Danshensu derivatives exert neuroprotective activities. An in vitro study revealed that these compounds could increase cell viability and reduce LDH (lactate dehydrogenase) leakage. Moreover, Danshensu-cysteine derivative compounds 6 and 8 could significantly inhibit lipid peroxidation of cell membrane and regulate the expression of apoptosis-related protein (Bcl-2, Bax and caspase 3). An in vivo study demonstrated that treatment with compound 6 at 30 mg/kg markedly decreased the infarct volume of MCAO (middle cerebral artery occlusion) insulted rat brain. Furthermore, treatment with compound 6 showed the antioxidant capacity by increasing the activity of SOD (superoxide dismutase) and GPx (glutathione peroxidase) and decreasing the level of MDA (malondialdehyde) and the ROS (reactive oxygen species) production significantly. These results suggested that these novel conjugates exert significant neuroprotective effects as anti-ischaemia agents and those with high potential merit further investigation.

Green brazilian propolis action on macrophages and lymphoid organs of chronically stressed mice

Stress is a generic term that summarizes how psychosocial and environmental factors influence physical and mental well-being. The interaction between stress and immunity has been widely investigated, involving the neuroendocrine system and several organs. Assays using natural products in stress models deserve further investigation. Propolis immunomodulatory action has been mentioned and it has been the subject of scientific investigation in our laboratory. The aim of this study was to evaluate if and how propolis activated macrophages in BALB/c mice submitted to immobilization stress, as well as the histopathological analysis of the thymus, bone marrow, spleen and adrenal glands. Stressed mice showed a higher hydrogen peroxide (H(2)O(2)) generation by peritoneal macrophages, and propolis treatment potentiated H(2)O(2) generation and inhibited nitric oxide (NO) production by these cells. Histopathological analysis showed no alterations in the thymus, bone marrow and adrenal glands, but increased germinal centers in the spleen. Propolis treatment counteracted the alterations found in the spleen of stressed mice. New research is being carried out in order to elucidate propolis immunomodulatory action during stress.

Novel antidepressant-like activity of propolis extract mediated by enhanced glucocorticoid receptor function in the hippocampus

Propolis is a natural product made by honeybees that has been widely used in folk medicine with a broad spectrum of biological activities. To investigate the antidepressant-like activity of propolis extract, CD-1 mice were administered an ethanol extract of propolis (50, 100, or 200 mg/kg, p.o.) prior to the behavioral test. The propolis extract-treated group showed a dose-dependent decrease in immobility time in the FST and tail suspension test without altering locomotor activity. Propolis extract decreased the limbic hypothalamic-pituitary-adrenal axis response to the FST as indicated by an attenuated corticosterone response and decreased in c-fos immunoreactive neurons in the hippocampal dentate gyrus. Western blot analysis revealed a reduction in hippocampal glucocorticoid receptor (GR) expression following the FST, which was reversed by propolis extract. Propolis extract also increased pGR(S220)/(S234) ratio by a differential phosphorylation in S220 and S234. FST-induced downregulation of cAMP-responsive element binding protein phosphorylation at S133 (pCREB) was restored by propolis extract, showing a strong and positive relationship between pCREB and pGR(S220)/(S234) ratio. These findings suggest that the propolis extract potentiates antidepressant-like activity by enhancing GR function which is one of the therapeutic mechanisms of antidepressant; thus, propolis extract may provide a novel therapy for depression.

Traditional and modern uses of natural honey in human diseases: a review

Honey is a by-product of flower nectar and the upper aero-digestive tract of the honey bee, which is concentrated through a dehydration process inside the bee hive. Honey has a very complex chemical composition that varies depending on the botanical source. It has been used both as food and medicine since ancient times. Human use of honey is traced to some 8000 years ago as depicted by Stone Age paintings. In addition to important role of natural honey in the traditional medicine, during the past few decades, it was subjected to laboratory and clinical investigations by several research groups and it has found a place in modern medicine. Honey has been reported to have an inhibitory effect on around 60 species of bacteria, some species of fungi and viruses. Antioxidant capacity of honey is important in many disease conditions and is due to a wide range of compounds including phenolics, peptides, organic acids, enzymes, and Maillard reaction products. Honey has also been used in some gastrointestinal, cardiovascular, inflammatory and neoplastic states. This review covers the composition, physico-chemical properties and the most important uses of natural honey in human diseases.

A sigma-1 receptor antagonist (NE-100) prevents tunicamycin-induced cell death via GRP78 induction in hippocampal cells

Endoplasmic reticulum (ER) stress is involved in various diseases such as ischemia, Alzheimer's disease, and Parkinson's disease. The widely used selective sigma-1 receptor antagonist, N, N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)-phenyl]-ethylamine monohydrochloride (NE-100), has been shown to suppress ischemia-induced neuronal cell death in the murine hippocampus. In the present study, we investigated whether NE-100 might suppress neuronal cell death that is induced by ER stress in ischemic injury. These studies show that NE-100 protected the ER stress-induced cell death of murine hippocampal HT22 cells, but not the oxidative stress-induced cell death. This suggests that NE-100 may have a protective effect on the ER. However, another sigma-1 receptor antagonist (BD1047) did not suppress ER stress-induced cell death. In addition, NE-100 attenuated the upregulation of C/EBP homologous protein (CHOP) induced by ER stress and upregulated the expression of both the 50-kDa activating transcription factor 6 (p50ATF6) and the 78-kDa glucose-regulated protein (GRP78). However, NE-100 did not impact the expression of phosphorylated eukaryotic initiation factor 2α (p-eIF2α) nor splicing of X-box-binding protein 1 (XBP-1). These findings suggest that NE-100 suppresses ER stress-induced cell death via CHOP expression by the upregulation of GRP78 through ATF6 pathway, independent sigma-1 receptor antagonist effect.

Propolis changes the anticancer activity of temozolomide in U87MG human glioblastoma cell line

BACKGROUND

Propolis is a honey bee product which contains many active compounds, such as CAPE or chrysin, and has many beneficial activities. Recently, its anti-tumor properties have been discussed. We have tested whether the ethanolic extract of propolis (EEP) interferes with temozolomide (TMZ) to inhibit U87MG cell line growth.

METHODS

The U87MG glioblastoma cell line was exposed to TMZ (10-100 μM), EEP (10-100 μg/ml) or a mixture of TMZ and EEP during 24, 48 or 72 hours. The cell division was examined by the H3-thymidine incorporation, while the western blot method was used for detection of p65 subunit of NF-κB and ELISA test to measure the concentration of its p50 subunit in the nucleus.

RESULTS

We have found that both, TMZ and EEP administrated alone, had a dose- and time-dependent inhibitory effect on the U87MG cell line growth, which was manifested by gradual reduction of cell viability and alterations in proliferation rate. The anti-tumor effect of TMZ (20 μM) was enhanced by EEP, which was especially well observed after a short time of exposition, where simultaneous usage of TMZ and EEP resulted in a higher degree of growth inhibition than each biological factor used separately. In addition, cells treated with TMZ presented no changes in NF-κB activity in prolonged time of treatment and EEP only slightly reduced the nuclear translocation of this transcription factor. In turn, the combined incubation with TMZ and EEP led to an approximately double reduction of NF-κB nuclear localization.

CONCLUSIONS

We conclude that EEP presents cytotoxic properties and may cooperate with TMZ synergistically enhancing its growth inhibiting activity against glioblastoma U87MG cell line. This phenomenon may be at least partially mediated by a reduced activity of NF-κB.

Spices: the savory and beneficial science of pungency

Spicy food does not only provide an important hedonic input in daily life, but has also been anedoctically associated to beneficial effects on our health. In this context, the discovery of chemesthetic trigeminal receptors and their spicy ligands has provided the mechanistic basis and the pharmacological means to investigate this enticing possibility. This review discusses in molecular terms the connection between the neurophysiology of pungent spices and the "systemic" effects associated to their trigeminality. It commences with a cultural and historical overview on the Western fascination for spices, and, after analysing in detail the mechanisms underlying the trigeminality of food, the main dietary players from the transient receptor potential (TRP) family of cation channels are introduced, also discussing the "alien" distribution of taste receptors outside the oro-pharingeal cavity. The modulation of TRPV1 and TRPA1 by spices is next described, discussing how spicy sensations can be turned into hedonic pungency, and analyzing the mechanistic bases for the health benefits that have been associated to the consumption of spices. These include, in addition to a beneficial modulation of gastro-intestinal and cardio-vascular function, slimming, the optimization of skeletal muscle performance, the reduction of chronic inflammation, and the prevention of metabolic syndrome and diabetes. We conclude by reviewing the role of electrophilic spice constituents on cancer prevention in the light of their action on pro-inflammatory and pro-cancerogenic nuclear factors like NFκB, and on their interaction with the electrophile sensor protein Keap1 and the ensuing Nrf2-mediated transcriptional activity. Spicy compounds have a complex polypharmacology, and just like any other bioactive agent, show a balance of beneficial and bad actions. However, at least for moderate consumption, the balance seems definitely in favour of the positive side, suggesting that a spicy diet, a caveman-era technology, could be seriously considered in addition to caloric control and exercise as a measurement to prevent and control many chronic diseases associate to malnutrition from a Western diet.

Brazilian green propolis: anti-inflammatory property by an immunomodulatory activity

The immunomodulatory and anti-inflammatory activities of green propolis extracts from Apis mellifera were investigated using acute and chronic inflammation models. Swiss mice were anesthetized and a cotton pellet granuloma was implanted in subcutaneous tissue. Then the mice were divided into six groups and received apyrogenic water or different propolis extracts by oral route (5 mg/kg). According to the treatment the groups were designated as E1A, E1B, E10, E11, and E12. The control group received apyrogenic water. The treatment was performed by six days when the mice were killed. The blood and the bronchoalveolar lavage (BAL) were collected to measure the leukocyte recruitment. In acute pulmonary inflammation, Balb/c mice received lipopolysaccharide (LPS) of Escherichia coli by intranasal route for three days. Concomitantly the mice received by oral route apyrogenic water (control) or E10 and E11 propolis extracts. BAL was performed to assess the inflammatory infiltrate and cytokine quantification. The results showed that the E11 extract has anti-inflammatory property in both models by the inhibition of proinflammatory cytokines and increase of anti-inflammatory cytokines suggesting an immunomodulatory activity.

The role of bioactive compounds on the promotion of neurite outgrowth

Neurite loss is one of the cardinal features of neuronal injury. Apart from neuroprotection, reorganization of the lost neuronal network in the injured brain is necessary for the restoration of normal physiological functions. Neuritogenic activity of endogenous molecules in the brain such as nerve growth factor is well documented and supported by scientific studies which show innumerable compounds having neurite outgrowth activity from natural sources. Since the damaged brain lacks the reconstructive capacity, more efforts in research are focused on the identification of compounds that promote the reformation of neuronal networks. An abundancy of natural resources along with the corresponding activity profiles have shown promising results in the field of neuroscience. Recently, importance has also been placed on understanding neurite formation by natural products in relation to neuronal injury. Arrays of natural herbal products having plentiful active constituents have been found to enhance neurite outgrowth. They act synergistically with neurotrophic factors to promote neuritogenesis in the diseased brain. Therefore use of natural products for neuroregeneration provides new insights in drug development for treating neuronal injury. In this study, various compounds from natural sources with potential neurite outgrowth activity are reviewed in experimental models.

Green propolis phenolic compounds act as vaccine adjuvants, improving humoral and cellular responses in mice inoculated with inactivated vaccines

Adjuvants play an important role in vaccine formulations by increasing their immunogenicity. In this study, the phenolic compound-rich J fraction (JFR) of a Brazilian green propolis methanolic extract stimulated cellular and humoral immune responses when co-administered with an inactivated vaccine against swine herpesvirus type 1 (SuHV-1). When compared to control vaccines that used aluminium hydroxide as an adjuvant, the use of 10 mg/dose of JFR significantly increased (p < 0.05) neutralizing antibody titres against SuHV-1, as well as the percentage of protected animals following SuHV-1 challenge (p < 0.01). Furthermore, addition of phenolic compounds potentiated the performance of the control vaccine, leading to increased cellular and humoral immune responses and enhanced protection of animals after SuHV-1 challenge (p < 0.05). Prenylated compounds such as Artepillin C that are found in large quantities in JFR are likely to be the substances that are responsible for the adjuvant activity.

Pharmacodynamic and Pharmacokinetic Interactions of Propranolol with Garlic (Allium sativum) in Rats

Garlic preparations and propranolol (PRO) are agents recognized as cardioprotective and potent antihypertensive agents when they are used individually. However, there is no report available to explain the role of combined therapy during simultaneous hypertension and myocardial damage in rats. We aimed to determine the pharmacokinetic and pharmacodynamic interaction of PRO with garlic homogenate (GH), in rats. The influence of garlic on pharmacokinetics of PRO was determined by HPLC method; while pharmacodynamic interaction was studied in animals with hypertension (10% fructose) and myocardial damage (isoproterenol, 175 mg kg(-1), s.c. 2 days). PRO was given orally at 10 mg kg(-1) for 1 week, whereas, GH was administered at three different doses of 125, 250 and 500 mg kg(-1), p.o. in their respective groups during fourth to sixth week of high fructose (HF) period, once daily. Systolic blood pressure (SBP), heart rate, cholesterol, triglycerides, glucose, creatine phosphokinase-MB, lactate dehydrogenase, superoxide dismutase and catalase were measured and histopathological studies were carried out. The bioavailability and half life of PRO were significantly enhanced by 2- and 3-fold, respectively, in animals pretreated with garlic (250 mg kg(-1)). Administration of PRO and low to moderate doses of GH (125, 250 mg kg(-1)), either alone or together showed fall in fluid intake and body weight. The combined therapy of GH 250 mg kg(-1) and PRO was found to be most effective in reducing SBP, cholesterol, triglycerides and glucose. These observations suggest that careful addition of garlic in moderate doses in PRO regimen might result in beneficial effect during treatment of hypertensive animals with myocardial damage.

Therapeutic effects of propolis essential oil on anxiety of restraint-stressed mice

Propolis has a broad spectrum of biological activities; however, whether its essential oils have neuroprotective effects is unknown. In this study, we found that propolis essential oil (PEO) could significantly reverse the anxiety-like behavior of restraint-stressed mice, and has no effect on locomotor activity. Furthermore, PEO significantly decreased the plasma levels of cortisol (CORT), adrenocorticotropic hormone (ACTH) and malondialdehyde (MDA), whereas it increased the activity of superoxide dismutase (SOD) in restraint-stressed mice. These results strongly suggest that PEO has therapeutic effects on anxiety through antagonizing the hyperfunction of hypothalamic-pituitary-adrenal (HPA) axis and improving the ability of antioxidation in brain tissue.

Aqueous extract of brazilian green propolis: primary components, evaluation of inflammation and wound healing by using subcutaneous implanted sponges

Propolis is a chemically complex resinous bee product which has gained worldwide popularity as a means to improve health condition and prevent diseases. The main constituents of an aqueous extract of a sample of green propolis from Southeast Brazil were shown by high performance liquid chromatography/mass spectroscopy/mass spectroscopy to be mono- and di-O-caffeoylquinic acids; phenylpropanoids known as important constituents of alcohol extracts of green propolis, such as artepillin C and drupanin were also detected in low amounts in the aqueous extract. The anti-inflammatory activity of this extract was evaluated by determination of wound healing parameters. Female Swiss mice were implanted subcutaneously with polyesther-polyurethane sponge discs to induce wound healing responses, and administered orally with green propolis (500 mg kg(-1)). At 4, 7 and 14 days post-implantation, the fibrovascular stroma and deposition of extracellular matrix were evaluated by histopathologic and morphometric analyses. In the propolis-treated group at Days 4 and 7 the inflammatory process in the sponge was reduced in comparison with control. A progressive increase in cell influx and collagen deposition was observed in control and propolis-treated groups during the whole period. However, these effects were attenuated in the propolis-treated group at Days 4 and 7, indicating that key factors of the wound healing process are modulated by propolis constituents.

The neuroprotective effect of methanol extract of gagamjungjihwan and fructus euodiae on ischemia-induced neuronal and cognitive impairment in the rat

Gagamjungjihwan (GJ), a decoction consisting of five herbs including ginseng, Acori Graminei Rhizoma, Uncariae Ramulus et Uncus, Polygalae Radic and Frustus Euodiae (FE), has been widely used as herbal treatment for ischemia. In order to investigate the neuroprotective action of this novel prescription, we examined the influence of GJ and FE on learning and memory using the Morris water maze and studied their affects on the central cholinergic system in the hippocampus with neuronal and cognitive impairment. After middle cerebral artery occlusion was applied for 2 h, rats were administered GJ (200 mg kg(-1), p.o.) or FE (200 mg kg(-1), p.o.) daily for 2 weeks, followed by training and performance of the Morris water maze tasks. Rats with ischemic insults showed impaired learning and memory of the tasks. Pre-treatment with GJ and FE produced improvement in the escape latency to find the platform. Pre-treatments with GJ and FE also reduced the loss of cholinergic immunoreactivity in the hippocampus. The results demonstrated that GJ and FE have a protective effect against ischemia-induced neuronal and cognitive impairment. Our results suggest that GJ and FE might be useful in the treatment of vascular dementia.

Molecular characterization of propolis-induced cell death in Saccharomyces cerevisiae

Propolis, a natural product of plant resins, is used by the bees to seal holes in their honeycombs and protect the hive entrance. However, propolis has also been used in folk medicine for centuries. Here, we apply the power of Saccharomyces cerevisiae as a model organism for studies of genetics, cell biology, and genomics to determine how propolis affects fungi at the cellular level. Propolis is able to induce an apoptosis cell death response. However, increased exposure to propolis provides a corresponding increase in the necrosis response. We showed that cytochrome c but not endonuclease G (Nuc1p) is involved in propolis-mediated cell death in S. cerevisiae. We also observed that the metacaspase YCA1 gene is important for propolis-mediated cell death. To elucidate the gene functions that may be required for propolis sensitivity in eukaryotes, the full collection of about 4,800 haploid S. cerevisiae deletion strains was screened for propolis sensitivity. We were able to identify 138 deletion strains that have different degrees of propolis sensitivity compared to the corresponding wild-type strains. Systems biology revealed enrichment for genes involved in the mitochondrial electron transport chain, vacuolar acidification, negative regulation of transcription from RNA polymerase II promoter, regulation of macroautophagy associated with protein targeting to vacuoles, and cellular response to starvation. Validation studies indicated that propolis sensitivity is dependent on the mitochondrial function and that vacuolar acidification and autophagy are important for yeast cell death caused by propolis.

An antioxidant phytotherapy to rescue neuronal oxidative stress

Oxidative stress is involved in the pathogenesis of ischemic neuronal injury. A Chinese herbal formula composed of Poria cocos (Chinese name: Fu Ling), Atractylodes macrocephala (Chinese name: Bai Zhu) and Angelica sinensis (Chinese names: Danggui, Dong quai, Donggui; Korean name: Danggwi) (FBD), has been proved to be beneficial in the treatment of cerebral ischemia/reperfusion (I/R).This study was carried out to evaluate the protective effect of FBD against neuronal oxidative stress in vivo and in vitro. Rat I/R were established by middle cerebral artery occlusion (MCAO) for 1 h, followed by 24 h reperfusion. MCAO led to significant depletion in superoxide dismutase and glutathione and rise in lipid peroxidation (LPO) and nitric oxide in brain. The neurological deficit and brain infarction were also significantly elevated by MCAO as compared with sham-operated group. All the brain oxidative stress and damage were significantly attenuated by 7 days pretreatment with the aqueous extract of FBD (250 mg kg(-1), p.o.). Moreover, cerebrospinal fluid sampled from FBD-pretreated rats protected PC12 cells against oxidative insult induced by 0.2 mM hydrogen peroxide, in a concentration and time-dependent manner (IC(50) 10.6%, ET(50) 1.2 h). However, aqueous extract of FBD just slightly scavenged superoxide anion radical generated in xanthine-xanthine oxidase system (IC(50) 2.4 mg ml(-1)) and hydroxyl radical generated in Fenton reaction system (IC(50) 3.6 mg ml(-1)). In conclusion, FBD was a distinct antioxidant phytotherapy to rescue neuronal oxidative stress, through blocking LPO, restoring endogenous antioxidant system, but not scavenging free radicals.

Inhibitors of microglial neurotoxicity: focus on natural products

Microglial cells play a dual role in the central nervous system as they have both neurotoxic and neuroprotective effects. Uncontrolled and excessive activation of microglia often contributes to inflammation-mediated neurodegeneration. Recently, much attention has been paid to therapeutic strategies aimed at inhibiting neurotoxic microglial activation. Pharmacological inhibitors of microglial activation are emerging as a result of such endeavors. In this review, natural products-based inhibitors of microglial activation will be reviewed. Potential neuroprotective activity of these compounds will also be discussed. Future works should focus on the discovery of novel drug targets that specifically mediate microglial neurotoxicity rather than neuroprotection. Development of new drugs based on these targets may require a better understanding of microglial biology and neuroinflammation at the molecular, cellular, and systems levels.

San-Huang-Xie-Xin-Tang Protects against Activated Microglia- and 6-OHDA-Induced Toxicity in Neuronal SH-SY5Y Cells

San-Huang-Xie-Xin-Tang (SHXT), composed of Coptidis rhizoma, Scutellariae radix and Rhei rhizoma, is a traditional Chinese herbal medicine used to treat gastritis, gastric bleeding and peptic ulcers. This study investigated the neuroprotective effects of SHXT on microglia-mediated neurotoxicity using co-cultured lipopolysaccharide (LPS)-activated microglia-like BV-2 cells with neuroblastoma SH-SY5Y cells. Effects of SHXT on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity were also examined in SH-SY5Y cells. Results indicated SHXT inhibited LPS-induced inflammation of BV-2 cells by downregulation of iNOS, NO, COX-2, PGE₂, gp91^phox, iROS, TNF-α, IL-1β, inhibition of IκBα degradation and upregulation of HO-1. In addition, SHXT increased cell viability and down regulated nNOS, COX-2 and gp91^phox of SH-SY5Y cells co-cultured with LPS activated BV-2 cells. SHXT treatment increased cell viability and mitochondria membrane potential (MMP), decreased expression of nNOS, COX-2, gp91^phox and iROS, and inhibited IκBα degradation in 6-OHDA-treated SH-SY5Y cells. SHXT also attenuated LPS activated BV-2 cells- and 6-OHDA-induced cell death in differentiated SH-SY5Y cells with db-cAMP. Furthermore, SHXT-inhibited nuclear translocation of p65 subunit of NF-κB in LPS treated BV-2 cells and 6-OHDA treated SH-SY5Y cells. In conclusion, SHXT showed protection from activated microglia- and 6-OHDA-induced neurotoxicity by attenuating inflammation and oxidative stress.