Juan L. Hancke

Schisandra chinensis (Turcz.) Baill

Different aspects of the pharmacology of Schisandra chinensis fruit and dibenzo- wx a,c cyclooctene lignans from this plant are reviewed focusing in particular on the antihepa- totoxic, antioxidant and antitumoural activities, and on the effects on physical performance and on the central nervous system. Q 1999 Elsevier Science B.V. All rights reserved.

Andrographolide interferes with binding of nuclear factor-κB to DNA in HL-60-derived neutrophilic cells

1 Andrographolide, the major active component from Andrographis paniculata, has shown to possess anti‐inflammatory activity. Andrographolide inhibits the expression of several proinflammatory proteins that exhibit a nuclear factor kappa B (NF‐κB) binding site in their gene. 2 In the present study, we analyzed the effect of andrographolide on the activation of NF‐κB induced by platelet‐activating factor (PAF) and N‐formyl‐methionyl‐leucyl‐phenylalanine (fMLP) in HL‐60 cells differentiated to neutrophils. 3 PAF (100 nM) and fMLP (100 nM) induced activation of NF‐κB as determined by degradation of inhibitory factor B α (IκBα) using Western blotting in cytosolic extracts and by binding to DNA using electrophoretic mobility shift assay (EMSA) in nuclear extracts. 4 Andrographolide (5 and 50 μM) inhibited the NF‐κB‐luciferase activity induced by PAF. However, andrographolide did not reduce phosphorylation of p38 MAPK or ERK1/2 and did not change IκBα degradation induced by PAF and fMLP. 5 Andrographolide reduced the DNA binding of NF‐κB in whole cells and in nuclear extracts induced by PAF and fMLP. 6 Andrographolide reduced cyclooxygenase‐2 (COX‐2) expression induced by PAF and fMLP in HL‐60/neutrophils. 7 It is concluded that andrographolide exerts its anti‐inflammatory effects by inhibiting NF‐κB binding to DNA, and thus reducing the expression of proinflammatory proteins, such as COX‐2.

Hyperforin prevents β -amyloid neurotoxicity and spatial memory impairments by disaggregation of Alzheimer's amyloid- β -deposits

The major protein constituent of amyloid deposits in Alzheimers disease (AD) is the amyloid β-peptide (Aβ). In the present work, we have determined the effect of hyperforin an acylphloroglucinol compound isolated from Hypericum perforatum (St Johns Wort), on Aβ-induced spatial memory impairments and on Aβ neurotoxicity. We report here that hyperforin: (1) decreases amyloid deposit formation in rats injected with amyloid fibrils in the hippocampus; (2) decreases the neuropathological changes and behavioral impairments in a rat model of amyloidosis; (3) prevents Aβ-induced neurotoxicity in hippocampal neurons both from amyloid fibrils and Aβ oligomers, avoiding the increase in reactive oxidative species associated with amyloid toxicity. Both effects could be explained by the capacity of hyperforin to disaggregate amyloid deposits in a dose and time-dependent manner and to decrease Aβ aggregation and amyloid formation. Altogether these evidences suggest that hyperforin may be useful to decrease amyloid burden and toxicity in AD patients, and may be a putative therapeutic agent to fight the disease.

Testicular toxicity assesment of Andrographis paniculata dried extract in rats

The possible testicular toxicity of Andrographis paniculata, Nees (Acanthaceae) standardized dried extract was evaluated in male Sprague Dawley rats for 60 days. No testicular toxicity was found with the treatment of 20, 200 and 1000 mg/kg during 60 days as evaluated by reproductive organ weight, testicular histology, ultrastructural analysis of Leydig cells and testosterone levels after 60 days of treatment. It is concluded that Andrographis paniculata dried extract did not produce subchronic testicular toxicity effect in male rats.

Hypoglycemic effect of lupin seed γ-conglutin in experimental animals and healthy human subjects

A lupin seed γ-conglutin-enriched preparation was tested in a glucose overload trial with both murine models and adult healthy volunteers. The results with rats showed a dose-dependent significant decrease of blood glucose concentration, which confirmed previous findings obtained with the purified protein. Moreover, three test-product doses equivalent to 630, 315, and 157.5 mg γ-conglutin, orally administered 30 min before the carbohydrate supply, showed a relevant hypoglycemic effect in human trials. Insulin concentrations were not significantly affected. The general hematic parameters did not change at all. This is the first report on the glucose-lowering effect of lupin γ-conglutin in human subjects.

Andrographolide reduces IL-2 production in T-cells by interfering with NFAT and MAPK activation

The nuclear factor of activated T cells (NFAT) is a transcription factor essential for cytokine production during T-cell activation and is the target of several immunosuppressive drugs. Andrographolide is a diterpenic labdane that possesses anti-inflammatory and immunomodulatory effects. Several studies propose that andrographolide can reduce the immune response through inhibition of the nuclear factor kappa B (NF-kappaB) and mitogen-activated protein kinases (MAPK) such as extracellular signal regulated kinase 1/2 (ERK1/2) pathways. Moreover, andrographolide reduces IFN-gamma and IL-2 production induced by concanavalin A in murine T-cell. Nevertheless, the mechanisms involved in the decrease of cytokine production are unknown. In the present study, we determined that andrographolide reduced IL-2 production in Jurkat cells stimulated with phorbol myristate acetate and ionomycin (PMA/Ionomycin). We then showed that andrographolide reduced NFAT luciferase activity and interfered with its nuclear distribution, with these effects being linked to an increase in c-jun-N-terminal kinase (JNK) phosphorylation. Additionally, reduction of NF-kappaB activity in Jurkat cells treated with andrographolide was observed. Using Western blotting, we demonstrated that andrographolide decreased ERK1 and ERK5 phosphorylation induced by anti-CD3 or PMA/Ionomycin. Andrographolide did not affect cell viability at concentration of 10 and 50 muM; however, our results suggest that andrographolide increase early apoptosis at 100 muM. We concluded that andrographolide can exert immunomodulatory effects by interfering with NFAT activation and ERK1 and ERK5 phosphorylation in T-cells.

Tetrahydrohyperforin prevents cognitive deficit, Aβ deposition, tau phosphorylation and synaptotoxicity in the APPswe/PSEN1ΔE9 model of Alzheimer's disease: a possible effect on APP processing

Alzheimers disease (AD) is a neurodegenerative disorder characterized by a progressive deterioration of cognitive abilities, amyloid-β peptide (Aβ) accumulation and synaptic alterations. Previous studies indicated that hyperforin, a component of the St Johns Wort, prevents Aβ neurotoxicity and some behavioral impairments in a rat model of AD. In this study we examined the ability of tetrahydrohyperforin (IDN5607), a stable hyperforin derivative, to prevent the cognitive deficit and synaptic impairment in an in vivo model of AD. In double transgenic APPswe/PSEN1ΔE9 mice, IDN5706 improves memory and prevents the impairment of synaptic plasticity in a dose-dependent manner, inducing a recovery of long-term potentiation. In agreement with these findings, IDN5706 prevented the decrease in synaptic proteins in hippocampus and cortex. In addition, decreased levels of tau hyperphosphorylation, astrogliosis, and total fibrillar and oligomeric forms of Aβ were determined in double transgenic mice treated with IDN5706. In cultured cells, IDN5706 decreased the proteolytic processing of the amyloid precursor protein that leads to Aβ peptide generation. These findings indicate that IDN5706 ameliorates AD neuropathology and could be considered of therapeutic relevance in AD treatment.

Store-operated calcium entry mediates intracellular alkalinization, ERK1/2, and Akt/PKB phosphorylation in bovine neutrophils

Neutrophil’s responses to G protein‐coupled chemoattractants are highly dependent on store‐operated calcium (Ca2+) entry (SOCE). Platelet‐activating factor (PAF), a primary chemoattractant, simultaneously increases cytosolic‐free Ca2+, intracellular pH (pHi), ERK1/2, and Akt/protein kinase B (PKB) phosphorylation. In this study, we looked at the efficacy of several putative SOCE inhibitors and whether SOCE mediates intracellular alkalinization, ERK1/2, and Akt/PKB phosphorylation in bovine neutrophils. We demonstrated that the absence of external Ca2+ and the presence of EGTA reduced the intracellular alkalinization and ERK1/2 phosphorylation induced by PAF, apparently via SOCE influx inhibition. Next, we tested the efficacy of several putative SOCE inhibitors such as 2‐aminoethoxydiphenyl borate (2‐APB), capsaicin, flufenamic acid, 1‐{β‐[3‐(4‐methoxy‐phenyl)propoxy]‐4‐methoxyphenethyl}‐1H‐imidazole hydrochloride (SK&F 96365), and N‐(4‐[3,5‐bis(trifluoromethyl)‐1H‐pyrazol‐1‐yl]phenyl)‐4‐methyl‐1,2,3‐thiadiazole‐5‐carboxamide (BTP2) on Ca2+ entry induced by PAF or thapsigargin. 2‐APB was the most potent SOCE inhibitor, followed by capsaicin and flufenamic acid. Conversely, SK&F 96365 reduced an intracellular calcium ([Ca2+]i) peak but SOCE partially. BTP2 did not show an inhibitory effect on [Ca2+]i following PAF stimuli. 2‐APB strongly reduced the pHi recovery, whereas the effect of flufenamic acid and SK&F 96365 was partial. Capsaicin and BTP2 did not affect the pHi changes induced by PAF. Finally, we observed that 2‐APB reduced the ERK1/2 and Akt phosphorylation completely, whereas the inhibition with flufenamic acid was partial. The results suggest that 2‐APB is the most potent SOCE inhibitor and support a key role of SOCE in pH alkalinization and PI‐3K–ERK1/2 pathway control. Finally, 2‐APB could be an important tool to characterize Ca2+ signaling in neutrophils.

Andrographolide reduces cognitive impairment in young and mature AβPPswe/PS-1 mice

Alzheimer’s disease (AD) is a neurodegenerative disorder in which the amyloid-β (Aβ) oligomers are a key factor in synaptic impairment and in spatial memory decline associated with neuronal dysfunction. This impairment includes synaptic failure associated with the loss of synaptic proteins that contribute to AD progression. Interestingly, the use of natural compounds is an emergent conceptual strategy in the search for drugs with therapeutic potentials for treating neurodegenerative disorders. In the present study, we report that andrographolide (ANDRO), which is a labdane diterpene extracted from Andrographis paniculata, increases slope of field excitatory postsynaptic potentials (fEPSP) in the CA1 region of hippocampal slices and inhibits long-term depression (LTD), protecting the long-term potentiation (LTP) against the damage induced by Aβ oligomers in vitro, most likely by inhibiting glycogen synthase kinase-3β (GSK-3β). Additionally, ANDRO prevents changes in neuropathology in two different age groups (7- and 12-month-old mice) of an AβPPswe/PS-1 Alzheimer’s model. ANDRO reduces the Aβ levels, changing the ontogeny of amyloid plaques in hippocampi and cortices in 7-month-old mice, and reduces tau phosphorylation around the Aβ oligomeric species in both age groups. Additionally, we observed that ANDRO recovers spatial memory functions that correlate with protecting synaptic plasticity and synaptic proteins in two different age groups. Our results suggest that ANDRO could be used in a potential preventive therapy during AD progression.

Platelet-activating factor increases pH(i) in bovine neutrophils through the PI3K–ERK1/2 pathway

Platelet‐activating factor (PAF) is known to stimulate a variety of neutrophil activities, including chemotaxis, phagocytosis, degranulation, reactive oxygen species production and intracellular pH increase. The purpose of this study was to investigate the effect of PAF on pH(i), specifically if these changes in pH are the result of phosphatidylinositol 3‐kinase (PI3K) and mitogen‐activated protein kinase (MAPK) pathway activation in bovine neutrophils. PAF caused intracellular alkalinization in 2′,7′‐bis‐(2‐carboxyethyl)‐5‐(and‐6)‐carboxyfluorescein acetoxymethyl ester‐loaded bovine neutrophils. This phenomenon seems to be mediated by amiloride‐sensitive Na+/H+ exchange, and is inhibited by WEB2086 (a selective PAF receptor antagonist), genistein (a tyrosine kinase inhibitor), wortmannin and LY294002 (PI3K inhibitors), and PD98059 and UO126 (MEK inhibitors). PAF 100 nM induced an increase in tyrosine phosphorylation of proteins 62, 44 and 21 kDa with a maximum response at 2 min of incubation. Unlike human neutrophils, bovine neutrophils are strongly stimulated by PAF via phosphorylation of ERK1/2 (extracellular‐signal‐regulated protein kinase) with an EC50 of 30 and 13 nM, respectively. PAF MAPK activation was also inhibited by WEB2086, pertussis toxin (PTX), genistein, wortmannin, LY294002, PD98059 and UO126 in bovine neutrophils. The ERK1/2 activation is dependent on PI3K pathway, because protein kinase B was phosphorylated by PAF and inhibited by wortmannin and LY294002, but not by U0126. Our results suggest that PAF induces intracellular alkalinization via PI3K–MAPK activation. This effect is upstream regulated by PAF receptor, PTX‐sensitive G protein, tyrosine kinase, PI3K and MEK1/2 in bovine neutrophils.