Antihyperalgesic Activity of Quillaic Acid Obtained from Quillaja Saponaria Mol.

BACKGROUND: Quillaja saponaria Mol. bark contains a high concentration of triterpene saponins that have been used for centuries as a cleansing, antiinflammatory and analgesic agent in Chilean folk medicine. In earlier studies, in mice, both the anti-inflammatory as well as the antinociceptive effect of the major sapogenin, quillaic acid have been demonstrated (QA). OBJECTIVE: To determine the antihyperalgesic effect of QA one and seven days after itpl administration of complete Freund's adjuvant (CFA) in male mice using the hot plate test in the presence of complete Freund's adjuvant (HP/CFA) as an acute and chronic skeletal muscle pain model. METHODS: The present study evaluated the antihyperalgesic activity of QA against acute and chronic skeletal muscle pain models in mice using the hot plate test in the presence of complete Freund's adjuvant (HP/CFA), at 24 h (acute assay) and 7 days (chronic assay) , with dexketoprofen (DEX) as the reference drug. RESULTS: In acute and chronic skeletal muscle pain assays, QA at 30 mg/kg ip elicited its maximal antihyperalgesic effects (65.0% and 53.4%) at 24 h and 7 days, respectively. The maximal effect of DEX (99.0 and 94.1 at 24 h and 7 days, respectively) was induced at 100 mg/kg. CONCLUSION: QA and DEX elicit dose-dependent antihyperalgesic effects against acute and chronic skeletal muscle pain, but QA is more potent than DEX in the early and late periods of inflammatory pain induced by CFA.

Variation of the alkaloid content of Peumus boldus (boldo).

Eighteen alkaloids were detected in the bark, leaves, wood and roots of Peumus boldus, including traces of secoboldine, N-methylsecoboldine (boldine methine), glaucine and norreticuline, not reported previously as constituents of this species. Using appropriate standards, we quantified thirteen of them by UHPLC-MS/MS. Boldine was dominant in the bark, and laurolitsine in wood and roots. The alkaloid composition of the leaves, determined for 130 individually identified trees, classified by age and sex, was highly variable, where N-methyllaurotetanine, laurotetanine, coclaurine and in some cases isocorydine predominated, but not boldine.

Neuroprotective Effect of a New 7,8-Dihydroxycoumarin-Based Fe2+/Cu2+ Chelator in Cell and Animal Models of Parkinson's Disease.

Disturbed iron homeostasis, often coupled to mitochondrial dysfunction, plays an important role in the progression of common neurodegenerative diseases such as Parkinson's disease (PD). Recent studies have underlined the relevance of iron chelation therapy for the treatment of these diseases. Here we describe the synthesis, chemical, and biological characterization of the multifunctional chelator 7,8-dihydroxy-4-((methylamino)methyl)-2H-chromen-2-one (DHC12). Metal selectivity of DHC12 was Cu2+ ∼ Fe2+ > Zn2+ > Fe3+. No binding capacity was detected for Hg2+, Co2+, Ca2+, Mn2+, Mg2+, Ni2+, Pb2+, or Cd2+. DHC12 accessed cells colocalizing with Mitotracker Orange, an indication of mitochondrial targeting. In addition, DHC12 chelated mitochondrial and cytoplasmic labile iron. Upon mitochondrial complex I inhibition, DHC12 protected plasma membrane and mitochondria against lipid peroxidation, as detected by the reduced formation of 4-hydroxynonenal adducts and oxidation of C11-BODIPY581/591. DHC12 also blocked the decrease in mitochondrial membrane potential, detected by tetramethylrhodamine distribution. DHC12 inhibited MAO-A and MAO-B activity. Oral administration of DHC12 to mice (0.25 mg/kg body weight) protected substantia nigra pars compacta (SNpc) neurons against MPTP-induced death. Taken together, our results support the concept that DHC12 is a mitochondrial-targeted neuroprotective iron-copper chelator and MAO-B inhibitor with potent antioxidant and mitochondria protective activities. Oral administration of low doses of DHC12 is a promising therapeutic strategy for the treatment of diseases with a mitochondrial iron accumulation component, such as PD.

Topical anti-inflammatory activity of quillaic acid from Quillaja saponaria Mol. and some derivatives.

OBJECTIVES: Quillaic acid is the major aglycone of the widely studied saponins of the Chilean indigenous tree Quillaja saponaria Mol. The industrial availability of quillaja saponins and the extensive functionalization of this triterpenoid provide unique opportunities for structural modification and pose a challenge from the standpoint of selectivity in regard to one or the other secondary alcohol group, the aldehyde, and the carboxylic acid functions. The anti-inflammatory activity of this sapogenin has not been studied previously and it has never been used to obtain potential anti-inflammatory derivatives. METHODS: A series of quillaic acid derivatives were prepared and subjected to topical assays for the inhibition of inflammation induced by arachidonic acid or phorbol ester. KEY FINDINGS: Quillaic acid exhibited strong topical anti-inflammatory activity in both models. Most of its derivatives were less potent, but the hydrazone 8 showed similar potency to quillaic acid in the TPA assay. CONCLUSIONS: The structural modifications performed and the biological results suggest that the aldehyde and carboxyl groups are relevant to the anti-inflammatory activity in these models.

Antinociceptive activity of Quillaja saponaria Mol. saponin extract, quillaic acid and derivatives in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Quillaja saponaria bark contains a high percentage of triterpene saponins and has been used for centuries as a cleansing and analgesic agent in Chilean folk medicine. AIM OF THE STUDY: The topical and systemic analgesic effects of a commercial partially purified saponin extract, 3ß,16α-dihydroxy-23-oxoolean-12-en-28-oic acid (quillaic acid), methyl 3ß,16α-dihydroxy-23-oxoolean-12-en-28-oate and methyl 4-nor-3,16-dioxoolean-12-en-28-oate. MATERIALS AND METHODS: The samples were assessed in mice using the topical tail-flick and i.p. hot-plate tests, respectively. RESULTS: All the samples showed activity in both analgesic tests in a dose-dependent manner. The most active against tail flick test was commercial partially purified saponin extract (EC50 27.9 mg%, w/v) and more than the ibuprofen sodium. On hot-plate test, methyl 4-nor-3, 16-dioxoolean-12-en-28-oate was the most active (ED50 12.2 mg/kg) and more than the ibuprofen sodium. CONCLUSIONS: The results of the present study demonstrated that Quillaja saponaria saponins, quillaic acid, its methyl ester, and one of the oxidized derivatives of the latter, elicit dose-dependent antinociceptive effects in two murine thermal models.

Antifungal activity of saponin-rich extracts of Phytolacca dioica and of the sapogenins obtained through hydrolysis.

A saponin-rich extract of Phytolacca dioica L. berries, its acid hydrolysate, and its major aglycone, phytolaccagenin, were assayed for antifungal activity against ATCC standard cultures of Candida albicans and Cryptococcus neoformans, and against clinical isolates of these fungi. The activity of the extract was either low or negligible, but the hydrolysate, containing the sapogenins, including phytolaccagenin, and also pure phytolaccagenin, showed promising antifungal potency. Hydrolysis of a natural product extract is shown to be a useful modification leading to improved bioactivity.

Molecular modeling of the alpha9alpha10 nicotinic acetylcholine receptor subtype.

This study reports the comparative molecular modeling, docking and dynamic simulations of human alpha9alpha10 nicotinic acetylcholine receptors complexed with acetylcholine, nicotine and alpha-conotoxin RgIA, using as templates the crystal structures of Aplysia californica and Lymnaea stagnalis acetylcholine binding proteins. The molecular dynamics simulations showed that Arg112 in the complementary alpha10(-) subunit, is a determinant for recognition in the site that binds small ligands. However, Glu195 in the principal alpha9(+), and Asp114 in the complementary alpha10(-) subunit, might confer the potency and selectivity to alpha-conotoxin RgIA when interacting with Arg7 and Arg9 of this ligand.

8-NH2-boldine, an antagonist of alpha1A and alpha1B adrenoceptors without affinity for the alpha1D subtype: structural requirements for aporphines at alpha1-adrenoceptor subtypes.

Structure-activity analysis of 21 aporphine derivatives was performed by examining their affinities for cloned human alpha (1A), alpha (1B) and alpha (1D) adrenoceptors (AR) using membranes prepared from rat-1 fibroblasts stably expressing each alpha (1)-AR subtype. All the compounds tested competed for [ (125)I]-HEAT binding with steep and monophasic curves. The most interesting compound was 8-NH (2)-boldine, which retains the selective affinity for alpha(1A)-AR (pKi = 6.37 +/- 0.21) vs. alpha(1B)-AR (pKi = 5.53 +/- 0.11) exhibited by 1,2,9,10-tetraoxygenated aporphines, but shows low affinity for alpha(1D)-AR (pKi < 2.5). Binding studies on native adrenoceptors present in rat cerebral cortex confirms the results obtained for human cloned alpha (1)-AR subtypes. The compounds selective for the alpha (1A) subtype discriminate two binding sites in rat cerebral cortex confirming a mixed population of alpha (1A)- and alpha (1B)-AR in this tissue. All compounds are more selective as inhibitors of [ (3)H]-prazosin binding than of [ (3)H]-diltiazem binding to rat cerebral cortical membranes. A close relationship was found between affinities obtained for cloned alpha (1A)-AR and inhibitory potencies on noradrenaline-induced contraction or inositol phosphate accumulation in tail artery, confirming that there is a homogeneous functional population of alpha(1A)-AR in this vessel. On the contrary, a poor correlation seems to exist between the affinity of 8-NH (2)-boldine for cloned alpha (1D)-AR and its potency as an inhibitor of noradrenaline-induced contraction or inositol phosphate accumulation in rat aorta, which confirms that a heterogeneous population of alpha (1)-AR mediates the adrenergic response in this vessel.

Effects of some antioxidative aporphine derivatives on striatal dopaminergic transmission and on MPTP-induced striatal dopamine depletion in B6CBA mice.

(S)-(+)-boldine, an aporphine alkaloid displaying antioxidative and dopaminergic properties, and six of its derivatives (glaucine, 3-bromoboldine, 3-iodoboldine, 8-aminoboldine, 8-nitrosoboldine and 2,9-O,O'-dipivaloylboldine) were tested for these properties in comparison with their parent compound. All the tested compounds displayed in vitro antioxidative properties equal to or slightly weaker than those of boldine, and equal to or stronger than (+/-)-6-hydroxy-2,5,7,8,-tetramethylchromane-2-carboxylic acid (Trolox), a water-soluble vitamin E analogue, used as a reference compound. All the aporphine compounds tested displaced [3H]SCH 23390 and [3H]raclopride from their specific binding sites in rat striatum. When tested on dopamine (DA) metabolism in the striatum of B6CBA mice, all the compounds, except 8-aminoboldine, increased striatal levels of DOPAC and HVA, and the HVA/DA ratio, indicating that they cross the blood-brain barrier and that they seem to act as dopamine antagonists in vivo. B6CBA mice were sensitive to the neurotoxic action of MPTP on dopaminergic neurons as indicated by the strongly decreased striatal levels of DA, DOPAC and HVA following administration of MPTP (20 mg/kg, i.p.). Among these aporphine derivatives, only 3-bromoboldine was able to reduce the MPTP-induced decrease of striatal levels of DA and DOPAC, whereas (R)-apomorphine (5 mg/kg, s.c.) and acetylsalicylic acid (100 mg/kg, i.p.), used as reference compounds, were very active. These data suggest that potent in vitro antioxidative properties and the ability to cross the blood-brain barrier are not sufficient criteria to predict the inhibition of neuronal degeneration induced by MPTP.