RESUMO
Two polysaccharides abbreviated ANP and AAP were isolated from the young buds of Acanthopanax sciadophylloides. ANP consisted of L-arabinose, D-mannose, D-glucose and D-galactose in a ratio of ca 1.0:2.6:2.5:1.4 and its weight average molecular weight (Mw) was 1.07×10(4). AAP consisted of L-arabinose, D-galactose and 4-O-methyl-D-glucuronic acid in a ratio of ca 5:10:1, and its Mw was estimated to be 8.40×10(4). ANP was suggested to be an acetylated heteropolysaccharide, whereas AAP was speculated to be a type II arabinogalactan on the basis of structural analysis data. Both polysaccharides were found to stimulate NO production and induce the expression of cytokine mRNAs including IL-1ß, IL-6, IL-10 and TNF-α on RAW264.7 cells. They also induced NF-κB activation in RAW-Blue cells. NO production and NF-κB activation by both polysaccharides were decreased by pretreatment with neutralizing anti-TLR-4 and anti-CD14 antibodies but not with anti-TLR-2, anti-SR-A, anti-CD11c, and anti-Dectin-1 antibodies. Therefore, these immunostimulating effects of ANP and AAP were suggested to be promoted by the interaction through the membrane receptors, TLR-4 and CD14. In addition to immunomodulating effects, ANP showed anti-HSV-2 effects in vitro.
Assuntos
Antivirais , Eleutherococcus/química , Herpesvirus Humano 2/efeitos dos fármacos , Fatores Imunológicos , Polissacarídeos , Animais , Antivirais/química , Antivirais/isolamento & purificação , Antivirais/farmacologia , Linhagem Celular , Chlorocebus aethiops , Citocinas/genética , Feminino , Flores/química , Herpes Simples/tratamento farmacológico , Fatores Imunológicos/química , Fatores Imunológicos/isolamento & purificação , Fatores Imunológicos/farmacologia , Lipopolissacarídeos , Camundongos Endogâmicos BALB C , NF-kappa B/metabolismo , Óxido Nítrico/metabolismo , Fitoterapia , Polissacarídeos/química , Polissacarídeos/isolamento & purificação , Polissacarídeos/farmacologia , RNA Mensageiro/metabolismo , Células VeroRESUMO
Distamycin A (Dst) is an antibiotic which binds to the minor groove of double-stranded DNA at A/T-rich regions. We have examined the affinity and mode of Dst binding to DNA duplexes containing a conserved A/T core and variable terminal A/T regions by using circular dichroism spectroscopy. The observed circular dichroism spectra were analyzed by singular value decomposition and fitted to a two-step binding model. The result clearly shows a correlation between the affinity for Dst and the preference for Dst-DNA 1:1 binding over 2:1 binding. The A/T stretches that prefer 1:1 binding form high-affinity 1:1 complexes, whereas those preferring 2:1 binding form stable 2:1 complex with low overall affinities. The terminal A/T residues of the Dst binding region play an important role in the stabilization/destabilization of the 1:1 and 2:1 complexes, resulting in a terminal residue-dependent variation of the binding affinity and the binding mode preference.
