Neurosedative and antioxidant activities of phenylpropanoids from ballota nigra.

Ballota nigra is a European plant known for its neurosedative properties. In this study the ability of five phenylpropanoids (verbascoside, forsythoside B, arenarioside, ballotetroside. and caffeoyl malic acid) isolated from a hydroalcoholic extract, to bind to benzodiazepine, dopaminergic, and morphinic receptors was investigated. To carry out these studies, affinity tests with rat striata, entire brains and receptor rich preparations were employed. In addition, the phenolic aspect of these five phenylpropanoid esters led to investigate antioxidant activities using cell-free experiments and cellular experiments including isolated polymorphonuclear neutrophils (PMN). Effects of phenylpropanoid esters against reactive oxygen species as superoxide anion. peroxide hydrogen, hypochlorous acid and hydroxyl radical were tested. These molecules are liberated by PMN during inflammatory disorders, so that reproduction of this process in vitro stimulating PMN by chemical stimulants was undertaken. Results show that four of the five compounds are able to bind to the studied receptors. Inhibitory concentrations at 50 % were determined and vary fr om 0.4 to 4.7 mg/ml. This may be in relation with the Ballota nigra known neurosedative activities. Results concerning antioxidant investigations evidence all ability to scavenge reactive oxygen species. Inhibitory concentrations at 50 % obtained are comparable to those of known antioxidant drugs (mesna or N-acetyl cysteine). Moreover, the use of different stimuli having various pathways of action on PMN oxidative metabolism permits to establish that each phenylpropanoid ester has its own particular way of action by using proteine kinase C or phospholipase C pathways.