Essential oil of Lippia alba and its main constituent citral block the excitability of rat sciatic nerves

Lippia alba is empirically used for infusions, teas, macerates, and hydroalcoholic extracts because of its antispasmodic, analgesic, sedative, and anxiolytic effects. Citral is a mixture of trans-geranial and cis-neral and is the main constituent of L. alba essential oil and possesses analgesic, anxiolytic, anticonvulsant, and sedative effects. The present study evaluated the effects of the essential oil of L. alba (EOLa) and citral on compound action potentials (CAPs) in Wistar rat sciatic nerves. Both drugs inhibited CAP in a concentration-dependent manner. The calculated half-maximal inhibitory concentrations (IC50) of peak-to-peak amplitude were 53.2 µg/mL and 35.00 µg/mL (or 230 µM) for EOLa and citral, respectively. Peak-to-peak amplitude of the CAP was significantly reduced by 30 µg/mL EOLa and 10 µg/mL citral. EOLa and citral (at 60 and 30 µg/mL, values close to their respective IC50 for CAP blockade) significantly increased chronaxy and rheobase. The conduction velocity of the first and second CAP components was statistically reduced to ∼86% of control with 10 µg/mL EOLa and ∼90% of control with 3 µg/mL citral. This study showed that EOLa inhibited nerve excitability and this effect can be explained by the presence of citral in its composition. Both EOLa and citral showed inhibitory actions at lower concentrations compared with other essential oils and constituents with local anesthetic activity. In conclusion, these data demonstrate that EOLa and citral are promising agents in the development of new drugs with local anesthetic activity.

Potencial terapêutico e uso de plantas medicinais em uma área de Caatinga no estado do Ceará, nordeste do Brasil / Therapeutic potential and use of medicinal plants in an area of the Caatinga in the state of Ceará, northeastern Brazil

O presente trabalho visou o levantamento etnobotânico das plantas medicinais, verificando a versatilidade das espécies utilizadas e o consenso de uso e/ou conhecimento entre os informantes, do Distrito de Aratama, no Município de Assaré, Ceará. As informações etnobotânicas foram obtidas através de entrevistas estruturadas e semi-estruturadas com os moradores locais. Foram citadas 116 espécies com fins medicinais pertencentes a 103 gêneros e 58 famílias com destaque para Fabaceae (10ssp.), Asteraceae (7spp.) e Lamiaceae (6spp.). Entre as espécies levantadas, Mentha spicata L., Rosmarinus officinalis L., Allium sativum L., Bauhinia cheilantha (Bong.), Ximenea americana L., se destacaram como as mais versáteis dentro da comunidade. As indicações terapêuticas citadas foram agrupadas em 16 categorias de sistemas corporais, dos quais as Desordens mentais e comportamentais, as Afecções ou dores não definidas, os Transtornos do sistema respiratório, as Doenças de pele e do tecido celular subcutâneo, e os Transtornos do sistema sensorial (ouvidos), mostram maior concordância entre os informantes na utilização de espécies para tratar um sistema corporal especifico. Os resultados mostraram elevada riqueza da flora medicinal presente na caatinga. Neste sentido, torna-se necessária a intensificação de estudos que avaliem e consolidem as propriedades químicas e farmacológicas destas espécies.

This study is about an ethnobotanical survey of medicinal plants, checking the versatility of the species used and the consensus of use and/or knowledge among informants from the Aratama District, in the municipality of Assaré, state of Ceará, Brazil. The ethnobotanical information was obtained through structured interviews and semi-structured interviews with local residents. Approximately, 116 species were mentioned for medicinal purposes, belonging to 103 genera and 58 families, especially Fabaceae (10ssp.), Asteraceae (7spp.) and Lamiaceae (6spp.). Among the surveyed species, Mentha spicata L., Rosmarinus officinalis L., Allium sativum L. and Bauhinia cheilantha (Bong.) Ximenea americana L. stood out as the most versatile in the community. The therapeutic indications mentioned were grouped into 16 categories of body systems; the mental and behavioral disorders, disorders or pain not defined, disorder of the respiratory system, skin diseases and subcutaneous tissue disorder, and disorder of the sensory system (ears) showed greater agreement among informants in the use of species to treat a specific body system. The results showed a high species richness of the medicinal flora present in the Brazilian Caatinga. Thus, it is necessary to intensify and consolidate studies assessing the chemical and pharmacological properties of these species.