In-vitro characterization of the pharmacological effects induced by (–)-α-bisabolol in rat smooth muscle preparations

Abstract

The present study deals with the pharmacological effects of the sesquiterpene alcohol (-)-α-bisabolol on various smooth-muscle preparations from rats. Under resting tonus, (-)-α-bisabolol (30-300 µmol/L) relaxed duodenal strips, whereas it showed biphasic effects in other preparations, contracting endothelium-intact aortic rings and urinary bladder strips, and relaxing these tissues at higher concentrations (600-1000 µmol/L). In preparations precontracted either electromechanically (by 60 mmol/L K(+)) or pharmacomechanically (by phenylephrine or carbachol), (-)-α-bisabolol showed only relaxing properties. The pharmacological potency of (-)-α-bisabolol was variable, being higher in mesenteric vessels, whereas it exerted relaxing activity with a lesser potency on tracheal or colonic tissues. In tissues possessing spontaneous activity, (-)-α-bisabolol completely decreased spontaneous contractions in duodenum, whereas it increased their amplitude in urinary bladder tissue. Administered in vivo, (-)-α-bisabolol attenuated the increased responses of carbachol in tracheal rings of ovalbumin-sensitized rats challenged with ovalbumin, but was without effect in the decreased responsiveness of urinary bladder strips in mice treated with ifosfamide. In summary, (-)-α-bisabolol is biologically active in smooth muscle. In some tissues, (-)-α-bisabolol preferentially relaxed contractions induced electromechanically, especially in tracheal smooth muscle. The findings from tracheal rings reveal that (-)-α-bisabolol may be an inhibitor of voltage-dependent Ca(2+) channels.

α-bisabolol-loaded lipid-core nanocapsules reduce lipopolysaccharide-induced pulmonary inflammation in mice

“…We demonstrated that α-bis can modulate LPS-induced hyperresponsiveness in an ARDS model by improving the lung function triggered by pretreatment with α-bis-LNCs, as observed by the decrease in lung elastance after a methacholine challenge. Consistent with our results, Siqueira et al 46 have shown that tracheal rings of rats challenged with ovalbumin and treated previously with α-bis (aerosol) reduced the hyperresponsive phenotype, and they showed that α-bis may act as an inhibitor of voltagedependent Ca 2+ channels. Similarly, Roberts et al, 47 using a porcine isolated tissue bath (from coronary and splenic arteries), demonstrated that α-bis was able to inhibit calciuminduced contractions and that the removal of extracellular calcium inhibited its responses.…”

Vasorelaxation induced by methyl cinnamate, the major constituent of the essential oil of Ocimum micranthum, in rat isolated aorta

“…In fact, in the latter preparations, both EOOM and its main constituent E‐MC more potently inhibited cholinergic‐induced contractions than KCl‐induced contractions . This suggests that E‐MC acts against contractile responses that preferentially recruit pharmacomechanical coupling in rat airway tissues, a finding that is clearly different from other essential oils and volatile compounds that preferentially act on electromechanically induced contractions …”

“…) inhibited cholinergic‐induced contractions more potently than contractions elicited by KCl, with IC 50 values for the relaxant effects against carbachol‐induced contractions being significantly lower than those against KCl‐induced contractions . This suggests that, in rat airway tissues, E‐MC acts against contractile responses that preferentially recruit receptor‐operated Ca 2+ channels (ROCCs), a finding that clearly differs from other volatile compounds that preferentially act on electromechanically induced contractions . In strips from rat gastrointestinal smooth muscle, both EOOM and E‐MC exerted equipotent antispasmodic effects against KCl‐ and carbachol‐induced contractions, which likely resulted from a decrease in Ca 2+ levels in smooth muscle cells .…”

“…1 This suggests that, in rat airway tissues, E-MC acts against contractile responses that preferentially recruit receptor-operated Ca 2+ channels (ROCCs), a finding that clearly differs from other volatile compounds that preferentially act on electromechanically induced contractions. [7][8][9] In strips from rat gastrointestinal smooth muscle, both EOOM and E-MC exerted equipotent antispasmodic effects against KCl-and carbachol-induced contractions, which likely resulted from a decrease in Ca 2+ levels in smooth muscle cells. 10 These findings support the incorporation of O. micranthum in herbal remedy preparations in folk medicine.…”

Variations in Chemical Composition, Vasorelaxant and Angiotensin I‐Converting Enzyme Inhibitory Activities of Essential Oil from Aerial Parts of Seseli pallasii Besser (Apiaceae)

“…The dry roots of S. sibiricum yield an essential oil containing a-pinene and b-pinene, myrcene, limonene, p-cymene, b-phellandrene (major constituent), fenchone, fenchyl alcohol and acetate, fenchyl hydroxycinnamate, osthol, p-hydroxy cinnamate, sesibricin, imperatorin and bergapten. [27] According to the abovementioned literature data, more than 50% of SP1 tested oil was potentially vasorelaxant active. The action appears to be tranquillizing.…”