Inhibition of Mouth Skeletal Muscle Relaxation by Flavonoids of Cistus ladanifer L.: A Plant Defense Mechanism Against Herbivores

Abstract

Cistus ladanifer exudate is a potent inhibitor of the sarcoplasmic reticulum Ca2+-ATPase (Ca2+-pump) of rabbit skeletal muscle, a well-established model for active transport that plays a leading role in skeletal muscle relaxation. The low concentration of exudate needed to produce 50% of the maximum inhibition of the sarcoplasmic reticulum Ca2+-ATPase activity, 40-60 microg/ml, suggests that eating only a few milligrams of C. ladanifer leaves can impair the relaxation of the mouth skeletal muscle of herbivores, as the exudate reaches up to 140 mg/g of dry leaves in summer season. The flavonoid fraction of the exudate accounts fully for the functional impairment of the sarcoplasmic reticulum produced by the exudate (up to a dose of 250-300 microg/ml). The flavonoids present in this exudate impair the skeletal muscle sarcoplasmic reticulum function at two different levels: (i) by inhibition of the Ca2+-ATPase activity, and (ii) by decreasing the steady state ATP-dependent Ca2+-accumulation. Among the exudate flavonoids, apigenin and 3,7-di-O-methyl kaempferol are the most potent inhibitors of the skeletal muscle sarcoplasmic reticulum. We conclude that the flavonoids of this exudate can elicit an avoidance reaction of the herbivores eating C. ladanifer leaves through impairment of mouth skeletal muscle relaxation.

Significance of flavonoids in plant resistance: a review

“…A physiological mechanism by which flavonoid exudates can elicit an avoidance reaction of herbivores was recently described (Sosa et al 2004). The exudate of Cistus ladanifer L. contains apigenin and 3,7-di-O-methylkaempferol which inhibit skeletal muscle sarcoplasmic reticulum (Ca 2+ -ATPase), thus impairing mouth skeletal relaxation.…”

Significance of Flavonoids in Plant Resistance and Enhancement of Their Biosynthesis

“…The biochemical basis for nematode resistance of banana is formed by flavan-3,4-diols and condensed tannins (Collingborn et al, 2000). A physiological mechanism by which flavonoid exudates can elicit an avoidance reaction in herbivores was recently described (Sosa et al, 2004). The exudate of Cistus ladanifer L. contains apigenin and 3,7-di-O-methylkaempferol, which inhibit the skeletal muscle sarcoplasmic reticulum (Ca 2+ -ATPase), thus impairing mouth skeletal relaxation.…”

Mechanisms of Neuroprotection by Polyphenols

“…It has been demonstrated the ability of flavonoids, such as quercetin, and wine polyphenols to bind and affect the activity of ion pump ATPases in several tissues [147][148][149][150] as well as that of topoisomerase [151][152][153].…”