Antispasmodic and vasodilator activities of Morinda citrifolia root extract are mediated through blockade of voltage dependent calcium channels.
BACKGROUND
Morinda citrifolia (Noni) is an edible plant with wide range of medicinal uses. It occurs exclusively in tropical climate zone from India through Southeast Asia and Australia to Eastern Polynesia and Hawaii. The objective of this study was to explore the possible mode(s) of action for its antispasmodic, vasodilator and cardio-suppressant effects to rationalize its medicinal use in gut and cardiovascular disorders.


METHODS
Isolated tissue preparations such as, rabbit jejunum, rat and rabbit aorta and guinea pig atria were used to test the antispasmodic and cardiovascular relaxant effects and the possible mode of action(s) of the 70% aqueous-ethanolic extract of Morinda citrifolia roots (Mc.Cr).


RESULTS
The Mc.Cr produced a concentration-dependent relaxation of spontaneous and high K(+) induced contractions in isolated rabbit jejunum preparations. It also caused right ward shift in the concentration response curves of Ca(++), similar to that of verapamil. In guinea-pig right atria, Mc.Cr caused inhibition of both atrial force and rate of spontaneous contractions. In rabbit thoracic aortic preparations, Mc.Cr also suppressed contractions induced by phenylephrine (1.0 μM) in normal- Ca(++) and Ca(++)-free kreb solutions and by high K(+), similar to that of verapamil. In rat thoracic aortic preparations, Mc.Cr also relaxed the phenylephrine (1.0 μM)-induced contractions. The vasodilatory responses were not altered in the presence of L-NAME (0.1 mM) or atropine (1.0 μM) and removal of endothelium.


CONCLUSIONS
These results suggest that the spasmolytic and vasodilator effects of Mc.Cr root extract are mediated possibly through blockade of voltage-dependent calcium channels and release of intracellular calcium, which may explain the medicinal use of Morinda citrifolia in diarrhea and hypertension. However, more detailed studies are required to assess the safety and efficacy of this plant.
Gilani
Anwarul Hassan
AH
Natural Product Research Division, Department of Biological and Biomedical Sciences, Aga Khan University Medical College, Karachi, Pakistan. anwar.gilani@aku.edu
Mandukhail
Saf-ur-Rehman
SU
Iqbal
Javeid
J
Yasinzai
Masoom
M
Aziz
Nauman
N
Khan
Aslam
A
Najeeb-ur-Rehman
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects*; D003967:Diarrhea / Q000188:drug therapy; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects / Q000502:physiology; D006973:Hypertension / Q000188:drug therapy; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D032066:Morinda; D009119:Muscle Contraction / Q000187:drug effects*; D010276:Parasympatholytics / Q000494:pharmacology* / Q000627:therapeutic use; D010656:Phenylephrine; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D018517:Plant Roots; D011188:Potassium; D011817:Rabbits; D051381:Rats; D014665:Vasodilator Agents / Q000494:pharmacology* / Q000627:therapeutic use; D014700:Verapamil / Q000494:pharmacology
D015220:Calcium Channels; D010276:Parasympatholytics; D010936:Plant Extracts; D014665:Vasodilator Agents; D010656:Phenylephrine; D014700:Verapamil; D011188:Potassium; D002118:Calcium