Pharmaceutical interest

Cardiovascular properties: The toxic principles of Antiaris toxicaria Lesch. are cardiac glycosides (Chen KK et al., 1983) which bind to the Na+,

Uses: This plant is the "Arbor Toxicaria" of Georgius Everhardus Rumphius (1628-1702), who wrote in Thesaurus Amboinensis that "everything perishes that its wind touches, as so too do all animals shun it when they pass this tree, while the birds fly over". Although it is a little exaggerated, the plant is dreadfully toxic. The latex of Antiaris toxicaria Lesch. has been used in the Asia-Pacific either alone or mixed with the juice of Strychnos (see p.), Amor-phophallus, Dioscorea, Lophopetalum or Derris, to make arrow and dart poison, and occasionally for judicial sentence. The process of getting the arrow-poison has been first reported by Mr L Wray (Curator and State Geologist of Perak) in the Kew Bulletin edition of October 1891 as follows: "the sap is obtained from the tree by scoring the bark and is heated on a spatula till evaporated, leaving a dark gummy substance in which the arrow is dipped. About 3 ounces and a half of sap will do for 100 arrow points".

Fig. 49. Antiaris toxicaria Lesch.

Fig. 50. Cardenolides bind to Na+/K+ ATPase protein (A) and inhibit therefore the active transfer of Na+ out of the sarcolemma. Na+ being in excess in the sarcolemma is transferred actively out of the sarcolemma through a Na+/Ca2+ protein (B) which transfers meanwhile Ca2+ into the sarcolemma. Increase of Ca2+ into the sarcolemma results in stronger myofibril (M) contraction, hence stronger cardiac contraction.

Fig. 50. Cardenolides bind to Na+/K+ ATPase protein (A) and inhibit therefore the active transfer of Na+ out of the sarcolemma. Na+ being in excess in the sarcolemma is transferred actively out of the sarcolemma through a Na+/Ca2+ protein (B) which transfers meanwhile Ca2+ into the sarcolemma. Increase of Ca2+ into the sarcolemma results in stronger myofibril (M) contraction, hence stronger cardiac contraction.

K+-ATPase pumps of the cardiac myocytes. In normal conditions, the contraction cycle of myocytes consists of 5 electrical events or phases, which correspond to the transfers of sodium, calcium and potassium ions through the sarcolemma transtubular membrane. The first phase, or phase 0, corresponds to a massive entry of sodium ions through fast sodium ions channels and therefore resulting in the depolarization of the sarcolemma membrane. During the phases 1, 2 and 3, or repolarization, calcium ions and sodium ions enter the cell and potassium ions leave the cells slowly. During phase 4, or diastole, sodium ions are transported out of the cell and potassium ions are transported in the cell through a transtubular Na+/ K+-ATPase protein. The binding of cardiac glycosides to Na+/ K+-ATPase results in an elevation of intracellular sodium which stimulates Na+/Ca2+ exchanges, leading therefore to increased intracellular calcium and enhanced contractility of the myofibrils (Fig. 50).

Cardenolide aglycone
Reasons, Remedies And Treatments For Heartburns

Reasons, Remedies And Treatments For Heartburns

Find Out The Causes, Signs, Symptoms And All Possible Treatments For Heartburns!

Get My Free Ebook


Post a comment