Hydroquinone, Anthraquinone and Cardiac Glycosides

Hydroquinone Glycosides

The most well-known hydroquinone glycosides are arbutin and methylarbutin, which are inactive in glycoside form. Their antibacterial properties emerge only when hydroquinone is released during kidney excretion of the sugar component. For optimal effect, sodium bicarbonate (baking soda) is added to tea or prepared medicine to alkalinize urine. Bearberry is the most recognized plant for this effect. Although cranberry leaves contain comparable amounts of arbutin and fewer tannins, which can irritate the gastric mucosa, their use is less common. Smaller amounts of arbutin are found in blueberry, pear, and heather leaves.

Anthraquinone Glycosides

Anthraquinone glycosides, derived from anthrone, dihydroxyanthrone, and anthraquinone structures, are used as purgatives that act in the colon. There, intestinal flora bacteria break down the glycosides into simple anthraquinones, which exert strong laxative effects by stimulating the intestinal mucosa, increasing histamine and prostaglandin release, enhancing peristalsis, and promoting mucus secretion. Prolonged use can lead to dependency and potential liver or kidney damage. These should not be used in children, during pregnancy, menstruation, or with hemorrhoids. Plants containing these compounds include rhubarb root, alder buckthorn bark, and cascara buckthorn fruits, as well as purgatives in aloe and senna.

Cardiac Glycosides

Cardiac glycosides, steroidal glycosides, influence the dynamics and rhythm of a diseased heart muscle. Over thirty aglycones and numerous glycosides are known. A weakened heart is more responsive to these compounds than a healthy one, reacting to doses that have no effect on a normal heart. These glycosides are toxic, but in therapeutic doses, they enhance heart efficiency by increasing systolic contraction, boosting blood output per beat, reducing residual blood in the heart, and enhancing diastolic dilatation to allow more blood inflow while lowering venous pressure. Their major drawback is slow excretion from the body despite good absorption, posing a risk of accumulation. Cardiac glycosides should only be used under medical supervision in standardized medications to prevent dangerous poisoning.