EFFECTS OF Momordica charantia LEAVES FLAVONOID-RICH-FRACTION ON ATP HYDROLYTIC ENZYMES AND ADENOSINE DEAMINASE IN CAFFEINE INDUCED PROSTATE DAMAGE OF MALE RATS

1 Background of Study

Caffeine, along with theophylline and theobromine, are natural alkaloid methylxanthines that are normally found together in substances such as coffee, tea, chocolate, energy drinks, and carbonated beverages, such as cola and other soft drinks (Fredholm et al., 1999; Yoshimura 2005; Mitchell et al., 2014; McLellan et al., 2016).

Caffeine behaves as a competitive antagonist of adenosine receptors, which are found throughout the brain and body and are thought to regulate the sleep-walking cycle, the stress response, and learning and memory. The presence of caffeine inhibits intracellular enzyme phosphodiesterase, thereby preventing the conversion of cyclic AMP to non-cyclic AMP. It is through this transformation that caffeine is believed to exert its influence on the sympathetic nervous system (Nehlig et al., 1992). Additionally, very high and toxic doses of caffeine increase the risk of severe ventricular arrhythmias by increasing the release of calcium from intracellular stores (Thelandar et al., 2010; Wolk et al., 2012; Temple et al., 2017).

Nonetheless, caffeine remains one of the most widely consumed psychoactive substances throughout the world (Fredholm et al., 1999; Yoshimura 2005; Mitchell et al., 2014; McLellan et al., 2016). Average caffeine consumption is estimated at about 70-76mg/person per day worldwide, although in many parts of the western world, including North America, Sweden, and Finland, this number rises to 210mg/day (Fredholm et al., 1999). In today’s popular culture, caffeine is widely reviewed as a beneficent substance that can increase alertness and improve mood and performance (McLellan et al., 2016). Thus, an increasing number of people have become highly dependent on the drug, especially in fast-paced societies (Heckman et al., 2010; Cappelleti et al., 2015). Indeed, many studies investigating the effects of caffeine consumption have indicated some benefits, including increased alertness, reduced symptoms of sleep deprivation and delayed onset of neurological disorders such as Alzheimer’s disease, Parkinson’ disease, and other age-related declines in cognitive performance (Alhaider et al., 2010; Santos et al., 2010; Alhaider and Alkadhi 2015; Panza et al., 2015; Nehlig 2016).

ATP hydrolysis is the catabolic reaction process by which chemical energy that has been stored in the high-energy phosphoanhydride bonds in adenosine triphosphate (ATP) is released by splitting these bonds, for example in muscles, by producing work in the form of mechanical energy. The product is adenosine diphosphate (ADP) and an inorganic phosphate (Pi). ADP can be further hydrolyzed to give energy, adenosine monophosphate (AMP), and another inorganic phosphate (Pi) (Lodish et al., 2013). ATP hydrolysis is the final link between the energy derived from food or sunlight and useful work such as muscle contraction, the establishment of electrochemical gradients across membranes, and biosynthetic processes necessary to maintain life. Hydrolysis of the phosphate groups in ATP is especially exergonic, because the resulting inorganic phosphate molecular ion is greatly stabilized by multiple resonance structures, making the products (ADP and Pi) lower in energy than the reactant (ATP). The high negative charge density associated with the three adjacent phosphate units of ATP also destabilizes the molecule, making it higher in energy. Hydrolysis relieves some of these electrostatic repulsions, liberating useful energy in the process by causing conformational changes in enzyme structure. In humans, approximately 60 percent of the energy released from the hydrolysis of ATP produces metabolic heat rather than fuel the actual reactions taking place (Berne et al., 2010). Due to the acid-base properties of ATP, ADP, and inorganic phosphate, the hydrolysis of ATP has the effect of lowering the pH of the reaction medium. Under certain conditions, high levels of ATP hydrolysis can contribute to lactic acidosis. Hydrolysis of the terminal phosphoanhydridic bond is a highly exergonic process. The amount of released energy depends on the conditions in a particular cell. Specifically, the energy released is dependent on concentrations of ATP, ADP and Pi. As the concentrations of these molecules deviate 4 from values at equilibrium, the value of Gibbs free energy change (ΔG) will be increasingly different. In standard conditions (ATP, ADP and Pi concentrations are equal to 1M, water concentration is equal to 55 M) the value of ΔG is between -28 to -34 kJ/mol. The range of the ΔG value exists because this reaction is dependent on the concentration of Mg2+ cations, which stabilize the ATP molecule. The cellular environment also contributes to differences in the ΔG value since ATP hydrolysis is dependent not only on the studied cell, but also on the surrounding tissue and even the compartment within the cell. Variability in the ΔG values is therefore to be expected (Philips et al., 2018).

Allopurinol is a medication used to decrease high blood uric acid levels, it is specifically used to prevent gout, prevent specific types of kidney stones and for the high uric acid levels that can occur with chemotherapy, it is taken by mouth or injected into a vein (Pacher et al., 2006).
Luteolin is a flavone, a type of flavonoid, with a yellow crystalline appearance (Mann, 1992).
Luteolin was first isolated in pure form, and named, in 1829 by the French chemist Michel Eugène Chevreul (Thomson, 1838). The luteolin empirical formula was determined by the Austrian chemists Heinrich Hlasiwetz and Leopold Pfaundler in 1864 (Hlasiwetz and Pfaundler, 1864). In 1896, the English chemist Arthur George Perkin proposed the correct structure for luteolin (Perkin, 1896). Perkin’s proposed structure for luteolin was confirmed in 1900 when the Polish-Swiss chemist Stanislaw Kostanecki (1860–1910) and his students A. Różycki and J. Tambor synthesized luteolin (Thorpe, 1913).

Luteolin is a tetrahydroxyflavone in which the four hydroxy groups are located at positions 3′, 4′, 5 and 7. It is thought to play an important role in the human body as an antioxidant, a free radical scavenger, an anti-inflammatory agent and an immune system modulator as well as being active against several cancers. It has a role as an EC 2.3.1.85 (fatty acid synthase) inhibitor, an antineoplastic agent, a vascular endothelial growth factor receptor antagonist, a plant metabolite, a nephroprotective agent, an angiogenesis inhibitor, a c-Jun N-terminal kinase inhibitor, an anti-inflammatory agent, an apoptosis inducer, a radical scavenger and an immunomodulator. It is a 3′-hydroxyflavonoid and a tetrahydroxyflavone. It is a conjugate acid of a luteolin-7-olate (Mann, 1992).

Luteolin is a naturally-occurring flavonoid, with potential anti-oxidant, anti-inflammatory, apoptosis-inducing and chemopreventive activities. Upon administration, luteolin scavenges free