Selected anthraquinones as potential free radical scavengers and P-glycoprotein inhibitors.

Disruption of homeostasis can increase the amount of free radicals formed during metabolic processes. This phenomenon known as oxidative stress can have numerous negative outcomes. The role of dietary antioxidants is to help the prevention of oxidative stress. We investigated free radical scavenging capacity of six structurally similar anthraquinones (alizarin, purpurin, chrysophanol, emodin, aloe-emodin and 1,3,8-trihydroxyanthraquinone) for inactivating a set of ten hydroxy and peroxy free radicals. The antioxidant capacity of anthraquinones was estimated by considering Gibbs free energy of three studied reaction mechanisms: hydrogen atom transfer (HAT), single-electron transfer followed by proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET). The geometry of all participants in chemical reactions was optimized using the M06-2X/6-311++G(d,p) level of theory. Benzene, pentyl ethanoate, dimethyl sulfoxide and water were used to investigate the impact of solvent polarity on the thermodynamic feasibility of antiradical reactions. It was found that HAT and SPLET mechanisms are operative and competitive, while the SET-PT mechanism is not thermodynamically plausible. Among the studied anthraquinones, AL and PU showed the highest scavenging capacity. Their reactivity toward free radicals decreases as follows:˙OH > (CH3)3C-O˙ ≈ ˙OCH3 > CCl3-O-O˙ > PhO˙ > ˙OOH ≈ CH2[double bond, length as m-dash]CH-O-O˙ ≈ CH3-O-O˙ ≈ CH2[double bond, length as m-dash]CH-CH2-O-O˙ ≫ O2˙-. Inhibition activity of anions of the selected six anthraquinones toward P-glycoproteins was estimated using docking analysis. The obtained results suggest that all the investigated compounds are potential inhibitors of P-glycoproteins under physiological conditions, indicating them as potential protectors against patient resistance toward various anticancer drugs.

Tuberculous lymphadenitis as a cause of obstructive jaundice.

Obstructive jaundice secondary to abdominal tuberculosis is extremely rare. We present a patient with jaundice secondary to compression of the common bile duct by TB lymphadenitis. A 49-year-old woman was admitted to our department for nausea,epigastric pain and jaundice. Abdominal ultrasonography and computer tomography scan were suggestive of stenosis of the distal common bile duct caused by a retro pancreatic mass. At laparotomy, an enlarged lymph node behind the head of the pancreas was found, causing compression and stenosis of the distal parts of the choledochus. The lymph node frozen section analysis showed epithelioid granuloma with caseous necrosis,strongly suggesting tuberculous origin. Choledochoduodenal anastomosis was performed. Definitive pathohistological examination confirmed TB lymphadenitis. ATB should be considered as a potential cause of jaundice especially in immuno compromised patients and endemic areas. Diagnosing abdominal tuberculosis can be a challenging task. No satisfactory diagnostic gold standard is available so that in most cases the diagnosis cannot be reached before exploratory laparotomy.Early detection enables successful conservative treatment and eliminates the necessity of surgery.