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In nature, DNA exists primarily in a highly compacted form. The compaction of DNA in vivo is mediated by cationic proteins: histones in somatic nuclei and protamines in sperm chromatin. The extreme, nearly crystalline packaging of DNA by protamines in spermatozoa is thought to be essential for both efficient genetic delivery as well as DNA protection against damage by mutagens and oxidative species. The protective role of protamines is required in sperm, as they are sensitive to ROS damage due to the progressive loss of DNA repair mechanisms during maturation. The degree to which DNA packaging directly relates to DNA protection in the condensed state, however, is poorly understood. Here, we utilized different polycation condensing agents to achieve varying DNA packaging densities and quantify DNA damage by free radical oxidation within the condensates. Although we see that tighter DNA packaging generally leads to better protection, the length of the polycation also plays a significant role. Molecular dynamics simulations suggest that longer polyarginine chains offer increased protection by occupying more space on the DNA surface and forming more stable interactions. Taken together, our results suggest a complex interplay among polycation properties, DNA packaging density, and DNA protection against free radical damage within condensed states.

Background: The objective of the study was to evaluate the antidiarrheal and antinociceptive activities of ethanol extract and its chloroform and pet ether fraction of Phrynium imbricatum (Roxb.) leaves in mice., Methods: In the present study, the dried leaves of P. imbricatum were subjected to extraction with ethanol, and then it was fractioned by chloroform and pet ether solvent. Antidiarrheal effects were tested by using castor oil-induced diarrhea, castor oil-induced enteropooling, and gastrointestinal transit test. Antinociceptive activity was evaluated by using the acetic acid-induced writhing test and formalin-induced paw licking test., Results: The standard drug loperamide (5 mg/kg) showed significant (p<0.001) inhibitory activity against castor oil-induced diarrhea, in which all the examined treatments decreased the frequency of defecation and were found to possess an anti-castor oil-induced enteropooling effect in mice by reducing both weight and volume of intestinal content significantly, and reducing the propulsive movement in castor oil-induced gastrointestinal transit using charcoal meal in mice. The results showed that the ethanol extract of P. imbricatum leaves has significant dose-dependent antinociceptive activity, and among its two different fractions, the pet ether fraction significantly inhibited the abdominal writhing induced by acetic acid and the licking times in formalin test at both phases., Conclusions: These findings suggest that the plant may be a potential source for the development of a new antinociceptive drug and slightly suitable for diarrhea, as it exhibited lower activity. Our observations resemble previously published data on P. imbricatum leaves.