Lapachol acetylglycosylation enhances its cytotoxic and pro-apoptotic activities in HL60 cells.

Lapachol is a plant-derived naphthoquinone that kills several types of cancer cells. Derivatives of this molecule may therefore prove to be useful chemotherapeutic agents. In this study, we explored whether glycosylation increases the cytotoxic potency of lapachol towards HL-60 human leukemia cells. Two beta-glycosides were synthesized and characterized: LA4A (lapachol-ß-glucoside) and LA4C (lapachol-N-acetylglucosamine-ß-glucoside). The sugar moieties of both novel molecules were per-acetylated to facilitate cellular uptake. The IC50 values (in µM) for LA4A (5.7) and LA4C (5.3) were lower than those for lapachol (25). LA4A and LA4C triggered typical signs of apoptosis, such as the exposure of phosphatidylserine on the outside of cells, chromatin condensation, DNA fragmentation and a decrease of the mitochondrial transmembrane potential (ΔΨm) prior to cell lysis. Moreover, DNA fragmentation triggered by the lapachol-glycosides was reduced by pre-treatment with the caspase inhibitor, z-VAD-fmk. While LA4A and LA4C activated caspases-3, -8 and -9, lapachol failed to activate these apoptotic proteases, even when used at high concentrations. Finally, the toxicity of lapachol and its derivatives was also tested on non-tumor cells. We used human peripheral neurons (PeriTox test) to evaluate the side effect potential of these compounds. LA4C was clearly less toxic than LA4A. We conclude that LA4C had the most favorable profile as drug candidate (high tumor cell toxicity, reduced neurotoxicity). In general, this study shows that the cytotoxicity of lapachol towards HL-60 can be enhanced by glycosylation, and that the therapeutic ratio may be modified by the type of sugar added.

Inflammatory activity modulation by hypertonic saline and pentoxifylline in a rat model of strangulated closed loop small bowel obstruction.

BACKGROUND: Intestinal obstruction is an abdominal disease associated to mortality, especially if complicated with sepsis. Resuscitation increases survival, although controversies remain concerning to therapeutic strategy. METHODS: To assess the effects of hypertonic saline and pentoxifylline on the inflammatory response and oxidative stress, Wistar rats underwent a laparotomy loop intestinal obstruction and ischemia. After 24 h, the intestinal segment was resected (IO) without any other treatment and resuscitation/pentoxifylline were administered according to the group: Ringer's lactate (RL); hypertonic saline (HS); pentoxifylline (PTX); Ringer's lactate with pentoxifylline (RL + PTX); hypertonic saline with pentoxifylline (HS + PTX) and the control group (CG) that was not submitted to ischemia and obstruction. Mean arterial pressure (MAP) was recorded 4 times, and euthanasia was done 3 h after the resuscitation to obtain lung tissue, for malondialdehyde (MDA) by thiobarbituric acid reactive substances (TBARS) method, inflammatory cytokines were assessed using ELISA and NF-κΒ by Western blotting. RESULTS: The initial MAP levels were higher in the RL and HS groups than in the others; however, the last measurement was similar among all the groups. IL-1ß, IL-6 and CINC-1 (Cytokine-Induced Neutrophil Chemoattractant-1) were lower in the HS, PTX and HS + PTX groups compared with the IO and RL groups. IL-10 was lower in the HS + PTX group than in the IO group. NF-κB in the HS, PTX and HS + PTX groups were lower than in the IO group; NF-κB in the HS + PTX group was lower than in the RL group. MDA in the lung was lower in the HS + PTX group compared with other groups. CONCLUSION: Hypertonic saline and pentoxifylline, both alone and in combination, attenuated oxidative stress and the activation of NF-κB, leading to a decrease in the inflammatory response.