Context:Punica granatum L (Punicaceae) flower is an important diabetes treatment in oriental herbal medicine.Objective: This study investigates the inflammation effects of pomegranate flower (PFE) ethanol extract in LPS-induced RAW264.7 cells.Materials and methods: PFE (10, 25, 50, 100 μg/mL) was applied to 1 μg/mL LPS-induced RAW 264.7 macrophages in vitro. Levels of nitric oxide (NO), prostaglandin E2 (PGE2) and pro-inflammatory cytokines interleukin (IL)-1β (IL-1β), interleukin (IL)-6 (IL-6) and tumor necrosis factor (TNF-α) in the supernatant fraction were determined using enzyme-linked immunosorbent assay (ELISA). Expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), phosphorylation of mitogen-activated protein kinase (MAPK) subgroups extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and P38, as well as nuclear factor-κB (NF-κB) activation in extracts were detected via Western blot.Results: 10–100 μg/mL PFE decreased the production of NO (IC50 value = 31.8 μg/mL), PGE2 (IC50 value = 54.5 μg/mL), IL-6 (IC50 value = 48.7 μg/mL), IL-1β (IC50 value = 71.3 μg/mL) and TNF-α (IC50 value = 62.5 μg/mL) in LPS-stimulated RAW 264.7 cells significantly. A mechanism-based study showed that phosphorylation of ERK1/2, p38, JNK and translocation of the NF-B p65 subunit into nuclei were inhibited by the PFE treatment.Discussion and conclusion: These results show that PFE produced potential anti-inflammatory effect through modulating the synthesis of several mediators and cytokines involved in the inflammatory process.

The substitution of methyl (Me or −CH3) by trifluoromethyl (TFM or −CF3) is frequently used in medicinal chemistry. However, the exact effect of −CH3/–CF3 substitution on bioactivity is still controversial. We compiled a data set containing 28 003 pairs of compounds with the only difference that −CH3 is substituted by −CF3, and the statistical results showed that the replacement of −CH3 with −CF3 does not improve bioactivity on average. Yet, 9.19% substitution of −CH3 by −CF3 could increase the biological activity by at least an order. A PDB survey revealed that −CF3 prefers Phe, Met, Leu, and Tyr, while −CH3 prefers Leu, Met, Cys, and Ile. If we substitute the −CH3 by −CF3 near Phe, His, and Arg, the bioactivity is most probably improved. We performed QM/MM calculations for 39 −CH3/–CF3 pairs of protein–ligand complexes and found that the −CH3/–CF3 substitution does achieve a large energy gain in some systems, although the mean energy difference is subtle, which is consistent with the statistical survey. The −CF3 substitution on the benzene ring could be particularly effective at gaining binding energy. The maximum improvements in energy achieved −4.36 kcal/mol by QM/MM calculation. Moreover, energy decompositions from MM/GBSA calculations showed that the large energy gains for the −CH3/–CF3 substitution are largely driven by the electrostatic energy or the solvation free energy. These findings may shed some light on the biological activity profile for −CH3/–CF3 substitution, which should be useful for further drug discovery and drug design.

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