Liuwei Dihuang (LWDH), a classic Chinese medicinal formula, has been used to improve or restore declined functions related to aging and geriatric diseases, such as impaired mobility, vision, hearing, cognition and memory. Here, we report on the effect and possible mechanisms of LWDH mediated protection of β-amyloid (Aβ) induced paralysis in Caenorhabditis elegans using ethanol extract (LWDH-EE) and water extract (LWDH-WE). Chemical profiling and quantitative analysis revealed the presence of different levels of bioactive components in these extracts. LWDH-WE was rich in polar components such as monosaccharide dimers and trimers, whereas LWDH-EE was enriched in terms of phenolic compounds such as gallic acid and paeonol. In vitro studies revealed higher DPPH radical scavenging activity for LWDH-EE as compared to that found for LWDH-WE. Neither LWDH-EE nor LWDH-WE were effective in inhibiting aggregation of Aβ in vitro. By contrast, LWDH-EE effectively delayed Aβ induced paralysis in the transgenic C. elegans (CL4176) model which expresses human Aβ1–42. Western blot revealed no treatment induced reduction in Aβ accumulation in CL4176 although a significant reduction was observed at an early stage with respect to β-amyloid deposition in C. elegans strain CL2006 which constitutively expresses human Aβ1–42. In addition, LWDH-EE reduced in vivo reactive oxygen species (ROS) in C. elegans (CL4176) that correlated with increased survival of LWDH-EE treated N2 worms under juglone-induced oxidative stress. Analysis with GFP reporter strain TJ375 revealed increased expression of hsp16.2::GFP after thermal stress whereas a minute induction was observed for sod3::GFP. Quantitative gene expression analysis revealed that LWDH-EE repressed the expression of amy1 in CL4176 while up-regulating hsp16.2 induced by elevating temperature. Taken together, these results suggest that LWDH extracts, particularly LWDH-EE, alleviated β-amyloid induced toxicity, in part, through up-regulation of heat shock protein, antioxidant activity and reduced ROS in C. elegans.

In this article, we present density functional theory (DFT) calculations on the iron(IV)-oxo catalyzed methane C-H activation reactions for complexes in which the Fe(IV)═O core is surrounded by five negatively charged ligands. We found that it follows a hybrid pathway that mixes features of the classical σ- and π-pathways in quintet surfaces. These calculations show that the Fe-O-H arrangement in this hybrid pathway is bent in sharp contrast to the collinear character as observed for the classical quintet σ-pathways before. The calculations have also shown that it is the equatorial ligands that play key roles in tuning the reactivity of Fe(IV)═O complexes. The strong π-donating equatorial ligands employed in the current study cause a weak π(FeO) bond and thereby shift the electronic accepting orbitals (EAO) from the vertically orientated O pz orbital to the horizontally orientated O px. In addition, all the equatorial ligands are small in size and would therefore be expected have small steric effects upon substrate horizontal approaching. Therefore, for the small and strong π-donating equatorial ligands, the collinear Fe-O-H arrangement is not the best choice for the quintet reactivity. This study adds new element to iron(IV)-oxo catalyzed C-H bond activation reactions.