Oral administration of Centella asiatica (L.) Urb leave aqueous extract ameliorates cerebral oxidative stress, inflammation, and apoptosis in male rats with type-2 diabetes.

Centella asiatica is claimed to have a neuroprotective effect; however, its ability to protect the cerebrum against damage in diabetes has never been identified. The aims were to identify the possibility that C. asiatica ameliorates inflammation, oxidative stress, and apoptosis in the cerebrum in diabetes. C. asiatica leave aqueous extract (C. asiatica) (50, 100, and 200 mg/kg/b.w.) were given to diabetic rats for 28 days. Changes in rats' body weight, food and water intakes, and insulin and FBG levels were monitored. Following sacrificed, cerebrum was harvested and subjected for histological, biochemical, and molecular biological analyses. The results revealed treatment with C. asiatica was able to ameliorate the loss in body weight, the increase in food and water intakes, the decrease in insulin, and the increase in FBG levels in diabetic rats. Additionally, histopathological changes in the cerebrum and levels of p38, ERK, JNK, cytosolic Nrf2, Keap-1, LPO, RAGE, and AGE levels decreased; however, PI3K, AKT, IR, IRS, GLUT-1, nuclear Nrf2, Nqo-1, Ho-1, and anti-oxidative enzymes (SOD, CAT, and GPx) levels increased in diabetic rats receiving C. asiatica. Furthermore, C. asiatica treatment also caused cerebral inflammation and apoptosis to decrease as indicated by decreased inflammatory markers (cytosolic NF-κB p65, p-Ikkß, Ikkß, iNOS, COX-2, TNF-α, IL-6, and IL-1ß), decreased pro-apoptosis markers (Casp-3, 9, and Bax), but increased anti-apoptosis marker, Bcl-2. Activity level of Na+/K+, Mg2+, and Ca2+-ATPases in the cerebrum also increased by C. asiatica treatment. Conclusions: C. asiatica treatment helps to prevent cerebral damage and maintain near normal cerebral function in diabetes.

Self-assembly of single amino acid/pyrene conjugates with unique structure-morphology relationship.

This article describes the self-assembly of π-conjugated building blocks composed of single amino acid and pyrene (Py) moieties. In aqueous conditions, the Py-capped amino acids undergo self-assembly through various non-covalent interactions such as hydrogen-bonding, π-π stacking as well as electrostatic interactions to form supramolecular nanostructures in acidic and basic conditions. Interestingly, we found that the blend of different Py-gelators with oppositely charged amino acids (Py-Glu and Py-Lys) displays unique nano-structural morphologies and gelation properties of the resulting hydrogels at physiological pH when compared with single Py conjugates, which was attributed to additional electrostatic interactions. Overall, this report illustrates the importance of two-component supramolecular co-assembled hydrogels and their structure-morphology relationship, improved mechanical properties, and biocompatibility and thus provides a new insight into the design of self-assembled nanomaterials.

The role of amino acids on supramolecular co-assembly of naphthalenediimide-pyrene based hydrogelators.

This report describes the two component self-assembly of π-capped amino acid hydrogelators (serine (S), aspartic acid (D), glutamic acid (E) or lysine (K)) prepared from pyrene (Py) based donor and naphthalenediimide (NDI) based acceptor molecules. The co-assembly can be triggered to form hydrogels by varying the pH conditions and the major driving forces behind the hydrogelation were found to be the formation of a strong charge-transfer (CT) complex and hydrogen bonding interactions at suitable pH conditions. The NDI-Py blends with matched donor/acceptor amino acid pairs undergo self-assembly under acidic pH conditions, whereas the blend (NDI-S + Py-K) with a mismatched amino acid pair forms a stable hydrogel under physiological pH conditions. UV-Vis, FTIR and rheological studies clearly indicate the formation and the stability of these CT-induced hydrogels. These hydrogels are of nanofibrous morphology with an average diameter of about 6-9 nm as evidenced by TEM analysis. In addition, this novel NDI-Py mixed component system exhibited good biocompatibility towards PC3 cells. Overall, since hydrogels based on CT-mediated two-component assemblies are very rare, our newly discovered NDI-Py hydrogels provide chemical insights into the design of a CT-induced hydrogelator and might facilitate various applications in biomedical engineering.

Self-Assembled Peptide-Based Hydrogels as Scaffolds for Proliferation and Multi-Differentiation of Mesenchymal Stem Cells.

Fluorenyl-9-methoxycarbonyl (Fmoc)-diphenylalanine (Fmoc-FF) and Fmoc-arginine-glycine--aspartate (Fmoc-RGD) peptides self-assemble to form a 3D network of supramolecular hydrogel (Fmoc-FF/Fmoc-RGD), which provides a nanofibrous network that uniquely presents bioactive ligands at the fiber surface for cell attachment. In the present study, mesenchymal stem cells (MSCs) in Fmoc-FF/Fmoc-RGD hydrogel increase in proliferation and survival compared to those in Fmoc-FF/Fmoc-RGE hydrogel. Moreover, MSCs encapsulated in Fmoc-FF/Fmoc-RGD hydrogel and induced in each defined induction medium undergo in vitro osteogenic, adipogenic, and chondrogenic differentiation. For in vivo differentiation, MSCs encapsulated in hydrogel are induced in each defined medium for one week, followed by injection into gelatin sponges and transplantation into immunodeficient mice for four weeks. MSCs in Fmoc-FF/Fmoc-RGD hydrogel increase in differentiation into osteogenic, adipogenic, and chondrogenic differentiation, compared to those in Fmoc-FF/Fmoc-RGE hydrogel. This study concludes that nanofibers formed by the self-assembly of Fmoc-FF and Fmoc-RGD are suitable for the attachment, proliferation, and multi-differentiation of MSCs, and can be applied in musculoskeletal tissue engineering.