A low toxic synthetic dendrimer conjugated podophyllotoxin nanodevice with potent antitumor activity against the DMBA/TPA induced mouse skin carcinogenesis model

Dendrimer-conjugated podophyllotoxin suppresses DENA-induced HCC progression by modulation of inflammatory and fibrogenic factors

Podophyllotoxin has been explored as an anticancer, antiviral, and antibacterial agent; however, its low water solubility and toxicity limit its use. In this study, the efficacy of a more soluble and less toxic polyamidoamine (PAMAM) dendrimer-conjugated podophyllotoxin (DPODO) was evaluated against chemically induced hepatocellular carcinoma (HCC) in mice. HCC was induced by giving 0.01% diethylnitrosamine (DENA) in drinking water for 16 weeks. The HCC-induced mice were treated with 10 or 20 mg per kg body weight DPODO. The DENA administration led to HCC development, characterized by anisocytosis, karyomegaly, inflammation and degenerative changes in the liver. The DPODO treatment at 10 mg and 20 mg doses significantly reduced the histopathological changes in liver tissue. The DPODO treatment also significantly lowered the levels of inflammatory markers IL-6 and NF-κB in serum and tissue, respectively. Further, the treatment also significantly reduced fibrous tissue deposition in the liver, which was further confirmed by the reduced mRNA levels and tissue expression of fibrogenic markers TGF-β and α-SMA in the liver. The results of the present study indicate that DPODO treatment suppresses the progression of HCC by modulating the inflammatory and fibrogenic factors, which play important roles in HCC development.

Dendrimer conjugated estramustine nanocrystalline 'Dendot': An effective inhibitor of DMBA-TPA induced papilloma formation in mouse

Clinically approved anticancer drug estramustine mediates its function by impairing microtubule polymerization. However, the low aqueous solubility and high toxicity limit its anticancer activity via the oral route. Previously, efforts have been made to develop an enhanced water soluble form of estramustine as estramustine phosphate (EM) but acidic gastrointestinal pH breaks the phosphate derivative via oral administration. As an alternative approach, we have made an effort to enhance solubility and minimize toxicity in vivo by conjugating EM to a poly(amidoamine) (PAMAM) dendrimer, which generated the sustained release of dendrimer conjugate (DEM). To the best of our knowledge, for the first time, we report the direct proof of the nano-crystalline 'DenDot' of DEM on TEM image. The toxicity study showed that both EM and DEM were nontoxic up to 20mg/kg. A comparative anti-papilloma study was also performed with EM and dendrimer conjugates (DEM) using a two-stage mouse skin carcinogenesis model. We found that DEM was more effective in inhibiting skin tumor formation than EM. Histopathology and immunohistochemistry studies further indicated that DEM treatment increased cell apoptosis, and reduced epithelial hyperplasia, cell proliferation and inflammation in skin tissues of mice. In addition, the synthetic DEM conjugate inhibited skin tumor progression more effectively than EM.

Crocin Attenuates Kindling Development and Associated Cognitive Impairments in Mice via Inhibiting Reactive Oxygen Species-Mediated NF-κB Activation

Crocin is a pharmacologically active carotenoid pigment mainly present in the stigmas of Crocus sativus L. (Iridaceae). It has been well explored in experimental animal models of cognitive impairments, depression, anxiety and epilepsy. This study was designed to understand the effect of crocin on pentylenetetrazol (PTZ)-induced kindling development and its associated cognitive deficit in mouse. Crocin treatment at 5, 10 and 20 mg/kg p.o. doses showed a marked reduction in severity of PTZ-induced seizures. There was an increase in novel object preference index and discrimination ratio in the crocin-treated groups in the novel object recognition test. Its treatment also increased percentage spontaneous alternations in T-maze test at all the tested doses. Histopathological examination by Nissl staining showed a reduction in dark neurons in the hippocampal pyramidal layer of crocin-treated animals in contrast to vehicle control, indicating a decrease in neuronal damage. Biochemical estimations showed a significant increase in superoxide dismutase activity and reduced reactive oxygen species (ROS) in the hippocampus of crocin-treated animals. Immunohistochemistry results revealed attenuation in the levels of nuclear factor-κB (NF-κB) and phosphorylated NF-κB in the hippocampal sections of crocin-treated animals. The results of this study concluded that crocin treatment increased seizure threshold, thus inhibiting PTZ-induced kindling development and improving cognitive functions. The effect was found to be due to suppression of seizure-induced ROS generation and its linked NF-κB pathway-associated neuronal damage.

Interactions of dendrimers with biological drug targets: reality or mystery - a gap in drug delivery and development research

Dendrimers have emerged as novel and efficient materials that can be used as therapeutic agents/drugs or as drug delivery carriers to enhance therapeutic outcomes. Molecular dendrimer interactions are central to their applications and realising their potential. The molecular interactions of dendrimers with drugs or other materials in drug delivery systems or drug conjugates have been extensively reported in the literature. However, despite the growing application of dendrimers as biologically active materials, research focusing on the mechanistic analysis of dendrimer interactions with therapeutic biological targets is currently lacking in the literature. This comprehensive review on dendrimers over the last 15 years therefore attempts to identify the reasons behind the apparent lack of dendrimer-receptor research and proposes approaches to address this issue. The structure, hierarchy and applications of dendrimers are briefly highlighted, followed by a review of their various applications, specifically as biologically active materials, with a focus on their interactions at the target site. It concludes with a technical guide to assist researchers on how to employ various molecular modelling and computational approaches for research on dendrimer interactions with biological targets at a molecular level. This review highlights the impact of a mechanistic analysis of dendrimer interactions on a molecular level, serves to guide and optimise their discovery as medicinal agents, and hopes to stimulate multidisciplinary research between scientific, experimental and molecular modelling research teams.