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Toxicology and drug delivery by cucurbit[n]uril type molecular containers.

Hettiarachchi G, Nguyen D, Wu J, Lucas D, Ma D, Isaacs L, Briken V - PLoS ONE (2010)

Bottom Line: This result suggests that CB[7]-bound drug molecules can be released from the container to find their intracellular target.It demonstrates the uptake of containers by cells and intracellular release of container-loaded drugs.These results provide initial proof-of-concept towards the use of CB[n] molecular containers as an advanced drug delivery system.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America.

ABSTRACT

Background: Many drug delivery systems are based on the ability of certain macrocyclic compounds - such as cyclodextrins (CDs) - to act as molecular containers for pharmaceutical agents in water. Indeed beta-CD and its derivatives have been widely used in the formulation of hydrophobic pharmaceuticals despite their poor abilities to act as a molecular container (e.g., weak binding (K(a)<10(4) M(-1)) and their challenges toward chemical functionalization. Cucurbit[n]urils (CB[n]) are a class of molecular containers that bind to a variety of cationic and neutral species with high affinity (K(a)>10(4) M(-1)) and therefore show great promise as a drug delivery system.

Methodology: In this study we investigated the toxicology, uptake, and bioactivity of two cucurbit[n]urils (CB[5] and CB[7]) and three CB[n]-type containers (Pentamer 1, methyl hexamer 2, and phenyl hexamer 3). All five containers demonstrated high cell tolerance at concentrations of up to 1 mM in cell lines originating from kidney, liver or blood tissue using assays for metabolic activity and cytotoxicity. Furthermore, the CB[7] molecular container was efficiently internalized by macrophages indicating their potential for the intracellular delivery of drugs. Bioactivity assays showed that the first-line tuberculosis drug, ethambutol, was as efficient in treating mycobacteria infected macrophages when loaded into CB[7] as when given in the unbound form. This result suggests that CB[7]-bound drug molecules can be released from the container to find their intracellular target.

Conclusion: Our study reveals very low toxicity of five members of the cucurbit[n]uril family of nanocontainers. It demonstrates the uptake of containers by cells and intracellular release of container-loaded drugs. These results provide initial proof-of-concept towards the use of CB[n] molecular containers as an advanced drug delivery system.

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Related in: MedlinePlus

HepG2 toxicology assays using various containers.This assay showed high cell viability and low toxicity. HepG2 MTS (A) and AK (B) assays were conducted using the procedure described in Fig 2.
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pone-0010514-g003: HepG2 toxicology assays using various containers.This assay showed high cell viability and low toxicity. HepG2 MTS (A) and AK (B) assays were conducted using the procedure described in Fig 2.

Mentions: Toxicity studies using the MTS and AK assays for the liver cell line, HepG2, provided similar results to the HEK293 cells (Figure 3A). The MTS assay for distilled water treated HepG2 population indicated a percent cell viability of 0.28% which was comparable to that of erythromycin estolate at 1 mM (9% cell viability). However, interestingly, the cell viability for erythromycin at 1 mM indicated high survival at approximately 97%. HepG2 treatment with 1 mM of CB[7], CB[5], 1, 2 and 3 resulted in 96, 97, 101, 102% and 96% cell viability respectively compared to 100% viability in the untreated cell population (Figure 3A). These results were also reflected in the AK assay. Untreated cells indicated only 40% cell death while erythromycin and erythromycin estolate treatment resulted in 76 and 103% relative cell death. The containers CB[7], CB[5], 1, 2, and 3 provided values of 22, 24, 23, 17, and 4% death respectively in the HepG2 cell line, in turn supporting the high survival values of the MTS assay and untreated cell population (Figure 3B).


Toxicology and drug delivery by cucurbit[n]uril type molecular containers.

Hettiarachchi G, Nguyen D, Wu J, Lucas D, Ma D, Isaacs L, Briken V - PLoS ONE (2010)

HepG2 toxicology assays using various containers.This assay showed high cell viability and low toxicity. HepG2 MTS (A) and AK (B) assays were conducted using the procedure described in Fig 2.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2865549&req=5

pone-0010514-g003: HepG2 toxicology assays using various containers.This assay showed high cell viability and low toxicity. HepG2 MTS (A) and AK (B) assays were conducted using the procedure described in Fig 2.
Mentions: Toxicity studies using the MTS and AK assays for the liver cell line, HepG2, provided similar results to the HEK293 cells (Figure 3A). The MTS assay for distilled water treated HepG2 population indicated a percent cell viability of 0.28% which was comparable to that of erythromycin estolate at 1 mM (9% cell viability). However, interestingly, the cell viability for erythromycin at 1 mM indicated high survival at approximately 97%. HepG2 treatment with 1 mM of CB[7], CB[5], 1, 2 and 3 resulted in 96, 97, 101, 102% and 96% cell viability respectively compared to 100% viability in the untreated cell population (Figure 3A). These results were also reflected in the AK assay. Untreated cells indicated only 40% cell death while erythromycin and erythromycin estolate treatment resulted in 76 and 103% relative cell death. The containers CB[7], CB[5], 1, 2, and 3 provided values of 22, 24, 23, 17, and 4% death respectively in the HepG2 cell line, in turn supporting the high survival values of the MTS assay and untreated cell population (Figure 3B).

Bottom Line: This result suggests that CB[7]-bound drug molecules can be released from the container to find their intracellular target.It demonstrates the uptake of containers by cells and intracellular release of container-loaded drugs.These results provide initial proof-of-concept towards the use of CB[n] molecular containers as an advanced drug delivery system.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America.

ABSTRACT

Background: Many drug delivery systems are based on the ability of certain macrocyclic compounds - such as cyclodextrins (CDs) - to act as molecular containers for pharmaceutical agents in water. Indeed beta-CD and its derivatives have been widely used in the formulation of hydrophobic pharmaceuticals despite their poor abilities to act as a molecular container (e.g., weak binding (K(a)<10(4) M(-1)) and their challenges toward chemical functionalization. Cucurbit[n]urils (CB[n]) are a class of molecular containers that bind to a variety of cationic and neutral species with high affinity (K(a)>10(4) M(-1)) and therefore show great promise as a drug delivery system.

Methodology: In this study we investigated the toxicology, uptake, and bioactivity of two cucurbit[n]urils (CB[5] and CB[7]) and three CB[n]-type containers (Pentamer 1, methyl hexamer 2, and phenyl hexamer 3). All five containers demonstrated high cell tolerance at concentrations of up to 1 mM in cell lines originating from kidney, liver or blood tissue using assays for metabolic activity and cytotoxicity. Furthermore, the CB[7] molecular container was efficiently internalized by macrophages indicating their potential for the intracellular delivery of drugs. Bioactivity assays showed that the first-line tuberculosis drug, ethambutol, was as efficient in treating mycobacteria infected macrophages when loaded into CB[7] as when given in the unbound form. This result suggests that CB[7]-bound drug molecules can be released from the container to find their intracellular target.

Conclusion: Our study reveals very low toxicity of five members of the cucurbit[n]uril family of nanocontainers. It demonstrates the uptake of containers by cells and intracellular release of container-loaded drugs. These results provide initial proof-of-concept towards the use of CB[n] molecular containers as an advanced drug delivery system.

Show MeSH
Related in: MedlinePlus