Polyglutamic Acid-Gated Mesoporous Silica Nanoparticles for Enzyme-Controlled Drug Delivery.

Mesoporous silica nanoparticles (MSNs) are highly attractive as supports in the design of controlled delivery systems that can act as containers for the encapsulation of therapeutic agents, overcoming common issues such as poor water solubility and poor stability of some drugs and also enhancing their bioavailability. In this context, we describe herein the development of polyglutamic acid (PGA)-capped MSNs that can selectively deliver rhodamine B and doxorubicin. PGA-capped MSNs remain closed in an aqueous environment, yet they are able to deliver the cargo in the presence of pronase because of the hydrolysis of the peptide bonds in PGA. The prepared solids released less than 20% of the cargo in 1 day in water, whereas they were able to reach 90% of the maximum release of the entrapped guest in ca. 5 h in the presence of pronase. Studies of the PGA-capped nanoparticles with SK-BR-3 breast cancer cells were also undertaken. Rhodamine-loaded nanoparticles were not toxic, whereas doxorubicin-loaded nanoparticles were able to efficiently kill more than 90% of the cancer cells at a concentration of 100 µg/mL.

Antibacterial Attributes of Apigenin, Isolated from Portulaca oleracea L.

The flavonoid apigenin was isolated from aerial part of P. oleracea L. The dried sample of plant was powdered and subjected to soxhlet extractor by adding 80 mL of ethanol : water (70 : 30). The extract was centrifuged at 11000 rpm for 30 min; supernatant was taken for further use. The fraction was concentrated and subjected to PTLC. The R f value of isolated apigenin was calculated (0.82). Purified material was also subjected to its IR spectra, LC-MS, NMR, and HPLC for structural elucidation. The apigenin so-obtained was subjected to antibacterial activity on five pathogenic bacterial strains like Pseudomonas aeruginosa, Salmonella typhimurium, Proteus mirabilis, Klebsiella pneumoniae and Enterobacter aerogenes; among all the bacterial strains, Salmonella typhimurium (17.36 ± 0.18) and Proteus mirabilis (19.12 ± 0.01) have shown maximum diameter of inhibition zone for flavonoid and remaining bacterial strains have shown moderate diameter of inhibition zone when compared with control values 14.56 ± 0.21 and 11.68 ± 0.13, respectively. The minimum inhibitory concentration (MIC) of the flavonoid isolated from P. oleracea L. was tested at the concentration ranging from undiluted sample to 10 mg per mL of concentration. The minimum inhibition concentration (MIC) for the flavonoid for all tested bacterial strains was found to be >4 mg per mL. Hence, the apigenin has antibacterial property and can be used to develop antibacterial drugs.