Engineering hydrophobically modified chitosan for enhancing the dispersion of respirable microparticles of levofloxacin

The potential of amphiphilic chitosan formed by grafting octanoyl chains on the chitosan backbone for pulmonary delivery of levofloxacin has been studied. The success of polymer synthesis was confirmed using FT-IR and NMR, whilst antimicrobial activity was assessed against Pseudomonas aeruginosa. Highly dispersible dry powders for delivery as aerosols were prepared with different amounts of chitosan and octanoyl chitosan to study the effect of hydrophobic modification and varying concentration of polymer on aerosolization of drug. Powders were prepared by spray-drying from an aqueous solution containing levofloxacin and chitosan/amphiphilic octanoyl chitosan. L-leucine was also used to assess its effect on aerosolization. Following spray-drying, the resultant powders were characterized using scanning electron microscopy, laser diffraction, dynamic light scattering, HPLC, differential scanning calorimetry, thermogravimetric analysis and X-ray powder diffraction. The in vitro aerosolization profile was determined using a Next Generation Impactor, whilst in vitro antimicrobial assessment was performed using MIC assay. Microparticles of chitosan have the property of mucoadhesion leading to potential increased residence time in the pulmonary mucus, making it important to test the toxicity of these formulations. In-vitro cytotoxicity evaluation using MTT assay was performed on A549 cell line to determine the toxicity of formulations and hence feasibility of use. The MTT assay confirmed that the polymers and the formulations were non-cytotoxic. Hydrophobically modifying chitosan showed significantly lower MIC (4-fold) than the commercial chitosan against P. aeruginosa. The powders generated were of suitable aerodynamic size for inhalation having a mass median aerodynamic diameter less than 4.5 lm for formulations containing octanoyl chitosan. These highly dispersible powders have minimal moisture adsorption and hence an emitted dose of more than 90% and a fine particle fraction (FPF) of 52%. Powders with non-modified chitosan showed lower dispersibility, with an emitted dose of 72% and FPF of 20%, as a result of high moisture adsorption onto the chitosan matrix leading to cohesiveness and subsequently decreased dispersibility

Relationship between the Floristic Composition and Soil Characteristics of a Tropical Rainforest (TRF)

Hutan Rimba Alam (HRA), Putrajaya is an urban forest which is the habitat for various tropical rainforest species. A field survey was undertaken to state the floristic composition, investigate the soil characteristics and identify the relationship between the recorded plant communities and soil characteristics. Six plots sized 10 × 10 m square were established in a lowland area of which 93 individual trees were identified. Moreover, the floristic composition revealed vascular tree communities consisting of 10 botanical families, 15 genera, and 27 species with Dipterocarpaceae as being predominant. Based on the important value index (IVI), Mangifera odorata (Anacardiaceae) was the highest (IVI = 68.80%). Furthermore, large trees such as Koompassia excelsa (Becc.) Taub. (Fabaceae) and Sandoricum koetjape (Burm.f.) Merr. (Meliaceae), with heights ranging from 17 m to 24 m, indicated that HRA is on the way to becoming a mature forest. The soil pH in all plots showed acidic properties, with a mean pH of 4.69 that is considered normal for tropical rainforests. The pH of the soils in HRA, Putrajaya had a positive correlation with the CEC and with nitrogen, but the value was low; however, the correlation was negative with C and P. The CEC had a relatively low correlation with C, N and P. Carbon had a very high correlation with N but low with P. Meanwhile, nitrogen had a very negatively low correlation with P. Extractable phosphorus exhibited a mean of 2.22 mg/kg which is normally used in plants for fruits, roots, and flower development. The present study revealed that plant communities in the urban forest in Putrajaya, meaning the diversity of the plant species belonging to a wide range of families, were established on acid soil, matching with the overall characteristics of tropical forest soils. With regard to the climate change context, which is leading to many altered ecosystems, the authors expect that the outputs of this research will be valued by decision makers for a better management of the forest

Aconitum lycoctonum L. (Ranunculaceae) mediated biogenic synthesis of silver nanoparticles as potential antioxidant, anti-inflammatory, antimicrobial and antidiabetic agents

Abstract In this study, a polar extract of Aconitum lycoctonum L. was used for the synthesis of silver nanoparticles (AgNPs), followed by their characterization using different techniques and evaluation of their potential as antioxidants, amylase inhibitors, anti-inflammatory and antibacterial agents. The formation of AgNPs was detected by a color change, from transparent to dark brown, within 15 min and a surface resonance peak at 460 nm in the UV–visible spectrum. The FTIR spectra confirmed the involvement of various biomolecules in the synthesis of AgNPs. The average diameter of these spherical AgNPs was 67 nm, as shown by the scanning electron micrograph. The inhibition zones showed that the synthesized nanoparticles inhibited the growth of Gram-positive and negative bacteria. FRAP and DPPH assays were used to demonstrate the antioxidant potential of AgNPs. The highest value of FRAP (50.47% AAE/mL) was detected at a concentration of 90 ppm and a DPPH scavenging activity of 69.63% GAE was detected at a concentration of 20 µg/mL of the synthesized AgNPs. 500 µg/mL of the synthesized AgNPs were quite efficient in causing 91.78% denaturation of ovalbumin. The AgNPs mediated by A. lycoctonum also showed an inhibitory effect on α-amylase. Therefore, AgNPs synthesized from A. lycoctonum may serve as potential candidates for antibacterial, antioxidant, anti-inflammatory, and antidiabetic agents