Seasonal Variations in Carnosic Acid Content of Rosemary Correlates with Anthocyanins and Soluble Sugars

Seasonal variations may influence the quality and quantity of biologically active ingredients in medicinal plants. Rosemary (Rosmarinus officinalis L.) a member of the Lamiaceae family, contains valuable antioxidant, anticancer and antibacterial substances, including Carnosic acid (CA). Here, the fluctuations of important active compounds present in rosemary leaf extracts collected in Golestan, Iran were studied during the year of 2012-2013. Plant phenolics, flavonoids, ascorbates, anthocyanins and soluble sugars were analyzed spectrophotometrically, while CA content was measured by High Performance Liquid Chromatography (HPLC). The highest amounts of total flavonoids occurred in autumn; while CA, phenolics, ascorbic acids and soluble sugars were greatest in winter, probably due to regional high precipitation and subtle winters. Most of the above indicated active compounds were low in early summer. Furthermore, total anthocyanins and soluble sugars showed significant positive correlations with CA over the year. These data suggest that rosemary extracts from the collected leaves in winter contain greater amounts of biologically active compounds; and can be used for standardization of plant materials harvested throughout a year

Application of Molecular Dynamics in Coating Ag-Conjugated Nanoparticles with Potential Therapeutic Applications

Drug delivery systems may benefit from nanoparticles synthesized using biological methods. While chemical reduction of particles is facilitated by some active compounds present in the bio-extract, other active compounds, with potential therapeutic activities, may be adsorbed onto the surface of nanoparticles. However, the mechanism of bio-based nanoparticle synthesis is still under debate. Here, we first employed a molecular dynamics (MD) approach to theoretically predict the coating of a hypothetical 4.5 nm silver nanoparticle with four selected rosemary (Rosmarinus Officinalis L.) active compounds (rosmanol, isorosmanol, carnosol, and carnosic acid). Analysis of density maps and radial distribution functions (RDF) values suggested that the examined compounds had strong hydrophobic properties and could instantaneously be adsorbed to the nanoparticle surfaces. Next, we experimentally examined the capacity of rosemary leaf extract to synthesize and coat Ag-conjugated nanoparticles. The data obtained from ultraviolet–visible spectroscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy and X-ray powder diffraction analyses confirmed the production of spherical Ag-conjugated nanoparticles with an average size of 12-15 nm, coated with proteins, secondary metabolites and other active compounds. Since this method can predict the dynamic behavior of therapeutic compounds when they are in contact with nanoparticles, we believe it provides a valid and new avenue to designing new therapeutic nanoparticles