Saša Đurović

Biological activity and chemical profile of Lavatera thuringiaca L. extracts obtained by different extraction approaches

BACKGROUND Lavatera thuringiaca L. is herbaceous perennial plant from Malvaceae family, which is known for its biological activity and richness in polyphenolic compounds. Despite this, the information regarding the biological activity and chemical profile is still insufficient. PURPOSE Aim of this study was to investigate biological potential and chemical profile of Lavatera thuringiaca L., as well as influence of applied extraction technique on them. STUDY DESIGN AND METHODS Two conventional and four non-conventional extraction techniques were applied in order to obtain extracts rich in bioactive compound. Extracts were further tested for total phenolics, flavonoids, condensed tannins, gallotannins and anthocyanins contents using spectrophotometric assays. Polyphenolic profile was established using HPLC-DAD analysis. Biological activity was investigated regarding antioxidant, cytotoxic and antibacterial activities. Four antioxidant assays were applied as well as three different cell lines for cytotoxic and fifteen bacterial strain for antibacterial activity. RESULTS AND CONCLUSION Results showed that subcritical water extraction (SCW) dominated over the other extraction techniques, where SCW extract exhibited the highest biological activity. Study indicates that plant Lavatera thuringiaca L. may be used as a potential source of biologically compounds.

Fatty acid profile of stinging nettle leaves: application of modern analytical procedures for sample preparation and analysis

Stinging nettle is a perennial plant with significant biological activity and a long history of application in folk medicine and as food. Its activity is ascribed to its chemical composition. Its leaves contain different classes of compounds including fatty acids. This study deals with the isolation of fatty acids in stinging nettle leaves using a rapid extraction system for solid–liquid extraction (Soxtherm) with petroleum ether as the solvent. The obtained results indicate that the saturated fatty acids are more abundant than unsaturated fatty acids. The most abundant fatty acids are C12 : 0 (20.94%, 348.07 μg g−1), C16 : 0 (18.57%, 309.06 μg g−1), and C18 : 1 (13.16%, 219.44 μg g−1), whereas the fatty acid with the lowest content is C17 : 1 (0.13%, 2.20 μg g−1). Prior to analysis, the method is validated to obtain accurate and precise results. The limit of detection and limit of quantification are 0.012–0.038% and 1.67–7.03%, whereas the precision and accuracy are 83–126% and 1.67–7.03%, respectively. The validation parameters are >0.999, 0.011–0.032%, 0.012–0.038%, 1.67–7.03%, 83–126%, 0.22–5.24%, and 0.38–6.94% for linearity, limit of detection, limit of quantitation, precision, accuracy, inter-day precision, and intra-day precision, respectively, confirming the suitability of this method for fatty acid analysis.

Subcritical water extraction as a cutting edge technology for the extraction of bioactive compounds from chamomile: Influence of pressure on chemical composition and bioactivity of extracts

The study was designed to determine the relationship between chemical structure, bioactivity and pressure during the subcritical water extraction (SCW) of chamomile. Extraction was carried out at isothermal conditions (100 °C) at five different pressures (10, 30, 45, 60 and 90 bar). Twenty three polyphenolic compounds were identified in the extracts, whereby apigenin was found to be the dominant compound (61.53-1344.99 mg/kg). Results suggest that the lowest applied pressure has negligible effect on phenolic recovery from chamomile, but also the use of pressures above than 45 bar was proven as needlessly. By using in vitro assays, influence of pressure on antioxidant, cytotoxic and enzyme-inhibitory activities of the extracts was evaluated. Extracts obtained at 30, 45 and 60 bar exhibited stronger bioactivities than at 10 and 90 bar. It was concluded that pressure exert a significant influence on chemical composition of extracts, and thus on biological activity of chamomile extracts.

Effects of Orange Leaves Extraction Conditions on Antioxidant and Phenolic Content: Optimization Using Response Surface Methodology

ABSTRACT In the last few years, bioactive components or their extraction techniques are gaining special interest in scientific areas. In this framework, orange leaves were used for preparation of extracts with high content of biologically active compounds. To optimize the extraction process, three levels and three variables of Box–Behnken design with response surface methodology were applied. Investigated responses were the total phenolic content (TPC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, cupric ion reducing antioxidant capacity (CUPRAC), and ferric reducing antioxidant power (FRAP). Independent variables were methanol concentration (10–90%), temperature (20–60°C), and extraction time (60–180 min). Experimentally obtained results were fit into a second-order polynomial model with multiple regression. Analysis of variance was used to estimate model fitness and determine optimal conditions for processing. Estimated optimal conditions were 90% methanolic solution, 60°C and 180 min using these parameters; the predicted values of investigated responses were 43.19 mg GAE/g (GAE: gallic acid equivalents), 43.04 mg TE/g (TE: trolox equivalents), 139.34 and 93.76 mg TE/g for TPC, DPPH, CUPRAC, and FRAP, respectively. The obtained optimal conditions could be considered as an alternative strategy for developing novel functional products.