ABSTRACT
BACKGROUND: Saussurea lappa is one of the popular Ayurvedic herb; costunolide and dehydrocostus lactones are well-known sesquiterpene lactones contained in many plants used as popular herbs, such as S. lappa, and have been considered as potential candidates for the treatment of various types of tumor. OBJECTIVE: The present study was used for the quantification of costunolide and dehydrocostus lactone in S. lappa and its polyherbal formulations, stability studies of markers and characterization of their degradants. MATERIALS AND METHODS: HPLC analysis was performed on Waters NOVAPAK HR C18 column (300 mm × 3.9 mm i.d., 6 µm) using isocratic elution with acetonitrile and water (60:40% v/v). RESULTS: The calibration curves of both analytes showed good linearity within the established range 5-100 µg/ml. The limits of detection (LOD) and quantification (LOQ) were 1.5 and 4.6 µg/ml for costunolide and 1.3 and 4.0 µg/ml for dehydrocostus lactone, respectively. Good results were achieved with respect to repeatability (%RSD < 2.0) and recovery (99.3-101.8%). CONCLUSION: The method was found to be precise, accurate, specific, and was successfully used for analyzing costunolide and dehydrocostus lactone in S. lappa and its polyherbal formulations. The developed method was found to be suitable for stability studies of markers and characterization of their degradation products.
ABSTRACT
We have demonstrated the self-assembled DNA nanoparticles capable of controlled disassembly in response to a single nucleotide change (SNC) in a target nucleic acid. The DNA nanoparticles (avg diameter=51+/-22 nm) were constructed by joining two types of streptavidin-DNA conjugates with 2 molar equiv of a linker strand that carries complementary sequences to both conjugates. Nanoparticle disassembly triggered by a target strand (i.e., a perfect complement to the linker) selectively over mismatched targets was achieved by kinetically controlled nucleation occurring at a 6-nt overhang in the linker. The disassembly process was shown to be dramatically slowed down when using mismatch targets in which the SNC was positioned at the fourth nucleotide from the 3'-end. To verify whether the controlled disassembly also works for a SNC located in the middle of a target strand, we tested a deleterious Z variant (G1024A) of human alpha(1)-antitrypsin as a mismatch target (60-nt) carrying the point mutation at position 39. The wild-type target completed the disassembly process in less than 10 min, whereas the mismatch Z-type target could not complete the disassembly even in 3 h. The DNA nanoparticles are promising for sequence-dependent controlled release of short nucleic acids, including siRNA and antisense oligonucleotides, and construction of smart nanomaterials capable of sensing and processing single-nucleotide polymorphisms.
