Structure elucidation of organic compounds from natural sources using 1D and 2D NMR techniques

Cytotoxicity and Antioxidant Activity of New Biologically Active Constituents from Salvia Lanigra and Salvia Splendens

“…The acetone extracts of Salvia lanigra and Salvia splendens and the n-butanol extract of Salvia lanigra were repeatedly chromatographed over normal-phase silica gel, silica gel for flash and reversed-phase silica gel to give five diterpenes (1-5), two triterpenioc acids (6 and 7), one sterol (8), two flavones (9 and 10) and one phenolic acid (11). The known compounds were identified as horminone (1) [10][11][12] and 7-O-ethylhorminone (2), [10][11][12][13] ursolic acid (6) and oleanolic acid (7), [14] β-sitosterol (8), [15,16] salvigenin (9) and apigenin (10) by comparing their spectral data (mass spectrometry, 1 H-and 13 C NMR) with those reported previously. [17][18][19] Cell survival was evaluated by adding 10 μL of 5 mg/ml MTT in 0.1 mM, pH 7.4 phosphate buffered saline to each well, and re-incubating plates in 5% CO 2 /air for 4 hrs at 37°C.…”

“…The 1 H and 13 C NMR measurements were obtained with a Bruker NM spectrometer operating at 300, 400 and 500 MHz (for 1 H) and 100 and 75 MHz (for 13 C) in Acetone-d 6 , DMSO-d 6 or CDCl 3 solution, and chemical shifts were expressed in δ (ppm) with reference to TMS, and coupling constant (J) in Hertz. 13 C multiplicities were determined by the DEPT pulse sequence (135 o ). HMQC NMR experiments were carried out using a Bruker AMX-500 high field spectrometer equipped with an IBM Aspect-2000 processor and with software VNMR version 4.1 or NUTS program for NMR.…”

Detailed 1H and 13C NMR structural assignments of four sesquiterpene lactones isolated from Eremanthus elaeagnus (Asteraceae)

“…[13] Nowadays, the evolution of NMR techniques allows for a more detailed analysis of the chemical structure of NPs and some experiments can be specifically employed to generate more information, such as 2D NMR results. [14][15][16] The Eremanthus Less (Asteraceae: Vernonieae) genus is endemic to Brazil, comprises 22 species, and has demonstrated to be a rich source of new NPs with an expressive range of biological activities such as antimicrobial, antitumor, schistosomicidal, and antioxidant. [17][18][19] Among these compounds, 4,5-dihydro-1 0 ,2 0 -epoxyeremantholide-C (1), 4,5-dihydro-2 0 ,3 0 -dihydroxy-15-desoxy goyazensolide…”

Structural Elucidation of Pimarane and Isopimarane Diterpenoids: The 13C NMR Contribution

“…Pimaranes and isopimaranes ( Figure 1) have several chiral centers, with methylene and methine carbons with very similar chemical environments. The unequivocal identification of these compounds is difficult and not possible without application of several spectroscopic techniques, mainly 1D ( 1 H, 13 C, DEPT, INEPT) and 2D NMR experiments (COSY, HSQC, HMBC, NOESY), as demonstrated in a recent review [5]. The 13 C NMR spectra can be obtained in several deuterated solvents, with deuteriochloroform being one of the most used.…”