Dehydroleucodine, a Sesquiterpene Lactone from Gynoxys verrucosa, Demonstrates Cytotoxic Activity against Human Leukemia Cells.
Ordóñez, Paola E; Sharma, Krishan K.; Bystrom, Laura M.; Alas, Maria A.; Enriquez, Raul G.; Malagón, Omar; Jones, Darin E.; Guzman, Monica L.; Compadre, Cesar M.; Journal of natural products 79 (2016) 691–696; doi:10.1021/acs.jnatprod.5b00383

data_1543449
_publ_section_title
;
 Dehydroleucodine, a Sesquiterpene Lactone from Gynoxys verrucosa,
 Demonstrates Cytotoxic Activity against Human Leukemia Cells.
;
_journal_issue                   4
_journal_name_full               'Journal of natural products'
_journal_page_first              691
_journal_page_last               696
_journal_paper_doi               10.1021/acs.jnatprod.5b00383
_journal_volume                  79
_journal_year                    2016
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C15 H18 O3'
_chemical_formula_sum            'C15 H18 O3'
_chemical_formula_weight         246.29
_space_group_crystal_system      orthorhombic
_space_group_IT_number           19
_space_group_name_Hall           'P 2ac 2ab'
_space_group_name_H-M_alt        'P 21 21 21'
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   difmap
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           'SHELXL-2014/7 and CIFFIX'
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   7.5528(2)
_cell_length_b                   11.7831(3)
_cell_length_c                   14.1030(3)
_cell_measurement_reflns_used    9959
_cell_measurement_temperature    90.0(2)
_cell_measurement_theta_max      68.14
_cell_measurement_theta_min      4.89
_cell_volume                     1255.10(5)
_computing_cell_refinement       '<i>APEX2</i> (Bruker-AXS, 2006)'
_computing_data_collection       '<i>APEX2</i> (Bruker-AXS, 2006)'
_computing_data_reduction        '<i>APEX2</i> (Bruker-AXS, 2006)'
_computing_molecular_graphics    '<i>XP in SHELXTL</i> (Sheldrick, 2008a)'
_computing_publication_material
'<i>SHELX</i> (Sheldrick, 2008a) and <i>CIFFIX</i> (Parkin, 2013)'
_computing_structure_refinement  '<i>SHELXL-2014/7</i> (Sheldrick, 2008a)'
_computing_structure_solution    '<i>SHELXT</i> (Sheldrick, 2008a)'
_diffrn_ambient_temperature      90.0(2)
_diffrn_detector_area_resol_mean 5.6
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.996
_diffrn_measurement_device_type  'Bruker X8 Proteum diffractometer'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0411
_diffrn_reflns_av_unetI/netI     0.0206
_diffrn_reflns_Laue_measured_fraction_full 0.997
_diffrn_reflns_Laue_measured_fraction_max 0.996
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -3
_diffrn_reflns_limit_k_max       14
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       16
_diffrn_reflns_limit_l_min       -16
_diffrn_reflns_number            17038
_diffrn_reflns_point_group_measured_fraction_full 0.997
_diffrn_reflns_point_group_measured_fraction_max 0.994
_diffrn_reflns_theta_full        67.679
_diffrn_reflns_theta_max         68.198
_diffrn_reflns_theta_min         4.891
_diffrn_source                   'fine-focus rotating anode'
_exptl_absorpt_coefficient_mu    0.724
_exptl_absorpt_correction_T_max  0.942
_exptl_absorpt_correction_T_min  0.861
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   '<i>SADABS</i> (Sheldrick, 2008b)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.303
_exptl_crystal_description       slab
_exptl_crystal_F_000             528
_exptl_crystal_size_max          0.210
_exptl_crystal_size_mid          0.150
_exptl_crystal_size_min          0.080
_refine_diff_density_max         0.184
_refine_diff_density_min         -0.165
_refine_diff_density_rms         0.039
_refine_ls_abs_structure_details
; 
Flack 'x' determined using 934 quotients [(I+)-(I-)]/[(I+)+(I-)] 
[Parsons, Flack and Wagner (2013)]. 
;
_refine_ls_abs_structure_Flack   0.01(4)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.054
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     166
_refine_ls_number_reflns         2273
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.054
_refine_ls_R_factor_all          0.0286
_refine_ls_R_factor_gt           0.0284
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0434P)^2^+0.2989P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0751
_refine_ls_wR_factor_ref         0.0753
_reflns_Friedel_coverage         0.704
_reflns_Friedel_fraction_full    0.997
_reflns_Friedel_fraction_max     0.992
_reflns_number_gt                2264
_reflns_number_total             2273
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            np5b00383_si_001.cif
_cod_data_source_block           x14509
_cod_database_code               1543449
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_min   0.863
_shelx_estimated_absorpt_t_max   0.944
_exptl_absorpt_special_details
; 
In addition to absorption, multi-scan techniques also correct other slowly 
varying changes in scale factor over reciprocal space, such as those caused 
by x-ray beam inhomogeneity, goniometer imperfection, crystal longer than 
the x-ray beam cross section, absorption by the crystal mounting fibre etc. 
These account, by and large, for much of the difference between estimated 
values of Tmin and Tmax and the _exptl_absorpt_correction_ values. 
;
_shelx_res_checksum              33102
_shelx_hkl_checksum              38701