ent-Kaurane Diterpenoids with Neuroprotective Properties from Corn Silk ( Zea mays).
Qi, Xiao-Li; Zhang, Ying-Ying; Zhao, Peng; Zhou, Le; Wang, Xiao-Bo; Huang, Xiao-Xiao; Lin, Bin; Song, Shao-Jiang; Journal of natural products 81 (2018) 1225–1234; doi:10.1021/acs.jnatprod.7b01017

data_1553330
_publ_section_title
;
 ent-Kaurane Diterpenoids with Neuroprotective Properties from Corn Silk (
 Zea mays).
;
_journal_issue                   5
_journal_name_full               'Journal of natural products'
_journal_page_first              1225
_journal_page_last               1234
_journal_paper_doi               10.1021/acs.jnatprod.7b01017
_journal_volume                  81
_journal_year                    2018
_chemical_formula_sum            'C20 H28 O4'
_chemical_formula_weight         332.42
_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'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2014/7
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   8.8766(2)
_cell_length_b                   10.9773(3)
_cell_length_c                   18.1040(5)
_cell_measurement_reflns_used    6124
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      68.34
_cell_measurement_theta_min      4.71
_cell_volume                     1764.07(8)
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.1170
_diffrn_reflns_av_unetI/netI     0.0846
_diffrn_reflns_Laue_measured_fraction_full 0.998
_diffrn_reflns_Laue_measured_fraction_max 0.998
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -20
_diffrn_reflns_number            11107
_diffrn_reflns_point_group_measured_fraction_full 0.998
_diffrn_reflns_point_group_measured_fraction_max 0.998
_diffrn_reflns_theta_full        58.917
_diffrn_reflns_theta_max         58.917
_diffrn_reflns_theta_min         4.711
_exptl_absorpt_coefficient_mu    0.688
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.252
_exptl_crystal_description       block
_exptl_crystal_F_000             720
_refine_diff_density_max         0.437
_refine_diff_density_min         -0.404
_refine_diff_density_rms         0.118
_refine_ls_abs_structure_details
;
 Flack x determined using 905 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   0.1(2)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.115
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     221
_refine_ls_number_reflns         2528
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.115
_refine_ls_R_factor_all          0.0695
_refine_ls_R_factor_gt           0.0642
_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^)+(0.1051P)^2^+0.0452P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1545
_refine_ls_wR_factor_ref         0.1595
_reflns_Friedel_coverage         0.714
_reflns_Friedel_fraction_full    0.997
_reflns_Friedel_fraction_max     0.997
_reflns_number_gt                2312
_reflns_number_total             2528
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            np7b01017_si_002.cif
_cod_data_source_block           cu_20170725B_0ma_a
_cod_database_code               1553330
_shelx_shelxl_version_number     2014/7
_shelx_res_checksum              32715
_shelx_hkl_checksum              5394