Determination of Structure and Cytotoxicity of Ten Undescribed Steroidal Glycosides from Allium cristophii × A. macleanii ‘Globemaster’

‘Globemaster’ is an ornamental hybrid cultivar whose parent plants are Allium cristophii and A. macleanii. The chemical constituents of ‘Globemaster’ bulbs have not yet been examined; thus, a systematic phytochemical investigation was undertaken herein. A series of chromatographic separations of the MeOH extract of ‘Globemaster’ bulbs afforded 27 steroidal glycosides (1–27), which are classified into 23 spirostanol glycosides (1–8 and 11–25), two furostanol glycosides (9 and 26), a pregnane glycoside (10), and a cholestane glycoside (27). The structures of the hitherto undescribed compounds (1–10) were determined from the two-dimensional NMR spectroscopic data and hydrolysis. The cytotoxicity of the isolated compounds (1–27) toward HL-60 human promyelocytic leukemia cells, A549 human adenocarcinoma lung cancer cells, and SBC-3 human small-cell lung cancer cells was evaluated. Compounds 8, 22, 23, 24, and 26 exhibited cytotoxicity toward all cell lines in a dose-dependent manner, with IC50 values in the 1.3–49 µM range.

In 2020, approximately 19 million new cancer cases and 10 million cancer-related deaths were documented globally.Approximately 2.2 million and 470,000 new cases of lung cancer and leukemia and 1.8 million and 310,000 related deaths were estimated in 2020, respectively.Apart from breast cancer, lung cancer is the leading cause of cancerrelated mortality in women worldwide [18].Although anticancer agents such as cisplatin, carboplatin, etoposide, and irinotecan are effective against small-cell lung cancer (SCLC), patients relapse at a relatively high rate [19].Thus, the development of new anticancer agents is desirable for improving the treatment of cancer patients worldwide.
The 1 H and 13 C NMR spectral data of 7 (C 56 H 92 O 28 ) were similar to those of (25R [22], which was isolated from Chlorophytum comosum, except for the signals attributable to the F-ring part of the aglycone.Analysis of the 1 H-1 H COSY and HSQC spectra of 7 revealed that the methylene carbon assignable to C-24 (δ C 29.3) of the aglycone in desgalactotigonin was replaced by an oxygenated methine carbon (δ C 81.

Plant Material
The bulbs of 'Globemaster' were purchased from Fuji-engei (Okayama, Japan) in 2014.A voucher specimen was kept at the herbarium of the Tokyo University of Pharmacy and Life Sciences (KS-2014-009).

Extraction and Isolation
The bulbs of 'Globemaster' (fresh weight, 7.2 kg) were extracted with MeOH (28 L, 60 • C) for 2 h.Then, the solution was evaporated under reduced pressure to obtain MeOH extract ( 460    Table 3. 1 H NMR spectral data of the sugar and acyl moieties of 1-10 in C 5 D 5 N (1) .Table 4. 13 C NMR spectral data of 1-10 in C 5 D 5 N (1) .

Figure 3 .
Figure 3. Representative NOE correlations of the F-ring part of 3.

Figure 3 .
Figure 3. Representative NOE correlations of the F-ring part of 3.