## 2 Results and Discussion
The correlation between 1\({}^{\prime}\)-H at \(\delta\) 5.12 ppm and 4\({}^{\prime}\)-C at \(\delta\) 97.65 (C-4 of glucopyranosyl moiety), and 1\({}^{\prime\prime}\)-H at \(\delta\) 5.04 ppm and 4\({}^{\prime\prime}\)-C at \(\delta\) 105.58 (C-4 of galactopyranosyl moiety) was found in the HMBC (Supplementary Figure S1D). Cumulatively, the evidence from several analytical data, allowed us to conclude that the glycosylated product obtained from the galactosylation reaction of CK was 20-O-[\(\beta\)-D-lactopyranosyl]-20(S)-protopanaxadiol. There has been a continuous search for active and novel anticancer agents over the past decade. Ginsenoside, the chief pharmacologically active component of ginseng, produces a collection of pharmacological responses. The compounds Rh\({}_{2}\), F12, CK, and CKGal were tested for in vitro cytotoxicity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolzolium bromide (MTT) colorimetric assay against four different cancer-cell lines. A recent study has shown that F12 effectively repressed the spread of various cancer-cell lines, showing much better in vitro cytotoxicity than Rg3 [27]. The ginseng CK has gained a particular interest in cancer chemoprevention and treatment. [PERSON] et al. (2000) showed that CK induced an anticancer or anti-metastatic activity by preventing tumor invasion  
Figure 3: High-resolution quadrupole-time-of-flight electrospray-ionization mass spectrometry (HR-QTOF ESI/MS) analysis showing the product of CK. Mass analysis of product ([M + H]\({}^{+}\)\(m/\)z\({}^{+}\) 785.5060) confirmed that the product was a monogalactoside derivative of CK (C\({}_{42}\)H\({}_{72}\)O\({}_{13}\), calculated molecular weight, [M + H]\({}^{+}\)\(m/\)z\({}^{+}\) 785.505). or averting chromosomal activation and tumorigenesis [17]. CK in combination with \(\gamma\)-ray radiation was suggested for cancer therapy by [PERSON] et al. (2009) [12]. Likewise, [PERSON] et al. (2013) revealed for the first time the participation of endoplasmic reticulum stress in the induction of apoptosis by CK in HT-29 cells [2]. Our results indicated that CKGal showed good cytotoxic activities compared to three other compounds tested. The cell viability of gastric carcinoma (AGS), skin melanoma (B16F10), cervical carcinoma (HeLa), and brain carcinoma (U87 MG) was reduced to approximately 8.7%, 2.6%, 7.3%, and 13.7%, respectively, compared to controls, when treated with 200 \(\upmu\)mol of CKGal (Figure 4). The IC\({}_{50}\) values (50% inhibitory concentration) of CKGal for AGS, B16F10, HeLa, and U87 MG cells were 4.487, 22.4, 40.38, and 40.38 \(\upmu\)mol, respectively. CK inhibited AGS and B16F10 cell lines with an IC\({}_{50}\) value of 25.99 \(\upmu\)mol and 35.17 \(\upmu\)mol, respectively. Rh\({}_{2}\) showed better activity against all the cell lines tested than F12, and showed the best anticancer activity in U87 MG glioblastoma cells, whereas CK was most effective against HeLa cell lines (Supplementary Table S1). The ginseng CK is a monoglycoside derivative of protopanaxadiol, whereas F12 and CKGal are diglycoside derivatives of protopanaxadiol. Our study with ginensoides has shown that the in vitro cytotoxicity of CKGal against different cancer-cell lines was much higher than that of F12, which was reported to have a much better cytotoxicity than Rg3, another diglycoside derivative of protopanaxadiol. [28]. However, the fact that ginensoside CKGal exhibited stronger inhibitory activity against cancer cells than ginensoside CK is contrary to a previous finding, which says that the presence of more sugar moieties in ginensosides decreases its inhibitory activity against cancer cells [28]. The improvement in such a biological property may have resulted from the presence of a different sugar moiety (lactose) instead of glucose in the protopanaxadiol. While ginensoides exhibit therapeutic activity, attachment of the sugar units enhances the solubility of compounds.