Molecules 2016, 21, 734
7 of 8
3
β
,20
α
,24-trihydroxy-29-norolean-12-en-28-oic acid [13]. By the method described in
1
and
2, the
sugar unit of 3 was identified as D-glucose.
1
Compound 1a: H-NMR (600 MHz, pyridine-d5)
δ
5.51 (1H, br t, H-12), 4.80/4.76 (2H, each s, H2-29,
3.60 (1H, dd, J = 9.6, 5.8 Hz, H-3), 3.25 (1H, dd, J = 13.0, 4.9 Hz, H-18), 1.25 (6H, s, H3-23/ H3-24), 1.03
(3H, s, H3-27), 1.01 (3H, s, H3-26), 0.88 (3H, s, H3-25); 13C-NMR (150 MHz, Pyr)
δ
39.3 (C-1), 28.4 (C-2),
78.4 (C-3), 39.7 (C-4), 56.1 (C-5), 19.1 (C-6), 33.6 (C-7), 40.1 (C-8), 48.4(C-9), 37.7 (C-10), 24.2 (C-11),
123.3 (C-12), 144.5 (C-13), 42.4 (C-14), 28.6 (C-15), 24.1 (C-16), 47.4 (C-17), 48.3 (C-18), 42.4 (C-19), 149.5
(C-20), 38.7 (C-21), 30.8 (C-22), 29.1 (C-23), 16.9 (C-24), 15.9 (C-25), 17.7 (C-26), 26.5 (C-27), 179.9 (C-28),
107.4 (C-29).
1
Compound 3a: H-NMR (600 MHz, pyridine-d5)
δ 5.57 (1H, brs, H-12), 4.50 (1H, d, J = 10.8 Hz, H-23),
3.65/3.64(2H, m, H-3/H-23), 3.38 (1H, dd, J = 13.6, 5.5Hz, H-18), 1.60 (3H, s, H3-29), 1.56 (3H, s,
H3-24),1.26 (3H, s, H3-27), 0.99 (3H, s, H3-26), 0.86 (3H, s, H3-25); 13C-NMR (150 MHz, Pyr)
δ
38.7 (C-1),
28.3 (C-2), 80.2 (C-3), 43.2 (C-4), 56.4 (C-5), 19.1 (C-6), 33.6 (C-7), 39.8 (C-8), 48.1 (C-9), 37.1 (C-10), 23.9
(C-11), 122.6 (C-12), 144.4 (C-13), 42.1 (C-14), 28.4 (C-15), 28.4 (C-16), 46.8 (C-17), 44.4 (C-18), 48.2 (C-19),
69.9 (C-20), 36.3 (C-21), 35.2 (C-22), 23.6 (C-23), 64.5 (C-24), 16.0 (C-25), 17.0 (C-26), 26.0 (C-27), 180.7
(C-28), 25.7 (C-29).
3.6. Bioassay
The cytotoxicity of compounds 1–5 against three human cancer cell lines, human gastric carcinoma
(SGC-7901), human colon carcinoma (HCT 116) and human liver hepatocellular carcinoma (HepG2)
were assayed at the National Center for Drug Screening, Shanghai, China. Sulforhodamine B (SRB)
(Sigma-Aldrich Chemie GmbH, Munich, Germany) was used to test the effects of the compounds on
cell growth and viability [15]. Adriamycin was used as the positive control. All tests were performed
in triplicate, and results are expressed as IC50 values.
4. Conclusions
The present work 1r1 eported three new nortriterpenoid saponins, akebonoic acid
1
28-O-
B (
that the two caffeoylation of nortriterpenoidal saponins (
Lardizabalaceae for the first time. 3 -akebonoic acid ( ) showed interesting cytotoxicity against
HCT-116, HepG2 and SGC-7901 cell lines, with IC50 values of 9.1, 15.2 and 41.0 M, respectively.
β
-D-glucopyranosyl-(1
Ñ
6 )-
β
-D-glucopyranosyl ester (
1
), Holboelliside A (
2
) and Holboelliside
3
) isolated from the stem of Holboellia coriacea, along with five known compounds. It is noteworthy
and ) were isolated from family
2
3
α
5
µ
In addition, the saccharide unit attached at C-28 of this type of nortriterpenoids may greatly reduce
the in vitro cytotoxicity.
Supplementary Materials: The HR-ESI-MS, 1H- and 13C-NMR and 2D-NMR spectra (Figures S1–S21) of
compounds 1–3 are available online at www.mdpi.com/1420-3049/21/6/734/s1.
Acknowledgments: We thank Zhang Dai-Gui (Key Laboratory of Plant Resources Conservation and Utilization,
Jishou University) for the collection and authentication of plant material. This work was supported by the National
Nature Science Foundation of China (No. 31400308) and the Research Foundation of Education Bureau of Hunan
Province, China (No. 14C0569).
Author Contributions: In this paper, Guanhua Li, Ye Li and Hualiang He performed the extraction and isolation
of the compounds; Zhiwen Li performed the bioassays; Wenbing Ding carried out the structural elucidations and
the manuscript writing; and Youzhi Li designed and coordinated the study and reviewed the manuscript.
Conflicts of Interest: The authors declare no conflict of interest.
References
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2.
Flora of China Editorial Committee. Flora of China; Science Press: Beijing, China, 2001; Volume 29, p. 13.
Zhu, Z.; Chen, T.; Pi, H.F.; Ruan, H.L.; Wu, J.Z.; Zhang, P. A new triterpenoid saponin and other saponins
from the roots of Holboellia coriacea. Chem. Nat. Compd. 2015, 51, 89–893. [CrossRef]