ChemPlusChem
10.1002/cplu.201800334
FULL PAPER
researchers more easily and comprehensively to understand the
formation of natural product gels.
concentrations which produced gels when samples are prepared by the
above method.
Keywords: natural product • natural product gelators • natural
product gel • gel formation • solvent
Experimental Section
Materials and instrumentation
[1]
a) T. F. Molinski, Org. Lett. 2014, 16, 3849-3855; b) D. J. Newman, G. M.
Cragg, J. Nat. Prod. 2016, 79, 629-661; c) T. Rodrigues, D. Reker, P.
Schneider, G. Schneider, Nat. Chem. 2016, 8, 531-541; d) I. Paterson,
E. A. Anderson, Science 2005, 310, 451-453.
Reagents were purchased from Sigma Aldrich, Fluka, and Alfa Aesar and
used as received, without further purification, unless otherwise stated. All
[
[
2]
3]
a) J. Achan, A. O. Talisuna, A. Erhart, A. Yeka, J. K. Tibenderana, F. N.
Baliraine, P. J. Rosenthal, U. D'Alessandro, Malar. J. 2011, 10, 1-12; b)
M. E. Wall, Med. Res. Rev. 1998, 18, 299-314; c) D. L. Klayman, Science
solvents used were of analytical grade. Compounds 3, 4, 5 and 12 were
prepared using our previously disclosed method.[3a] UV-Vis spectra was
obtained on a TU-1900 PERSEE spectrometer. IR spectra was recorded
on a Perkin Elmer Spectru FT-IR spectrophotometer as KBr pellets and
the absorption frequencies were expressed in reciprocal centimeters
1985, 228, 1049-1055.
a) K. Zhi, H. T. Zhao, X. Yang, H. Zhang, J. Wang, J. Wang, J. M.
Regenstein, Nanoscale 2018, 10, 3639-3643; b) B. G. Bag, R. Majumdar,
Chem. Rec. 2017, 17, 1-34.
cm−1). Mass spectral studies were carried out on a Agilent 6890N GC-MS
EI). 1D-NMR experiments were performed on a Bruker DRX-400 at
(
(
[
[
4]
5]
J. Liu, J. Ethnopharmacol. 1995, 49, 57-68.
400MHz. X-ray Diffraction patterns were obtained using X’pert pro mpd
Z. Cai, S. Hou, Y. Li, B. Zhao, Z. Yang, S. Xu, J. Pu, J. Drug Targeting
2008, 16, 178-184.
diffractometer with Cu Kα radiation ( λ =1.5418 Å), employing a scanning
rate of 10° min −1 in the 2 θ range from 5° to 30° and 40 kV and 40 mA .
Solid samples of compound 3, 4, 5, and 12 prepared in different solvents
were obtained by lyophilization
[
6]
T. Kikuchi, E. Uchiyama, M. Ukiya, K. Tabata, Y. Kimura, T. Suzuki, T.
Akihisa, J. Nat. Prod. 2011, 74, 137-144.
[
[
[
7]
8]
9]
P. Wal, A. Wal, G. Sharma, A. Rai, Syst. Rev. Pharm. 2011, 2, 96-103.
R. H. Cichewicz, S. A. Kouzi, Med. Res. Rev. 2004, 24, 90-114.
a) P. Terech, R. G. Weiss, Chem. Rev. 1997, 97, 3133-3160; b) S. Datta,
S. Bhattacharya, Chem. Soc. Rev. 2015, 44, 5596-5637.
Synthesis and Identification of Compound 13
2 2
600 mg of 3 was dissolved in 60 mL CH Cl and a mixture of pyridine (1.2
[
10] a) Y. Wu, W. Ding, Q. He, Food Hydrocolloids 2017; b) K. Liu, X. Jiang,
P. Hunziker, Nanoscale 2016, 8, 16091-16156.
ml) and acetic anhydride (3.6 ml) was added. The reaction mixture was
stirred at room temperature for 18 h. The progress of the reaction was
monitored by TLC. On reaction completion, it was washed with 5% HCl,
[
[
11] B. O. Okesola, D. K. Smith, Chem. Soc. Rev. 2016, 45, 4226-4251.
12] B. G. Bag, S. Das, S. N. Hasan, A. C. Barai, RSC Adv. 2017, 7, 18136-
H
2
2 2
O, NaCl saturated and extracted with CH Cl followed by drying over
18143.
anhydrous Na SO . Afterfiltration, the organic phase was filtered and
2
4
[
13] a) A. Aggeli, I. Nyrkova, M. Bell, R. Harding, L. Carrick, T. McLeish, A.
Semenov, N. Boden, Proc. Natl. Acad. Sci. 2001, 98, 11857-11862; b) B.
A. Simmons, C. E. Taylor, F. A. Landis, V. T. John, G. L. McPherson, D.
K. Schwartz, R. Moore, J. Am. Chem. Soc. 2001, 123, 2414-2421; c) L.
A. Estroff, A. D. Hamilton, Chem. Rev. 2004, 104, 1201-1218; d) P. Flory,
Faraday Discuss. Chem. Soc. 1974, 57, 7-18; e) R. Wang, C. Geiger, L.
Chen, B. Swanson, D. G. Whitten, J. Am. Chem. Soc. 2000, 122, 2399-
concentrated under reduced pressure. The residue was subjected to a
silica gel column eluted with Hexane/acetone=50:1 to yield the pure
compound 13. Compound 13 was a white amorphous solid, EIMS m/z: 469
+
1
[
M ] (C32
52
H O
2
). H-NMR (CDCl
3
, 400MHz) δ 4.68(1H, d, H-29a), 4.57(1H,
); 1.69,
,100MHz) δ
), 152.0 (C-22), 109.4 (C-29), 81.1 (C-3), 55.4 (C-5), 50.4
d, H-29b), 4.48(1H, dd, H-3), 2.37 (1H, dt, H-19), 2.04 (OCOCH
.26, 1.03, 0.94, 0.85, 0.84, 0.79 (7×-CH
71.1 (OCOCH
3
1
1
); 13C-NMR(CDCl
3 3
3
2
400.
14] a) S. Wu, J. Gao, T. J. Emge, M. A. Rogers, Cryst. Growth Des. 2013,
3, 1360-1366; b) J. Gao, S. Wu, T. J. Emge, M. A. Rogers,
(
(
(
C-9), 48.3 (C-18), 48.1 (C-19), 42.9 (C-17), 42.8 (C-14), 40.9 (C-8), 39.8
C-20), 38.5 (C-4), 38.1 (C- 1), 37.8 (C-10), 37.1 (C-13), 35.5 (C-16), 34.3
C-7), 29.8 (C-21), 29.6 (C-23), 28.0 (C-2, 15), 25.3 (C-12), 21.3 (C- 11),
[
[
1
CrystEngComm 2013, 15, 4507-4515; c) S. Wu, J. Gao, T. J. Emge, M.
A. Rogers, Soft Matter 2013, 9, 5942-5950; d) Y. Lan, M. Corradini, R.
Weiss, S. Raghavan, M. Rogers, Chem. Soc. Rev. 2015, 44, 6035-6058.
15] a) K. C. Bentz, S. E. Walley, D. A. Savin, Soft Matter 2016, 12, 4991-
20.8 (OCOCH 3 ), 19.1 (C-30), 18.2 (C-6), 17.9 (C-28), 16.5 (C-25), 16.1
(
C-26), 15.9 (C-24), 14.6 (C-27). Compound 13 was identified as lupeol 3-
acetate by comparison of its NMR data with this reported in the
5001; b) N. Yan, Z. Xu, K. K. Diehn, S. R. Raghavan, Y. Fang, R. G.
Weiss, J. Am. Chem. Soc. 2013, 135, 8989-8999; c) A. Pal, J. Dey,
Langmuir 2013, 29, 2120-2127; d) J. Gao, S. Wu, M. Rogers, J. Mater.
Chem. 2012, 22, 12651-12658; e) W. Edwards, C. A. Lagadec, D. K.
Smith, Soft Matter 2011, 7, 110-117; f) A. Wicklein, S. Ghosh, M.
Sommer, F. Wꢀrthner, M. Thelakkat, ACS nano 2009, 3, 1107-1114.
Gelation tests
In a test tube (1.5 mL volume, 10 mm diameter), 10 mg sample was mixed
with 0.5 mL solvent and the mixture was heated until the solid dissolved
(
Judgment basis: 1, it is transparent and clear solution; 2, the solution does
not occur Tyndall phenomenon). The resulting solution was cooled to
0 °C (natural cooling.) and then allowed to stand for 24 h at this
[16] a) Y. Qin, A Course in General Physics: Heat, Higher Education Press,
Beijing, China, 2004; b) F. W. Sears, M. W. Zemansky, H. D. Young,
University physics, Addison-Wesley, New York, 1964; c) M. Alonso, E. J.
Finn, Fundamental university physics Addison-Wesley, New York, 1967.
[17] a) C. Janiak, J. Chem. Soc., Dalton Trans. 2000, 0, 3885-3896; b) A.
Ajayaghosh, S. J. George, J. Am. Chem. Soc. 2001, 123, 5148-5149.
[18] D. Swinehart, J. Chem. Educ 1962, 39, 333.
2
temperature. When the test tube could be inverted without change of
shape of its content, it was identified as a gel (G). If slow change of shape
of its content was detectable when the test tube was inverted, then the
sample was designated as a viscous (V). Test tube with only liquid was
referred to as a solution or sol (S). When a precipitate appeared after the
gelator dissolved in a liquid or could not be dissolved, the designations
were precipitate (P) and insoluble (I), respectively. All samples
concentrations were expressed in % as the ratio of gelator weight (mg) to
liquid volume (mL). Ethanol and water mixtures were expressed as volume
ratios. The critical gelator concentrations (CGC) are the lowest gelator
[19] E. Braude, J. Chem. Soc. (Resumed) 1950, 379-384.
[20] Q. Wang, Y. Yang, H. Gao, Problems on Hydrogen Bonding in Organic
Chemistry, Tianjin University Press, Tianjin, China, 1993.
[21] a) M. B. Smith, J. March, March's advanced organic chemistry: reactions,
mechanisms, and structure, Wiley-Interscience, New York: , 2001; b) F.
This article is protected by copyright. All rights reserved.