L. Du et al. / Carbohydrate Research 455 (2018) 32e38
37
H of rhamnoglucosyl), 3.22 (m, 2H, H3), 2.71 (t, 2H, J ¼ 7.7 Hz, H2),
2.00 (m, 3H, -COCH3), 1.20 (m, 3H of CH3 of rhamnosyl); IR (KBr,
cm¡1): 3408 (OH), 1736 (C¼O), 1640 (C¼C). ESI-MS (m/z): 690
(M1þ2H2O-H)-, M1 corresponding exactly to the molecular weight
of 600-O-ethanoyl- neohesperidin dihydrochalcone.
corresponding exactly to the molecular weight of 600-O- lauroyl -
neohesperidin dihydrochalcone.
4.2.3.4. 600-O-palmitoyl-neohesperidin dihydrochalcone (3f). Rf:
0.45. 1H-NMR (DMSO-d6, 500 MHz, ppm):
d
12.33 (s, 2H, -OH5),
0
0
0
9.15 (s, 1H, -OH5 ), 7.02 (d, 2H, J ¼ 8.4 Hz, H2 and H6 ), 6.67 (d, 2H,
4.2.3. General procedure for 600-O-lauroyl-neohesperidin (3b), 600-
O-palmitoyl- neohesperidin (3c), 600-O-lauroyl-neohesperidin
dihydrochalcone (3e) and 600-O-palmitoyl-neohesperidin
0
0
00
J ¼ 8.5 Hz, H3 and H5 ), 5.99 (s, 2H, H6 and H8), 5.44 (m, 1H, H1 ),
5.40 (m, 1H, 2000-OH of neohesperidin dihydrochalcone), 5.11 (m, 1H,
000
000
H1 ), 5.08 (d, 1H, J ¼ 5.1 Hz, 4 -OH of neohesperidin dihy-
drochalcone), 4.70 (d, 1H, J ¼ 4.8 Hz, 400-OH of neohesperidin
dihydrochalcone), 4.68 (d, 1H, J ¼ 4.4 Hz, 300-OH of neohesperidin
dihydrochalcone), 4.50 (d, 1H, J ¼ 5.8 Hz, 3000-OH of neohesperidin
dihydrochalcone (3f) synthesis in continuous flow microreactors
Method C: 0.49 mmol of the neohesperidin was dissolved in
10 mL 2-methyl -2-butanol/DMSO ¼ 4:1 (feed 1, ~0.049 M) and
3.92 mmol vinyl laurate or vinyl palmitate were dissolved in 10 mL
2-methyl-2-butanol (feed 2; ~0.39 M). Lipozyme TL IM (0.87 g)
were filled in silica gel tubing (inner diameter ID ¼ 2.0 mm,
length ¼ 1 m). The next reaction procedure is similar to Method B.
00
dihydrochalcone), 4.26 (d,1H, J ¼ 11.9 Hz, H6 acylated), 4.09 (m,1H,
00
H6 acylated), 3.71e3.20 (m, 8H, H of rhamnoglucosyl), 3.25 (m, 2H,
H3), 2.78 (t, 2H, J ¼ 7.7 Hz, H2), 2.28 (m, 2H, -CH2-CO-), 1.26 (m, 26H
of (CH2)13 of palmitoyl), 1.20 (m, 3H of CH3 of rhamnosyl), 0.86 (t,
3H, J ¼ 7.0 Hz, CH3). IR (KBr, cm¡1): 3415 (OH), 1740 (C¼O), 1643
(C¼C). ESI-MS (m/z): 886 (M1þ2H2O-H)-, M1 corresponding exactly
to the molecular weight of 600-O-palmitoyl-neohesperidin
dihydrochalcone.
4.2.3.1. 600-O-lauroyl-neohesperidin (3b). Rf: 0.45. 1H-NMR (DMSO-
0
d6, 500 MHz, ppm):
d
12.03 (s, 1H, H5), 9.11 (s, 1H, -OH3 ), 6.93 (s,
0
0
0
1H, -OH5 ), 6.92 (d, 1H, J ¼ 2.9 Hz, H6 ), 6.87 (m, 1H, H2 ), 6.10 (d, 1H,
J ¼ 2.2 Hz, H8), 6.06 (d, 10H00 , J ¼ 2.2 Hz, H6), 5.49 (m, 1H, H2), 5.44 (m,
00
000
1H, H1 ), 5.41 (m, 1H, 2 -OH of neohesperidin),5.16 (m, 1H, H1 ),
5.10 (s, 1H, 4000-OH of neohesperidin), 4.74 (d, 1H, J ¼ 4.8 Hz, 400-OH
of neohesperidin), 4.69 (d, 1H, J ¼ 4.4 Hz, 300-OH of neohesperidin),
4.50 (d, 1H, J ¼ 5.8 Hz, 3000-OH of neohesperidin), 4.26 (d, 1H,
4.3. Vitro antibacterial experiment methods
The antibacterial activity of neohesperidin ester derivatives was
performed against gram positive bacteria Staphylococcus aureus
(ATCC 25923) and the gram negative bacteria Escherichia coli (ATCC
25922) by using cup plate method. Ampicillin sodium was
employed as standard to compare the results. The tests were car-
ried out using a suspension containing the overnight culture of
bacteria (~108 CFU mLꢁ1). The molten agar containing the microbial
culture was transferred in a sterile Petri dish. Wells of 8 mm in
diameter were vertically placed on the previously seeded agar
00
00
J ¼ 11.9 Hz, H6 acylated), 4.03 (m, 1H, H6 acylated), 3.77 (s, 3H of
-OCH3 of phenyl), 3.73e3.14 (m, 8H, H of rhamnoglucosyl), 3.22 (m,
1H, H3), 2.73 (d, 1H, J ¼ 3.2 Hz, H3), 2.22 (m, 2H, -CH2-CO-), 1.17 (m,
3H of CH3 of rhamnosyl), 1.26 (m, 18H of (CH2)9 of lauroyl), 0.85 (t,
3H, J ¼ 7.0 Hz, CH3). IR (KBr, cm¡1): 3415 (OH), 1738 (C¼O), 1647
(C¼C). ESI-MS (m/z): 828 (M1þ2H2O-H)-, M1 corresponding exactly
to the molecular weight of 600-O- lauroyl-neohesperidin.
plates and were filled with 50 mL compounds, DMSO solvent was
4.2.3.2. 600-O-palmitoyl-neohesperidin (3c). Rf: 0.48. 1H-NMR
used as a control to observe the solvent effects. After the plates
were incubated at 37 ꢀC for 24 h, the diameters of the distinctly
clear zones were measured using a metric ruler. All the experi-
ments were performed in triplicate. The antibacterial test results
are presented in Table 2.
0
(DMSO-d6, 500 MHz, ppm):
d
12.04 (s, 1H, -OH5), 9.10 (s, 1H, -OH3 ),
0
0
0
6.92 (s,1H, H5 ), 6.91 (d,1H, J ¼ 2.9 Hz, H6 ), 6.87 (m,1H, H2 ), 6.10 (d,
1H, J ¼ 2.2 Hz, H8), 6.06 (d, 1H, J ¼ 2.2 Hz, H6), 5.49 (m, 1H, H2), 5.48
000
00
(m, 1H, H1 ), 5.46 0(00m, 1H, 2 -OH of neohesperidin), 5.15 (m, 1H,
000
H1 ), 5.10 (s, 1H, 4 -OH of neohesperidin), 4.74 (d, 1H, J ¼ 4.8 Hz,
400-OH of neohesperidin), 4.68 (d, 1H, J ¼ 4.4 Hz, 300-OH of neo-
Acknowledgment
hesperidin), 4.30 (d, 1H, J ¼ 5.8 Hz, 3000-OH of neohesperidin), 4.28
00
00
(d, 1H, J ¼ 11.9 Hz, H6 acylated), 4.03 (m, 1H, H6 acylated), 3.77 (s,
3H of -OCH3 of phenyl), 3.73e3.15 (m, 8H, H of rhamnoglucosyl),
3.22 (m, 1H, H3), 2.73 (d, 1H, J ¼ 3.2 Hz, H3), 2.22 (m, 2H, -CH2-CO-),
1.17 (m, 3H of CH3 of rhamnosyl), 1.23 (m, 26H of (CH2)13 of pal-
mitoyl), 0.85 (t, 3H, J ¼ 7.0 Hz, CH3). IR (KBr, cm¡1): 3415 (OH),1740
(C¼O), 1643 (C¼C). ESI-MS (m/z): 884 (M1þ2H2O-H)-, M1 corre-
sponding exactly to the molecular weight of 600-O- palmitoyl-
neohesperidin.
The authors would like to thank the Natural Science Foundation
of Zhejiang Province (LY17B020010 and LY13B020010), the National
Science and Technology Support Project (2015BAD14B0305), the
International Cooperation Project 948 (2014-4-29), the National
Natural Science Foundation of China (21306172), the Science and
Technology Research Program of Zhejiang Province (2014C32094)
as well as the Natural Science Foundation of Zhejiang University of
Technology (116004029) for financial support.
4.2.3.3. 600-O-lauroyl-neohesperidin dihydrochalcone (3e). Rf: 0.40.
References
1H-NMR (DMSO-d6, 500 MHz, ppm):
d
12.33 (s, 1H, -OH5), 8.80 (s,
0
0
0
1H, -OH3 ), 6.79 (d, 1H, J ¼ 8.3 Hz, H5 ), 6.65 (d, 1H, J ¼ 1.9 Hz, H6 ),
0
00
6.58 (m, 1H, H2 ), 5.99 (s, 2H, H6 and H8), 5.44 (m, 1H, H1 ), 5.39 (m,
1H, 2000-OH of neohesperidin dihydrochalcone), 5.09 (m, 1H, H1 ),
000
5.06 (d, 1H, J ¼ 5.1 Hz, 4000-OH of neohesperidin dihydrochalcone),
4.70 (d, 1H, J ¼ 4.9 Hz, 400-OH of neohesperidin dihydrochalcone),
4.68 (d, 1H, J ¼ 4.4 Hz, 300-OH of neohesperidin dihydrochalcone),
4.50 (d, 1H, J ¼ 5.8 Hz, 3000-OH of neohesperidin dihydrochalcone),
00
00
4.25 (d, 1H, J ¼ 12.9 Hz, H6 acylated), 4.10 (m, 1H, H6 acylated),
3.72 (s, 3H of -OCH3 of phenyl), 3.67e3.16 (m, 8H, H of rhamno-
glucosyl), 3.22 (m, 2H, H3), 2.73 (t, 2H, J ¼ 7.7 Hz, H2), 2.27 (m, 2H,
-CH2-CO-), 1.26 (m, 18H of (CH2)9 of lauroyl), 1.20 (m, 3H of CH3 of
rhamnosyl), 0.83 (t, 3H, J ¼ 7.0 Hz, CH3). IR (KBr, cm¡1): 3415 (OH),
1738 (C¼O), 1648 (C¼C). ESI-MS (m/z): 830 (M1þ2H2O-H)-, M1