6
D.S. dos Santos et al. / Bioorg. Med. Chem. xxx (2014) xxx–xxx
rated fatty chain resulted in improved antiproliferative activity
(mean TGI 16.9
g mLÀ1, 6d).
Compound 5e
l
100
50
The exchange of a carbon atom with an oxygen atom in the six-
member ring (Table 3, series 7) caused a worsening in mean anti-
proliferative activity when compounds 7a, 7b, and 7d were com-
pared with compounds 5a, 5b, 5d, and 6d. However, when this
oxygenated six-member ring was associated with a monounsatu-
rated fatty chain, its mean antiproliferative activity improved
g mLÀ1 for 7c) compared with that of 5c (mean
0
(mean TGI = 15.0
l
TGI >67.7
l
g mLÀ1) and 6c (mean TGI = 36.3
l
g mLÀ1).
These data suggest that the antiproliferative activity is influ-
enced by the structural variation in the fatty acid amides, including
both the fatty acid derivative moiety and the moiety attached to
the nitrogen atom.
The data in Tables 2–4 shows that most of the fatty acid amides
studied showed activity against most of the cell lines, with a broad
spectrum inhibition profile, and there were varied significant differ-
ences in cell selectivity and safety. Among the benzylamide deriva-
tives (series 1–3), based on the mean TGI, five compounds showed a
potential antiproliferative: 1d, (R)-2c, (S)-3c, (R,S)-3d, and (S)-3e.
Among these, compounds (S)-3c and (S)-3e were noted for exhibit-
ing the lowest mean TGI values. Furthermore, compound (S)-3c
showed high activity and selectivity for ovarian cancer cells with
U251
MCF7
-50
-100
NCI/ADR-RES
786-0
NCI-H460
PC-3
OVCAR-3
Vero
-3
-2
-1
250
100
101
102
0,25
2,5
25
10
10
10
-1
Concentration (µg.mL
)
Figure 4. Dose–response analysis of cell growth inhibition by compound 5e against
several cell lines.
was observed when a comparison was made with a non-tumor cell
line (VERO, TGI = 7.6 l
g mLÀ1).
a
phenotype of multiple drug resistance (NCI-ADR/RES,
TGI = 7.1
g mLÀ1) and glioma cell lines (U251, TGI = 17.8 g mLÀ1),
as well as a favorable safety profile when compared with non-
tumor cells (HaCat, TGI = 36.8
g mLÀ1). In contrast, compound
(S)-3e showed high activity for glioma cells (U251, TGI =
5.1
g mLÀ1), prostate cancer cells (PC-3, TGI = 7.7 g mLÀ1) and
the resistant ovarian cancer cells (NCI-ADR/RES, TGI =
16.4
g mLÀ1) cell lines but with relative selectivity and a favorable
safety profile when compared with a non-tumor cell line (HaCat,
TGI = 77.2
g mLÀ1). However, compound (R,S)-3d, derived from
Among the heterocyclic derivatives, two compounds were effi-
cacious in inhibiting the proliferation of more than one cell line:
compound 5c, which demonstrated specificity of action in glioma
l
l
l
(U251, TGI = 5.8
notype (NCI-ADR/RES, TGI = 5.6
cer cell line (OVCAR-3, TGI = 14.0
death to glioma cells (U251, LC50 = 14.2); and compound 5e, which
was specific for glioma (U251, TGI = 12.0
g mLÀ1), and ovarian
cancer cells with an MDR phenotype (NCI-ADR/RES, TGI =
7.7 and caused cell death to glioma cells (U251,
g mLÀ1
l
g mLÀ1), ovarian cancer cells with an MDR phe-
l
g mLÀ1) and another ovarian can-
g mLÀ1), as well as causing cell
l
l
l
l
l
l
l
)
ricinoleic acid and methyl benzylamine, showed good growth inhi-
LC50 = 44.4). Although there was loss of both potency and specific-
ity of action with an additional unsaturation in the fatty acid chain,
compound 5e appeared to have a more favorable safety profile
than that of compound 5c, as it yielded the greatest difference of
activity between tumor and non-tumor cell lines (VERO,
bition and cell death for the glioma cell line (U251, TGI =
13.9
favorable safety profile when compared with a non-tumor cell line
(VERO, TGI = 59.1
g mLÀ1). The dose–response analysis of cell
l
g mLÀ1, LC50 = 63.6), with a high degree of selectivity and a
l
growth inhibition by compound (R,S)-3d is displayed in Figure 3.
The ethanolamine derivative (R)-4d showed an excellent mean
TGI, with growth inhibition and death for most of the cell lines, but
with relative selectivity. Furthermore, no favorable safety profile
TGI = 45.1 and 10.6 l
g mLÀ1, respectively). The dose–response
analysis of cell growth inhibition by compound 5e is displayed in
Figure 4. Ovarian cancer is difficult to diagnose, and recurrence
may occur through multidrug resistance. Both compounds 5c and
5e showed a better potency for ovarian cancer cells with an MDR
phenotype than for native ovarian cancer cells, a very relevant
result given the importance of the search of new drugs for cancers
with MDR.
Among all tested compounds, compound (R)-5d showed the
best mean TGI value, exhibiting growth inhibition and cell death
for most of the lines but without selectivity. This compound
appears to have a general cytotoxic effect.
Compound(R,S)-3d
100
50
0
The morfolyl amine derivative 7c showed a good mean TGI,
with growth inhibition for the most of cell lines, but with relatively
good selectivity and a moderately favorable safety profile when
comparing tumor and non-tumor cell lines.
U251
3. Conclusions
MCF7
-50
NCI/ADR-RES
786-0
NCI-H460
PC-3
In conclusion, the work presented herein demonstrates that
several fatty acid amides exhibited potent and selective antiprolif-
erative activity in the cancer cell lines tested. In general, benzyla-
mide derivatives showed a clear structure-activity relationship,
with an interesting activity profile when there was a hydroxyl
group in the fatty chain and/or a methyl group in the benzylamino
moiety, as well as an unsaturated chain. For the other derivatives,
the results of the growth inhibition assay demonstrate that TGI is
OVCAR-3
Vero
-100
-3
-2
-1
0,25
100
101
102
250
2,5
25
10
10
10
Concentration (µg.mL )
-1
Figure 3. Dose–response analysis of cell growth inhibition by compound (R,S)-3d
against several cell lines