Ester and amide derivatives of rhodamine B exert cytotoxic effects on different human tumor cell lines

Abstract

Three esters of rhodamine B (1–3) differing in their alkyl chain lengths as well as several rhodamine B amides (4–9) were synthesized in good yields and tested for their cytotoxicity in SRB assays employing several human tumor cell lines. The rhodamine B esters were unselective but showed cytotoxicity of as low as EC50 = 0.15 ± 0.02 µM. The rhodamine B amides were slightly less cytotoxic but showed good selectivity against MCF-7 and A2780 tumor cell lines. Especially a morpholinyl derivative 4 was ~20 time more cytotoxic for MCF-7 than for nonmalignant NIH 3T3 cells.

Mitocanic Di- and Triterpenoid Rhodamine B Conjugates

“…The triterpenoid skeleton is equally important. Here, too, it was shown that "simple" RhoB conjugates 1-9 ( Figure 3) also had lower cytotoxicity than the corresponding triterpenoid analogs, but their tumor cell/non-tumor cell selectivity was also diminished (Table 1) [91]. Of special interest seems the morpholinyl derivative 4 inasmuch as this compound held the highest selectivity of this series with respect to MCF-7 carcinoma cells (S = (EC 50, NIH 3T3 / EC 50, MCF-7 ) > 19.5) and A2780 ovarian cancer cells (S = (EC 50, NIH 3T3 / EC 50, A27807 ) > 18.1) [90].…”

“…The triterpenoid skeleton is equally important. Here, too, it was shown that “simple” RhoB conjugates 1 – 9 ( Figure 3 ) also had lower cytotoxicity than the corresponding triterpenoid analogs, but their tumor cell/non-tumor cell selectivity was also diminished ( Table 1 ) [ 91 ].…”

In vivo biodistribution of kinetically stable Pt2L4 nanospheres that show anti-cancer activity

“…While some specific palladium-based Pd 2 L 4 nanospheres are highly toxic, 14,28–30 other structures, especially with similar design to our framework have shown little toxicity. 12,15,31 Recent studies revealed the high toxicity of rhodamine derivatives, 37,38 making our systems, with the well-defined nanosphere and linked toxic units, interesting candidates for structure-cytotoxicity assays. We anticipate differences between the molecular building blocks and their nanosphere analogues.…”

“…Next to the required spectroscopic features for in vivo detection, rhodamine B amide derivatives have shown recently potent cytotoxicity against different human cancer types. 37,38 Furthermore, singlet oxygen formation using rhodamine dyes emerged as a tool in photodynamic therapy of tumor cells. 39,40 Therefore, rhodamine functionalization of nanospheres can yield systems which are not only suitable for in vivo imaging, but also can have cytotoxic properties by themselves or through light driven singlet oxygen ( 1 O 2 ) formation.…”

“…12,41,42 Pt 2 L 4 spheres are prepared according to a recently published procedure. 38 L RB (1 eq. ), and [Pt(BF 4 )(MeCN) 4 ] (0.6 eq.)…”