Citrus Limonoids Induce Apoptosis in Human Neuroblastoma Cells and Have Radical Scavenging Activity

Abstract

Citrus limonoid glucosides, a family of fruit bioactive compounds, were postulated to have free radical-scavenging and apoptosis-inducing properties against certain types of cancers. Four highly purified limonoid glucosides, limoin 17beta D-glucopypranoside (LG), obacunone 17beta D-glucopyranoside (OG), nomilinic acid 17beta D-glucopyranoside (NAG), and deacetylnomilinic acid 17beta D-glucopyranoside (DNAG) were tested for superoxide radical (O(2)(-))-quenching activity and cytotoxic action against undifferentiated human SH-SY5Y neuroblastoma cells in culture. All 4 scavenged O(2)(-) as measured by inhibition of pyrogallol decomposition in a spectrophotometric assay. Quenching by NAG in particular emulated an equivalent concentration of vitamin C. When added to the medium of SH-SY5Y cells in culture, micromolar amounts of LG and OG, compared with untreated controls, caused a cessation of cell growth and rapid cell death (P < 0.001); NAG and DNAG were better tolerated, but nonetheless toxic as well. Cytotoxicity was related to a concentration- and time-dependent increase in caspase 3/7 activity, suggesting that limonoid glucosides were capable of inducing apoptosis. Arrested cell growth and the induction of apoptosis were confirmed by flow cytometry and DNA fragmentation analysis. Importantly, caspase induction at 12 h correlated with cell survival at 24 h (P = 0.046), suggesting that apoptosis was the primary cause of cell death. We conclude that citrus limonoid glucosides are toxic to SH-SY5Y cancer cells. Cytotoxicity is exerted through apoptosis by an as yet unknown mechanism of induction. Individual limonoid glucosides differ in efficacy as anticancer agents, and this difference may reside in structural variations in the A ring of the limonoid molecule.

Pyrogallol as a glutathione depletorinduces apoptosis in HeLa cells

“…•-level in pheochromocytoma PC12 cells (11), human neuroblastoma SH-SY5Y cells (23) and juxtaglomerular As4.1 cells (24). Therefore, we attempted to determine whether ROS scavengers prevent pyrogallol-induced cell death through the reduction of intracellular O 2…”

Natural Products Modulate the Multifactorial Multidrug Resistance of Cancer

“…In vitro limonoids inhibit the growth of estrogen receptor-negative and -positive human breast cancer cells. Limonoids have also been found to target and stop neuroblastoma cells [149]. The decreased colon tumor-genesis associated with ingesting orange juice may be explained by the potential chemopreventive effect of limonin, hesperidin, and other flavonoids [150].…”

Lepidotrichilins A and B, New Protolimonoids with Cytotoxic Activity from Trichilia Lepidota (Meliaceae)

“…These compounds were identified by comparison of their spectroscopic data (MS, IR, 1D-1 H and 13 C-NMR, 2D-NMR) with those reported in the literature [9]. The methanol extract of T. lepidota leaves was processed on several chromatographic columns affording two steroids, β-sitosterol (7) and stigmasterol (8) and the protolimonoid deoxyflindissone (6). The methanol extract of T. lepidota wood affording the coumarin scopoletin (9).…”

“…Previous investigations involving limonoids isolated of another Meliaceae species, namely Melia azedarach, have demonstrated antiproliferative activity against an adenocarcinoma epithelial cell line A549 [7]. Additionally, it has been proved that limonoids from Citrus fruits demonstrated in vitro the capacity to induce apoptosis and to inhibit the proliferation of neuroblastoma cells [8].…”

“…In the present paper, we describe the isolation and characterization of the mixture of two new protolimonoids named lepidotrichilin A (1) and lepidotrichilin B (2), along with the known protolimonoids 21,23-epoxy-7α-21α-dihydroxyapotirucalla-14,24-dien-3-one (3), 21,23-epoxy-7α-21β-dihydroxyapotirucalla-14,24-dien-3-one (4), dysorane D (5) and deoxyflindissone (6), the steroids β-sitosterol (7) and stigmasterol (8) and the coumarin scopoletin (9), whose structures are summarized in Figure 1. The structures of the known and new compounds were established on the basis of spectral data, mainly 1 H-and 13 C-NMR (1D and 2D), HRESIMS spectra and by comparison with literature data.…”