epoxyazadiradione and nimbin

Thirty-five limonoids, including 15 of the azadiradione type (1-15), five of the gedunin type (16-20), four of the azadirachtin type (21-24), nine of the nimbin type (25-33), and two degraded limonoids (34, 35), isolated from Azadirachta indica seed extracts, were evaluated for their cytotoxic activities against five human cancer cell lines. Seven compounds (3, 6, 7, 16, 18, 28, and 29) exhibited cytotoxic activity against one or more cell lines. Among these compounds, 7-deacetyl-7-benzoylepoxyazadiradione (7), 7-deacetyl-7-benzoylgeduin (18), and 28-deoxonimbolide (28) exhibited potent cytotoxic activity against HL60 leukemia cells with IC(50) values in the range 2.7-3.1 μM. Compounds 7, 18, and 28 induced early apoptosis in HL60 cells, observed by flow cytometry. Western blot analysis showed that compounds 7, 18, and 28 activated caspases-3, -8, and -9 in HL60 cells. This suggested that compounds 7, 18, and 28 induced apoptotic cell death in HL60 cells via both the mitochondrial- and the death receptor-mediated pathways. Futhermore, compound 7 was shown to possess high selective cytotoxicity for leukemia cells since it exhibited only weak cytotoxicity against a normal lymphocyte cell line (RPMI 1788).

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Azadirachta; Drug Screening Assays, Antitumor; HL-60 Cells; Humans; Limonins; Lymphocytes; Mitochondria; Molecular Structure; Receptors, Death Domain; Seeds

Neem seed preparations contain not only azadirachtin as the active insect antifeedant or growth regulator but also a variety of their limonoids, some of which are cytotoxic to N1E-115 neuroblastoma (mouse), 143B.TK- osteosarcoma (human) and Sf9 (insect) cultured cell lines. The most potent of these limonoids is nimbolide with an IC50 ranging from 4 to 10 microM, and averaging 6 microM for the three cell lines. Other limonoids of decreasing potency and their average IC50 values (microM) are epoxyazadiradione 27 microM, salannin 112 microM, and nimbin, deacetylnimbin and azadirachtin each >200 microM (practically nontoxic). Nimbolide at 10 microM acts rapidly in the neuroblastoma cells to induce blebbing associated with disruption of plasma membranes almost instantaneously and 50% loss of cell viability with 30 min. At 5 microM nimbolide, the cells become elongated and assume a neuronal shape accompanied by spikes and lamellipodia within 1-2 hr followed shortly thereafter by extensive cytological changes and and vacuolization associated with irreversible processess leading to cell death. Calcium is apparently not involved the cytotoxic effect since a calcium-free medium, leading to profound morpholigical changes, does not alter the sensitivity to nimbolide. In contrast, epoxyazadiradione requires higher concentrations and a few hr for 50 % viability loss without major morphological changes, indicating a difference in mode of action for nimbolide and epoxyazadiradione. and epoxyazadiradione.

Topics: Animals; Cell Line; Cell Survival; Cytotoxins; Diterpenes; Humans; Insecticides; Lactones; Limonins; Male; Mice; Neuroblastoma; Norsteroids; Osteosarcoma; Rabbits; Seeds; Sperm Motility; Spermatozoa; Spodoptera; Structure-Activity Relationship; Triterpenes; Tumor Cells, Cultured