6-deacetylnimbin and nimbin

Azadirachta indica, known as neem tree and traditionally called "nature's drug store" makes part of several African pharmacopeias and is widely used for the preparation of homemade remedies and commercial preparations against various illnesses, including malaria. Employing a bio-guided fractionation approach, molecules obtained from A. indica ripe and green fruit kernels were tested for activity against early sporogonic stages of Plasmodium berghei, the parasite stages that develop in the mosquito mid gut after an infective blood meal. The limonoid deacetylnimbin (3) was identified as one the most active compounds of the extract, with a considerably higher activity compared to that of the close analogue nimbin (2). Pure deacetylnimbin (3) appeared to interfere with transmissible Plasmodium stages at a similar potency as azadirachtin A. Considering its higher thermal and chemical stability, deacetylnimbin could represent a suitable alternative to azadirachtin A for the preparation of transmission blocking antimalarials.

Topics: Animals; Antimalarials; Azadirachta; Female; Limonins; Mice, Inbred BALB C; Molecular Structure; Plasmodium berghei; Seeds

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

The use of ethylenediamine in methanol is described for the selective cleavage of the acetate group in nimbin (1) to 6-deacetyl nimbin (1a) under microwave irradiation. This method enables to deacetylate without affecting other functional groups such as α,β-unsaturated ketone, ester, ether, etc. in certain tetranortriterpenoids and other acetate-containing natural compounds.

Topics: Acetylation; Biological Products; Ethylenediamines; Limonins; Microwaves; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular

A new piperidine alkaloid and three known tetranortriterpenoids were isolated from the methanol extracts of the rhizomes of Arisaema decipiens Schott (Araceae) and their chemical structures were identified as (-)-(2R*,3S*,6S*)-N,2-dimethyl-3-hydroxy-6-(9-phenylnonyl) piperidine (1), 6-deacetylnimbin (2), 28-deoxonimbolide (3) and nimbin (4). The N-methylated derivative (1a) of 1 was synthesized. Compound 1 exhibited weak inhibitory activity against the MCF-7 cell line, while compound 1a showed potential inhibitory activity against the MCF-7 cell line with an IC₅₀ value of 4.6 μM and weak inhibitory activity against K562 and SK-OV-3 cells. This plant in genus Arisaema is firstly reported as the source of limonoids that are considered a natural antitumor herbal medicine.

Topics: Alkaloids; Antineoplastic Agents; Arisaema; Breast Neoplasms; Cell Line, Tumor; Drug Screening Assays, Antitumor; Drugs, Chinese Herbal; Ethnicity; Female; Humans; Limonins; Magnetic Resonance Imaging; Ovarian Neoplasms; Piperidines; Rhizome