Mahanimbine, a carbazole alkaloid was isolated from an ether extract of the stem bark
of Murraya koenigii whilst Murrayafoline A was isolated from petroleum ether extract
of the roots of Murraya koenigii. S-Benzyldithiocarbazate is a dithiocarbazic acid Schiff
base derived from S-alkyl esters. They were found to exhibit cytotoxic activity against
CEM-SS human T-lymphoblastic leukemic cells. The cytotoxic activity of
Mahanimbine, Murrayafoline A and S-Benzyldithiocarbazate that inhibit 50 % growth
(IC₅₀) of CEM-SS were 6 µg/ml, S µg/ml and 7.S µg/ml respectively. For comparative
purposes, the IC₅₀ of several commercial cytotoxic drugs against CEM-SS were
determined. The inhibition effect of Mahanimbine, Murrayafoline A and SBenzyldithiocarbazate
were better than Methotrexate (IC₅₀ > 30 µg/ml), Doxorubicine
(IC₅₀ = 21 µg/ml), Cytarabine (IC₅₀ > 30 µg/ml) and Colchecine (IC₅₀ = 8 µg/ml).These compounds were found to be less active than cis-diamine dichloroplatinwn and
Vinorelbine tartrate with a IC₅₀ value of 3 µg/ml. In contrast, these three compounds
were found to be less active against normal mouse fibroblasts cell, 3T3 with the IC₅₀
value of 11 µg/ml (Mahanimbine), 17 µg/ml (Murrayafoline A) and 10 µg/ml (SBenzyldithiocarbazate)
respectively. The study showed that the proliferation of cells
was inhibited before the cells were being killed. In addition, Mahanimbine,
MurrayafolineA and S-Benzyldithiocarbazate caused programmed cell death by
showing apoptotic features such as nucleus fragmentation, cell shrinkage, membrane
blebbing and formation of apoptotic bodies. These were further confirmed with DNA
laddering in agarose gel electrophoresis assay due to DNA fragmentation. DNA
laddering was obtained after 24 hours of treatment by these three compounds in a doseindependent
but time-dependent way. Mahanimbine and Murrayafoline A were shown
to arrest CEM-SS cells at G1 phase of cell cycle using flowcytometry method. As a
result, Mahanimbine, Murrayafoline A and S-Benzyldithiocarbazate were found as
potent antitumor agents
