Send Orders for Reprints to reprints@benthamscience.ae Letters in Drug Design & Discovery, 2017, 14, 000-000 1 RESEARCH ARTICLE 1570-1808/17 $58.00+.00 ©2017 Bentham Science Publishers Antiproliferative Effects of Nerium oleander Stem and Mitotic Arrest Induced by Cardenolide Odoroside B on NCI-H460 Cancer Cells Kehkashan Arshad Qamar a,* , Ahsana Dar Farooq a,b , Bina S. Siddiqui a , Nurul Kabir b , Naseema Khatoon a , Shakil Ahmed c , Shaista Erum c and Sabira Begum a a H.E.J. Research Institute of Chemistry, b Dr. Panjwani Center for Molecular Medicine and Drug Research, c Industrial Analytical Center, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan Abstract: Background: Nerium oleander extract preparations have been used in the Arab folk- medicine for the treatment of solid tumors. Objective: In the current investigation, bioassay-guided fractionation of N. oleander stem methano- lic extract was performed to identify the active compound(s) responsible for its antiproliferative activity and the mechanism of action of the active compounds was explored. Methods: The methanolic extract, fractions and sub-fractions were screened against four human cancer cell lines: HT-144, MCF-7, NCI-H460 and SF-268 using sulforhodamine B assay. The ef- fects of the active compounds on the cytoskeleton and nuclei of NCI-H460 cells were studied using immunofluorescence microscopy. Results: The more active petroleum ether insoluble sub-fraction led to the isolation of five pure compounds viz adynergenin, adynerin, hemidesmin-2, odoroside A and odoroside B. Odoroside A was the most potent compound with GI 50 : 0.04 and LC 50 : 0.74 µM against NCI-H460 cell line, while odoroside B demonstrated moderate growth inhibition and cytotoxicity (GI 50 : 6.7; LC 50 : 54 µM). After 24 hours’ treatment with odoroside B (50 µM) abnormal mitotic spindles were ob- served, while > 90% mitotic cells were arrested in the prophase stage. Conclusion: N. oleander stem possesses significant antiproliferative effects against the aforemen- tioned cell lines and the cardenolide odoroside B induces mitotic arrest of NCI-H460 cells in the prophase stage. Keywords: Nerium oleander, antiproliferative, odoroside B, cytoskeleton, immunofluorescence, mitotic arrest. 1. INTRODUCTION Nerium oleander (Apocynaceae family) is an evergreen tree distributed in Indo-Pakistan subcontinent, tropical and subtropical regions, and the Mediterranean. It has been used in the folklore medicine for the treatment of solid tumors and skin diseases like corns, eczema, herpes, psoriasis, ringworm infections, scabies, sores and warts [1-3]. Ingestion of parts of this plant causes toxicity due to the presence of cardiac glycosides such as oleandrin and oleandrigenin [4]. Many cardiac glycosides and pregnanes e.g. neridienone A and neridienone B have been isolated from the stem and twigs of N. oleander [5, 6]. Several of these compounds have demonstrated anticancer effects, e.g. neridienone A exhibited *Address correspondence to this author at the H.E.J. Research Institute of Chemistry, University of Karachi, Karachi 75270, Pakistan; Tel: +92 21 34819017; Fax: +92 21 34819018; E-mail: kehkashanqamar@gmail.com IC 50 of 0.68 and 2.5 µg/ml against human malignant fibro- blast and liver tumor cell lines, respectively [5]; the com- pound 3β-O-(β-D-diginosyl)-14-hydroxy-5β,14β-card-20(22)- enolide also demonstrated significant antiproliferative effects (IC 50 : 0.18 and 1.5 µM) against the aforementioned human cancer cell lines [7]. It has been recently demonstrated that the cardenolides from the Apocynaceae family including the genus Nerium exhibit the capability to regulate cancer cell survival and death through multiple signaling pathways [8]. The proteins involved in cell division such as microtu- bules are important targets for anticancer drugs [9]. Microtu- bules form the bipolar mitotic-spindle apparatus at the time of cell division, which is essential for the equal separation and distribution of chromosomes to the daughter cells [10]. This process requires a dynamic balance between polymeri- zation and depolymerization processes of microtubules. The treatment of cancer cells with anti-microtubule drugs dis- A R T I C L E H I S T O R Y Received: February 09, 2017 Revised: July 07, 2017 Accepted: July 11, 2017 DOI: 10.2174/1570180814666170727142145