Stigmalactam from Orophea enterocarpa induces human cancer cell apoptosis via a mitochondrial pathway.

Ratana Banjerdpongchai,Benjawan Wudtiwai,Wilart Pompimon

doi:10.7314/apjcp.2014.15.23.10397

Ratana Banjerdpongchai, Benjawan Wudtiwai + Show 1 more

Open Access

https://doi.org/10.7314/apjcp.2014.15.23.10397

Copy DOI

Abstract

Stigmalactam, an aristolactam-type alkaloid extracted from Orophea enterocarpa, exerts cytotoxicity against several human and murine cancer cell lines, but the molecular mechanisms remain elusive. The aims of this study were to identify the mode and mechanisms of human cancer cell death induced by stigmalactam employing human hepatocellular carcinoma HepG2 and human invasive breast cancer MDA-MB-231 cells as models, compared to normal murine fibroblasts. It was found that stigmalactam was toxic to HepG2 and MDA-MB-231 cells with IC50 levels of 23.0±2.67 μM and 33.2±4.54 μM, respectively, using MTT assays. At the same time the IC50 level towards murine normal fibroblast NIH3T3 cells was 24.4±6.75 μM. Reactive oxygen species (ROS) production was reduced in stigmalactam-treated cells dose dependently after 4 h of incubation, indicating antioxidant activity, measured by using 2',7',-dichlorohydrofluorescein diacetate and flow cytometry. Caspase-3 and caspase-9 activities were increased in a dose response manner, while stigmalactam decreased the mitochondrial transmembrane potential dose-dependently in HepG2 cells, using 3,3'-dihexyloxacarbocyanine iodide and flow cytometry, indicating mitochondrial pathway-mediated apoptosis. In conclusion, stigmalactam from O. enterocarpa was toxic to both HepG2 and MDA-MB-231 cells and induced human cancer HepG2 cells to undergo apoptosis via the intrinsic (mitochondrial) pathway.

Highlights

Orophea enterocarpa is in Annonaceae family, found endemically in southern and eastern parts of Thailand
Stigmalactam, an aristolactam-type alkaloid extracted from Orophea enterocarpa, exerts cytotoxicity against several human and murine cancer cell lines, but the molecular mechanisms remain elusive
The aims of this study were to identify the mode and mechanisms of human cancer cell death induced by stigmalactam employing human hepatocellular carcinoma HepG2 and human invasive breast cancer MDA-MB-231 cells as models, compared to normal murine fibroblasts

Summary

Introduction

Orophea enterocarpa is in Annonaceae family, found endemically in southern and eastern parts of Thailand. For other species of Orophea, O. uniflora is endemic in India whereas O. palawanensis is found in Philippines. Various bioactive alkaloids are extracted from medicinal herbs such as nitidine chloride from Zanthoxylum nitidum with anticancer effect against breast cancer cells (Sun et al, 2014). Camptothecin, a potent alkaloid drug with an anticancer effect, is extracted from the bark and stem of Camptotheca acuminata, which contains the mechanism of action to inhibit topoisomerase I activity (Efferth et al, 2007; Ulukan and Swaan, 2002). There has been a report of aqueous extract of C. acuminata fruit containing antitumor effects on human endometrial carcinoma cells via the accumulation of cyclin-A2 and -B1, activation of caspase-3 and -7, similar to the effect of camptothecin (Lin et al, 2014)

Objectives

Methods

Results