Cattleianal and Cattleianone: Two New Meroterpenoids from Psidium cattleianum Leaves and Their Selective Antiproliferative Action against Human Carcinoma Cells.

Engy A Mahrous,Maha M Salama,Ahmed M Al-Abd,Magda M Fathy,Fatema R Saber,Fathy M Soliman

doi:10.3390/molecules26102891

Abstract

The Myrteacae family is known as a rich source of phloroglucinols, a group of secondary metabolites with notable biological activities. Leaves of Psidium cattleianum were extracted with chloroform: methanol 8:2 to target the isolation of phloroglucinol derivatives. Isolated compounds were characterized using different spectroscopic methods: nuclear magnetic resonance (NMR), ultra-violet (UV) and mass spectrometry (MS). Two new phloroglucinols were evaluated for cytotoxicity against a panel of six human cancer cell lines, namely colorectal adenocarcinoma cells (HT-29 and HCT-116); hepatocellular carcinoma cells (HepG-2); laryngeal carcinoma (Hep-2); breast adenocarcinoma cells (MCF7 and MDA-MB231), in addition to normal human melanocytes HFB-4. Additionally, cell cycle analysis and annexin-V/FITC-staining were used to gain insights into the mechanism of action of the isolated compounds. The new phloroglucinol meroterpenoids, designated cattleianal and cattleianone, showed selective antiproliferative action against HT-29 cells with IC50’s of 35.2 and 32.1 μM, respectively. Results obtained using cell cycle analysis and annexin-V/FITC-staining implicated both necrosis and apoptosis pathways in the selective cytotoxicity of cattleianal and cattleianone. Our findings suggest that both compounds are selective antiproliferative agents and support further mechanistic studies for phloroglucinol meroterpenoids as scaffolds for developing new selective chemotherapeutic agents.

Highlights

Myrtaceous plants exert a myriad of biological activities including anti-diabetic, cytotoxic, anti-inflammatory and anti-bacterial biofilm activities [1,2,3]
Two new meroterpenoids were isolated from the chloroform: methanol extract of Psidium cattleianum leaf
Phloroglucinols can occur as monomers, dimers or as terpene adduct such as phloroglucinol meroterpenoids of Eucalyptus and Psidium [18]

Summary

Introduction

Myrtaceous plants exert a myriad of biological activities including anti-diabetic, cytotoxic, anti-inflammatory and anti-bacterial biofilm activities [1,2,3]. Ninety-three compounds were identified in the aqueous leaves0 extract of P. cattleianum where catechin, gallic acid and vanillic acid were reported as the major constituents [6]. Leaves of P. cattleianum are used in folk medicine as an anti-hemorrhagic, antispasmodic and anti-diarrheal agent [7], but recent investigations have uncovered a selective anti-proliferative effect of P. cattleianum leaf extract against human carcinoma cells [8,9]. A closely related species, Psidium guavaja, showed cytotoxic activity in prostate cancer cell lines that was mediated through the induction of apoptosis [10]. Phytochemical investigation of P. guajava resulted in the isolation of sixteen phloroglucinol meroterpenoids which all displayed cytotoxicity against five human cell lines with IC50 reported below

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