Phytochemical Investigation and Evaluation of the Cytotoxic Activity of Carica papaya L. "Caricaceae" Cultivated in Iraq

Abstract

Carica papaya (C. papaya) L. is a tropical tree that belongs to the family Caricaceae; it is native to South America but now widely cultivated in tropical and subtropical regions of the world. The different parts of C. papaya have many therapeutic activities and it is used traditionally for the treatment of many diseases and conditions. The research efforts on C. papaya extracts to date show a promising potential for providing renewable bio products with several reported bioactivities. The information about the phytochemical constituents and therapeutic potentials of Iraqi C. papaya is very scarce. The study aimed to investigate the phytochemical constituents of Iraqi C. papaya leaves and stems and to evaluate the cytotoxic activity of the leaves extract. In order to investigate the phytochemical constituents of C. papaya leaves and stems extracts each of the studied parts of the plant was extracted by hot method by soxhlet apparatus using 85% ethanol and fractionation was done by separating the active constituents according to the differences in their polarities using n-hexane, chloroform, ethyl acetate and n-butanol. Preliminary identification of different active constituents was performed by specific chemical tests, thin layer chromatography (TLC), high-performance liquid chromatography (HPLC) and gas chromatography/ mass spectrometry (GC/MS). Qualitative and quantitative assessment for number of selected compounds was performed using high-performance liquid chromatography (HPLC) analysis. Depending on the results of thin layer chromatography and high-performance liquid chromatography, this study revealed the presence of β-sitosterol, stigmasterol, carpaine, caffeic acid, p-coumaric acid, catechin, XVIII apigenin, ferulic acid, quercetin, kaempferol, mycetrin, gallic acid and chlorogenic acid in the different fractions of Carica papaya leaves and stems extracts. Isolation of active constituents was done using preparative layer chromatography (PLC) and preparative high-performance liquid chromatography. The isolated compounds were identified using analytical thin layer chromatography TLC, analytical high-performance liquid chromatography, Fourier-transform infrared spectroscopy (FT-IR), ultraviolet (UV) spectroscopy, high-performance compact mass spectrometer (CMS). This study confirmed the identity of the isolated compound that were S1 (β-sitosterol), S2 (carpaine), S3 (kaempferol), S5 (p-coumaric acid), S6 (caffeic acid), S7(ferulic acid) in different fractions of the Carica papaya leaves and stems extracts. An unknown compound (S4) that was isolated from n-hexane extract of the leaves by preparative layer chromatography PLC; to determine the structure of (S4), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet (UV) spectroscopy and nuclear magnetic resonance (NMR) analysis were performed and (S4) was proposed to be squalene. The relative concentration of phytochemical constituents of the different fractions of Carica papaya was different between the leaves and the stems extracts. The gas chromatography/ mass spectrometry (GC/MS) analysis revealed that the presence of number of compounds that are known to have many biological and pharmacological activities in the n-hexane extract of Carica papaya leaves and stems extracts.