Extraction of Phenolic Compounds from Olive Leaf Extracts and Their Effect on Proliferation of Human Carcinoma Cell Lines

Abstract

The aim of this work was to evaluate the effect of different olive leaf extracts (OLE) from different leaf growing stages on human carcinoma cell lines. OLE were tested in human carcinoma cell lines in vitro and cells were plated in 96-microtiter culture plates for each OLE concentration. Fresh (F) and freeze-dried (FD) leaves exhibited phenolic compounds in the range of 2.09 ± 0.10 to 8.44 ± 0.64 and 7.72 ± 0.56 to 24.65 ± 1.9 mg gallic acid equivalents/g leaves, respectively. OLE from several Portuguese olive tree cultivars were found to inhibit the growth of human carcinoma cell lines in a range of 2.09-8.44 μg phenolic compound/well (209-844 μg/ml) and 0.07-2.40 μg phenolic compounds/well (7-240 μg/ml) for fresh and freeze-dried leaves, respectively. Young (Y) leaves have revealed the highest cell growth inhibition ranging from about 95% for Cobrançosa, followed by 90% for Cobrançosa, 90% for Arbequina and 75% for Arbequina for cell lines A549, HeLa, A431 and OE21, respectively. The lowest cell growth inhibition (35%) was observed for Galega (Y) leaf extract on cell line A549. However, FD samples exhibited a distinctive pattern since cell growth inhibition was highest at highest extract dilution tested, for A431 (Galega Y) followed by A549 (Cobrançosa Y) with cell inhibition of 75% and 70%, respectively. The data presented in this work strongly suggest that OLEs inhibit the growth of human carcinoma cell lines.

The antioxidant properties and microbial load of Moringa oleifera leaves dried using a prototype convective air-dryer

“…The lowest TPC found in fresh leaf samples (26.56 ± 1.59 mg/g GAE) when compared with dried leaves. Similar observations have been reported in previous studies on dried M. oleifera leaves compared to fresh leaves ( Zullaikah et al, 2019 , Saini et al, 2014 ) and in several types of leaves ( Martinho et al, 2019 , Roshanak et al, 2016 , Rabeta and Lin, 2015 ). It is also worth noting that Hossain et al (2010) even reported that the lower total phenolics and antioxidant capacity of fresh samples were not due to the dilution effect caused by its high moisture content, even after they corrected for its moisture content values.…”

Effect of Removing the Bitter Taste of Olive Leaves on Its Antioxidant and Antibacterial Properties in Some Food Products

“…The phenolic and flavonoid content of olive leaves varies according to many factors such as climatic conditions, moisture content, age and variety of the plant, agricultural practices and the extraction procedures used (Ghomari et al, 2019). Martinho et al (2019) found that phenolic compounds in fresh and freeze-dried leaves ranging from 2.09 to 8.44 and 7.72 to 24.65 mg gallic acid equivalents/g leaves, respectively. Furthermore, the free radical scavenging activities of extracts was measured by the ability to scavenge DPPH radical.…”

Roles of Drying, Size Reduction, and Blanching in Sustainable Extraction of Phenolics from Olive Leaves

“…On the other hand, in some research studies, freeze-drying has shown significant potential for the increased liberation of phenolics from the cell wall matrices. The research of Ghelichkhani et al [25] demonstrated that freeze-dried olive leaves have great potential for extraction of total phenolic content (TPC), representing around 446.63 mg gallic acid equivalents (GAE)/g d.w. Martinho et al [26] compared freeze-dried and non-dried (fresh) olive leaves and found polyphenolic concentrations in the range of 7.72-24.65, and 2.09-8.44 mg GAE/g leaves, respectively.…”