Effect of Essential Oils on the Release of TNF-α and CCL2 by LPS-Stimulated THP‑1 Cells

Abstract

Plants and their constituents have been used to treat diverse ailments since time immemorial. Many plants are used in diverse external and internal formulations (infusions, alcoholic extracts, essential oils (EOs), etc.) in the treatment of inflammation-associated diseases, such as those affecting the respiratory tract or causing gastrointestinal or joint problems, among others. To support the traditional uses of plant extracts, EOs have been assessed for their alleged anti-inflammatory properties. However, the effect of EOs on the release of cytokines and chemokines has been much less reported. Considering their traditional use and commercial relevance in Portugal and Angola, this study evaluated the effect of EOs on the in vitro inhibition of the cytokine tumor necrosis factor-α (TNF-α) and the chemokine (C-C motif) ligand 2 (CCL2) by lipopolysaccharide (LPS)-stimulated human acute monocytic leukemia cells (THP-1 cells). Twenty EOs extracted from eighteen species from seven families, namely from Amaranthaceae (Dysphania ambrosioides), Apiaceae (Foeniculum vulgare), Asteraceae (Brachylaena huillensis, Solidago virgaurea), Euphorbiaceae (Spirostachys africana), Lamiaceae (Lavandula luisieri, Mentha cervina, Origanum majorana, Satureja montana, Thymbra capitata, Thymus mastichina, Thymus vulgaris, Thymus zygis subsp. zygis), Myrtaceae (Eucalyptus globulus subsp. maidenii, Eucalyptus radiata, Eucalyptus viminalis) and Pinaceae (Pinus pinaster) were assayed for the release of CCL2 and TNF-α by LPS-stimulated THP-1 cells. B. huillensis, S. africana, S. montana, Th. mastichina and Th. vulgaris EOs showed toxicity to THP-1 cells, at the lowest concentration tested (10 μg/mL), using the tetrazolium dye assay. The most active EOs in reducing TNF-α release by LPS-stimulated THP-1 cells were those of T. capitata (51% inhibition at 20 μg/mL) and L. luisieri (15–23% inhibition at 30 μg/mL and 78–83% inhibition at 90 μg/mL). L. luisieri EO induced a concentration-dependent inhibition of CCL2 release by LPS‑stimulated THP-1 cells (23%, 54% and 82% inhibition at 10, 30 and 90 μg/mL, respectively). These EOs are potentially useful in the management of inflammatory diseases mediated by CCL2 and TNF‑α, such as atherosclerosis and arthritis.

Sustainable Extraction Techniques for Obtaining Antioxidant and Anti-Inflammatory Compounds from the Lamiaceae and Asteraceae Species

“…Therefore, the observed anti-inflammatory properties of the extracts could be linked to the presence of specific phenolic compounds [ 14 ]. However, the contributions of other types of compounds cannot be discarded, since the anti-inflammatory effect of terpenes, presented in the essential oil of these plants, has been described [ 4 , 11 ].…”

“…3 TEAC (Trolox Equivalent Antioxidant Capacity) as mmol Trolox/g extract. 4 ORAC (Oxygen Radical Absorbance Capacity) as mmol Trolox/g extract. A-D Different superscript letters denote significant differences within a column (p < 0.05).…”

“…As mentioned by other authors, borneol and camphor, some of the mainly constituents in several Asteracea spp. essential oil, significantly inhibited nitric oxide production, CCL2 (Chemokine (C-C motif) ligand 2) release and cytokines (TNF-α, IL-1β and IL-6) secretion in macrophages [4,11]. Rt: retention time.…”

“…Origanum majorana L., also known as marjoram, is another species of Lamiaceae that has been appreciated because of its therapeutic properties against gastrointestinal, respiratory and neurological disorders. Extracts from marjoram, including its essential oil, have been reported to possess antimicrobial, antioxidant, anti-proliferative and anti-inflammatory activities [4,6]. Caffeic acid derivatives and flavonoids, along with ursolic acid, carvacrol and terpineol, have been associated with these biological activities [1,6].…”

“…In this regard, the Lamiaceae and Asteraceae families represent a great source of valued plant species. These species are often used as flavoring ingredients in many culinary preparations, but are also considered as medicinal herbs, where their beneficial effects have been mainly related to phenolic compounds [ 3 , 4 ].…”