Potential anti‐inflammatory effects of Melaleuca alternifolia essential oil on human peripheral blood leukocytes

Abstract

The fungicidal and bactericidal actions of the essential oil (EO) of Melaleuca alternifolia seem well established, but their anti-inflammatory and antioxidative effects remain unclear. This study investigated in vitro the possible role of whole Melaleuca alternifolia EO as a modulator of the inflammatory/non-specific immune response by exploring the chemotaxis and kinetic radical oxygen species (ROS) production of leukocytes and cytokine secretion in peripheral blood mononuclear cells (PBMCs) in humans. The influence of Melaleuca alternifolia EO on the chemotaxis under agarose of isolated neutrophils (PMNs) was evaluated. The kinetics of ROS production by stimulated total circulating leukocytes was followed over 2 h by recording the fluorescence intensity of oxidized dihydrorhodamine 123. The effects of this EO on pro-(interleukin IL-2) and anti-(IL-4 and IL10) inflammatory cytokine secretions were determined by ELISA following incubation of PBMCs with the EO for 24 h. Melaleuca alternifolia EO was inefficient on the chemotaxis of PMNs. It exerted an antioxidant effect, reducing ROS production throughout the kinetic study. Melaleuca alternifolia EO inhibited PBMC proliferation, as revealed by a reduction in IL-2 secretion by stimulated lymphocytes. This EO at 0.1% directly increased the secretion of the anti-inflammatory cytokine IL-4 compared with IL-4 secretion without EO (18.5 +/- 10.0 vs 3.3 +/- 1, p < 0.05), and also increased IL-10 secretion at 0.01% (94.9 +/- 38.7 vs 44.1 +/- 18, ns). Melaleuca alternifolia EO may not only act as an anti-inflammatory mediator through its antioxidant activity but may also efficiently protect the organism by reducing the proliferation of inflammatory cells without affecting their capacity to secrete anti-inflammatory cytokines.

Essential Oils’ Chemical Characterization and Investigation of Some Biological Activities: A Critical Review

“…EOs have shown their action as hepatoprotective agents in ageing polyunsaturated fatty acids mammals and it has been proved that they possess a beneficial impact upon the PUFAs, in particular the long chain C20 and C22 acids [48]. Moreover, essential oils being able to scavenge free radicals may also play an important role in some disease prevention, such as brain dysfunction, cancer, heart disease, and immune system decline [49].…”

“…Recently, essential oils have been used in clinical settings to treat inflammatory diseases, such as rheumatism, allergies, or arthritis [45]. Melaleuca alternifolia EO was reported to have a considerable anti-inflammatory activity [46,47,48]. This activity is correlated with its major compound: α-terpineol [49].…”

Essential Oils from Ugandan Medicinal Plants: In Vitro Cytotoxicity and Effects on IL‐1β‐Induced Proinflammatory Mediators by Human Gingival Fibroblasts

“…For decades, essential oils have been recognised to exhibit notable biological activities, including antioxidant [13, 14] and antimicrobial [15] attributes. Some essential oils, such as that from the plant Melaleuca alternifolia , also exhibit anti-inflammatory activities [16, 17]. …”

Chemical composition and antibacterial activities from the essential oils of myrtaceae species planted in Brazil

“…Moreover, leaves and stem of several Melaleuca species are source of essential oils used for medicinal purposes. Many of such oils present anti-inflammatory, 5 fungicide, 6 acaricide, 7 antiviral 8 properties and are also active against Gram-positive and Gram-negative bacteria. 9 Besides, the essential oils of M. alternifolia and related species exhibit activity against herpes simplex virus (HSV), causal agent of labial herpes.…”