The study “Medicinal Effects of Bromelain (Ananas comosus) Targeting Oral Environment as an Anti-oxidant and Anti-inflammatory Agent ” by Lee et al. (2018) examined bromelain, described as a pineapple-derived enzyme mixture, in lab tests focused on oxidative stress and inflammation. The authors discuss oral conditions such as stomatitis and periodontal disease as part of the rationale, then evaluate bromelain using reactive oxygen species (ROS), meaning highly reactive oxygen-containing molecules, assays, and an inflammation model in macrophage cells. Tumor necrosis factor alpha (TNF-α) is presented as one example of an inflammation-related signal linked with tissue breakdown in periodontal disease.

This scientific paper describes bromelain as being of “significant clinical interest” and notes that prior work has explored bromelain in immune-related and inflammatory settings. The paper also explains the role of antioxidants, noting that antioxidant materials can reduce oxidative stress by interrupting chain reactions that damage cells. In the oral setting, the authors describe stomatitis as inflammation of the mouth mucosa and describe periodontal disease as inflammation and destruction of the tissues that support teeth, and they point to inflammatory mediators as signals that can amplify these responses.

A key idea in the paper is that oxidative stress and immune signaling can interact during inflammation. To explore this, the researchers used two approaches: antioxidant scavenging assays in vitro and cell-based experiments that measured inflammation-related markers after an inflammatory trigger (lipopolysaccharide (LPS)).

The researchers purified bromelain from pineapple ( Ananas comosus) stem and bark. In the described process, plant material was dried, extracted with 70% ethanol, and proteins were precipitated using ammonium sulfate. Purification included ion-exchange chromatography (DEAE-cellulose) and gel filtration (G-150). The paper reports an overall yield of about 49% and “17-fold purification.”

Antioxidant activity was measured using assays designed to assess different free-radical or reactive species scavenging actions:

1. 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assay
2. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay
3. Hydrogen peroxide (H2O2) scavenging assay
4. Superoxide dismutase (SOD)-like activity assay

For anti-inflammatory testing, the study used RAW 264.7 macrophage cells, a mouse immune cell line commonly used in laboratory inflammation research. Cells were treated with bromelain and then stimulated with lipopolysaccharide (LPS) to provoke an inflammatory response. The study assessed nitric oxide (NO) scavenging and measured inflammation-related markers at the protein level using western blotting and at the messenger RNA (mRNA) level using reverse transcription polymerase chain reaction (RT-PCR).

Across the antioxidant assays reported, scavenging activity generally increased as bromelain concentration increased within each assay’s tested range. For example, at 500 μg/mL, bromelain showed:

• ABTS scavenging: 95.58%
• DPPH scavenging: 68.07%
• Hydrogen peroxide (H2O2) scavenging: 92.89%

They also report half maximal inhibitory concentration (IC50) values (how much is needed to reach 50% inhibition) for these antioxidant measures: 131.2 μg/mL (ABTS), 145.9 μg/mL (DPPH), 124.3 μg/mL (H2O2), and 147.9 μg/mL (SOD-like).

One clear point from the reported results is that hydrogen peroxide scavenging was strong and had an IC50 close to the positive control used in that assay.

In the cell-based testing, bromelain showed higher nitric oxide (NO) radical scavenging as concentration increased up to 5000 μg/mL, reaching 56.12% at the highest tested level.

The paper links this measurement to inducible nitric oxide synthase (iNOS), which can increase NO production during inflammatory signaling in macrophages, and frames lower NO as consistent with anti-inflammatory activity in this lab model.

Using western blotting, the study reports that bromelain inhibited LPS-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression in a dose-dependent range of 6.25 to 50 μg/mL.

The abstract states that bromelain “inhibited the band expression dose-dependently” for iNOS and COX-2.

The study reports reduced phosphorylation in mitogen-activated protein kinase (MAPK) pathways in LPS-stimulated cells, including changes in phosphorylated ERK, JNK, and p38.

Activator protein-1 (AP-1) is described as a transcription factor complex involving Jun and Fos family proteins. In this model, bromelain “significantly suppressed” c-Fos induction and reduced c-Jun and phosphorylated c-Jun signals.

At the gene expression level, reverse transcription polymerase chain reaction (RT-PCR) results showed dose-dependent decreases in cyclooxygenase-2 (COX-2), tumor necrosis factor alpha (TNF-α), and inducible nitric oxide synthase (iNOS) messenger RNA (mRNA) in LPS-stimulated RAW 264.7 cells. The paper notes that these mRNA results were consistent with the protein-level pattern seen in western blots.

In the discussion, the authors write: “We have clearly demonstrated that bromelain isolated from an Ananas comosus extract has a significant anti-oxidant activity, as well as anti-inflammatory ability.”

Staying within what this scientific paper tested, the results show that bromelain acted as an antioxidant in several in vitro scavenging assays and was associated with lower levels of multiple inflammation-related markers in an LPS-stimulated RAW 264.7 macrophage cell model. These are laboratory findings that describe changes in biochemical activity, gene expression, and signaling pathways under controlled conditions.

The authors discuss potential relevance to the oral environment and mention oral conditions such as stomatitis as part of the research rationale. However, the experiments reported are not clinical tests in humans and do not measure prevention, treatment, or cure of oral disease. The paper also calls for “more systematic studies… in the future,” which supports the need for further research on real-world use, dosing, and safety.

This summary is a paraphrase of a 2018 scientific paper. In the reported experiments, purified bromelain from pineapple showed antioxidant activity in multiple in vitro assays and was associated with lower inflammation-related markers, including iNOS, COX-2, and TNF-α, plus changes in MAPK and activator protein-1 (AP-1) signaling in LPS-stimulated RAW 264.7 macrophage cells. A quotable takeaway from the study is that bromelain showed “significant anti-oxidant activity” alongside “anti-inflammatory ability” in the tested laboratory models.