How Plant Extracts From Southern Africa Can Calm Inflammation

Jenn Hoskins
5th February, 2024

How Plant Extracts From Southern Africa Can Calm Inflammation

Crown Honeyflower (Melianthus comosus), one of the medicinal plants examined in the study.

Public Domain Photograph
Inflammation is a natural bodily response to injury or infection, but chronic inflammation is linked to numerous health problems including arthritis, heart disease, and even cancer. For centuries, traditional medicine systems have utilized plants to combat inflammation, and research continues to validate these practices. A team from Griffith University recently investigated the anti-inflammatory potential of eight southern African medicinal plants[1]. This study aimed to identify which plants, and potentially which compounds within them, could effectively reduce inflammation by targeting key signaling molecules in the immune system. The research focused on extracts from the leaves of Melianthus comosus (honey flower), Tetradenia riparia (misty plume bush), Warburgia salutaris (pepper-bark tree), and five other species traditionally used for pain and inflammation relief in southern Africa. Inflammation involves the release of various signaling molecules called cytokines, which recruit immune cells to the site of injury. Excessive cytokine production can lead to damaging chronic inflammation. The researchers used a cell-based model, employing RAW 264.7 macrophages – a type of immune cell – stimulated with lipopolysaccharide (LPS) to mimic an inflammatory response. They then measured the levels of six key cytokines: interleukin-1β (IL-1β), IL-6, tumour necrosis factor-α (TNF-α), interferon-gamma (IFN-γ), monocyte chemoattractant protein 1 (MCP-1), and macrophage inflammatory protein (MIP)-2). The results showed that ethanol extracts of Melianthus comosus, Tetradenia riparia, and Warburgia salutaris were particularly effective at reducing inflammation. These extracts inhibited the release of IL-1β, IL-6, and TNF-α by more than 50-fold in the stimulated macrophages. Interestingly, an aqueous (water-based) extract of M. comosus also demonstrated significant, broad-spectrum inhibition of all the cytokines and chemokines tested. This suggests that different extraction methods can yield different anti-inflammatory profiles from the same plant. Further investigation of the M. comosus ethanol extract using advanced chemical analysis (UHPLC-HRMS) identified four compounds: crassolide, deoxylimonoic acid D-ring-lactone, 2-hydroxynonanoic acid, and 5-noniloxytryptamine. While the specific contribution of each compound to the observed anti-inflammatory effects requires further study, their identification provides a starting point for understanding the plant’s mechanism of action. This study builds upon previous ethnobotanical research identifying plants with traditional anti-inflammatory uses[2]. Earlier work demonstrated that extracts from Peltophorum africanum exhibited antioxidant and anti-inflammatory activity, inhibiting the lipoxygenase enzyme[2]. Similarly, research on Punica granatum (pomegranate) identified ellagic acid, gallic acid, and punicalagin as potential anti-inflammatory compounds by reducing the production of nitric oxide and other inflammatory mediators[3]. The current study expands on this knowledge by focusing on a different set of southern African plants and utilizing a more comprehensive cytokine profiling approach. Notably, the discovery of crassolide in M. comosus is particularly interesting when considered alongside research on soft corals. A study isolating compounds from Lobophytum crassum identified crassumolides that also exhibited anti-inflammatory properties, inhibiting the production of iNOS and COX-2[4]. This suggests that the crassolide structure may be a common feature in natural products with anti-inflammatory activity, potentially offering a new avenue for drug development. The findings from Griffith University support the traditional use of these southern African plants as anti-inflammatory remedies and provide a scientific basis for their potential therapeutic applications. The identification of specific compounds within M. comosus opens the door for further research into their individual and combined effects on inflammation, potentially leading to the development of novel anti-inflammatory treatments.

MedicineBiochemPlant Science

References

Main Study

1) Leaf extracts of eight selected southern African medicinal plants modulate pro-inflammatory cytokine secretion in LPS-stimulated RAW 264.7 macrophages.

Published 4th February, 2024

https://doi.org/10.1007/s10787-023-01420-9

Related Studies

2) The anti-inflammatory and antioxidant activity of 25 plant species used traditionally to treat pain in southern African.

https://doi.org/10.1186/s12906-015-0669-5

3) Anti-inflammatory potential of ellagic acid, gallic acid and punicalagin A&B isolated from Punica granatum.

https://doi.org/10.1186/s12906-017-1555-0

4) Cytotoxic and anti-inflammatory cembranoids from the soft coral Lobophytum crassum.

https://doi.org/10.1021/np8004584


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