Scientists show how Manuka and Ohia Lehua honeys differ in their antioxidant potential, demonstrating that while Manuka honey has a higher phenolic content, Ohia Lehua honey excels in reducing oxidative stress and promoting healthy antioxidant defenses.
Study: Phytochemical composition and antioxidant activity of Manuka honey and Ohia Lehua honey. Image credit: Valentyn Volkov/Shuttersotck.com
The use of honey as medicine is widespread across cultures, primarily due to its antioxidant and anti-inflammatory properties that protect tissues from oxidative stress. A recent study published in the journal Nutrients studied the different components of Manuka honey (MH) and Ohia lehua honey (OLH) that contribute to their anti-inflammatory properties.
The harmful effects of oxidative stress
Oxidative stress results from an imbalance between reactive oxygen species (ROS) and the body’s antioxidant defenses. During the inflammatory response to injury or infection, immune cells such as macrophages and neutrophils release ROS.
Excess ROS can oxidize and damage cellular proteins, lipids and nucleic acids, thereby inducing a cycle of immunological inflammatory responses. Unlike the treble inflammationwhich drives the healing response, long-term inflammation amplifies tissue damage and contributes to chronic disease.
Inflammatory pathways such as nuclear factor kappa B (NF-κB), cyclooxygenase (COX), and mitogen-activated protein kinase (MAPK) pathways lead to increased production of pro-inflammatory cytokines like interleukin -6 (IL-6). These cytokines induce inflammation, oxidative stress and activation of the NLRP3 inflammasome. NLRP3 increases inflammation and can trigger chronic inflammatory diseases like type 2 diabetes and atherosclerosis.
The components of honey
Honey is a natural product mainly composed of fructose, glucose and water. It also contains many phenolic plant compounds, enzymes and organic acids, as well as hydrogen peroxide (H2Oh2) and methylglyoxal (MG), which are both bioactive compounds.
Honey is a traditional medicine used to reduce inflammation and oxidative stress. Its antioxidant properties are essential for the prevention of cardiovascular risk factors, diseases and cancer.
MH is pure honey produced by bees in New Zealand that feed primarily on the Manuka shrub (Leptospermum scoparium), while OLH honey is produced in the Ka’u District on the Big Island of Hawaii from bees feeding on Metrosiderospolymorpha flowers.
MH and Kanuka honey inhibit inflammation in immune and cancer cell cultures. The phenolic acids and flavonoids in honey also have antioxidant activity.
Previous studies have established that honey can inhibit multi-drug resistant bacteria like Staphylococcus aureus And Pseudomonas aeruginosa. With its high sugar concentrations, acidic pH and bioactive content, honey prevents microbial growth and wound infection and promotes tissue repair.
The antimicrobial mechanisms of honey are peroxide-based or not. Peroxide honey converts glucose to gluconic acid and hydrogen peroxide through glucose oxidase. Comparatively, peroxide-free honey like MH relies on polyphenols and the formation of methylglyoxal, which suppresses glucose peroxidase activity.
About the study
The present study examined the composition of MH and OLH, particularly the concentrations of polyphenolic plant compounds present in these types of honey. Additional in vitro experiments were carried out to evaluate their antioxidant activity by determining the ability of the extracts to scavenge free radicals.
The present study performed various in vitro studies tests, including ferric ion reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and H2Oh2 and nitric oxide (NO) scavenging tests. Trolox, a synthetic analogue of vitamin E, has also been used to measure the antioxidant capacity of foods, beverages and supplements.
In vivo The tests examined total oxidative stress (TOS), total antioxidant capacity (TAC), and oxidative stress index (OSI), which reflects the ratio of TOS to TAC in a rat model of inflammation. Levels of advanced oxidation protein products (AOPP), total thiols, malondialdehyde (MDA), which indicates levels of lipid peroxidation, and NO, a signaling molecule of the endothelium, nerve and immune system , were also measured. in vivo.
Phenolic profile
MH had a phenolic content ten times higher than that of OLH. Both honey products contained a wide range of phenolic compounds, with non-flavonoids like hydroxybenzoic acid comprising approximately 90% and 68%, respectively, of phenolic compounds like 2,4-dihydroxybenzoic acid and gallic acid in MH and OLH.
Flavonoids include the anti-inflammatory and free radical scavenger apigenin-glucoside, quercetin-glucoside, and quercetin, all of which were only present in MH. Pinocembrin-glucoside was present in MH and OLH.
Antioxidant properties
OLH had a high level in vivo antioxidant activity, mainly achieved by reducing serum oxidative activity. Furthermore, OLH reduced TOS, OSI, and MDA more than the nonsteroidal anti-inflammatory drug (NSAID) diclofenac, in addition to increasing TAC and SH.
OLH prevents lipid peroxidation, reduces oxidative stress, and increases antioxidant capacity rather than inhibiting NO and protein oxidation pathways. At the lowest concentration of OLH, the antioxidant activity was the highest. Conversely, inhibition of TOS and OSI was more potent at higher dilutions, while exceeding the observed effects of diclofenac.
MH exhibited limited antioxidant activity at all dilutions compared to its potent antibacterial activity. MH reduced NO and AOPP and increased SH levels, exceeding the effects of diclofenac.
TOS and OSI were moderately reduced. Higher dilutions were less effective than diclofenac or Trolox. Notably, the composition and concentration of phenolic compounds in MH are variable, which can alter its antioxidant properties.
Syringe Acid inhibits pro-inflammatory pathways and eliminates free radicals. MH has a high content of methylsyringic acid, which protects DNA from oxidative damage.
Conclusions
MH was associated with ten times higher phenolic content than OLH, attributed to its antioxidant capacity; however, these effects were concentration dependent. Conversely, OLH significantly reduces oxidative stress by eliminating free radicals and increases the antioxidant capacity of serum.
Honey is an essential and traditional functional food; therefore, components present in honey need to be identified and studied to determine their potential impact on human health. These natural foods should be explored as promising sources of antioxidant activity via diet.
Journal reference:
- Morar, II, Pop, RM, Peitzner, E., and others. (2025). Phytochemical composition and antioxidant activity of Manuka honey and Ohia Lehua honey. Nutrients. doi:10.3390/nu17020276.