Peter Brooks

Manuka ( Leptospermum ) honeys from Australia (Aust) and New Zealand (NZ) contain high levels of aromatic compounds, though only a subset are true phenolics in that they contain a hydroxyl group attached to an aromatic ring. Consequently, the traditional Folin-Ciocalteu Total Phenolic Content (FC-TPC) assay fails to detect many non-phenolic aromatic compounds that may confer health benefits. This paper quantified both phenolic and non-phenolic aromatic compounds in monofloral manuka honeys using high-performance liquid chromatography with diode array detection (HPLC-DAD) and the FC-TPC assay. In addition, this study evaluated the capacity of the honeys to inhibit 15-lipoxygenase (15-LOX), an enzyme that causes peroxidation of long chain polyunsaturated fatty acids. Australian (n = 7) and New Zealand (n = 6) Leptospermum scoparium ( L. scoparium ) honeys showed the highest total aromatic concentrations by HPLC-DAD (>2100 mg/kg), significantly exceeding those of L. liversidgei (n = 5), L. whitei (n = 5), and L. speciosum (n = 3) honeys. The FC-TPC assay identified higher phenolic levels in L. scoparium and L. polygalifolium honeys than in the other species studied. Sugar free Australian and New Zealand manuka honey aromatic extracts were potent inhibitors of 15-LOX enzyme, with IC ₅₀ values recorded at 50 , 13.2 ± 0.7%) and New Zealand (13.1 ± 1.9%) L. scoparium honeys were more potent in inhibiting 15-LOX than L. liversidgei (IC ₅₀ , 37.5 ± 6.3%) and L. speciosum (IC ₅₀ , 36.6 ± 10.5%). Overall, this study demonstrates that HPLC-DAD provides a more comprehensive assessment of aromatic compounds in manuka honey than the FC-TPC assay and highlights the potential contribution of these compounds to anti-inflammatory activity.

Food security remains one of the most critical global challenges of the 21st century. Traditional tree crops domesticated by indigenous people have the potential to increase food security and improve the livelihoods of smallholders in developing countries. However, the nut characteristics of many traditional tree crop species in the tropics are poorly understood. In particular, physical and chemical characteristics are important to explore when selecting trees to commercialise. Three species, Barringtonia procera, B. edulis, and B. nova-hiberniae, have a long history of traditional use and domestication in Pacific Island countries. The aim of this study was to explore the physical and chemical characteristics of Barringtonia spp. in three Pacific countries: Solomon Islands, Vanuatu, and Fiji. There were significant differences in kernel weight, oil concentration, and fatty acid concentration among the countries. The kernel weight was significantly higher in Solomon Islands compared with those in Vanuatu and Fiji (9.65 g, 7.61 g, and 5.64 g, respectively). Average kernel weight in Fiji was well above 3 g, which indicated that processing could be commercially viable. The total oil concentration was significantly higher in Vanuatu and Solomon Islands than Fiji, with average concentrations of 38.96% in Solomon Islands, 47.11% in Vanuatu, and 26.20% in Fiji. Barringtonia spp. exhibited high concentrations of unsaturated fatty acids, similar to other tropical nuts, which suggests that it may be a potential healthy oil for human consumption. Notably, kernel size, oil concentration, and fatty acid composition varied geographically, potentially due to climatic differences and historical seed transfer. Our study demonstrated the potential of Barringtonia to be commercialised to enhance food and nutrition security and provide a guide for cultivar selection.

Natural products have evolved antimicrobial properties that can be exploited in our search for new ways of treating infectious diseases. This study evaluates the antimicrobial properties and chemical profiles of honey produced by the Australian stingless bee species Tetragonula carbonaria , Tetragonula hockingsi , and Austroplebeia australis against selected human pathogens. Using broth microdilution methods, we found that all tested honey samples had antimicrobial activity. The fungal dermatophyte species Trichophyton interdigitale displayed the highest susceptibility (average MICs: 4%–9% [wt/wt]), followed by Staphylococcus aureus (9%–11%), Escherichia coli (10%–13%), and Cryptococcus neoformans (24%–34%). T. carbonaria honey had the highest overall activity, while A. australis honey was the weakest. After heat treatment at 80°C for 30 min to remove hydrogen peroxide (H ₂ O ₂ )-based activity, T. carbonaria and T. hockingsi honey retained significant non-peroxide activity against E. coli (14% and 17%, respectively) and S. aureus (17% and 18%, respectively), although their efficacy against the fungal pathogens diminished. Chemical analysis revealed distinct differences in H ₂ O ₂ production, color intensity, phenolic and antioxidant content, density, and pH among the honey types. The dynamic generation of H ₂ O ₂ in stingless bee honey was remarkably prolonged, with some samples producing H ₂ O ₂ for more than 6 days. Proteomic analysis identified diverse proteins that may contribute to antimicrobial efficacy. Phenolic extracts had antimicrobial activity, with flavonoids identified as potential contributors. T. carbonaria honey re-tested after 18 years of storage retained substantial non-peroxide-based activity. Overall, this study highlights the unique properties of stingless bee honeys and their potential as natural antimicrobial agents. IMPORTANCE: Antimicrobial resistance poses a critical global health challenge. Various natural products have evolved as a defense against microbial attack and can be exploited as novel therapeutic agents. While honey from the European honey bee ( Apis mellifera ) is well studied, the medicinal potential of Australian stingless bee honey remains underexplored. This study demonstrates that honeys produced by the stingless bee species Tetragonula carbonaria , Tetragonula hockingsi , and Austroplebeia australis possess unique antimicrobial properties that persist after heat treatment and following long-term storage and are distinct from the antimicrobial properties of honey bee honey. Diverse bioactive compounds, including phenolics and proteins, were seen, underscoring the complexity of these honeys as antimicrobial agents. These honeys have potential as sustainable, natural solutions for combating drug-resistant infections and could extend the scope of honey-based therapeutics.

Baccharis dracunculifolia DC. is a dioecious shrub native to South America and the main botanical source of green propolis, an important commercial and medicinal product produced by Apis mellifera L. This study evaluated the phytochemical composition and antioxidant activity of hydroethanolic extracts and essential oils from male and female plants collected from different populations. This is the first comparative analysis of genders from different populations, focusing on artepillin C, the main compound of industrial interest. Leaf extracts were analyzed by HPLC-DAD and LC-MS, while hydrodistilled essential oils were assessed using GC-FID and GC-MS. Antioxidant activity was measured using DPPH and ABTS assays. A total of 31 compounds were detected in the extracts, with 17 identified. Major constituents included 3,5-di-Ocaffeoylquinic acid , 4,5-di-O-caffeoylquinic acid, and artepillin C. Essential oils were rich in oxygenated sesquiterpenes, monoterpene and sesquiterpene hydrocarbons, with (E)- nerolidol, β-pinene, and limonene as the main volatiles. Male plants exhibited higher levels of non-volatile compounds, greater essential oil content, and stronger antioxidant activity in both extracts and oils. The highest artepillin C concentration was found in male leaves from both studied populations. These findings highlight the influence of gender and environment on the phytochemical profile, reinforcing its potential for highquality natural products.

(1) Background: The oil stability of tree nuts during storage can be influenced by storage conditions such as temperature, humidity, and moisture concentration. However, few studies have assessed how the presence of testa and shell affects the oil stability of tree nuts during storage. We aimed to determine how storage conditions affect oil stability in almond and canarium, in particular, the presence of testa and storage time of nut-in-shell (NIS). (2) Methods: We measured peroxide value (PV), free fatty acid (FFA) and hexanal concentrations of almond and canarium (blanched vs. kernel-in-testa) stored at 45 °C for 24 days. We also measured PV, FFA and fatty acid composition of canarium samples at days 0 and 140 stored as NIS under ambient conditions. (3) Results: The presence of testa in almond and canarium decreased hexanal and PV concentrations at day 24 of incubation. Canarium PV and FFA concentrations increased over 140 days of storage in the shell compared to day 0. However, both PV and FFA concentrations remained within the acceptable threshold during storage. No changes in fatty acid composition were found during NIS storage. (4) Conclusions: Testa and shell could act as a natural coating, slowing down oxidation rates. Hence, long-term storage on nuts in testa or nuts in shell are recommended for tree nuts.

Bioactivity-guided fractionation was used to isolate two compounds, tomentosenol A (1) and torellianone A (2), from a cerumen extract from Tetragonula carbonaria. The anti-fibrotic activity of these compounds was examined using human cultured neonatal foreskin fibroblasts (NFF) and immortalised keratinocytes (HaCaTs). Tomentosenol A (1), inhibited NFF and HaCaT cell proliferation and prevented NFF and HaCaT scratch wound repopulation at 12.5–25 µM concentrations. These inhibitory effects were associated with reduced cell viability, determined by tetrazolium dye (MTT) and sulforhodamine B (SRB) assays. Compound 1 further inhibited transforming growth factor-β₁ (TGF-β₁)-stimulated, NFF-myofibroblast differentiation and soluble collagen production; and was an effective scavenger of the model oxidant, 2,2-diphenyl-1-picrylhydrazyl (DPPH·), with an EC₅₀ value of 44.7 ± 3.1 µM. These findings reveal significant anti-fibrotic potential for cerumen-derived tomentosenol A (1).