Chemical diversity of kānuka: Inter- and intraspecific variation of foliage terpenes and flavanones of Kunzea (Myrtaceae) in Aotearoa/New Zealand

Kunzea (Myrtaceae) trees and shrubs, generally called kānuka, grow across most of Aotearoa/New Zealand (NZ). With the exception of K. sinclairii, an offshore island endemic, kānuka had been treated as an Australasian species K. ericoides. However, a 2014 taxonomic revision recognized ten species, all endemic to NZ. Kānuka chemistry is less studied than that of its closest relative in NZ, mānuka (Leptospermum scoparium), which shows very distinct regional foliage chemotypes. We have used a miniaturized method with GC and ¹H NMR to analyze foliage chemistry of voucher specimens from across the geographic ranges of the ten NZ Kunzea species. We found common mono- and sesquiterpenes, with α-pinene dominant in all samples, but only traces of antimicrobial triketones. Two unusual flavanones, with unsubstituted B-rings and known bioactivity against Phytophthora, did distinguish some of the samples. 5,7-Dihydroxy-6,8-dimethyl flavanone was only found at high concentrations in the three K. sinclairii samples in this study's sample set, but this compound has separately been reported in K. robusta samples from a nearby region. Therefore none of the NZ Kunzea species was distinguished by the chemistry analyzed in this study, but there is a possibility of regional flavonoid chemotypes cutting across the species boundaries.

Resistance of New Zealand Provenance Leptospermum scoparium, Kunzea robusta, Kunzea linearis, and Metrosideros excelsa to Austropuccinia psidii

Resistance to the pandemic strain of Austropuccinia psidii was identified in New Zealand provenance Leptospermum scoparium, Kunzea robusta, and K. linearis plants. Only 1 Metrosideros excelsa-resistant plant was found (of the 570 tested) and no resistant plants of either Lophomyrtus bullata or L. obcordata were found. Three types of resistance were identified in Leptospermum scoparium. The first two, a putative immune response and a hypersensitive response, are leaf resistance mechanisms found in other myrtaceous species while on the lateral and main stems a putative immune stem resistance was also observed. Both leaf and stem infection were found on K. robusta and K. linearis plants as well as branch tip dieback that developed on almost 50% of the plants. L. scoparium, K. robusta, and K. linearis are the first myrtaceous species where consistent infection of stems has been observed in artificial inoculation trials. This new finding and the first observation of significant branch tip dieback of plants of the two Kunzea spp. resulted in the development of two new myrtle rust disease severity assessment scales. Significant seed family and provenance effects were found in L. scoparium, K. robusta, and K. linearis: some families produced significantly more plants with leaf, stem, and (in Kunzea spp.) branch tip dieback resistance, and provenances provided different percentages of resistant families and plants. The distribution of the disease symptoms on plants from the same seed family, and between plants from different seed families, suggested that the leaf, stem, and branch tip dieback resistances were the result of independent disease resistance mechanisms.

Kanuka honey versus aciclovir for the topical treatment of herpes simplex labialis: a randomised controlled trial

OBJECTIVE

To compare New Zealand medical grade kanuka honey with topical aciclovir for the treatment of herpes simplex labialis.

DESIGN

Prospective parallel randomised controlled open-label superiority trial.

SETTING

76 community pharmacies across New Zealand between 10 September 2015 and 13 December 2017.

PARTICIPANTS

952 adults randomised within the first 72 hours of a herpes simplex labialis episode.

INTERVENTIONS

Random assignment 1:1 to either 5% aciclovir cream or medical grade kanuka honey (90%)/glycerine (10%) cream, both applied five times daily.

OUTCOME MEASURES

The primary outcome was time from randomisation to return to normal skin (stage 7). Secondary outcomes included time from randomisation to stage 4 (open wound), time from stage 4 to 7, maximal pain, time to pain resolution and treatment acceptability.

RESULTS

Primary outcome variable: Kaplan-Meier-based estimates (95% CI) for the median time in days for return to normal skin were 8 (8 to 9) days for aciclovir and 9 (8 to 9) for honey; HR (95% CI) 1.06 (0.92 to 1.22), p=0.56. There were no statistically significant differences between treatments for all secondary outcome variables. No related serious adverse events were reported.

CONCLUSION

There was no evidence of a difference in efficacy between topical medical grade kanuka honey and 5% aciclovir in the pharmacy-based treatment of herpes simplex labialis.

TRIAL REGISTRATION NUMBER

ACTRN12615000648527;Post-results.

Protocol for a randomised controlled trial of 90% kanuka honey versus 5% aciclovir for the treatment of herpes simplex labialis in the community setting

INTRODUCTION

Worldwide, about 90% of people are infected with the herpes simplex virus, 30% of whom will experience recurrent herpes simplex labialis, commonly referred to as 'cold sores', which can last up to 10 days. The most common treatment is aciclovir cream which reduces healing time by just half a day compared with no specific treatment. This is a protocol for a randomised controlled trial (RCT) to determine the efficacy of medical grade kanuka honey-based topical treatment (Honevo) in reducing the healing time and pain of cold sores, compared with topical aciclovir treatment (Viraban).

METHODS AND ANALYSIS

This open-label, parallel-group, active comparator superiority RCT will compare the efficacy of medical grade kanuka honey with 5% aciclovir cream in the treatment of cold sores in the setting of a pharmacy research network of 60 sites throughout New Zealand. Adults presenting with a cold sore (N=950) will be randomised by pharmacy-based investigators. The pharmacy-based investigators will dispense the investigational product to randomised participants and both study groups apply the treatment five times daily until their skin returns to normal or for 14 days, whichever occurs first. In response to a daily SMS message, participants complete an assessment of their cold sore healing, with reference to a visual guide, and transmit it to the investigators by a smartphone eDiary in real time. The primary outcome variable is time (in days) from randomisation to return to normal skin. Secondary endpoints include total healing time stratified by stage of the lesion at onset of treatment, highest pain severity and time to pain resolution.

ETHICS AND DISSEMINATION

New Zealand Ethics Registration 15/NTB/93. Results will be published in a peer-reviewed medical journal, presented at academic meetings and reported to participants.

TRIAL REGISTRATION NUMBER

Australia New Zealand Clinical Trials Registry: ACTRN12615000648527, pre-results.SCOTT Registration: 15/SCOTT/14 PROTOCOL VERSION: 4.0 (12 June 2017).

Randomised controlled trial of topical kanuka honey for the treatment of acne

OBJECTIVE

To investigate the efficacy of Honevo, a topical 90% medical-grade kanuka honey, and 10% glycerine (honey product) as a treatment for facial acne.

DESIGN

Randomised controlled trial with single blind assessment of primary outcome variable.

SETTING

Outpatient primary care from 3 New Zealand localities.

PARTICIPANTS

Of 136 participants aged between 16 and 40 years with a diagnosis of acne and baseline Investigator's Global Assessment (IGA) for acne score of ≥ 2.68, participants were randomised to each treatment arm.

INTERVENTIONS

All participants applied Protex, a triclocarban-based antibacterial soap twice daily for 12 weeks. Participants randomised to the honey product treatment arm applied this directly after washing off the antibacterial soap, twice daily for 12 weeks.

OUTCOME MEASURES

The primary outcome was ≥ 2 point decrease in IGA score from baseline at 12 weeks. Secondary outcomes included mean lesion counts and changes in subject-rated acne improvement and severity at weeks 4 and 12, and withdrawals for worsening acne.

RESULTS

4/53 (7.6%) participants in the honey product group and 1/53 (1.9%) of participants in the control group had a ≥ 2 improvement in IGA score at week 12, compared with baseline, OR (95% CI) for improvement 4.2 (0.5 to 39.3), p=0.17. There were 15 and 14 participants who withdrew from the honey product group and control group, respectively.

CONCLUSIONS

This randomised controlled trial did not find evidence that addition of medical-grade kanuka honey in combination with 10% glycerine to standard antibacterial soap treatment is more effective than the use of antibacterial soap alone in the treatment of acne.

TRIAL REGISTRATION NUMBER

ACTRN12614000003673; Results.

Fluorescence markers in some New Zealand honeys

The fluorescence characteristics of various New Zealand honeys were investigated to establish if this technique might detect signatures unique to manuka (Leptospermum scoparium) and kanuka (Kunzea ericoides) honeys. We found unique fluorescence profiles for these honeys which distinguished them from other New Zealand honey floral types. Two excitation-emission (ex-em) marker wavelengths each for manuka and kanuka honeys were identified; manuka honey at 270-365 (MM1) and 330-470 (MM2) nm and kanuka honey at 275-305 (KM1) and 445-525 (KM2) nm. Dilution of manuka and kanuka honeys with other honey types that did not possess these fluorescence profiles resulted in a proportional reduction in fluorescence signal of the honeys at the marker wavelengths. By comparison, rewarewa (Knightia excelsa), kamahi (Weinmannia racemosa), and clover (Trifolium spp.) honeys did not exhibit unique fluorescence patterns. These findings suggests that a fluorescence-based screening approach has potential utility for determining the monoflorality status of manuka and kanuka honeys.

Randomised controlled trial of topical kanuka honey for the treatment of rosacea

OBJECTIVE

To investigate the efficacy of topical 90% medical-grade kanuka honey and 10% glycerine (Honevo) as a treatment for rosacea.

DESIGN

Randomised controlled trial with blinded assessment of primary outcome variable.

SETTING

Outpatient primary healthcare population from 5 New Zealand sites.

PARTICIPANTS

138 adults aged ≥ 16, with a diagnosis of rosacea, and a baseline blinded Investigator Global Assessment of Rosacea Severity Score (IGA-RSS) of ≥ 2. 69 participants were randomised to each treatment arm. 1 participant was excluded from the Honevo group, and 7 and 15 participants withdrew from the Honevo and control groups, respectively.

INTERVENTIONS

Participants were randomly allocated 1:1 to Honevo or control cream (Cetomacrogol), applied twice daily for 8 weeks.

MAIN OUTCOME MEASURES

The primary outcome measure was the proportion of participants who had a ≥ 2 improvement in the 7-point IGA-RSS at week 8 compared to baseline. Secondary outcomes included change in IGA-RSS and subject-rated visual analogue score of change in severity (VAS-CS) on a 100 mm scale (0 mm 'much worse', 100 mm 'much improved') at weeks 2 and 8.

RESULTS

24/68 (34.3%) in the Honevo group and 12/69 (17.4%) in the control group had a ≥ 2 improvement in IGA-RSS at week 8 compared to baseline (relative risk 2.03; 95% CI 1.11 to 3.72, p=0.020). The change in IGA-RSS for Honevo compared to control at week 2 minus baseline was -1 (Hodges-Lehman estimate, 95% CI -1 to 0, p=0.03), and at week 8 minus baseline was -1 (Hodges-Lehman estimate, 95% CI -1 to 0, p=0.005). The VAS-CS at week 2 was 9.1 (95% CI 3.5 to 14.7), p=0.002, and at week 8 was 12.3 (95% CI 5.7 to 18.9)¸ p<0.001 for Honevo compared to control.

CONCLUSIONS

Honevo is an effective treatment for rosacea.

TRIAL REGISTRATION NUMBER

This trial was registered in the Australian and New Zealand Clinical Trials Registry ACTRN12614000004662.

The effect of New Zealand kanuka, manuka and clover honeys on bacterial growth dynamics and cellular morphology varies according to the species

Treatment of chronic wounds is becoming increasingly difficult due to antibiotic resistance. Complex natural products with antimicrobial activity, such as honey, are now under the spotlight as alternative treatments to antibiotics. Several studies have shown honey to have broad-spectrum antibacterial activity at concentrations present in honey dressings, and resistance to honey has not been attainable in the laboratory. However not all honeys are the same and few studies have used honey that is well defined both in geographic and chemical terms. Here we have used a range of concentrations of clover honey and a suite of manuka and kanuka honeys from known geographical locations, and for which the floral source and concentration of methylglyoxal and hydrogen peroxide potential were defined, to determine their effect on growth and cellular morphology of four bacteria: Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. While the general trend in effectiveness of growth inhibition was manuka>manuka-kanuka blend>kanuka>clover, the honeys had varying and diverse effects on the growth and cellular morphology of each bacterium, and each organism had a unique response profile to these honeys. P. aeruginosa showed a markedly different pattern of growth inhibition to the other three organisms when treated with sub-inhibitory concentrations of honey, being equally sensitive to all honeys, including clover, and the least sensitive to honey overall. While hydrogen peroxide potential contributed to the antibacterial activity of the manuka and kanuka honeys, it was never essential for complete growth inhibition. Cell morphology analysis also showed a varied and diverse set of responses to the honeys that included cell length changes, cell lysis, and alterations to DNA appearance. These changes are likely to reflect the different regulatory circuits of the organisms that are activated by the stress of honey treatment.

microflora and other hydrothermal vegetation at the Wairakei-Tauhara geothermal field, New Zealand

Hydrothermal ecosystems are of high conservation and scientific value, but they are sensitive to external perturbations that result from development. This study examines the composition of vegetation at four plots at the Wairakei-Tauhara geothermal field, New Zealand, using the Scott height-frequency method, ground temperatures at 0.1- and 1-m depth, soil pH, and photographic surveys. It highlights the response of plant communities, in particular that of Kunzea ericoides var. microflora, in terms of composition, structure, and biomass index values, measures changes in ground temperature, as well as provides baseline data against which to compare future changes. It was found that optimal growing conditions for K. ericoides var. microflora are at temperatures above background conditions with a slightly acidic pH. Plots with cooler, less acidic conditions support more diverse plant communities, which also promote the establishment of invasive species. This suggests that the largest threats to thermotolerant vegetation in New Zealand, including K. ericoides var. microflora, are further decreases in ground temperature because the establishment of invasive species may result in thermolerant vegetation being out-competed in hydrothermal ecosystems. Recognising and understanding the ecological diversity and dynamics of hydrothermal ecosystems, as well as acknowledging the competing interests between development and conservation, is key to the management and protection of these areas.