Antibacterial oral sprays from kaffir lime (Citrus hystrix DC.) fruit peel oil and leaf oil and their activities against respiratory tract pathogens

Background and aim

Kaffir lime fruit peel oil and Kaffir lime leaf oil have been reported for their activities against respiratory tract pathogens. The purpose of the study was to develop clear oral sprays to be used as a first-defense oral spray.

Experimental procedure

Clear antibacterial oral sprays were prepared and analyzed for their respective active major compounds, using GC-MS. The sprays were tested against a Gr. A streptococcal clinical isolate and 3 standard respiratory tract pathogens, using Broth microdilution method. A 4-month stability test was carried out as well.

Results and conclusion

Six clear oral sprays, three formulae composed of Kaffir lime fruit peel oil (6, 10, 13%v/v KLO) and the other three formulae containing Kaffir lime leaf oil (4, 8, 12%v/v KLLO), were developed. The active compounds in KLO were α-terpineol and terpinene-4-ol whereas that in KLLO was citronellal. All oral sprays exhibited antibacterial activity against one Group A streptococcal clinical isolate and three respiratory pathogenic pathogens, Staphylococcus aureus ATCC 29213, Streptococcus pneumoniae ATCC 49619, and Haemophilus influenzae ATCC 49247, among which the strongest activity was against H. influenzae ATCC 49247. The antibacterial activity of all oral sprays remained unchanged in an accelerated stability test, at 4, 30, and 45 °C under 75% relative humidity, throughout the 4-month storage.

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Clear antibacterial oral sprays were prepared.

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Active major compounds were alpha-terpineol, terpinene-4-ol, and citronellal.

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The sprays showed strongest activities against Haemophilus influenzae ATCC 49247.

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The antibacterial activity was shown throughout 4-month storage.

Decreasing ten-year (2008-2018) trends of the prevalence of childhood asthma and air pollution in Southern Taiwan

Background

Asthma is a common pediatric chronic respiratory disease worldwide. Previous studies showed the prevalence of childhood asthma increased in developed countries as well as in Taiwan in the late 20th century. Recently, several reports from different parts of the world showed a reversed trend in this epidemic of childhood asthma prevalence. This study investigated the trend of childhood asthma through serial cross-section questionnaire surveys in the southern part of Taiwan, and identified associated factors related to this trend in elementary school children.

Methods

We used the Chinese version of the International Study of Asthma and Allergies in Childhood (ISAAC)²⁹ questionnaire to assess the asthma status of elementary school students aged 6–12 years in Tainan city in 3 independent study periods, namely, 2008–2009, 2010–2012, and 2017–2018. We assessed the trend of “asthma” and “related respiratory symptoms” across 3 study periods.

Results

Of the 19,633 respondents, 17,545 (89.4%) completed the questionnaires. After adjustment for covariates, the prevalence of asthma and related respiratory symptoms was significantly lower in 2017–2018 than in the 2 earlier periods. Among the protective factors, the increasing rate of breastfeeding might be partly responsible for the observed reduced prevalence of current asthma and exercise-induced wheeze, but not physician-diagnosed asthma. The presence of pets in the house was the risk factor that correlated with the prevalence of nocturnal cough. Pearson correlation analysis showed a significant correlation of the prevalence of physician-diagnosed asthma, current asthma, and exercise-induced wheezing with the concentrations of air pollutant particles with aerodynamic diameter ≤10 μM (PM₁₀) (r = 0.84, 0.77 and 0.81, respectively).

Conclusion

The prevalence of asthma and related respiratory symptoms has declined in elementary school-age children in southern Taiwan. The increased prevalence of breastfeeding, decreased rate of the presence of pets in the house, and improvement in outdoor air pollution seem to be related to this decreasing trend of asthma in school children. Our findings will provide the scientific base to empower prevention policy to reverse the trend of childhood asthma prevalence.

Trial registration

N/A