Deodorants and antiperspirants: identification of new strategies and perspectives to prevent and control malodor and sweat of the body

Deodorants and antiperspirants: New trends in their active agents and testing methods

Sweating is the human body's thermoregulation system but also results in unpleasant body odour which can diminish the self-confidence of people. There has been continued research in finding solutions to reduce both sweating and body odour. Sweating is a result of increased sweat flow and malodour results from certain bacteria and ecological factors such as eating habits. Research on deodorant development focuses on inhibiting the growth of malodour-forming bacteria using antimicrobial agents, whereas research on antiperspirant synthesis focuses on technologies reducing the sweat flow, which not only reduces body odour but also improves people's appearance. Antiperspirant's technology is based on the use of aluminium salts which can form a gel plug at sweat pores, obstructing the sweat fluid from arising onto the skin surface. In this paper, we perform a systematic review on the recent progress in the development of novel antiperspirant and deodorant active ingredients that are alcohol-free, paraben-free, and naturally derived. Several studies have been reported on the alternative class of actives that can potentially be used for antiperspirant and body odour treatment including deodorizing fabric, bacterial, and plant extracts. However, a significant challenge is to understand how the gel-plugs of antiperspirant actives are formed in sweat pores and how to deliver long-lasting antiperspirant and deodorant benefits.

Antimicrobial Effects of Tetraspanin CD9 Peptide against Microbiota Causing Armpit Malodour

Synthetic peptides, including tetraspanin CD9 peptides, are increasingly coming into focus as new treatment strategies against various organisms, including bacteria, that cause underarm odour. The use of deodorants and antiperspirants is associated with side effects. Therefore, it is critical to find an alternative therapeutic approach to combat underarm odour. The aim of this study is to investigate the antibacterial effect of tetraspanin CD9 peptides against the skin microbiota that cause malodour in the underarms. The antimicrobial activity of CD9 peptides against Micrococcus luteus (M. luteus), Bacillus subtilis (B. subtilis), Staphylococcus epidermidis (S. epidermidis), and Corynebacterium xerosis (C. xerosis) was investigated by the disc diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by broth microdilution assays using CD9 peptide concentrations ranging from 1 mg/mL to 0.0078 mg/mL. In addition, the anti-biofilm activity of the CD9 peptides was determined. The CD9 peptides showed different antibacterial activity with an inhibition zone of 7.67, 9.67, 7.00, and 6.00 mm for S. epidermidis, M. luteus, C. xerosis, and B. subtilis, respectively. All bacteria had the same MBC value of 1 mg/mL. A high MIC of CD9 peptides was observed for S. epidermidis and M. luteus at 0.5 mg/mL. The MIC values of B. subtilis and C. xerosis were 0.125 mg/mL and 0.25 mg/mL, respectively. CD9 peptides significantly inhibited biofilm development of S. epidermidis, B. subtilis, and C. xerosis isolates. The CD9 tetraspanin peptide has excellent antibacterial activity against bacteria that cause underarm odour. Therefore, the CD9 tetraspanin peptide is a promising alternative to deodorants and antiperspirants to combat commensal bacteria of the skin that cause underarm odour.

Long-Term Use of Antiperspirant is Associated with a Low Risk of Postoperative Complications in Patients with Axillary Osmidrosis

Purpose

Many patients with axillary osmidrosis (AO) cannot tolerate the local irritation of strong antiperspirants and discontinue AO use within a short time. This study evaluates the effect of long-term antiperspirant use on postoperative complications after osmidrosis surgery.

Patients and Methods

A total of 116 females (66 antiperspirant and 50 non-antiperspirant cases) who underwent osmidrosis surgery were retrospectively reviewed. Postoperative complications were compared between the 2 groups.

Results

Patients with long-term antiperspirant use had a lower risk of full-thickness skin necrosis compared with those who did not use antiperspirants (odds ratio [OR] = 0.048, 95% confidence Interval [CI]: 0.006–0.392, p = 0.005). Patients with antiperspirants use also had a lower risk of moderate-to-severe erythema compared to those without antiperspirants use (moderate vs mild erythema: OR = 0.351, 95% CI: 0.129–0.959, p = 0.041; severe vs mild erythema: OR = 0.161, 95% CI: 0.047–0.550, p = 0.004). Patients who used antiperspirants also had a lower risk of severe skin erosion compared to those who did not use antiperspirants (severe vs mild skin erosion: OR = 0.164, 95% CI: 0.037–0.725, p = 0.017). There was a trend of lower risk in moderate skin erosion in patients with antiperspirant use compared to those without antiperspirant use, but it was not statistically significant (moderate vs mild epidermal damage and peeling: OR = 0.406, 95% CI: 0.158–1.043, p = 0.061).

Conclusion

Postoperative complications in patients with AO who undergo osmidrosis surgery are lower in those with a long-term antiperspirant use compared to patients who did not use antiperspirants.

Do you often sniff yourself or others? Development of the Body Odor Sniffing Questionnaire and a cross-cultural survey in China and the USA

OBJECTIVES

Body odor can convey much information about an individual and thus we frequently engage in sniffing one's own and other people's body odor. However, there is scarce evidence on the within- and cross-cultural variation in body odor sniffing behaviors and no psychometric scale for specifically measuring such behaviors. Hence, our study aimed to develop the Body Odor Sniffing Questionnaire (BOSQ) and used it to make a cross-cultural comparison.

METHODS

In Study 1, 2,026 participants were recruited from our university, with one half used for exploratory factor analysis (EFA) to examine the factor structure of the BOSQ (sample 1) and the other half used for confirmatory factor analysis (CFA) to verify the factor structure (sample 2). In Study 2, 352 Chinese and 254 US participants were recruited to complete the BOSQ through Wenjuanxing and Amazon Mechanical Turk, enabling comparison of body odor sniffing behaviors across two cultures.

RESULTS

The Study 1 results showed that the BOSQ comprises 17 items in three factors: self-private body odor, others' body odor, and self-common body odor. The CFA results further supported that this three-factor model was a good fit. The Study 2 results showed that US participants scored higher overall and on the self-private body odor and others' body odor dimensions, whereas Chinese participants scored higher on the self-common body odor dimension.

CONCLUSIONS

The BOSQ demonstrated good reliability and validity, which is a useful tool for evaluating individuals' body odor sniffing behaviors. Cross-cultural difference existed as the US population reported a higher prevalence of body odor sniffing behavior, compared to the Chinese population.

An In Vitro HL-1 Cardiomyocyte-Based Olfactory Biosensor for Olfr558-Inhibited Efficiency Detection

Some short-chain fatty acids with a pungent or unpleasant odor are important components of human body odor. These malodors severely threaten human health. The antagonists of malodors would help to improve odor perception by affecting the interaction between odors and their receptors. However, the traditional odor detection and analysis methods, such as MOS, electrochemical, conductive polymer gas sensors, or chromatography-mass spectrometry are not suitable for screening the antagonists since they are unable to detect the ligand efficacy after odor-receptor binding. In this study, RT-PCR results showed that HL-1 cardiomyocytes endogenously express the olfactory receptor 558 (Olfr558) which can be activated by several malodorous short-chain fatty acids. Therefore, an in vitro HL-1 cardiomyocyte-based olfactory biosensor (HCBO-biosensor) was developed by combining cardiomyocytes and microelectrode array (MEA) chips for screening the potential antagonists of the Olfr558. Firstly, it showed that the biosensor specifically responded to ligands of Olfr558 through odor stimulation experiments. Then, an odor response model of HL-1 cardiomyocytes was constructed by a ligand of Olfr558 (isovaleric acid). The response feature of the in vitro HCBO-biosensor to individual odors and mixtures with a potential antagonist (citral or β-damascenone) were extracted and compared. Finally, the Olfr558-inhibited efficiency was indirectly detected by comparing the half-maximal inhibitory concentration of isovaleric acid. The results showed that β-damascenone greatly inhibited Olfr558 while citral showed no significant inhibitory effect. In conclusion, we built a novel screening method for the antagonists of Olfr558 based on HL-1 cardiomyocytes and the MEA chip which will assist odor-related companies to develop novel antagonists of Olfr558.