The role of capsaicin stimulation on the physicochemical properties of saliva and aroma release in model aqueous and oil systems

Capsaicin: Emerging Pharmacological and Therapeutic Insights

Capsaicin, the most prominent pungent compound of chilli peppers, has been used in traditional medicine systems for centuries; it already has a number of established clinical and industrial applications. Capsaicin is known to act through the TRPV1 receptor, which exists in various tissues; capsaicin is hepatically metabolised, having a half-life correlated with the method of application. Research on various applications of capsaicin in different formulations is still ongoing. Thus, local capsaicin applications have a pronounced anti-inflammatory effect, while systemic applications have a multitude of different effects because their increased lipophilic character ensures their augmented bioavailability. Furthermore, various teams have documented capsaicin's anti-cancer effects, proven both in vivo and in vitro designs. A notable constraint in the therapeutic effects of capsaicin is its increased toxicity, especially in sensitive tissues. Regarding the traditional applications of capsaicin, apart from all the effects recorded as medicinal effects, the application of capsaicin in acupuncture points has been demonstrated to be effective and the combination of acupuncture and capsaicin warrants further research. Finally, capsaicin has demonstrated antimicrobial effects, which can supplement its anti-inflammatory and anti-carcinogenic actions.

Time-course of pain and salivary opiorphin release in response to oral capsaicin differ in burning mouth syndrome patients, temporomandibular disorders patients and control subjects

OBJECTIVES

Opiorphin is an analgesic peptide released by salivary glands and capsaicin an agonist of TRPV1 receptors eliciting burning sensations. The primary objective of this study was to assess opiorphin release after stimulation of the tongue by capsaicin (STC). The secondary objectives were to compare opiorphin release after STC in 3 groups of subjects [healthy (CTRL), Burning Mouth Syndrome (BMS), painful Temporomandibular disorders (TMDp)] and pain evoked by STC in these 3 groups.

MATERIALS AND METHODS

Salivary opiorphin was assessed with high-performance liquid chromatography at 3 different time points (baseline, after 5 min and 20 min of STC). Pain was self-reported on a (0-10) numeric rating scale.

RESULTS

Three groups (N = 16) of adults were recruited at the Clinical Hospital Centre and School of Dental Medicine in Zagreb. Opiorphin levels were higher (1) in TMDp compared to CTRL in 1st (2.23 ± 1.72 pg/ul vs. 0.67 ± 0.44 pg/ul, p = 0.002) and 3rd sampling (2.44 ± 2.01 pg/ul vs. 0.74 ± 0.52 pg/ul, p = 0.020) and (2) within BMS group at 3rd sampling vs. baseline (p < 0.025). Pain scores were higher in BMS compared to TMDp (p < 0.025) and CTRL (p < 0.025).

CONCLUSION

This study evidenced (1) a differential basal amount of opiorphin in two pain conditions and control subjects (2) a differential kinetic of release of opiorphin after STC in CTRL, BMS and TMDp (3) a differential pain perception after STC in BMS and TMDp vs. CTRL, which can provide a readout for animal models.

CLINICAL RELEVANCE

The specific regulation of opiorphin release in patients with orofacial painful conditions provides valuable insights for clinicians and researchers in physiology and pathology and encourages further research in this area.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04694274. Registered on 01/05/2021.

The coming future: The role of the oral-microbiota-brain axis in aroma release and perception

The field of aroma release and perception during the oral process has been well studied. However, the traditional approaches have not fully explored the integration of oral biology, microbiology, and neurology to further understand aroma release and perception mechanisms. Herein, to address the existing challenges in this field, we introduce the oral-microbiota-brain axis (OMBA), an innovative framework that encapsulates the interactive relationships among saliva and the oral mucosa, the oral microbiota, and the brain in aroma release and perception. This review introduces the OMBA and highlights its role as a key interface facilitating the sensory experience of aroma. Based on a comprehensive literature survey, the specific roles of the oral mucosa, oral microbiota, saliva, and brain in the OMBA are discussed. This integrated approach reveals the importance of each component and the interconnected relationships within this axis in the overall process of aroma release and perception. Saliva and the oral mucosa play fundamental roles in aroma release and perception; the oral microbiota regulates aroma release and impacts olfactory perception; and the brain's intricate neural circuitry is central to the decoding and interpretation of aroma signals. The components of this axis are interdependent, and imbalances can disrupt aroma perception. The OMBA framework not only enhances our comprehension of aroma release and perception but also paves the way for innovative applications that could heighten sensory experiences.

Antimicrobial Properties of Capsaicin: Available Data and Future Research Perspectives

Capsaicin is a phytochemical derived from plants of the genus Capsicum and subject of intensive phytochemical research due to its numerous physiological and therapeutical effects, including its important antimicrobial properties. Depending on the concentration and the strain of the bacterium, capsaicin can exert either bacteriostatic or even bactericidal effects against a wide range of both Gram-positive and Gram-negative bacteria, while in certain cases it can reduce their pathogenicity by a variety of mechanisms such as mitigating the release of toxins or inhibiting biofilm formation. Likewise, capsaicin has been shown to be effective against fungal pathogens, particularly Candida spp., where it once again interferes with biofilm formation. The parasites Toxoplasma gondi and Trypanosoma cruzi have been found to be susceptible to the action of this compound too while there are also viruses whose invasiveness is significantly dampened by it. Among the most encouraging findings are the prospects for future development, especially using new formulations and drug delivery mechanisms. Finally, the influence of capsaicin in somatostatin and substance P secretion and action, offers an interesting array of possibilities given that these physiologically secreted compounds modulate inflammation and immune response to a significant extent.