What are the biological effects and delivery systems of capsaicin?
Introduction
Chili is famous for its spicy flavor and is one of the most commonly consumed spices in the world. Capsaicin (trans-8-methyl-Nvanilloyl-6-nonenamide, CAP) is the main biological compound in chili peppers, synthesized by capsaicin synthase in the placental tissue of chili fruit through the reaction of vanillin and branched chain fatty acids. In addition to CAP, many naturally occurring capsaicin compounds have also been found in chili peppers, including dihydrocapsaicin (8-methyl-N-vanillide), demethyldihydrocapsaicin (7-methyl-N-vanillide), high dihydrocapsaicin (trans-9-methyl-Nvanillide), and high capsaicin (9-methyl-N-vanillide). Among them, CAP and dihydrocapsaicin are considered the most important spicy ingredients, accounting for about 80% to 90% of the total capsaicin content, and can stimulate taste and nerves up to twice as much as a small amount of capsaicin.
CAP has traditionally been used as an analgesic for local treatment of muscle, joint, and neuropathic pain, acting by binding to the transient receptor - potential vanillin 1 (TRPV1) receptor located on neurotransmitter neurons in the peripheral nervous system. CAP has beneficial effects such as antioxidant, antimicrobial, anti-inflammatory, anti-cancer, anticancer, anti-tumor, anti obesity, heart and stomach protection, and metabolic regulation. A recent study suggests that CAP can regulate the circadian rhythm dysregulation of HepG2 cells. In this review, the beneficial biological functions and basic mechanisms of CAP were studied and discussed, and various dietary CAP delivery systems were evaluated based on their stability, loading efficiency, controlled release profile, and bioavailability.
Biological Efficacy of Capsaicin
Analgesic effect: analgesic effect
CAP is usually used as external medicine to treat chronic pain such as osteoarthritis, rheumatoid arthritis, diabetes neuropathy, non diabetes neuropathy and post herpetic neuralgia. Mechanism studies have shown that CAP can selectively bind to TRPV1, a cation channel with high permeability to Ca2+that can detect potential harmful stimuli. After exposure to CAP, TRPV1 receptors are desensitized, leading to a decrease in receptor function, which is also the reason for CAP induced analgesia. In addition, CAP can activate TRPV1 receptors, increase intracellular Ca2+levels, and release inflammatory neuropeptides (substance P). Through this calcium dependent process, substance P is completely consumed, and primary afferent fibers become desensitized or even damaged to further pain stimuli (including thermal, mechanical, and chemical toxic stimuli), thereby achieving analgesic effects.
Anti cancer effect
According to various studies, CAP has shown anti-cancer effects in various types of human cancers, such as gastric cancer, breast cancer, lung cancer, prostate cancer, colorectal cancer, pancreatic cancer, etc. CAP can regulate the expression levels of genes and enzymes involved in cancer cell proliferation, cell cycle arrest, signal transduction, apoptosis, and metastasis, thereby exhibiting significant anti-tumor activity.
CAP anti-cancer mechanism
Research has shown that CAP can inhibit fat production and increase lipid oxidation within adipocytes; By acting on gastrin, regulating hypothalamic satiety and suppressing appetite; Prevent weight gain by upregulating UCP2 and UCP3; By regulating the gut microbiota, heat production is enhanced and metabolic balance is maintained.
The anti obesity effect and potential mechanism of CAP
Circadian modulation effect day night regulatory effect
Circadian rhythm exists in almost all organisms. The disorder of circadian rhythm will lead to the occurrence of metabolic syndrome, including hypertension, hyperlipidemia, insulin resistance, atherosclerosis, etc. The central circadian rhythm is composed of multiple circadian oscillators, including two activators (CLOCK and BMAL1) and two inhibitors (PER and CRY), as well as other kinases and phosphatases. Plant hormones play an important role in regulating the circadian rhythm clock.
The improvement effect of CAP on circadian rhythm disorder in HepG2 cells
A new CAP drug delivery system with higher bioavailability
Summary
As an analgesic, CAP has been widely used in ointments, gel and patches to relieve pain. Clinical studies have reported many beneficial biological characteristics of CAP, including antioxidant, anti-inflammatory, anticancer, anti obesity, heart protecting, and circadian rhythm regulating effects. However, due to the short half-life, poor water solubility, low bioavailability, and strong burning sensation in the mouth and stomach caused by the spiciness of plasma, its clinical application has been adversely affected. In order to improve the oral bioavailability of CAP and alleviate irritation to the gastrointestinal mucosa, many strategies have been developed, including liposomes, nanoemulsions, and nanoparticles. These drug delivery systems have multiple advantages. Firstly, the stability, loading capacity, and encapsulation efficiency of CAP in these formulations are high, which improves their biocompatibility and oral bioavailability. Secondly, nanoscale capsules, particles, or droplets can reduce or even eliminate the sudden release of CAP and provide sustained release characteristics, extending the retention time of CAP in the digestive tract. In addition, the use of wall materials prevents large CAP crystals from directly contacting the surface of the gastric mucosa, reducing irritation to the gastric mucosa. In summary, by reviewing the biological efficacy and encapsulation methods of CAP, a theoretical basis is provided for the further development of CAP as a highly promising multifunctional food ingredient in nutritional supplements.
anna@hihealthbio.com