Capsaicin ((E)-Capsaicin) is a natural product extracted from Capsicum annuum, and is a TRPV1 agonist (EC50=0.29 μM). Capsaicin has antitumor, anti-inflammatory, antioxidant and neuroprotective activities.

METHODS: Human pharyngeal squamous carcinoma cells FaDu were treated with Capsaicin (50-300 µM) for 24-72 h. Cell viability was assayed using MTT Assay.
RESULTS: As the dose of Capsaicin increased, a decrease in enhanced cell growth was shown. Percentage of viable cells decreased with increase in incubation time. The IC50 value was about 150 µM. [1]
METHODS: Human oral epidermoid carcinoma cells KB were treated with Capsaicin (150-250 µM) for 24-48 h. Apoptosis was detected using Hoechst staining.
RESULTS: Capsaicin induced apoptosis in KB cells. [2]

METHODS: To investigate the effects on thermoregulation and locomotor activity, Capsaicin (10-20 mg/kg, saline+3% ethanol+10% Tween 80) was administered by single gavage to C57BL/6J mice with WT and TRPV1 KO.
RESULTS: Oral administration of capsaicin resulted in a long-term increase in TRPV1-dependent acute hypothermia and TRPV1-independent locomotor activity, in addition to activation of brain circuits controlling thermoregulation and metabolism. [3]
METHODS: To assay neuroprotective activity, Capsaicin (5-20 mg/kg) was administered orally to mice given scopolamine once daily for seven days.
RESULTS: Capsaicin exerted empirical neuroprotective effects through restoration of mitochondrial function, antioxidant effects and modulation of pro-inflammatory cytokines. A 10 mg/kg dose of Capsaicin for seven consecutive days was the most effective dose. [4]

Capsaicin is dissolved in DMSO and stored, and then diluted with appropriate medium before use[3]. FaDu cells are plated at a density of 1×105 cells/well on 24-well plate. After overnight growth, the cells are treated with various concentrations of Capsaicin (0 μM, 50 μM, 100 μM, 150 μM, 200 μM, 250 μM, 300 μM, and 350 μM) for 24, 48 and 72 hours, with medium replacement every 24 hours. At the end of treatment, 30 μL of the tetrazolium compound MTT, and 270 μL of fresh medium are added. After further incubation for 4 hours at 37°C, 200 μL of 0.1 N HCl in 10% SDS is added into each well to dissolve the tetrazolium crystals. Finally, the absorbance at a wavelength of 540 nm is recorded using an ELISA plate reader[3].