Chlorophyll a, the main photosynthetic pigment, serves a dual role in oxygenic photosynthesis: in light harvesting as well as in converting the energy of absorbed photons to chemical energy[1]. Chlorophyll a exhibits both antioxidant and immunostimulatory properties[2]. Chlorophyll a absorbs light most efficiently in the red and blue regions of the spectrum, with peak absorption at around 430 and 662 nanometers, respectively[3].
In vitro, treating 3T3-L1 cells for 48h with chlorophyll a at 0, 5, 10, or 30nM induced cell cycle arrest at the G0/G1 phase and caused a decrease in the S phase in a dose–response manner[4]. Treating HEK293 cells with chlorophyll a (5-20μg/mL) for 30min concentration-dependently inhibited lipopolysaccharide-induced tumor necrosis factor-α gene expression, with almost complete suppression observed at 5μg/mL[5]. Treating C3H10T1/2 cells with 10µg/mL chlorophyll a markedly down-regulated the protein levels of the adipogenic transcription factors CCAAT/enhancer-binding protein alpha (C/EBPα), peroxisome proliferator-activated receptor gamma (PPARγ), and adipocyte protein 2 (aP2)[6].
In vivo, topical pretreatment of BALB/c mice dorsal skin with 50 or 250μg chlorophyll a significantly and dose-dependently reduced both the incidence of tumors and the average number of tumors per mouse[7]. Feeding rats 1.2mmol/kg of natural chlorophyll a for 14 days completely blocked heme-induced increases in colonic cytotoxicity, epithelial hyperproliferation, accelerated epithelial turnover, and lipid-radical formation[8].
References:
[1] Björn LO, Papageorgiou GC, Blankenship RE, Govindjee. A viewpoint: why chlorophyll a?. Photosynth Res. 2009;99(2):85-98.
[2] Yang Z, Li F, Shen S, et al. Natural chlorophyll: a review of analysis methods, health benefits, and stabilization strategies. Crit Rev Food Sci Nutr. 2025;65(16):3069-3083.
[3] Martins T, Barros AN, Rosa E, Antunes L. Enhancing Health Benefits through Chlorophylls and Chlorophyll-Rich Agro-Food: A Comprehensive Review. Molecules. 2023 Jul 11;28(14):5344.
[4] Wu SJ, Ng LT, Wang GH, Huang YJ, Chen JL, Sun FM. Chlorophyll a, an active anti-proliferative compound of Ludwigia octovalvis, activates the CD95 (APO-1/CD95) system and AMPK pathway in 3T3-L1 cells. Food Chem Toxicol. 2010;48(2):716-721.
[5] Subramoniam A, Asha VV, Nair SA, et al. Chlorophyll revisited: anti-inflammatory activities of chlorophyll a and inhibition of expression of TNF-α gene by the same. Inflammation. 2012;35(3):959-966.
[6] Seo YJ, Kim KJ, Choi J, Koh EJ, Lee BY. Spirulina maxima Extract Reduces Obesity through Suppression of Adipogenesis and Activation of Browning in 3T3-L1 Cells and High-Fat Diet-Induced Obese Mice. Nutrients. 2018;10(6):712.
[7] Higashi-Okai K, Okai Y. Potent suppressive activity of chlorophyll a and b from green tea (Camellia sinensis) against tumor promotion in mouse skin. J UOEH. 1998;20(3):181-188.
[8] de Vogel J, Jonker-Termont DS, Katan MB, van der Meer R. Natural chlorophyll but not chlorophyllin prevents heme-induced cytotoxic and hyperproliferative effects in rat colon. J Nutr. 2005;135(8):1995-2000.