
Gold-bloom, Marigold, Marybud, Pot Marigold
Extracted from the flower of the marigold plant, calendula is used topically for wound healing (1). Major constituents of the leaves and stems of the plant include lutein and beta-carotene (2). Extracts from calendula demonstrated anti-inflammatory properties (3), which may improve wound healing (4), and antibacterial, antiparasitic (5), anti-HIV (6), cytotoxic and anti-tumor effects (9) (10) both in vitro and in vivo. Further, studies done in mice indicate hepato-, reno- (14), photo- (15), and cardioprotective (16) properties.
An herbal formulation containing calendula was found effective in reducing earache in children with acute otitis media (7) (8).
Topical application of a calendula cream was shown safe and effective in infants as well for treating diaper dermatitis (21).
Preliminary data support use of topical calendula for prophylaxis of acute dermatitis during radiation therapy (11) (13); and a mouthwash containing calendula against chemotherapy-induced stomatitis (17). More research is needed.
The triterpenoids from calendula have been shown to have anti-inflammatory (3) and anti-HIV (6)effects, and a calendula extract suppressed cell fusion, which may inhibit early events in the HIV replication cycle (6). The most active triterpenoid is a monoester of faradiol (1). Calendula also exhibits hepato- and reno-protective effects which are likely due to its antioxidant activity (14). The photoprotective effect of topical gel formulations of calendula is thought to be associated with an improvement in collagen synthesis in the sub-epidermal connective tissue (15). Calendula also affords cardioprotection which involves modulating the antioxidant and anti-inflammatory pathways by activation of Akt (a serine/threonine protein kinase) and Bcl2 (a protein that regulates apoptosis) and down regulation of tumor necrosis factor (TNF alpha) (16). In another study, calendula was shown to inhibit human gingival fibroblast-mediated degradation of collagen and matrix metalloprotease (MMP-2) activity (18).
In a recent study, the essential oil from calendula flowers was shown to have sun protection activity (19)
Application of a cream containing essential oil of calendula prevented UV-B-induced alterations in the skin in a study of rats (20). Calendula extract also accelerated healing of experimentally-induced thermal burns in rats by increasing collagen-hydroxyproline and hexosamine, bio-indicators of wound healing(4).
Calendula should be avoided during pregnancy and lactation because safety data are lacking (1).
Pommier P, et al. Phase III Randomized Trial of Calendula Officinalis Compared With Trolamine for the Prevention of Acute Dermatitis During Irradiation for Breast Cancer. J Clin Oncol 2004;22:1447-53.
Two hundred fifty-four patients who underwent surgery for breast cancer were randomized to receive either calendula or trolamine, a routine treatment for topical application during postoperative radiation therapy. Occurrence of grade 2 or higher acute dermatitis was significantly lower in patients who used calendula compared to those who used trolamine.
Due to differences in texture, color, and smell, the trial was single-blinded. Well-designed studies are needed to confirm the beneficial effects of calendula.
Bottom Line: Topical application of calendula may reduce painful swelling and irritation associated with radiation therapy. It has not been shown to treat cancer.
Naturally occurring chemicals derived from the marigold plant have been shown to reduce inflammation in laboratory studies. These chemicals, which are called triterpenoids, also inhibit HIV virus and some tumors. When applied to the skin, extracts of calendula help to heal wounds and inflammation after radiation therapy. More research is needed.
Radiation Therapy Associated Dermatitis
Two hundred fifty-four breast cancer patients undergoing radiation therapy participated in a trial of Calendula to see if it would reduce skin inflammation due to radiation therapy. The patients were randomly assigned to receive a topical ointment containing either Calendula or trolamine. Trolamine is a standard treatment for skin inflammation. Subjects who used calendula had fewer cases of severe skin inflammation. Because the texture, color, and smell of the two ointments were quite different, patients knew which treatment they were receiving but researchers did not know which treatment they had received. This study suggests that calendula ointment may be used as a preventive treatment for skin inflammation due to radiation therapy.