Calendula officinalis / Goudsbloem

CALENDULA OFFICINALIS L. / Goudsbloem

Familie: Asteraceae (Compositae) - Samengesteldbloemigen. Naam: Souci (Fr.), Ringelblumen (D.), Marigold (E.). Soorten: Calendula arvensis L. - Akkergoudsbloem, C. officinalis e.a. cultivars. Ecologie: Theofiet (eenjarige plant), geteeld - soms verwilderd. Inheems in Midden-, Oost- en Zuid-Europa. Materia medica, gebruikte delen van CalendulaCalendula flos of Flos sine calycibus, De gehele bloem, de hele bovengrondse bloeiende plant, maar vooral de bloemblaadjes van Calendula of­ficinalis L. en variëteiten Beschrijving: Geel, geel-oranje bloemblaadjes, iets glan­zend, naar lichtgeel verkleurend. Het sterk gekromde zaad mag weinig of niet aanwezig zijn.

Geur: zwak, vreemd.

Smaak: iets bitter en zoutig.

Oogst: Tijdens de bloei.

Import: Vooral uit de landen rond de Middellandse Zee, de Balkan en Egypte

Samenstelling; Inhoudstoffen

** Bitterstoffen o.a.: loliolide (= calendine) zijn sesquiterpeenlactonen (2)

* Flavonoïden o.a. isorhamnetine-glucosiden. In de lintbloemen tot 0,88 %, in de bloembo­dem tot 0,33 % (6)

* Oleanolzuur-glucosiden o.a. calenduloside met hemolytische werking (saponinen)

* Triterpeensaponinen: cytotoxisch, antitumoraal (l7)

* Etherische olie 0,2 % met alfa-cadinol

* Polysacchariden

* Carotenoïden (kleur) 1,50-3 %

Farmacologie, fysiologische werking

** Ontstekingswerend (3, 4, 7)

** Wondgenezend, bevordert de aanmaak van granulaatweefsel

* Emmenagogum, uterustonicum (5)

* Cholagogum

* Hypotensivum door perifere vasodilatatie (Valnet, VanHellemont)

* Werd vroeger veel als antiflogisticum en spasmolyticum gebruikt (obsoleet vlgs. Wichtl)

Indicaties, Medicinaal gebruik

Huid en slijmvliezen (vooral uitwendig)

** Alle verwondingen (eerste hulpmiddel)

** Eczeem. + drainagekruiden, teunisbloemolie

* Lichendermatosen (schimmelinfecties) + teatree e.o

* Huid- en slijmvliesontstekingen vooral van mond- en tandvlees, o.m. aften + Salvia en looistofplanten

* Maagontsteking + Matricaria, Glycyrrhiza

* Veneuze problemen ulcus cruris als zalf + veneuze planten / tromboflebitis als zalf

* Doorligwonden (decubitus) als zalf

Genitaal stelsel

* Dysmenorroe +zie vooral hormonale planten

Kanker

* Vooral van baarmoeder en maag (?)

Ander gebruik

Als sierplant en als afweerplant in de tuin

Als kleurstof voor kaas en andere zuivelgerechten, vroeger als vervanging (vervalsing) van saffraan, geeft zeker niet dezelfde smaak en kleurt ook niet goed. Wel te gebruiken als versiering van salades

Of om kruidenzeepjes te maken

Receptuur en gereidingswijzen

Infuus: 10', 2g (1 eetlepel) per kopje (150ml)

Decoct: flos et fol. 3', 30 g/1 liter Dos.: 5 kopjes daags

Ind.: maagzweer, kanker?

Tinctuur: 1:5 (g/ml): 10ml daags (Com.E)

Species: R./

Calendulae fl. 25 g Ber.: inf. 15', 50 g/1 l

Violae odorata hb. 25 g Dos.: 3 x daags 1 kopje

Scrophulariae rad. 50 g Ind.: furunkels, negenoog

Hydrolaat als lotion om de huid te reinigen

Als mondspoeling, gorgelmiddel met Echte salie of Echte kamille

Compres hydrolaat of aftreksel samen met lijnzaad of smeerwortel: rijping acessen

Zalf / Cosmetica: Veel gebruikt in combinatie met Echte kamille, Rode zonnehoed...

Geschiedenis en wetenschappelijk onderzoek

In de Oudheid was er veel verwarring over de naam. Is ‘klymenon’ van Dioscorides onze goudsbloem of de Akkergoudsbloem?

Ook in de M-E werd de latijnse benaming Calendula vaak gebruikt voor Chicorei of Paardebloem. Ze werden allen ‘heliotropium’ (zonnevolger) genoemd.

Pas in de 12de eeuw werd de Goudsbloem met zekerheid geteeld en gebruikt bij o.a. brandwonden en zweren.

Matthiolus (1500 - 1577) gebruikt de bladeren voor wonden en andere kwetsuren.

Dodonaeus (1554): “ de bloeme.... doen den vrouwen huer natuerlijcke crankheyt comen.” ........dat cruyt ghedroocht ende op gloeyende colen geleyt treckt die secondine ende doode vruchten sterckelijck af / als de roock daer af comende van onder ontfanghen wordt.

Referenties

    • Gracza L.: Planta med. 53/227 - 1987.

    • Willuhn G., Westhaus R.G.: Planta med. 53/304 - 1987.

    • Shipochliew T. e.a.: Vet. Med. Nauki 18/87 - 1981.

    • Peyroux J. e.a.: Onderzoeken bij ratten waarbij de an­tiflogistische werking werd aange­toond. Plantes méd. Phytoth. 15/210 - 1982.

    • Shipochliew T.: Onderzoek naar uterus­toniserend effect met een waterig extract van Calendula. Vet. Med. Nauki 18/94 - 1981.

    • Isakowa T.J.: Een flavonoïdenextract uit Calendula vertoonde een antiflogistische en choleretische werking. Farmatsiva (Mosc.) 5/31 - 1980.

    • Bochaud Y., Maître e.a.: Pharmazie 43/220 - 1988.

Andere referenties

    • Anon. Final report on the safety assessment of Calendula officinalis extract and Calendula officinalis. International Journal of Toxicology. 2001;20(Suppl 2):13-20.

    • Bako E, Deli J, Toth G. HPLC study on the carotenoid composition of Calendula products. Journal of Biochemical and Biophysical Methods. 2002;53(1-3):241-250.

    • Cordova CA, Siqueira IR, Netto CA, et al. Protective properties of butanolic extract of the Calendula officinalis L. (marigold) against lipid peroxidation of rat liver microsomes and action as free radical scavenger. Redox Report. 2002;7(2):95-102.

    • Graf J. Herbal anti-inflammatory agents for skin disease. Skin Therapy Letter. 2000;5(4):3-5.

    • Grieve M. Marigold. In: A Modern Herbal. New York: Dover Publishers, 1971. Available at: http://www.botanical.com/botanical/mgmh/mgmh.html Posted 1995. Accessed October 15, 2003.

    • Iauk L, Lo Bue AM, Milazzo I, Rapisarda A, Blandino G. Antibacterial activity of medicinal plant extracts against periodontopathic bacteria. Phytotherapy Research. 2003;17(6):599-604.

    • Jellin JM, Gregory P, Batz F, Hitchens K, et al, eds. Pharmacist's Letter/Prescriber's Letter. Natural Medicines Comprehensive Database, 3rd Edition. Stockton CA: Therapeutic Research Facility, 2000.

    • Kalvatchev Z, Walder R, Garzaro D. Anti-HIV activity of extracts from Calendula officinalis flowers. Biomedicine and Pharmacotherapy. 1997;51(4):176-180.

    • Klouchek-Popova E, Popov A, Pavlova N, Krusteva S. Influence of the physiological regeneration and epithelialization using fractions isolated from Calendula officinalis. Acta Physiol Pharmacol Bulg. 1982;8(4):63-67.

    • Marukami T, Kishi A, Yoshikawa M. Medicinal flowers. IV. Marigold. (2): Structures of new ionone and sesquiterpene glycosides from Egyptian Calendula officinalis. Chemical and Pharmacology Bulletin (Tokyo). 2001;49(8):974-978.

    • Perez-Carreon JI, Cruz-Jimenez G, Licea-Vega JA, Arce Popoca E, Fattel Fazenda S, Villa-Trevino S. Genotoxic and anti-genotoxic properties of Calendula officinalis extracts in rat liver cell cultures treated with diethylnitrosamine. Toxicology In Vitro. 2002;16(3):253-258.

    • Reider N, Komericki P, Hausen BM, Fritsch P, Aberer W. The seamy side of natural medicines: contact sensitization to arnica (Arnica montana L.) and marigold (Calendula officinalis L.). Contact Dermatitis. 2001;45(5):269-272.

    • Shipochliev T. Uterotonic action of extracts from a group of medicinal plants. [Article in Bulgarian] Veterinary Medicine of Nauki. 1981;18(4):94-98.

    • Shipochliev T, Dimitrov A, Aleksandrova E. Anti-inflammatory action of a group of plant extracts. [Article in Bulgarian] Veterinary Medicine of Nauki. 1981;18(6):87-94.

    • Yoshikawa M, Murakami T, Kishi A, Kageura T, Matsuda H.Medicinal flowers. III. Marigold. (1): hypoglycemic, gastric emptying inhibitory, and gastroprotective principles and new oleanane-type triterpene oligoglycosides, calendasaponins A, B, C, and D, from Egyptian Calendula officinalis. Chemistry and Pharmacology Bulletin (Tokyo). 2001;49(7):863-870.

    1. View Abstract: Klouchek-Popova E, et al. Influence of the physiological regeneration and epithelialization using fractions isolated from Calendula officinalis. Acta Physiol Pharmacol Bulg. 1982;8(4):63-7.

    2. View Abstract: Della Loggia R, et al. The role of triterpenoids in the topical anti-inflammatory activity of Calendula officinalis flowers.Planta Med. Dec1994;60(6):516-20.

    3. View Abstract: Wagner H, et al. Immunostimulating action of polysaccharides (heteroglycans) from higher plants. Arzneimittelforschung. 1985;35(7):1069-75.

    4. Mozherenkov VP, et al. Treatment of chronic conjunctivitis with Calendula. Med Sestra. Apr1976;35(4):33-4.

    5. Marinchev VN, et al. Use of calendula for therapy of chronic inflammatory diseases of eyelids and conjunctiva. Oftalmol Zh. 1971;26(3):196-8.

    6. View Abstract: Kalvatchev Z, et al. Anti-HIV activity of extracts from Calendula officinalis flowers. Biomed Pharmacother. 1997;51(4):176-80.

    7. View Abstract: Sarrell EM, Mandelberg A, Cohen HA. Efficacy of naturopathic extracts in the management of ear pain associated with acute otitis media. Arch Pediatr Adolesc Med. Jul2001;155(7):796-9.

    8. View Abstract: Yoshikawa M, Murakami T, Kishi A, Kageura T, Matsuda H. Medicinal flowers. III. Marigold. (1): hypoglycemic, gastric emptying inhibitory, and gastroprotective principles and new oleanane-type triterpene oligoglycosides, calendasaponins A, B, C, and D, from Egyptian Calendula officinalis. Chem Pharm Bull. Tokyo. Jul2001;49(7):863-70.

    9. View Abstract: Reider N, Komericki P, Hausen BM, Fritsch P, Aberer W. The seamy side of natural medicines: contact sensitization to arnica (Arnica montana L.) and marigold (Calendula officinalis L.). Contact Dermatitis. Nov2001;45(5):269-72.

Algemene literatuur, overzichten

Isaac O.: Calendula officinalis L. Ztschr. f. Phytoth. 16/357-370 - 1994.

Isaac O.: Die Ringelblume. Wissensch. Verl. Stuttgart - 1992.

Goudsbloem in oude kruidenboeken | Kunst en cultuur: Geschiedenis

Calendula, Herb Monograph - Flora Health Herb Encyclopedia

Globinmed - Calendula Monograph

http://www.ema.europa.eu/calendula_officinalis_flos/17928107enfin.pdf

WHO Monographs on Selected Medicinal Plants - Volume 2: Flos Calendulae

Plantaardigheden.nl - Leesmaar.nl Capitel 12 Deel 2 Cruijdeboeck 1554

Plantaardigheden.nl - Leesmaar.nl Boek 3 301 - 468 Naauwkeurige beschrijving der aardgewassen 1696

Wetenschappelijk onderzoek abstracts

J Basic Clin Physiol Pharmacol. 2009;20(1):73-9. Wound healing activity of flower extract of Calendula officinalis.

Preethi KC1, Kuttan R.

The effects of oral and topical application of Calendula officinalis flower extract on excision wounds made in rats were checked. The parameters assessed were the days needed for re-epithelization and percentage of wound closure. The hydroxy proline and hexosamine content in the granuloma tissue of the wound was also measured. The percentage of wound closure was 90.0% in the extract-treated group, whereas the control group showed only 51.1% on the eighth day of wounding (p < .01). The days needed for re-epithelization were 17.7 for the control animals; extract treatment at a dose of 20 or 100 mg/kg b.wt reduced the period to 14 and 13 days, respectively. A significant increase was observed in the hydroxy proline and hexosamine content in the extract-treated group compared with the untreated animals. The data indicate potent wound healing activity of C. officinalis extract

Indian J Exp Biol. 2009 Feb;47(2):113-20. Anti-inflammatory activity of flower extract of Calendula officinalis Linn. and its possible mechanism of action.

Preethi KC1, Kuttan G, Kuttan R.

Calendula officinalis flower extract possessed significant anti-inflammatory activity against carrageenan and dextran-induced acute paw edema. Oral administration of 250 and 500 mg/kg body weight Calendula extract produced significant inhibition (50.6 and 65.9% respectively) in paw edema of animals induced by carrageenan and 41.9 and 42.4% respectively with inflammation produced by dextran. In chronic anti-inflammatory model using formalin, administration of 250 and 500 mg/kg body weight Calendula extract produced an inhibition of 32.9 and 62.3% respectively compared to controls. TNF-alpha production by macrophage culture treated with lipopolysaccharide (LPS) was found to be significantly inhibited by Calendula extract. Moreover, increased levels of proinflammatory cytokines IL- 1beta, IL-6, TNF-alpha and IFN-gamma and acute phase protein, C- reactive protein (CRP) in mice produced by LPS injection were inhibited significantly by the extract. LPS induced cyclooxygenase-2 (Cox-2) levels in mice spleen were also found to be inhibited by extract treatment. The results showed that potent anti-inflammatory response of C. officinalis extract may be mediated by the inhibition of proinflammatory cytokines and Cox-2 and subsequent prostaglandin synthesis.

Acta Cir Bras. 2011 Feb;26(1):19-24. Angiogenic activity of Calendula officinalis flowers L. in rats.

Parente LM1, Andrade MA, Brito LA, Moura VM, Miguel MP, Lino-Júnior Rde S, Tresvenzol LF, Paula JR, Paulo NM.

In this work, angiogenic activity of Calendula officinalis L. (Asteraceae) ethanolic extract and dichloromethane and hexanic fractions were evaluated, considering medicinal properties, especially healing activity, are attributed to this plant.

METHODS:

Models using 36 rats and 90 embryonated eggs were used to evaluate healing and angiogenic activities of extracts and fractions of the plant, through the induction of skin wounds and the chorioallantoic membrane, respectively. The effect of vascular proliferation was also tested from the study to verify the intensity of expression of vascular endothelial growth factor (VEGF) in cutaneous wounds in rats.

RESULTS:

The angiogenic activity of the extract and the fractions was evidenced in both experimental models. It was verified that this effect is not directly related to the expression of VEGF and it could be associated to other pro-angiogenic factors.

CONCLUSION:

The healing activity referred to C. officinalis is related, among other factors, to its positive effect on angiogenesis, characterized by the induction of neovascularization.

Int J Tissue React. 2005;27(3):101-6. Results of the clinical examination of an ointment with marigold (Calendula officinalis) extract in the treatment of venous leg ulcers.

Duran V1, Matic M, Jovanovć M, Mimica N, Gajinov Z, Poljacki M, Boza P.

The aim of this study was to determine the therapeutic efficacy of marigold (Calendula officinalis) extract on the epithelialization of lower leg venous ulcers. The experiment was carried out in 34 patients with venous leg ulcers. The patients were divided into two groups. In the first (experimental) group, patients were treated with an ointment containing marigold extract, which was prepared in an apparatus devised by Soxleth and was incorporated into a neutral base. Twenty-one patients with 33 venous ulcers were treated. Therapy was applied twice a day for 3 weeks. The second group was a control group that consisted of 13 patients with 22 venous ulcers. In the control group, saline solution dressings were applied to ulcers for 3 weeks. In the experimental group the total surface of all the ulcers at the beginning of the therapy was 67,544 mm2. After the third week the total surface of all the ulcers was 39,373 mm2 (a decrease of 41.71%). In seven patients, complete epithelialization was achieved. In the control group the total surface of all the ulcers at the beginning of the therapy was 69,722 mm2. After the third week the total surface of all the ulcers was 58,743 mm2 (a decrease of 14.52%). In four patients, complete epithelialization was achieved. There was a statistically significant acceleration of wound healing in the experimental group (p < 0.05). The results obtained are preliminary, but they suggest the positive effects of the ointment with marigold extract on venous ulcer epithelialization.

Calendula HerbalGram

History and Cultural Significance

Historically, calendula was known as “poor man’s saffron” as it was used to color and flavor foods, specifically butter, cheese, custard, bread, cookies, soups, and rice dishes.2,7,9 Calendula petals are also added to salads and used as a dye for fabric and hair.2 Currently, the pigment of the bright orange calendula is used in the pharmaceutical industry to give a pleasant color to some medicinal preparations.7

British herbalists John Gerard (1545-1612) and Nicholas Culpepper (1616-1654) both mention “marigold,” and 20th century British author Maud Grieve states that it is primarily a local (topical) remedy and that applying the petals to insect stings will reduce pain and swelling.10 She also recommends a lotion made of the flowers for sprains and wounds and a water distillation of the flowers for sore and inflamed eyes. While the flowers are the part most often used medicinally, Mrs. Grieve also mentions that the juice from the leaves would remove warts and that eating the raw leaves in salad was useful in the treatment of childhood scrofula, a tubercular degeneration of the lymph glands.10

Folk medicine healers in Europe prepared infusions, extracts, and ointments with the petals to induce menstrual flow, to produce sweat during fevers, and to cure jaundice. In 19th century America, the Eclectic physicians used calendula internally to treat liver problems, stomach ulcers, conjunctivitis (inflammation of the mucous membrane that lines the eyelids, commonly called pink eye), and externally for superficial burns, bruises, and wounds.9 Traditionally, the flower was also used externally as an antiseptic and to help stop bleeding.11

Calendula flowers demonstrate both astringent and anti-inflammatory activity and calendula infusions, ointments, and tinctures have been employed to heal bruises, burns, cuts, and the minor infections that they cause.12,13 Calendula preparations are used for skin and mucous membrane inflammations, such as pharyngitis (inflammation of the throat), leg ulcers, boils, bed sores, gum inflammation, and rashes.4,7 Lotions, poultices, and compresses made with calendula flowers may also be used, based on which preparation is most suitable.14 Some herbalists recommend the plant’s essential oil for treating vaginal yeast infections.7

The German Commission E has approved the use of calendula flower internally and topically for treating inflammation of the mucous membranes of the mouth and throat, and externally for poorly healing wounds and foot ulcers.9 In the United Kingdom, calendula is approved as an herbal medicine for external use only in the General Sale List.4 In Canada, since the Natural Health Product (NHP) regulations went into effect in 2004, calendula is an active ingredient in NHPs requiring pre-marketing authorization and product licensing.15 Calendula flower ingredients are available in the United States for use in cosmetics, dietary supplements, and homeopathic remedies, and they are generally recognized as safe for food use (GRAS § 182.10) at 11 to 44 ppm (parts per million).2,4

Modern Research

Calendula’s healing properties, while established over centuries of use, are not well understood. Various activities have been shown for the essential oil and extracts of the flowers including the following: antimicrobial, anti-inflammatory, antibacterial, antifungal, antitumor, cytotoxic, anti-HIV, and wound healing.4,9 Recent studies investigating the calendic acid content of the calendula seed have found it to have antioxidant properties.16

While there are not many clinical studies to support the various uses of calendula, a few stand out. Loggia et al (1994) found that an ointment made with calendula flowers is effective in relieving the pain associated with cracked or tender nipples.17 In 2005, Duran et al obtained positive preliminary results for the use of calendula ointment in the treatment of venous leg ulcers.18 Another 2005 study (Fuchs et al) showed the protective effect of a calendula/rosemary cream preparation against irritant contact dermatitis caused by exposure to sodium laurel sulfate.19 A 1999 study suggested that a Romanian product containing calendula, burdock (Arctium lappa, Asteraceae), and herb-Robert (Geranium robertianum, Geraniaceae) was more successful than acyclovir (a common antiviral pharmaceutical medication) at resolving complaints and healing ulceration caused by herpetic keratitis (inflammation of the cornea and conjunctiva caused by herpes virus type I).20 (Note: The article cited is in Romanian and the plant parts were not specified in the English abstract.)

There are very few safety concerns regarding calendula. However, internal use of calendula preparations should be avoided during early pregnancy due to its ability to stimulate menstrual activity.21 Also, allergic hypersensitivity may be an issue for persons sensitive to other members of the plant family Asteraceae.21

Future Outlook

Most of the field trials and cultivation studies on calendula are evaluating its potential as a seed oil crop. According to a Kansas State University Research and Extension article from 2004, market potential for calendula is moderate to high, and the dried flowers can be sold for $4.80 to $39.00 per pound (dry weight).22 Estimated marketable yield of flowers, based on 43,560 plants per acre, is 1483 dry pounds/acre.22 Another report, from the British Columbia Ministry of Agriculture, Food and Fisheries in 2002, estimates that a grower could produce 175 pounds per quarter acre of organically-grown calendula flowers, which could be sold at an average price of $13.00 per pound.23

—Gayle Engels

References

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Tucker AO, Debaggio T. The Big Book of Herbs. Loveland, CO: Interweave Press; 2000.

European Scientific Cooperative on Phytotherapy. ESCOP Monographs. 2nd ed. New York: Thieme New York; 2003.

Wichtl M, ed. Brinckmann JA, Lindenmaier MP, trans. Herbal Drugs and Phytopharmaceuticals. 3rd ed. Stuttgart: Medpharm GmbH Scientific Publishers; 2004.

Bown D. Cultivars of Calendula. In: Calendula: An Herb Society of America Guide. Kirtland, OH: Herb Society of America; 2007.

Talbert R. What’s in a Name! In: Calendula: An Herb Society of America Guide. Kirtland, OH: Herb Society of America; 2007.

Foster S, Johnson RL. National Geographic Desk Reference to Nature’s Medicine. Washington, DC: National Geographic; 2006.

Samaha, Brother John M. Mary’s Gold. In: Calendula: An Herb Society of America Guide. Kirtland, OH: Herb Society of America; 2007.

Blumenthal M, Goldberg A, Brinckmann J, editors. Herbal Medicine: Expanded Commission E Monographs. Austin, TX: American Botanical Council; Boston: Integrative Medicine Communications; 2000.

Grieve M. A Modern Herbal. Vol. 2. New York: Dover Books; 1971.

Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics. 2nd ed. New York: Wiley-Interscience; 1996.

Foster S. 101 Medicinal Herbs: An Illustrated Guide. Loveland, CO: Interweave Press; 1993.

Tyler VE. Herbs of Choice: The Therapeutic Use of Phytomedicinals. New York: Pharmaceutical Products Press; 1994.

Hoffmann D. Medical Herbalism: The Science and Practice of Herbal Medicine. Rochester, VT: Healing Arts Press; 2003.

Government of Canada. Food and Drugs Act. Natural Health Products Regulations. P.C. 2003-847. Published June 5, 2003. http:// canadagazette.gc.ca/partII/2003/20030618/html/sor196-e.html. Accessed December 7, 2007.

Wilen RW, Barl B, Slinkard AE. Feasibility of Cultivation: Calendula as a Dual Purpose Industrial Oilseed and Medicinal Crop. ISHS Acta Horticulture 629 :XXVI International Horticultural Congress: The Future for Medicinal and Aromatic Plants. Available at: http://www. actahort.org/books/629/629_26.htm. Accessed August 26, 2007.

Loggia DR, Tubaro A, Sosa S, et al. The role of triterpenoids in the topical anti-inflammatory activity of Calendula officinialis [sic] flowers. Planta Med. 1994;60:516-520.

Duran V, Matic M, Jovanovć M, et al. Results of the clinical examination of an ointment with marigold (Calendula officinalis) extract in the treatment of venous leg ulcers. Int J Tissue React. 2005;27(3):101106.

Fuchs SM, Schliemann-Willers S, Fischer TW, Elsner P. Protective effects of different marigold (Calendula officinalis L.) and rosemary cream preparations against sodium-lauryl-sulfate-induced irritant contact dermatitis. Skin Pharmacol Physiol. July-August 2005;18(4):195-200.

Corina P, Dimitris S, Emanuil T, Nora R. Treatment with acyclovir combined with a new Romanian product from plants [abstract] [in Romanian]. Oftalmologia. 1999;46(1):55-57.

Brinker F. Herb Contraindications and Drug Interactions. 3rd ed. Sandy, OR: Eclectic Medical Publications; 2001. Plus online updates and additions, August 26, 2007.

Janke R, Farming a Few Acres of Herbs: Calendula. Manhattan, KS: Kansas State University; 2004.

Schimpf T, Joynt H. Certified Organic Versus Non-organic Budgets for Calendula Flower. Vancouver, BC: British Columbia Ministry of Agriculture, Food, and Fisheries; 2002.