Mechanism of Action of Wound Healing Activity of Calendula officinalis: A Comprehensive Review

Bhargab Deka1, Bedanta Bhattacharjee1, Anshul Shakya1, Abu Md Ashif Ikbal2*, Chayanika Goswami3, Santa Sarma3

1Department of Pharmaceutical Sciences, Faculty of Science and Engineering, Dibrugarh University, Dibrugarh – 786 004, Assam, India
2Department of Pharmacy, Tripura University (A Central University), Suryamaninagar- 799022, Tripura (W), India
3Department of Pharmacology, Girijananda Chowdhury Institute of Pharmaceutical Sciences- 781017

Received: 24-Oct-2020 , Accepted: 30-Dec-2020

Keywords: Calendula officinalis, Wound healing, Tissue regeneration

DOI: http://dx.doi.org/10.20510/ukjpb/9/i1/1609684673

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Abstract

Calendula officinalis is a short-lived aromatic herbaceous perennial plant. According to scientific literature, Calendula officinalis can also boost the wound healing activity. While the precise means it does is still unclear, it was assumed that the herb would increases the blood flow to the wound area, therefore supplying oxygen and nutrients necessary for tissue regeneration. The objective of the review is to understand and explore the relevant phytochemical and pharmacological information which will enhance it effective wound healing mechanism.  The data were identified using PubMed, Google Scholar, Scopus and bibliographic reviews of recent and old articles from an English literature search. After independent analysis by co-authors of the identified articles, data were analysed and extracted for the stated purpose.Calendula officinalis with its high quantity of flavonoids, it can help to minimize inflammation and speed up the healing process. Additional  usage for Calendula officinalis is that it can be a calming ointment, wash or tincture , since it can help to alleviate irritated wounds and minimize swelling and inflammation. Wound healing is a complex process, and Calendula officinalis have been historically used to treat minor wounds, skin irritation and minor burns. Data from large comparative clinical trials are needed before routine use can be recommended. Pharmacists and clinicians can effectively address patient questions about wound care and herbal therapies to help promote wound care practices that encourages wound healing and minimize poor outcomes such as infection or scaring.

INTRODUCTION

Wounds and  skin  disease  can  be  both  socially  and  financially  burdensome  to  an  individual.  Skin ulcers  and  wounds  ranked  in  the  top  5  of  the most economically burdensome skin diseases1.  Wound  care  products  and  therapies  can  promote  the  healing  process,  decreased the formation of wounds and enhances the properties of the fresh skin. Certain natural compounds have  demonstrated potential anti-inflammatory,  antimicrobial,  and  cell-stimulating  properties  that  may  aid  wound healing2,3. These  complementary  and alternative medicine (CAM) therapies using  plant  extracts have  been  used  in  wound  healing  for centuries. Homeopathic treatments as  discussed here are a branch of CAM therapy.
Approximately  33%  of  US  adults  use  some  form of  CAM4,5. In addition,  over  15  million Americans  use  CAM  (herbal products [including homeopathic] or high-dose vitamins) with their prescription  medications4. Comparative clinical trials for  homeopathic medications are becoming more  common;  however, the complexity  of  standardizing  scientific  methods  for  CAM  therapies  is  difficult. The  evidence-based  data  supporting  the use  of  CAM  is lacking4. CAM  therapies  for wound  healing are typically less expensive than prescription medications but have not been associated with bacterial resistance2,3. Several  CAM therapies have  been used historically for potential  effect s on skin healing; however, these products  have  not  shown  clear benefits  in clinical trials. Some  of  these  well-known products  include  aloe vera, ginkgo biloba, St. John’s wort, and honey. Additionally, other plant extracts  such as tea tree oil, oak bark, and Calendula officinalis extract have  also been used  for  their effects  on  wound  healing. This article focus on CAM in wound healing and,  more  specifically, the use  of Calendula officinalis.

WOUND HEALING

Skin  disorders  and  wounds  are  generally  defined  based  on  the  depth  of  injury, healing  time, healing  progression, underlying  pathology, associated  risk  of  mortality, and  the  effect on  quality  of life 6,7.  Surgical and  traumatic  wounds, burns, radiation  dermatitis, and abrasions (including scrapes and microdermabrasion) are  considered  acute  wounds, while  venous and arterial  leg ulcers,  fungating wounds, pressure  ulcers, and diabetic  ulcers are  classified  as chronic wounds. Healing  time and sequence  also  delineates  acute  versus  chronic  wounds. In  general, acute  wounds  can  repair themselves  in  an  orderly  and  timely manner  unlike  chronic  wounds 8.

Typical  wound  healing  progresses  through  key  phases. All  phases  must  occur  in  an  overlapping sequence  and  progress  until  healing  is  complete 9,10. Minor  wounds are superficial, shallow, noninfected  wounds  that  occur  in  patients  without  comorbid conditions that could complicate treatment (such as diabetes or immune deficiencies). Phase 1 of  wound  healing  controls bleeding9,11. Vascular constriction, platelet migration, and fibrin clot formation reestablish hemostasis shortly after vascular injury and  provide  an  extracellular  matrix for  cell  migration. Through  this process, mediators of wound  healing  attract  inflammatory cells  to  the  area of injury  progressing  into the  next  phase of  inflammation10. Phase 2  overlaps with  the previous  hemostasis  and  coagulation phase  and  begins  within  a  few  hours  of  injury. It is primarily  defined by the accumulation of leukocytes and macrophages11,12.  Macrophages  enter  the  wound  site and  release growth  factors, such  as platelet- derived growth  factor,  which  facilitate  the formation of new connective tissue (i.e. granular tissue)11. Macrophages also help  resolve inflammation and stimulate tissue  regeneration, facilitating  the  transition  from  the  inflammatory  to  reparative  phases  of  proliferation  and remodeling9. Occurring between 3 to 21 days  post injury,  phase 3 (proliferation) is characterized  by granulation  tissue  formation, re-epithelialization of the  wound  surface, and contraction of the wound margins9.12. Granulation tissue will contain macrophages, fibroblasts, and  immature collagen, all of  which  stimulate granulation tissue formation. Concurrently, blood vessels will stimulate capillary growth. Fibroblasts within the wound bed stimulate the production of collagen, one of the key components of  the extracellular matrix.

The final phase of  wound  healing (phase 4) can last for years and involves the  reorganization of collagen  fibers to create new skin9,12. New  skin  may gain less than  a quarter of its  final strength  in the  first 3 weeks and rarely  ever  reaches the same strength as uninjured  skin11.

MOLECULAR MECHANISM OF WOUND HEALING

Molecular Mechanism of Platelets on Wound Healing

In the initial stage of injury platelets were activated and it has an important role in clot formation during hemostasis after aggregation and attachment to the exposed collagen surfaces. The cytokines and other growth factors regulate the process. Cytokines acts on target cells by various routes like endocrine, paracrine, autocrine or intracrine routes and activate target cells thereby activating other cell signalling pathway. Cytokines can play various roles by acting on different targets.

Molecular Mechanism in the Inflammatory Cells on Wound Healing

Chemokines, which are small heparin binding proteins, promotes the movement of circulating inflammatory cells to the injury sites through the interaction with specific membrane bound receptors. Neutrophiles are the main cell type in the initial inflammation phase and begins to disappear after 24 – 36 h by cell death in the time of circulating monocytes enter the wound and mature into tissue macrophages that play crucial role in the healing of wounds. This mechanism is regulated by the chemokines IL – 8 which is released by neutrophiles which attracts the macrophages and other cells to the wound site.

Molecular biology in repair cells on wound healing

In correlation to macrophage – synthesized growth factors viz. PDGF, FGF, VEGF, TGF-alpha, TGF- beta, KGF etc. the fibroblast a component of granulation tissue, starts to migrate, proliferate and produce the components of ECM, such as glycosaminoglycans and proteoglycans as well as collagen, a critical event in the proliferation phase and wound healing in general. Collagen is secreted to the extracellular space in the form of procollagen and then cleaved of its terminal segments, which is known as tropocollagen. Tropocollagen aggregates with other similar molecules to form collagen filaments that are enriched in hydroxylysine and hydroxyproline moieties and enable it to form strong cross links.

The stability of the collagen fiber is based on the intermolecular cross – links makes collagen fiber more resistant. Higher the cross – links of collagen, more will be the bursting strength in wound healing.Thus, collagen forms close cross – links with other collagens and with protein molecules thereby increasing the tensile strength of the healing wound13.

REGULATIONS OF HERBAL MEDICINES

WHO has updated and released the guidelines and policies regarding herbal medicines time to time including the areas ranging from GACP (Good Agricultural and Collection Practices), GMP (Good Manufacturing Practices) etc. These guidelines and policies taken by WHO will help to address the variations in regulations and place the herbal medicine in the Global Market. Under the Drug and Cosmetic Act 1940  and Rules 1945 in India, herbal drugs are regulated which controls licensing, formulations, manufacturing, labeling, packing, import and export14.

Calendula officinalis

Calendula officinalis is a  well  known  medicinal  plants, and plant image display in Fig 1. It is native to Asia and southern Europe, but commonly found in gardens around the world. It  is commonly known as  Pot  marigold , has been used in many forms and for centuries as  an  herbal remedy belonging to the family Asteraceae  used for the treatment of wounds, burns, abrasions  and  dermatitis17. Calendula officinalis  leaves, flowers, extract  possess  wide  range of pharmacological activity viz wound  healing, diaphoretic, analgesic, anti-inflammatory, anti-HIV18.

The chemical  components  include  triterpenoids, saponins, flavonoids, carotenoids, fatty acids,  polysaccharides, essential oils. The concentrations of these compounds vary depending on geographical area, although the observed  physiological  effects of  topical Calendula officinalis appear  to be consistent. In vitro   studies shown  that plant extract of Calendula officinalis show  cytotoxic and tumor reducing potential on various  tumor cell lines derived from cervix, breast, leukemias, prostate, fibrosacomas17,19. Generally, for the  treatment  of  peptic ulcer, duodenal  ulcer , gastritis, colitis, mucous  membrane inflammation it has  also  been used internally. Calendula officinalis is  available  in  various formulations  including  creams,  lotions,  ointments, and gels. For  general  use, 2%-5% ointment  may  be applied 3  to  4 times daily as  needed. After tooth extraction it  is  also  used  as  a  mouth wash20. The Pharmacognostical profile and Organoleptic properties of  the Calendula officinalis  have  been compiled  in  the  Table 1.

PHYTOCHEMISTRY OF Calendula officinalis

Calendula officinalis  flower,  leaves , root  is  a  rich  source of  secondary plant  metabolites  and they differ in  different  part of  the plant25.  The  amount  of  these  phytometabolites may  varies  according  to the season, soil  composition and harvesting time25,27,28. Terpenoids, Flavonoids, quinones, coumarins and  volatile oils are commonly present  in Calendula officinalis29,30. The major  phytochemicals present in  different  parts of  the  plants  are  mentioned in  Table 2. The structure of some important bioactive components are illustrated in Fig 2.

WOUND HEALING ACTIVITY OF Calendula officinalis

In  ayurvedic  system of  medicine , it seems like Calendula officinalis  possess  scar easing  and emollient properties   by significantly  raising  the amount of collagen  metabolism , wound angiogenesis  in  wound  areas43 . By  addition of Calendula officinalis  flower  extract ,  Hill et al ., demonstrated  a  experimentation   conducted  on  scar reducing  and  massage  emollient  properties  produce  promising  effective  results44.  Ethanolic ,  hexane and dichloromethane  fraction of  Calendula officinalis  in  experimental  model enhance  wound  healing  and  angiogenic  activities. Treatment  with  ethanolic  extract  of  Calendula officinalis  increased  the  amount  of blood  vessel  and decreased  in  wound area compared to reference group45.  Another study suggested that application of Calendula officinalis extract  profoundly  enhances  epithelization  in chronic  venous  ulceration. In  the  thermal  induced  burns  in  rats, treatment  with  ethanolic floral extact of Calendula officinalis  showed  significant  improvement  in  wound  healing  activity  by  increasing  the level of hexosamine  and  collagen hydroxyproline content. Similarly, the levels of tissue  damage markers (alanine and aspartate amino transferase, alkaline phosphatase), acute  phase protein (orosomycid, heptaglobulin), lipid peroxidation should be decreased due to its potential antioxidant property46. Ethanolic  extract of  Calendula officinalis significantly  increase collagen synthesis and blood flow to the effective wounded sites47. Due to its  antimicrobial and antioxidant action, 2% Calendula officinalis gel and its daily  application produces better  healing of wounds48. Antiseptic and anti-inflammatory properties of Calendula officinalis extract heals wound  along  with  internal as well  as  external  ulcers. Because of its good stability, penetrability  and  ease of application the ointment base of Calendula officinalis is more acceptable in hydrophobic  medium49,50.  

10% Calendula officinalis ointment prescribed for Cheilitis exfoliative51. In vivo model of excisional wounds of BALB/c mice, Calendula officinalis may help to induce granulation tissue  formation by altering the appearance of connective  tissue growth factor (CTGF) and α-smooth muscle actin (α-SMA)52. An overview of wound healing  mechanism of Calendula officinalis  as  presented  in  Fig 3.

THERAPEUTIC USES OF Calendula Officinalis

Minor Wounds, Burns, And Abrasions

Historically,  topical  Calendula officinalis   was  used  to  treat  minor  wounds,  burns, and  abrasions;  however,  few  clinical  trials have  been  conducted  to  assess  its  efficacy  and  safety  for  these  indications.

An  animal  study  suggests  that  Calendula officinalis   is  beneficial  for  wound  healing, though,  such  conclusions cannot  be  reasonably  extrapolated to  humans87.  Currently, more  clinical  studies  need to  be  conducted  in  humans  for  this  specific  indication48.

Venous Ulcers

Venous  ulcer or stasis  ulcer  is  the  most  common  etiology of  lower  extremity  ulceration and affects  approximately  1% of  Americans88. Venous  ulcers  are  irregular,  shallow, and  usually recurrent.  Treatment typically includes leg elevation, compression therapy, wound dressings, pentoxifylline,  and  aspirin88Calendula officinalis   has  been  studied  as  a  possible  treatment  for  venous leg  ulcers.

In  an  open,  comparative  clinical  trial,  34 patients  with  venous  leg  ulcers  were  treated with  either  an  ointment  containing 7.5% marigold  extract  in  a  neutral  petrolatum  base  (from a local source in Serbia and Montenegro) applied  twice  daily for 3 weeks or saline solution  dressings applied  for 3 weeks89.  

At  the end  of  the 3-week  study  period, patients treated   with  the  Calendula officinalis  ointment  had  a  statistically  significant  reduction  in  the aggregate  ulcer  surface  area compared with  those in  the  placebo  group (-41.71% vs -14.52%, respectively; P < 0.05). The  number  of  wounds  achieving  complete  epithelialization  was  similar  in  both groups (7/21 Calendula officinalis   vs 4/13 placebo). Adverse  effects  were  not  reported. Despite  the  positive results, this  study lacked an  adequate  control group,  was  not  blinded, and  had  a small study population. Further  clinical trials are warranted  as benefit  was  shown89.

Radiation Dermatitis in Patients With Breast Cancer

Radiation  dermatitis  is  a  cutaneous  repercussion of  the  external  beam  ionizing radiation  used to treat  malignancies90.  Also  called “radiation skin  damage” or a “radiation burn,” it affects  approximately 95% of patients receiving  radiotherapy. Skin  changes  after  radiotherapy  may  be  minor,  reversible, and  self-limiting, but  can  be  serious  and  lead  to  ulceration,  infection, or permanent skin damage in some patients. Protective agents have been investigated. Controlled  studies have  not  shown  conclusive  results in  favor  of  specific  agents, but patients have anecdotally noted satisfaction with ointments90Calendula officinalis  has  also been studied in the prevention  of  radiation  dermatitis.

Calendula officinalis  was evaluated  in  an open, phase 3, single center clinical  trial for the  prevention of radiation dermatitis following  radiotherapy  for  breast cancer91. Women (n = 254)  were randomized  to  be  treated  with  Calendula officinalis   extract in  petroleum jelly (Pommade au Calendula officinalis  par Digestion; n= 126) or trolamine, the standard  of  care, (n = 128) applied by  patients at  least twice daily. Patients  with  more  pain  or erythema applied  the  products  more  frequently.

At the end of  the study, Radiation Therapy Oncology Group (RTOG) grade 2 or higher dermatitis was reported  less by  patients  receiving  Calendula officinalis  compared with  those in  the  trolamine  group (41% vs 63%, respectively; P < .001). Fewer patients treated with Calendula officinalis vs  trolamine  experienced  grade 3 toxicity (7% vs 20%, respectively; P = .034), required  treatment interruption (1 vs 15 patients), or  had an  allergic  reaction to  the  cream (0 vs 4 patients). Despite  better  overall  outcomes, patients  reported  that  it  was  more  difficult to  use  the  Calendula officinalis   formulation  than trolamine (30% vs 5%, respectively) and more physicians felt that there was less  compliance  with Calendula officinalis than  with  trolamine (84% vs 92%, respectively)91. Study  limitations include a  lack of  treatment  blinding  and  the  use of  petroleum  jelly (which itself may have beneficial effects) in the Calendula officinalis   formation.

A randomized, phase 3 study  compared  a  10% Calendula officinalis   cream  to  an  aqueous  cream (moisturizer) without  parabens (standard of care)  applied  twice  daily  before,  during  courses, and  after  radiation  therapy  for  breast  cancer92. Each  treatment was applied starting with the initial  radiotherapy session and  was  continued  until  2  weeks  after  the  last  session or  until  any  acute  radiation  skin  reaction  was  healed. There  were  390  patients  included in  the  study with  194 receiving Calendula officinalis cream and 196  receiving aqueous cream. No difference was  observed  between  the  use  of  Calendula officinalis   cream  compared  with  aqueous  cream for  the incidence of  RTOG grade 2 or greater dermatitis (23% vs 19%, respectively; P = .39). In  addition, no  differences were reported for other efficacy  outcomes such as patient-reported symptoms like  itchiness  and pain. However,  patients  reported that  the Calendula officinalis product  was  not  as  easy  to apply and  had  worse  absorption  quality than  the  aqueous  cream92.

Antihypertensive drugs

Excessivedoses of  Calendula officinalis  has been found  to possess hypertensive effects. Thereby, in combination with hypertensive drugs  may result in additive effects93.

Sedative drugs

Excessive doses of ingested preparation of Calendula officinalis  has been found  to possess sedative effects. Thereby, in combination with sedative agents may attributed additive effects. Calendula officinalis  has been shown to increase the sleep time caused by hexobarbital in rats93.

Hypoglycemic drugs

Calendula officinalis  can increased the activity of insulin or hypoglycemic drugs93.

Lipid lowering agent

Agents that minimize lipids and triglycerides , Calendula officinalis  can have an additive effect93.

ROLE OF THE PHARMACIST AND CLINICIAN IN THERAPY

When  recommending  a  topical product for wound  care, one  should  consider the  proper  dosage and frequency of application, patient age and weight, and the physical form of the preparation to be  applied. Various drug vehicles have specific  advantages and disadvantages, as described  previously66.

Patient  assessments  and histories are  necessary to  develop a  plan of  care for  any skin condition.  Items  identified  through a  patient  interview  should  guide  treatment and identify  areas of  additional need, such as patient and family  support, education, and goals of care. Patient information that should be obtained include: chief  complaint; a detailed medical history including concurrent illnesses; allergies and past medical conditions; medication history, as well as herbal and nutritional supplements; use of self- care products;  current  diet; tobacco use, alcohol consumption, and  exercise routine; and social interactions, hobbies, and  mobility, with a focus on  the  effects of these on wound healing.

Safety  risks,  such  as  allergic  reactions, exist  with  any  product, but may  be  increased  with  herbal products. In  addition, a  lack  of  regulation in  the  production  of  herbal and  alternative  products  could result in products  having  additives  and  preservatives94. To address these concerns,  pharmacists  and other  health  care   practitioners  should  always  recommend  using  products  from  trusted manufacturers and, in the case of  supplements  taken by  mouth, ensure  that  they are  US Pharmacopeia (USP) verified. The label with USP  Verified  Mark shows that the product95 :

Carries  the proclaim potency and  amount of  the ingredients listed

  •  Does not have specified contaminants present in  harmful levels
  •  Meets dissolution standards
  •  Has  been manufactured  according to  FDA and USP  guidelines for safe, sanitary, and  well-controlled  manufacturing practices

Advise  patients  to  know and  watch  for  symptoms  of  an  allergic  reaction  and  discontinue  using  the product  if  allergy  symptoms  appear. For minor skin wounds  and  abrasions,  pharmacists and nurse  practitioners  may  assist  with  proper selection of self-care products for appropriate wound dressing and infection prevention. Pharmacists   and  clinicians can  help  patients navigate the multitude of available preparations and recommend  appropriate  delivery  systems  that  are  best  suited  for particular skin conditions (as described previously). Additional Calendula officinalis and wound care resources for  pharmacists,  nurse practitioners,  and  patients  are  provided  in  the table. As front-line health care providers, pharmacists and  nurse practitioners may also identify patients with more serious or nonhealing  wounds that require  the  care  of  a physician. These  patients  should  be  referred  immediately96.

TOXICOLOGICAL EFFECT OF Calendula officinalis

Calendula officinalis   extract  has been found to be safe, non irritating, non genotoxic and nonmutagenic97. Oral administration of  floral  extract of C.officinalis  0.15g/kg/day given  for a  period  of 18 months  in hamstr were  found to be non toxic98.  Dermal  application  of  floral extract of C.officinalis produces allergic  reaction  in  human evaluated by the  patch testing  method  reported  in  clinical  studies99. Similarly, Bone; Braun and Cohen also  advised  to  patients  and  use  Calendula officinalis   preparation with caution. Patients with low  immunity  who  are  in  close  contact with  Calendula officinalis  showed an allergic reaction100Calendula officinalis  has the ability  to  stimulate labor , so  pregnant  women  are specially recommended   to  take care when using Calendula officinalis  preparation101.

CLINICAL STUDIES

In  traditional  medicine  system , C.officinalis  flowers are  reported to  be used  for treating  wounds, scars, skin damage, ulcers. The  therapeutic  application of Calendula officinalis   having  promising  effect are  assessed in human studies are compiled in Table 3. Topical application of Calendula officinalis  suspension or in tincture is used for the    treatment  of  reducing inflammation, controlling bleeding, acne. Additionally, it improve the blood flow to the affected areas and it heals internal as well as external ulcers.

FUTURE PROSPECTS OF HERBAL DRUGS

Now a days people are showing more interest towards the herbal medicines compared to synthetic drug due to its minimum side effects and economic. The various types of Phyto-pharmaceutical are present in the natural products which deliver different types pharmacological activities. The therapeutic efficacy of medicinal plant depends upon the concentration of phytochemical components such as alkaloid, glycoside, tannin, polyphenol, flavonoids, steroids, terpenoids, etc.

The extract of medicinal plant contains more than one phytoconstituents and produce synergistic effects along with antioxidant property. The flavonoids and polyphenol present in Calendula officinalis reduced the oxidative stress in the body and boost the normal cells to fight the diseases with more potency. These antioxidant components are used as nutrient supplement which keep body healthy by increasing the immunity system. It has been reported that the herbal medicines eradicate the diseases from the root level, while the synthetic drug suppressed the diseases. Presently, the novel drug delivery system such as Phytosomes, Liposomes, Niosomes etc improved the bioavailability and therapeutic efficacy of herbal extract.

CONCLUSION

Calendula officinalis is a important medicinal plant and used for the treatment of various diseases. Calendula officinalis is mostly used for the healing of wound by herbal practitioner and the data presented in the paper support significant wound healing activity. Further, health care practitioners should understand the use of CAM for wound healing to assist patients seeking self-care.

CONFLICT OF INTEREST

Nil

AUTHOR’S CONTRIBUTIONS

BD, BB, AS, AMAI, CG and SS equally contributed in the preparation of manuscript, and all author approved for the publication.

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