Herb Highlight

I wanted to share some information regarding the benefits of different herbs and integrative therapies. I am sharing a research paper that I did on licorice root. I hope you enjoy!

Glycyrrhiza glabra is an effective treatment for inflammation and wound healing.

By Julie Howell 08/14/2023

Abstract

Inflammation is a prominent symptom associated with many disease processes and can cause further complications in the body's organs if left untreated. Many standard medications for inflammation, like naproxen and corticosteroids, have unwanted side effects like bleeding concerns or trouble sleeping and weight gain. Finding a treatment to ease inflammation and help heal injuries is beneficial with something that is effective but does not have unwanted side effects. This paper aims to investigate the medicinal benefits of Glycyrrhiza glabra. This paper contains a variety of studies, including an in vitro study, a double-blind randomized, two randomized clinical trials, in vivo study, two histopathological assessments, a randomized experimental study, a research review, and a double-blind clinical trial. The clinical studies reviewed show that Glycyrrhiza glabra effectively treats inflammation and has healing benefits without complications using proper dosing.

Licorice Glycyrrhiza glabra root has been used for thousands of years and is part of the Fabaceae family. A literature review by Ding et al. (2022) found licorice to be the oldest and most widely used herbal remedy. Despite its many incredible medicinal benefits, Licorice has had a bad reputation for its many side effects and contraindications. Licorice is demulcent, antibacterial, and anti-inflammatory, among other things, which has been used for its wound healing and anti-inflammatory benefits (Mills et al., 2005). According to the research, some diagnoses that have had a positive impact from using licorice are fibromyalgia, osteoarthritis, SARS CoV2, wounds, and burn injuries. Some of the studies used a combination of Glycyrrhiza glabra and another herb, like Chen et al. (2021), with success in treating inflammation. Golmohammadii et al. (2023) used a hydroalcoholic licorice root extract to heal wounds with positive results. Many diagnoses benefit from licorice due to its diverse constituent characteristics. This paper will discuss Glycyrrhiza glabra and its potential as an effective inflammation and wound healing treatment when used correctly.

Contraindications

Some concern about using licorice is that it has glycyrrhiza acid, which is primarily responsible for most interactions and side effects. Deglycrrhizinated licorice (D.G.L.) is an extract that has had the glycyrrhizic acid removed, making it safer for use while keeping the benefits (Ulbricht, 2010). Licorice also has diuretic benefits, so use with digoxin is not recommended. Licorice affects hormones, is not recommended during pregnancy or lactating, and can increase blood pressure. Licorice can affect hormone therapy, diabetes, and electrolytes, so like any medication, licorice needs to have its dosing guidelines followed and for the patient to be followed by a practitioner to monitor for any side effects (Ulbricht, 2010).

Dosing

Licorice doses are for adults and should be used three to four times a day unless stated otherwise. The standard dosing noted by Peterson (2023): Decoction; Use 1 teaspoon up to 1 tablespoon. Fluid Extract; Use 2 to 5 milliliters. Infusion; Use 2 to 6 tablespoons. Powder; Use ½ to 1 teaspoon. Syrup; Use one teaspoon to 1 tablespoon. Tincture; Use 2 to 5 milliliters. Mills et al. (2005) specify the dosing recommendations: dried root by infusion or decoction: 3 to 12 g/day, 1;1 liquid extract at 2-6 ml/day, and note that high-dose treatments are not meant for long-term use and that the suggested length of treatment is 4 to 6 weeks.

Results

Cao et al. (2022) examined at a cellular level to see if licorice had benefits for SARS-CoV2. They compared protein binding characters to SARS CoV2 protein binding genes and noted that 101 genes intersected. It was found that the important active constituent, Phaseol in licorice, may reduce the inflammatory response and regulate cells, reducing tissue damage and cell death and promoting new tissue growth. Reisi et al. (2023) also examined licorice at a cellular level by creating a dressing for wounds with nanofibers and hydrogel to assess the healing steps of a wound, including hemostasis, inflammation, and healing phases. To generate this dressing, they used Thymus daenensus and Glycyrrhiza glabra. The dressings were not used in a study but tested in a laboratory to test all their characteristics, like hydrophilicity, swelling properties, and biodegradation rate. The dressing showed antibacterial, antioxidant, and wound-healing activities. The conclusion was that the synergistic effect of the dressing would promote wound healing.

The following studies were completed on animals to see the effects of Glycyrrhiza glabra on inflammation. Chen et al. (2021) used 34 male mice to see the impact of nonalcoholic fatty liver disease (NAFLD), which has gut inflammation. Nine mice were in a non-treatment group, 13 in the HFHS diet group, and 13 in the WLT extract group. This study used a mix of white peony, licorice, grape seeds, and broccoli extracts named WLT. The dosing for humans was established at 150 mg/d of licorice extract with 41.9% of glycyrrhizic acid, 250 mg/d of white peony extract with 35.19% of paeoniflorin, 100 mg/d of broccoli extract with 0.9% of sulforaphane, and 200 mg/d of grape seed extract with 94.8% of proanthocyanin. This study used a low dose of WLT for the mice, which included 22.5 mg/kg of licorice extract, 37.5 mg/kg of white peony extract, 15 mg/d of broccoli extract, and 30 mg/d of grape seed extract and was administered orally with their food. The mice were fed high sucrose diets with or without the WLT extract for 14 weeks and then fed high fatty diets for eight weeks to simulate non-fatty liver disease and introduced fecal microbiome. All groups of mice were then given antibiotic intervention daily. The data assessed included blood serum, blood glucose, metabolism, mRNA gene expressions of 11 proinflammatory cytokines, body mass, and weight, and the liver’s mass and appearance. WLT demonstrated hepatoprotective qualities in the mice fed the WLT extract and showed reduced inflammation.

Golmohammadii (2021) used 36 male rats to see the effects of hydro-alcoholic licorice root extract on surgical gastric ulcer healing. The extract was made from dried and ground licorice root that was then added to 70% ethanol for 72 hours at room temperature. The extract was filtered every 24 hours and added to fresh solvent until it was finally stored in vacuum distillation. There were three groups with 12 rats: a control group and two other treatment groups. All mice received a surgical incision in the gastric area. One group was treated with licorice hydro alcoholic extract at doses of 150 mg/kg, and the other at 300 mg/kg orally once daily for 21 days. The gastric tissue was assessed from 4 random rats from each group at 5, 10, and 20 days from the initial incision, and the results showed that both groups treated with licorice root extract had an accelerated healing process at the gastric surgery site compared to the control group.

A third animal study by Kazemi et al. (2020) investigated the effects of a nanoemulsion cream that contained lavender essential oil and licorice extract. The nanoemulsion cream was used to see the impact on healing deep skin wounds in rats. The licorice extract and lavender oil were purchased and then made into a nanoemulsion by using 2% w/v of both with an emulsifier of tween20 at 5% w/v and tween80 at 2.5% w/v and then magnetically stirred until a good oil base was formed. It was then sealed and placed in 35-degree Celsius storage. The aqueous solution, including glycerin at 15% w/v and polyethylene glycol 400 at 15% w/v, was mixed by stirring and then sealed and stored. The beaker containing the oil base was then placed into a 37-degree Celsius hot water bath on a heater, and the aqueous solution was added to the oil base until it became clear, then transferred to a dark bottle and stored at room temperature. Eighty-five male rats were randomly divided into five groups, each with 17 rats. The first group included untreated defects as a negative control group. The second group was treated with Eucerin ointment, the third group with lavender essential oil and licorice extract in emulsion, the fourth group with lavender and licorice in nanoemulsion forms, and the fifth group with phenytoin 1% as the positive control group. The wound was created with a surgical excision on the dorsal neck of each rat. Treatments were applied topically to cover the whole wound area and applied daily for 14 days. Data collected included wound size, histological tissue samples, oxidative stress factors, and RNA extraction and analysis. Data were assessed on days 2, 7, and 14, showing that the lavender and licorice nanoemulsion, emulsion, and phenytoin groups reduced the wound area and inflammation more than the other groups. While the nanoemulsion and phenytoin had the most outstanding results in granulation tissue, the nanoemulsion cream had the most significant effects in all the varying stages of wound healing.  

Shen et al. (2015) completed a study on the effects of burns also done on rats. Twenty-four male rats were divided into three groups randomly: a control group, a ringer solution-treated group, and a Gly-treated group, with eight rats in each group. The rats received full-thickness scald injury at 30% body surface. Glycyrrhizin at 60 mg/kg was administered intraperitoneally immediately and 24 hours after the burn in the Gly-treated group. The ringer solution-treated group received ringers at 4 ml/kg intraperitoneally immediately and 24 hours after the burn. Data assessed was blood serum from the aorta right after decapitation for assay of TNF-a and IL-1b, cytokines, organ tissue samples, and RNA expression. The results showed that the glycyrrhizin-treated group showed an antiinflammation effect and protected the organs from damage related to the burn injury.

A double-blinded randomized controlled clinical trial by Zabihi et al. (2023) investigated the effects of hydroalcoholic licorice extract on second-degree burns' wound healing process in humans. Dried roots were ground, and then 80% ethanol solvent was added. Contents were placed on a percolator in a closed container for 4 hours and then allowed to soak for 24 hours in the closed percolator. The remaining contents were then compressed, filtered, purified by decantation, and dried. The dried licorice extract was added to 1.160 ml of distilled water and 100 ul of folin-ciocalteu reagent. After several minutes, 300 ul sodium carbonate solution (20% w/v) was added and shaken, placed in a hot water bath, and then 10, 20, and 100 ug/ml concentrations were made. Participants were randomly divided into two groups, the control group had 26 participants, and the licorice extract group had 28. The control group received hydrogel with no extract, and the treatment group received hydrogel with licorice extract. The extract was topically applied twice daily for 15 days without wound dressing or bandages, and data were assessed on the first day and again on 3, 6, 10, and 15 days. The data analyzed included pain intensity, burning, redness, and inflammation. Inflammation was reduced in the licorice group by day three compared to the non-licorice group, which saw inflammation reduction on the sixth day.

Najafi et al. (2016) investigated the effects of glycyrrhiza glabra on inflammation. They used a double-blind clinical trial. Thirty-seven participants with head and neck cancer undergoing radiotherapy at 50-60 gy were divided into two groups. The extract was prepared using 500 g of Glycyrrhiza glabra root powder and added to 2 L of distilled water. The contents were stored overnight at room temperature and then filtered three times with thin cotton fabric. The solution was then placed on a vacuum distiller and refrigerated. The first group was an intervention group with nineteen participants receiving Glycyrrhiza aqueous extract and a control group with eighteen participants receiving a placebo. 100 cc of 50% aqueous extract of Glycyrrhiza for the treatment group and the same amount of placebo containing approved brown food dye in 2 L of water for the placebo group. Patients were to use 20 cc twice per day for 14 days. Participants were also asked to brush their teeth three times a day. Data assessed included mucous irritation, redness, and wounds. If wounds, the wound size was evaluated. The results indicated decreased oral mucositis, wound size, and decreased oral irritation for the participants receiving Glycyrrhiza aqueous extract.

Discussion

The research reviewed showed wound healing capabilities as a hydrogel dressing, nanoemulsion cream, hydro alcoholic extract, aqueous extract, additive to food, and intraperitoneally. The studies also used a combination of extract or licorice as a stand-alone treatment. Glycyrrhiza glabra demonstrated healing benefits to burns, incisions, oral mucositis, and hepatic protective qualities. The dosing varied by route of administration, with topical use being the most observed. None of the studies reviewed used the DGL extract, showing that Glycyrrhiza glabra can be safely used and effective without unwanted side effects. With the various studies researched, Glycyrrhiza glabra shows promising results as an effective inflammation and wound healing treatment when dosed correctly in humans and animals alike.

Conclusion

All of the studies showed improvement in wound healing and inflammation. Varying doses and different extract types of Glycyrrhiza glabra were used. Some studies on humans and animals, but all had consistent results with improvement or preventative qualities for inflammation and wounds. All of the studies were on the small side, and most researched studies were completed on animals or testing healing properties in the lab. More extensive studies done on humans would be beneficial to see the full healing spectrum of Glycyrrhiza glabra. Chen et al. (2021) was a complex study to understand. Zabihi et al. (2023) did state that the intervention and control groups had different burn percentages, with the licorice extract group having a higher percentage rate of burn area, indicating that the burn wound healing process was more desirable in the licorice extract group and that it does not affect the results, and may show a better result than the effect obtained. Najafi et al. (2016) did say that a more extensive, better-designed study should be completed. However, the literature reviewed does support the use of Glycyrrhiza glabra as an effective treatment for inflammation and wound healing. 

References

Cao, J.-F., Gong, Y., Wu, M., Yang, X., Xiong, L., Chen, S., Xiao, Z., Li, Y., Zhang, L., Zan, W., & Zhang, X. (2022). Exploring the mechanism of action of licorice in the treatment of COVID-19 through bioinformatics analysis and molecular dynamics simulation.  Frontiers in Pharmacology,13, 1003310. https://doi.org/10.3389/fphar.2022.1003310

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Kazemi, M., Mohammadifar, M., Aghadavoud, E., Vakili, Z., Aarabi, M. H., & Talaei, S. A. (2020). Deep skin wound healing potential of lavender essential oil and licorice extract in a form: Biochemical, histopathological, and gene expression evidence.  Journal of Tissue Viability, 29(2), 116–124. https://doi.org/10.1016/j.jtv.2020.03.004

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