Comparing efficacy of curcumin with other treatment modalities in oral submucous fibrosis management - A systematic review and meta-analysis

Abstract

Background

Oral Submucous Fibrosis, OSF is an inflammatory mucosal disorder prevalent in areca nut chewing belts of the world. Although various treatments are available for its management, none provide complete resolution.Curcumin, an indigenous product, improves burning sensation, mouth opening along with other clinical signs of OSF and is potentially viable therapeutic option for its management.

Objectives

To assess the available evidence for employing curcumin in improving symptoms in patients with OSF.

Methods

Systematic search was carried out in e-databases from January 2010 until July 2023 to identify relevant clinical trials comparing curcumin to active and/or nonactive controls (placebo) for the management of OSF.

Results

A total of 20 studies were used for qualitative analysis out of which 11 studies were considered for quantitative synthesis.Curcumin was found to be highly effective in alleviating pain/burning sensation, improving mouth opening (MO), cheek flexibility, tongue protrusion and induces positive histological changes in patients with OSF.The standardized mean difference in mouth opening between both the Curcumin and Multivitamin group showed a statistically significant difference favouring the Curcumin group (SMD, 0.37, 95% CI = 0.18–0.56, p - 0.0001, I²- 0%).

Conclusion

Statistically curcumin was noted to be as effective as Aloe vera, lycopene and steroids in relieving symptoms of OSF in stages 1 and 2 and improving MO. It is seen to improve histopathological picture of lesions thereby suggesting its active role in preventing malignant transformation. Its found to be more effective than multivitamins in improving mouth opening of patients in OSF.

1. Introduction

Oral Submucous Fibrosis (OSF) is a premalignant disorder commonly seen in Southeast Asian countries where betel nut is commonly chewed. Incidence of OSF is now reported worldwide due to immigration and cross border travel. Consumption of areca nut, chillies, nutritional deficiencies, genetic and immunological processes are its potential etiological factors (Ref [1]).

In India, almost 0.2–2.3% males and 1.2–4.6 % females suffer from OSF (Ref [2]). In almost 7–30% cases malignant transformation of OSF takes place as reported across studies in India, Pakistan and Taiwan (Ref [3,4]).

Topical and intralesional steroids, fibrinolytics, antioxidants, dietary supplements, lycopene, immunized milk have been tried for management of OSF but none offer complete relief. Curcumin (diferuloylmethane) has sparked interest in recent years for its anti-inflammatory, immunity boosting, antioxidant, antiviral, antimicrobial, antifungal, antiallergic and anti-cancer properties. Numerous clinical trials with inconclusive outcomes are reported in literature for management of OSF. This necessitates the need of systematic review and meta-analysis to qualitatively and statistically evaluate available data for the benefit of masses.

2. Methodology

This systematic review and meta-analysis were performed in accordance with PRISMA 2020 (Ref [5])statement guidelines, the Cochrane Handbook for systematic reviews of interventions (Ref [6]) version 5.1.0 and is registered at PROSPERO under the registration code, CRD42023446682.

The research question was “Is there a difference in the chemo-preventive efficacy of curcumin as compared to other medical interventions in the management of Oral Submucous Fibrosis?”

2.1. Inclusion criteria

Population (P): Subjects diagnosed clinically or histopathologically with OSF.

Interventions (I): Studies using topical/systemic forms of curcumin.

Comparison (C): Studies using any other medicinal intervention or placebo.

Outcome (O): Primary outcome: Studies assessing either or all of the following outcomes at minimum of one week follow-up interval mouth opening (MO) or Inter-incisal distance, burning sensation, tongue protrusion, cheek flexibility.

Secondary outcome: Studies assessing color of mucosa, blanching, presence of fibrous bands and histopathological grading at minimum of one week follow-up interval.

3. Exclusion criteria

• •Studies involving participants with history of significant medical conditions or on medication that could affect the effect of the agents.
• •Studies involving multiple drugs in combination with curcumin that will have synergistic effect with curcumin.
• •Single drug trials without control group.
• •Observational study designs, case reports, case series, cross-sectional studies and reviews.
• •Article reporting only abstracts and whose full-texts were not available in the database.

Study design(S): Clinical trials, randomized controlled studies (RCT), non-randomized control trials (NRS), Quasi experimental studies, and cohort studies.

3.1. Search strategy

From January 2010 to July 2023, a comprehensive search was conducted throughout PubMed, MEDLINE, DOAJ, Cochrane Library, and Scopus databases for English-language literature. Based on PICOS, pertinent MeSH terminology and free text terms were chosen. MeSH terms used were oral sub mucous fibrosis, curcumin, clinical trials, randomized control trials. Boolean operators (OR, AND) were used to frame the search strategy and Google Scholar, Greylist, and OpenGrey were used for cross-reference, citation chasing, and grey literature screening of the articles.

3.2. Screening and selection of studies

Based on eligibility requirements, two reviewers separately completed a three-step process to choose studies from databases. The titles were initially reviewed as per inclusion criteria. In second phase, screening was done using abstract as a guide. In third step, full articles were read to confirm that the studies met the eligibility requirements. Cohen's kappa was used to determine degree of concordance between two reviewers: 0.92 for titles, abstracts and 0.94 for texts. Through extensive conversation, third author was able to address disagreements between writers and reviewers.

3.3. Data extraction

This was done in “Microsoft Excel version (2013)” spreadsheet as per the standard guidelines (Table 1).

Table 1.

Study design and characteristics table.

Study Id	Study Design	Sample Size I1/I2/I3/C1/C2	Intervention & Dosage	Control &Dosage	Mode of administration- I1/I2/I3/C1/C2	Outcome assessed	Authors Conclusions
Upadhyay P et al 2023	Prospective, randomized, and comparative study	30/−/−/30/-	Curcumin lozenges Total daily dose was 2 g	Topical clobetasol propionate (0.05%) 15 g of tube for one week use	S/−/−/T/-	Burning sensation Mouth opening	Clobetasol provides better improvement for the management of Stage I and II OSMF.
Namratha K et al., 2023	Intervention Study	14/−/−/14/-	Capsule curcumin 400 mg twice daily for three months	Placebo (Sugar capsule) Twice daily	S/−/−/S/-	Mouth opening Burning sensation	In combination therapy in the initial management curcumin can help patients with their clinical symptoms.
Verma N et al., 2022	Open label, prospective, comparative and randomized controlled study	39/−/−/40/-	Curcumin Capsule 2 capsule twice daily, for 12 weeks Curcumin gel Local application 3 times a day for 12 weeks	Conventional or Standard Treatmentprescribed by the investigator Dose Not mentioned	S + T/−/−/L/-	Burning sensation Mouth opening	SNEC 30 capsule and gel showed better results Also test formulations were more effective in decreasing burning sensation OSF patients
Deepak TA et al., 2021	Non-RCT	15/−/−/15/-	Curcumin tablet 1000 mg (500 mg BD)	Topical Steroid Gel 0.01% gel thrice daily	S/−/−/T/-	Burning Mouth opening	Curcumin is comparatively more efficient than steroids
Rajbhoj A et al., 2021	Parallel group, prospective study	30/−/−/30/-	Curcumin gel + physiotherapy 5 mg of gel to be applied 3–4 times a day	Aloe Vera gel + oral physiotherapy exercises Total 5 mg of gel to be applied 3–4 times a day	T/−/−/T-	Burning Mouth opening	Aloe Vera gel is more efficacious in burning sensation improvement without any side effects.
Sweta DS et al., 2021	Comparative study	15/−/−/15/15	Turmeric and jaggery application Twice a day	Topical application of KenacortTM 0.1% Twice a day Advised mouth opening exercisesTwice a day	T/−/−/T/E	Mouth opening	Topical application of kenacort found to be better as compared to use of jaggery and physiotherapy
Srivastava R et al., 2021	Prospective study	40/−/−/40/-	Curcumin lozenges Turmeric extract 100 mg along with clove oil 10 mg three times daily for 3 months.	Intralesional infiltration of 2 ml dexamethasone + hyaluronidase 1500 Twice a week for 3 months	S/−/−/L/-	Burning sensation Mouth opening Tongue protrusion	Clinical improvement in the curcumin group
Zeya T et al., 2021	Comparative study	10/10/10/10/-	Curcumin tablet 350 mg- thrice daily Curcumin capsules 500 mg- twice daily Curcumin oil 10 ml topically for 15 min twice daily	Multivitamin tablets 500 mg- twice daily	S/S/T/S/-	Burning sensation Mouth opening Tongue protrusion Cheek flexibility	Turmeric is a safe, nontoxic, and an effective substitute for many conventional drugs
Lanjekar A 2020	No RCT	40/−/−/40/-	Mucoadhesive semisolid gel of curcumin 1 cm patch to be used 3 times daily for 6 weeks	Mucoadhesive semisolid gel of triamcinolone acetonide and hyaluronidase 1 cm patch to be used 3 times daily for 6 weeks	T/−/−/T/-	Mouth Opening Burning Sensation Color of Oral Mucosa	Curcumin role in treatment of oral cancers and precancer lesion is very promising.
Piyush P et al., 2019	Randomized placebo-controlled parallel study	30/−/−/30/30	Curcumin and Piperine 300 mg 300 mg 1 tablet two times daily	Lycopene capsules 8 mg 8 mg 1 tablet two times daily Placebo capsules constituting of starch IP and lactose monohydrate IP Once daily	S/−/−/S/S	Mouth opening Burning sensation Tongue protrusion Cheek flexibility	Curcumin and Lycopene are equally effective in the management of both subjective and objective symptoms of OSF
Rai A et al., 2019	Randomized parallel‐group multi‐arm single‐center trial	40/40/-/39/-	Turmix Tablet 3 times per day for 12 weeks Turmix Tablet 3 times per day for 12 weeks Turmix Mouthwash 2 times per day for 12 weeks	Antioxidant Capsule Twice daily for 12 weeks	S/S + T/-/S/-	Burning sensation Mouth opening Tongue protrusion	Superior improvement in mouth opening, tongue protrusion in patients who are given combination therapy
Ara S 2018	Randomized single blinded placebo controlled clinical trial study	50/−/−/50/-	Curcumin capsules 500 mg- 2 capsules per day	Placebo capsule 2 capsules per day	S/−/−/S/-	Burning Sensation Mouth opening Tongue protrusion Cheek flexibility	curcumin group showed statistically significant improvement in subjective signs and symptoms,histopathological changes when compared with placebo group
Meshram M 2018	Non RCT	20/−/−/20/20	Turmeric gel Thrice daily for 1 month	Ultrasound therapy Alternate days in a week for one month Aloe-Vera gel Thrice daily for one month	T/−/−/U/T	Burning sensation Mouth opening Tongue protrusion	Aloe-Vera and Turmeric, proved as safe, non-invasive and effective treatment modalities in improving mouth opening, tongue protrusion, cheek flexibility and reduction in burning sensation
Saran G et al., 2018	Randomized Clinical Trial	30/−/−/30/-	Curcumin tablets One tablet thrice daily for 3 months	Lycopene capsules (Lycored) One tablet 2 times a day for 3 months	S/−/−/S/-	Burning sensation Mouth opening	lycopene is better than curcumin in improving mouth opening and both the medication showed beneficial effect on reducing symptoms
Shah A et al., 2018	Comparative study	30/30/30/30/-	Curcumin tablet 350 mg- thrice daily for 15 days Curcumin capsules 500 mg- twice daily for 15 days Curcumin oil 10 ml topically for 15 min twice daily	Multivitamin tablets 500 mg- twice daily	S/S/T/S/-	Burning sensation Mouth opening Tongue protrusion Cheek flexibility	Statistically significant improvement was observed with systemic curcumin and curcumin oil when compared to multivitamin tablets
Dhimole A et al., 2017	Non RCT	15/15/-/15/-	Turmix tablets 300 mg- twice daily Heal plus gel Three times a day	Multivitamin group of drugs	S/T/-/S/-	Burning sensation Mouth opening Cheek flexibility Tongue protrusion	Systemic therapy of curcumin is best in improving clinical signs and symptoms.
Kopuri R et al., 2016	Non RCT	15/−/−/15/-	Curcumin Longa (Haridra capsules) 800 mg/day in 2 divided doses for 3 months	Lycopene (Lycored capsules) 8 mg/day in 2 divided doses for 3 months	S/−/−/S/-	Burning sensation Mouth opening Blanching Fibrous bands	Lycopene is better when compared to curcumin
Hazarey V et al., 2015	RCT	15/−/−/15/-	Curcumin lozenges (Longvida) 2 g per day	Tenovate ointment (clobetasol propionate (0.05%) Apply the cream 3 times daily	S/−/−/T/-	Burning Sensation Mouth opening	Combination strategies for the more efficient than single therapeutic modality
Yadav M et al., 2014	Randomized open label, interventional study	20/−/−/20/-	Curcumin Longa (Turmix tablet) 2 tablets once daily for a period of 3 months	Submucosal intralesional injections of Dexamethasone with (1:80,000) Lignocaine Hydrochloride Weekly for 3 months.	S/−/−/-/L/-	Burning sensation Mouth opening Tongue Protrusion	Turmix is effective in reducing burning sensation in early OSF patients.
Das D et al., 2010	RCT	16/16/-/16/-	Curcumin Capsule Two capsules twice daily making a daily dose of 1 gm Turmeric Oil 12 drops of the oil making a daily dose of 600 mg	Multinal tablets 1 gm/day	S/S/-/S/-	Burning sensation Mouth opening Histological grading	Curcumin and turmeric oil is beneficial, affordable and noninvasive form of treatment in patients with OSMF.

C= Comparator group, I= Intervention group, D = Days, E = Exercises, L = Intralesional Injection, M = Months, OSMF= Oral submucous fibrosis, RCT = Randomized Controlled Trials, S= Systemic, T = Topical, U= Ultrasound therapyu, W=Weeks.

3.4. Assessment of the Risk of Bias (ROB) and quality

“Cochrane ROB assessment tool” (Ref [7]) was used for categorizing the studies into high, medium, and low risk for further inclusion in quantitative analysis. The quality of NRS was assessed using Minors checklist (Ref [8]), wherein the minimum outcome assessment at one week follow-up time interval was considered appropriate for the included studies.

3.5. Statistical analysis for quantitative synthesis

Utilizing Review Manager (RevMan) 5.3, statistical analysis was conducted. P < 0.05 was regarded as significant. The combined results were presented as mean and standard deviation for continuous data at 95% confidence intervals (CIs). To determine if the observed difference across the studies was homogenous or heterogeneous, chi-square and tau-square analyses were employed.

The I2 test was utilized to evaluate statistical heterogeneity at α = 0.10. Subgroup analysis was conducted for I²>50% and P ≤ 0.10. For I²>50%, random-effects model was applied. Also, the statistical significance was set at p-value (two-tailed) <0.05. Detection of publication bias using funnel plots done for studies exceeding 10 in number for each outcome assessed (Ref [9]).

4. Results

4.1. Literature search and study selection

The screening process is explained in the form of the PRISMA flowchart 2020 (Fig. 1)

Fig. 1.

PRISMA flow diagram.

4.2. Study characteristics

All included trials were unicentric published between 2010 and 2023, conducted in India. Seven studies were RCTs [14,[19], [20], [21],23,27,28], 13 studies were NRS [[10], [11], [12], [13],[15], [16], [17], [18],22,[24], [25], [26],29]. 1244 subjects were included, 665 in intervention group and 579 in control group.

Methodological heterogeneity was observed between studies due to differences in anatomic location of OSF and type of administration of intervention/control. Most studies advocated mouth exercises/mouth devices/cheek blowing exercise for 10 min twice a day along with motivational interviewing to improve MO.Outcome parameters assessed post-intervention varied across studies where changes in burning sensation, MO, tongue protrusion and cheek flexibility were considered as primary outcomes and were evaluated at varying time intervals of minimum of one week and maximum of nine months. The improvement of burning sensation/pain after having spicy food was assessed by VAS on ten-point Likert scale as mean pain score (Ref 10, 11–13, 16–29) or categorized as mild, moderate and severe pain (Ref 25, 26) or in percentage reduction from baseline (Ref 21) in eighteen studies. The improvement in the MO was evaluated as mean increase in scores post treatment in all studies. The improvement in tongue protrusion was recorded as mean increase in scores post treatment in nine studies (Ref 16,17, 19, 20, 21, 22, 24, 25, 28). The increase in cheek flexibility was measured as mean increase in scores post treatment in five studies (Ref 17, 19, 21, 24, 25). The secondary outcomes assessed across studies were color of mucosa (Ref 18), blanching (Ref 21, 26), presence of fibrous bands (Ref 22) and histopathological grading (Ref 29).

The study conducted by Verma N et al. (Ref 12) compared the combination of systemic and topical form of curcumin with convention standard treatment (not specified)and evaluated the outcomes burning sensation and MO as mean differences with the groups without providing the mean and standard deviation values.

Similarly, the study by Yadav M et al. (Ref 28) compared turmeric tablets with intralesional injections and Lanjekar A et al. (Ref 18) compared mucoadhesive curcumin gel with triamcinolone acetonide and hyaluronidase gel and evaluated outcomes of burning, MO and tongue protrusion as mean differences values.

The study by Sweta DS et al. (Ref 15) compared turmeric and jaggery application with topical Kenacort (topical steroid) and physiotherapy groups and evaluated the outcomes of MO only as mean values.

Hence, the four studies were not included in meta-analysis, and only qualitative analysis was conducted (Table 2).

Table 2.

Methodological index for non-randomized studies (MINORS).

	A clearly stated aim	Inclusion of consecutive patients	Prospective collection of data	Endpoints appropriate to the aim of the study	Unbiased assessment of the study endpoint	Follow-up period appropriate to the aim of the study	Loss to follow up less than 5%	Prospective calculation of the study size	bAn adequate control group	bContemporary groups	bBaseline equivalence of groups	bAdequate statistical analyses	Total
Upadhyay P et 2023	2	2	2	2	2	2	2	0	2	2	2	2	22
Namratha K et al 2023	2	2	2	2	2	2	2	2	2	2	2	2	24
Verma N et al 2022	2	2	2	2	2	2	2	0	2	2	2	2	22
Deepak TA et al 2021	2	1	2	2	1	2	2	0	2	2	2	2	20
Sweta DS et al 2021	2	1	1	2	1	2	2	0	2	2	2	0	17
Srivastava R et al 2021	2	2	2	2	2	2	2	0	2	2	2	2	22
Zeya T et al 2021	2	1	2	2	1	2	2	0	2	2	2	0	18
Lanjekar A et al 2020	2	2	2	2	2	2	2	0	2	2	2	2	22
Meshram M et al 2018	2	1	2	2	1	2	2	1	2	2	2	1	20
Shah A et al 2018	2	1	2	2	1	2	2	0	2	2	2	0	18
Dhimole A et al 2017	2	1	2	2	1	2	2	0	2	2	2	2	19
Kopuri R et al 2016	2	2	2	2	1	2	2	0	2	2	2	2	21
Das D et al 2010	2	1	2	2	2	2	2	0	2	2	2	0	19

The items are scored 0 (not reported), 1 (reported but inadequate) or 2 (reported and adequate). The global ideal score being 16 for non-comparative studies and 24 for comparative studies.

^bFor study with control group.

The studies conducted by Namratha K et al., 2023 (Ref 11), Srivastava R et al., 2021 (Ref 16), Piyush P et al., 2019 (Ref 19), Das D et al., 2010 (Ref 29) assessed the outcomes at different time intervals, scoring criteria and with different comparator groups, they were not considered for quantitative synthesis (Table 1). Study conducted by Deepak TA et al., 2021 (Ref 13) calculated the outcomes as mean percentage change, hence was not included in meta-analysis.

4.3. Assessments of the level of evidence, ROB and quality

The quality assessment of seven RCTs was executed according to the Cochrane ROB Tool (Ref 14, 19–21, 23, 27, 28) and thirteen studies using MINORS (Ref 10–13, 15–18, 22, 24–26, 29)In RCTs, two studies showed a low ROB (Ref 19,20), one presented a moderate risk (Ref 28) and four had a high ROB [14,21,23,27] (Fig. 2a, Fig. 2ba and b).

Fig. 2a.

Risk of Bias graph.

Fig. 2b.

Risk of bias of individual studies.

Score of 17–24 was observed in NRS trials. Majority of studies were scored 0 on criteria of prospective calculation of the study size and adequate statistical analyses (Table 2)

4.4. Synthesis of results

Eleven papers in all met the requirements for quantitative analysis's inclusion. Trials comprising many types of curcumin groups in the form of tablets, capsules, gels, or oils were analysed independently and regarded as distinct research. Subsequently, five meta-analyses (MA), including three subgroup analysis for different time intervals, was performed for assessing the mouth opening, mouth burning, and tongue protrusion efficacy of curcumin as compared to other medical interventions.

4.4.1. Curcumin versus steroid gel for mouth opening

The MA of two studies (Ref 21, 27) assessing the standardized mean difference (SMD) in mouth opening parameter at 6-month time interval between curcumin and steroid gel group was carried out using random effect model (REM). SMD for increase in mouth opening favoured curcumin group but the difference was statistically insignificant when compared to steroid gel group (p-0.23)

4.4.2. Curcumin versus lycopene for mouth opening

The MA of two studies (Ref 23, 26) assessing the SMD in mouth opening between Curcumin and Lycopene was carried out as subgroups analysis using REM according to the time interval of 1 month, 2 months and 3 months. At 1- month, significant difference in mouth opening favouring the curcumin group (p = 0.0001) was observed. At 2 and 3 months, SMD the in mouth opening between both the groups was statistically insignificant (p = 0.55) and (p = 0.42) respectively. When the total analysis using REM irrespective to the time interval was considered for a total sample size of 135 samples per curcumin and lycopene groups, the SMD in mouth opening between both the groups was again statistically insignificant (p = 0.68)

4.5. Curcumin versus aloe vera for mouth opening

The forest plot of two studies (Ref 14, 22) assessing the SMD in mouth opening parameter at 6-week time interval between curcumin and aloe vera group was carried out using REM. No significant difference was observed (p = 0.94)

4.6. Curcumin versus multivitamin

4.6.1. Mouth opening

The MA of two studies (Ref 20, 25), with two different forms of Curcumin each compared to the Multivitamin group assessing the SMD in mouth opening was carried out as subgroups analysis using REM according to the time interval of 2 weeks and 12 weeks. At 2

Weeks and 12 weeks, significant difference in SMD in mouth opening between both the groups favouring the curcumin group (p = 0.0009)respectively was observed. When the total analysis using REM irrespective to the time interval was considered for a total sample size of 220 and 216 samples for Curcumin and multivitamin groups respectively, the SMD in mouth opening between both the groups showed a statistically significant difference favouring the curcumin group (SMD, 0.37, 95% CI = 0.18–0.56, p - 0.0001, I 2 - 0%) (Fig. 3a)

Fig. 3a.

Forest plot comparing Curcumin with Multivitamin for mouth opening.

4.6.2. Tongue protrusion

The MA of four studies (Ref 17, 20, 24, 25), with different forms of curcumin each compared to the multivitamin group assessing the SMD in tongue protrusion was carried out as subgroups analysis using REM according to the time interval of 2, 4, 6, 8 and 12 weeks. At 2, 4, 6, 8 and 12 weeks, no statistically significant difference in SMD in tongue protrusion between both the groups was observed. Similarly, the total analysis using REM irrespective to the time interval was considered for a total sample size of 770 and 802 samples for curcumin and multivitamin groups respectively, the SMD in tongue protrusion between the groups was statistically insignificant (Fig. 3b).

Fig. 3b.

Forest plot comparing Curcumin with Multivitamin for Tongue protrusion.

DISCUSSION: Curcumin is the active ingredient of turmeric, a popular household Indian spice. Used since ancient times, in ayurveda, as an invaluable herb for its antifibrotic, anti-inflammatory, anti-oxidant, blood thinner, anti-carcinogenic and antibiotic properties, it has recently been observed to offer promising relief in cases of OSF in relieving burning mouth, improving mouth opening, tongue protrusion and cheek flexibility. This review concludes that curcumin is better than multivitamins in improving mouth opening in patients.Its usage also improves the histological picture of existing lesions thereby suggesting that it may play an active role in preventing the malignant transformation of existing lesions. It can therefore be used as an affordable, safe and effective intervention to conventional treatments in countries where the disease burden is high.

Conclusion: Curcumin is a naturally occurring powerful antioxidant and anti-inflammatory and offers great promise in improvement of symptoms of patients with OSF. It does not have any side effects that the synthetic medications like steroids and hyaluronidase- the current mainstay of OSF treatment may have. Statistically this review concludes that curcumin gives better therapeutic results than multivitamins in improving mouth opening in patients and is as good as steroids, lycopene and aloevera statistically.

Funding sources

None.

Author Contributions

M.W. and R.S.: writing original draft conceptualization: designing, analyzing, and interpreting the data: K.B, M.W, R.S, S.P: screening, analysis and interpretation of data: R.M, K.G. and R. S supervise and interpret the data. All authors are involved in drafting and revising of the manuscript.

Declaration of generative AI in scientific writing

None.

Conflict of Interest

None.