The purpose of the present investigation was to formulate and evaluate anti-nail-biting lacquers consisting of bitter herbal extracts. The hydroalcoholic extracts obtained from
Onychophagia (nail biting) means putting one or several fingers in the mouth and biting on nail with teeth. It is a chronic behavioral disorder in children and adults that commonly cooccur with thumb and finger sucking [
There are several approaches to cease from nail biting and finger sucking, such as painting a bitter tasting lacquer containing denatonium benzoate and sucrose octa-acetate onto the nails [
As in earlier studies, the pitfalls of classical anti-nail-biting lacquers were unclear toxicity of synthetic polymers and bitter substances, apply several times daily due to easy to wash off, and cross contamination of nail lacquers during cooking and eating [
A chronic habit of nail biting or finger sucking causes dry and peeling skin and leads to inflammation of the skin surrounding the nail [
A coating of nail lacquer can protect thin, friable, vulnerable, and irregular nails along with giving a sustainable exterior layer in order to make them look stronger and more beautiful [
Nail lacquers generally consist of film-forming polymers, volatile solvents, plasticizing agents, and dyes [
With regard to help people safely utilize nail lacquers, it is important to study the materials engaged in the production of nail lacquers. Synthetic resins (e.g., toluenesulfonamide-formaldehyde, polyvinyl butyral, and polyester resins) may lead to paronychia, onycholysis, and onychodystrophy [
Natural lac is a resin secreted by lac insects (e.g.,
The objective of this study was to develop nontoxic anti-nail-biting lacquers containing bitter herbal extracts obtained from
Ethanol was supplied by Thai Food and Chemical Co., Ltd., Bangkok, Thailand. All chemicals utilized in phytochemical screening were of analytical grade purchased from Sigma-Aldrich Corporation (Missouri, USA). Potassium bromide, FTIR grade, attained from Thermo Fisher Scientific (Massachusetts, USA). Folin-Ciocalteu was purchased from Loba Chemie (Mumbai, India). Gallic acid, sodium carbonate, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,4,6-tris(2-pyridyl)-s-triazine (TPTZ), acetate buffer, ferric chloride hexahydrate, and bovine serum albumin were procured from Sigma-Aldrich Corporation (Missouri, USA). L-Ascorbic acid was obtained from Chem-Supply Pty Ltd. (Gillman, South Australia). Ultrapure water generated by GenPure equipment (TKA Wasseraufbereitungssysteme GmbH, Niederelbert, Germany) and ICP multielement standard solution XIII obtained from Agilent Technologies (Santa Clara, USA) were utilized to determine heavy metal contents. Diclofenac diethylamine and microbiological media were acquired from Merck KGaA (Darmstadt, Germany). Iscove’s Modified Dulbecco’s Media (IMDM), fetal bovine serum (FBS), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and dimethyl sulfoxide (DMSO) were purchased from Sigma-Aldrich Corporation (Missouri, USA). Dewaxed bleached shellac and polyvinylpyrrolidone (PVP K30) USP were procured from Union Shellac Part., Ltd. (Bangkok, Thailand) and Shanghai Yuking Chemtech Co., Ltd. established by China Functional Polymer Industry Committee (Shanghai, China), respectively.
The dried aerial parts of
Dried aerial parts of
Preliminary phytochemical screening tests in the 10 mg/ml ethanolic solutions of
For ferric chloride test, several drops of 10%
For lead acetate test, a few drops of 10%
2 ml of glacial acetic acid and 1 ml of ferric chloride were transferred into 1 ml of sample solution, and then, 1 ml of concentrated sulfuric acid was added. The appearance of blue-green color represents the presence of glycosides.
Ten drops of each solution A and B were added to a test tube containing 2 ml of sample solution. After heating for 15 min at
For Dragendorff’s test, the sample solution was acidified with diluted hydrochloric acid. The mixture was heated on a water bath and then filtered through a Whatman no. 1 filter paper. Equal volumes of the resulting solution and Dragendorff’s reagent were reacted. The formation of an orange red precipitate indicates the existence of alkaloids.
For Mayer’s test, equal volumes of the resulting solution and Meyer’s reagent were mixed. The turbidity or a yellow precipitate indicates the presence of alkaloids.
For frothing test, 5 ml of distilled water was added to a test tube containing 2 ml of sample solution. The mixture was shaken for 5 min to observe the formation of 1 cm thick layer of stable liquid foams.
1.5 ml of sample solution was mixed with 1 ml of chloroform, and then, 1 ml of concentrated sulfuric acid was slowly added to form a reddish-brown layer at the junction specifying the presence of terpenoids.
For ferric chloride test, 2 ml of sample solution was treated with 1 ml of 10%
For Shinoda’s test, 1.5 ml of sample solution was treated with 1 ml of methanol. The solution was warmed, and magnesium ribbons were added. 5 drops of concentrated hydrochloric acid were carefully added, and orange or red color was observed for flavonoids.
1.5 ml of chloroform was mixed with 1.5 ml of sample solution. 0.5 ml of acetic anhydride and 1 ml of 10%
With regard to produce potassium bromide (KBr) pellets of
Total phenolic contents of
Free radical scavenging activities of samples were assessed by a modified DPPH method [
Ferric reducing antioxidant power (FRAP) assay was carried out in keeping with our foregoing report [
Inhibition of protein denaturation was determined according to our previous procedure [
After nitric acid assisted closed vessel microwave digestion, the concentrations of arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) in samples were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) as described in our previous report [
The microbiological examination including total aerobic mesophilic microorganisms (bacteria, yeast, and molds),
The cellular viability of human dermal fibroblasts was evaluated upon treatment with either bitter extract or bitter nail lacquer using MTT colorimetric assay [
Film-forming solutions with various concentrations (10, 15, 20, 25, and 30%
Evaluation of drying time and weight gain of extract-free nail lacquers.
Film-forming solution no. | Concentrations of shellac (% | Drying time (min) | Weight gain (g) |
---|---|---|---|
1 | 10 | 15 | |
2 | 15 | 16 | |
3 | 20 | 17 | |
4 | 25 | 21 | |
5 | 30 | 26 |
The formulations containing either
Composition, homogeneity, viscosity, and bitterness of nail lacquers containing bitter extract.
Formulation no. | Concentrations (% | Homogeneity | Viscosity | Bitterness | ||
---|---|---|---|---|---|---|
Shellac | ||||||
1 | 10 | 10 | +++ | + | + | |
2 | 10 | 15 | ++ | ++ | ++ | |
3 | 10 | 20 | ++++ | +++ | ++ | |
4 | 10 | 25 | + | +++ | + | |
5 | 20 | 10 | +++ | + | + | |
6 | 20 | 15 | ++ | ++ | +++ | |
7 | 20 | 20 | ++++ | +++ | ++++ | |
8 | 20 | 25 | + | ++++ | ++ | |
9 | 30 | 10 | Precipitation | + | + | |
10 | 30 | 15 | Precipitation | ++ | + | |
11 | 30 | 20 | Precipitation | +++ | + | |
12 | 30 | 25 | Precipitation | ++++ | + | |
13 | 10 | 10 | +++ | + | + | |
14 | 10 | 15 | +++ | ++ | ++ | |
15 | 10 | 20 | ++ | +++ | ++ | |
16 | 10 | 25 | + | +++ | + | |
17 | 20 | 10 | +++ | + | + | |
18 | 20 | 15 | +++ | ++ | +++ | |
19 | 20 | 20 | +++ | +++ | ++++ | |
20 | 20 | 25 | + | ++++ | + | |
21 | 30 | 10 | Precipitation | + | + | |
22 | 30 | 15 | Precipitation | ++ | + | |
23 | 30 | 20 | Precipitation | +++ | + | |
24 | 30 | 25 | Precipitation | ++++ | + |
The nail lacquers containing 20%
Composition of developed nail lacquers containing bitter extract and copolymer.
Formulation no. | Concentrations (% | |||
---|---|---|---|---|
Shellac | PVP K-30 | |||
7A | 20 | 10 | 10 | |
7B | 20 | 15 | 5 | |
19A | 20 | 10 | 10 | |
19B | 20 | 15 | 5 |
Each prepared formulation was gently applied in the same direction on an acrylic fake nail with a brush. After hardening of a film at
Physicochemical and mechanical properties of developed nail lacquers containing bitter extract and copolymer.
Formulation no. | pH | Viscosity (cP) | Drying time (min) | Weight gain (g) | Film thickness (mm) | Stress (N/mm2) |
---|---|---|---|---|---|---|
7A | ||||||
7B | ||||||
19A | ||||||
19B |
The water resistance test was done by applying a tested nail lacquer onto a Teflon tray, leaving it to dry, peeling it off, cutting it to the same size, weighing each piece of film (known dry weight,
The percentages of the remaining weight obtained from water resistance and bitterness release tests are illustrated in Table
Percentages of the remaining weight of lacquer films after testing in distilled water (at
Formulation no. | Water resistance test (in distilled water) | Bitterness release test (in simulated saliva) | ||
---|---|---|---|---|
Percentages of the remaining weight (%) | Time (min) | Percentages of the remaining weight (%) | Time (min) | |
7A | 180 | 60 | ||
7B | 180 | 40 | ||
19A | 180 | 60 | ||
19B | 180 | 40 |
A total of 20 healthy participants (10 males and 10 females) ranging in age from 18 to 30 years volunteered to participate in the study. All of them were non-Muslims and had no prior history of allergic reactions to alcohol, food, medicines, natural extracts, and cosmetic ingredients. In addition, they were advised to steer clear of drinking (except water) and eating for a time no less than 1 h before starting the test. Each formulated nail lacquer was applied on participants’ thumb nails once a day. After the nail lacquer had dried, participants evaluated the film appearances and bitterness intensities of nail lacquer films by finger touching, visualizing, and sucking, in line with their own perceptions and then answered questionnaires. Sensory assessments were performed in triplicate. The experimental protocol (REC 62.0912-038-4567) was approved by the Human Research Ethics Committee, Silpakorn University, Thailand.
The developed nail lacquers were stored individually in tightly closed amber glass containers. The physical stability of samples was evaluated by heat-cool cycling for six cycles between temperature of
pH values, viscosities, phase separation, sediment volumes, and colors of developed nail lacquers after six cycles of heating/cooling treatment.
Formulation no. | pH | Viscosity (cP) | Phase separation | Color |
---|---|---|---|---|
7A | No separation | Dark green | ||
7B | No separation | Dark green | ||
19A | No separation | Dark brown | ||
19B | No separation | Dark brown |
DPPH free radical scavenging and protein denaturation inhibitory activities of developed nail lacquers before and after six cycles of heating/cooling treatment.
Formulation no. | DPPH radical scavenging SC50 | Albumin denaturation IC50 | ||
---|---|---|---|---|
Before | After | Before | After | |
7A | ||||
7B | ||||
19A | ||||
19B | ||||
Ascorbic acid | ND | |||
Diclofenac diethylamine | ND |
ND: not determined.
Experimental data is shown as
The extraction yields of
Ethanolic extracts of
The structures of compounds in
FTIR spectra of
The total phenolic contents of
The lower the SC50 value (concentration of extract required to scavenge 50% of DPPH radicals) and the higher FRAP value (capacity of extract to reduce ferric (III) ion to ferrous (II) ion) imply the higher the antioxidant activity. The results revealed that
The lower value of albumin denaturation IC50 indicates the higher anti-inflammatory activity. It was observed that
Many earlier studies showed the positive correlation between total phenolic content, antioxidant activity, and anti-inflammatory property [
Maximum limits of Hg (1 mg/kg), Pb (20 mg/kg), As (5 mg/kg), and Cd (5 mg/kg) in cosmetics have been set by Association of South East Asian Nations (ASEAN) guidelines [
ASEAN microbiological limits in products for children under 3 years; eye area and mucous membranes were total aerobic mesophilic microorganisms not more than 500 cfu/g and specified pathogens including
This experiment was performed to assess the cytotoxic activities of bitter extracts at various concentrations on CRL-2076 human dermal fibroblasts. The percentages of cell viability upon 24 h treatments with
Percentages of CRL-2076 viability after 24 h incubation with
The extract-free nail lacquers were prepared by dissolving shellac in 95%
The nail lacquers containing
Table
Furthermore, the average values of drying time, weight gain, and film thickness of formulation No. 7A and No. 19A were greater than those of formulation No. 7B and No. 19B, respectively (Table
Tensile strength designated as a stress is estimated as units of applied force per area (N/mm2). Measured stress values of films derived from developed nail lacquers ranged from
Water resistance test was performed in distilled water. It could be seen that an increase in the concentration of shellac and a decrease in the concentration of PVP K-30 would lead to an increase in the water resistance as depicted in Tables
Bitterness release test was conducted in simulated salivary fluid pH 6.8, and the results are illustrated in Table
The results of the physicochemical and mechanical evaluation indicated that nail lacquer formulation No. 19A and No. 19B were not suitable for further evaluation by volunteers, for the following reasons. The nail lacquer formulation No. 19A was too viscous with the highest viscosity (
The selected nail lacquers including formulation Nos. 7A and 7B were assessed in 20 healthy volunteers by applying on the nail plates of the left and right thumbs, respectively. After the nail lacquer had dried, volunteers evaluated the film characteristics including smoothness, glossy, color, and adhesiveness by finger touching and visualizing. After that, they sucked their thumbs and maintained the bitter solutions in their mouths for 5 s to estimate the bitterness intensity. All volunteers completed this study and reported no side effects caused by nail lacquers. Eighty-five percent of the volunteers reported that the formulation No. 7A was more bitter than the formulation No. 7B while seventy-five percent of the volunteers found that the film of formulation No.7B presented better film characteristic than that of formulation No. 7A.
Because of their greater bitterness, the cytotoxicity assay was performed for formulation No. 7A and No. 19A. These developed nail lacquers were screened for their cytotoxic activities against CRL-2076 human dermal fibroblasts at different concentrations to determine the viability by MTT assay. The cell survival upon treatments of the formulations are depicted in Figures
The contents of Pb (
The stability studies were obtained to find out the alteration of pH values, viscosities, phase separation, colors, and biological activities. The results are shown in Tables
DPPH free radical scavenging and protein denaturation inhibitory activities of developed formulations subjected to accelerated stability were investigated and compared with freshly prepared nail lacquers. The results obtained are detailed in Table
Anti-nail-biting lacquers containing bitter herbal extracts were successfully prepared using shellac and PVP K-30 as film formers. Formulation No. 7A containing 20%
The data employed to support the findings of this study are contained in the article. The other data are available from the corresponding author upon request.
A preprint has previously been published [
All researchers state that there are no conflicts of interest.
This research was kindly supported by the Faculty of Pharmacy, Silpakorn University, Product Development Project under Innovative House by the Thailand Science Research and Innovation (TSRI), the National Science and Technology Development Agency (NSTDA), the National Research Council of Thailand (NRCT) (grant number RUG6250035), and H. A. Plus (Thailand) Co., Ltd.
Figure S1: formulation No. 7A containing