40 grams of dried Areca seeds were processed for the necessary grinding duration in a Planetary Mono Mill Pulverisette 6 (Fritsch, Germany) to make the Areca microbeads. A 250-milliliter agate (SiO2) grinding bowl and 50 silicate grinding balls with a diameter of 10 millimeters were used. At room temperature (25 + 2 °C), the Areca seeds were ground at a speed of 500 rpm for 5, 10, and 15 minutes. The finely ground Areca powder was next sifted for 20 minutes using a sieve shaker model AS 200 (Retsch, Germany) with an amplitude of 1 millimeter to separate the particles to the required size range of 400–800 micrometers. The Areca powder was chosen for integration into the formulations as microbeads after being ground to fulfill particular particle size parameters.

The particle size and morphology of milled Areca seed were examined using a compound microscope Primostar 3 (Zeiss, Germany). The inspection was carried out at 100× magnification.

Shaanxi Honghao Bio-Tech Co., Ltd., Shaanxi, China, contributed the powdered Areca seed, which was obtained by extracting Areca seeds in 95% ethanol. The chemical properties of the extracted powder were investigated using a modified experimental technique based on Wang and Lee (1997) investigation. The Ultimate 3000 (Thermo Fischer Scientific, Germany) automated High-Performance Liquid Chromatography was used. With a mobile phase consisting of a linear gradient from 5% v/v acetic acid in distilled water to methanol, Inertsil columns ODS-35 nm (size 4.6×250 mm) were used. A reference solution of gallic acid in distilled water at 0.2% w/v was utilized for testing, whereas the sample was Areca ethanolic extract powder in distilled water at 2% w/v. The flow rate was 0.8 ml/min, the injection volume was 20 microliters, and the wavelength was adjusted at 280 nanometers.

The moisture content of the extracted Areca seed powder was measured with a Moisture Analyzer model HR83 (Mettler Toledo, Switzerland) using the Loss on Drying technique. Aluminum pans were dried for 60 minutes at 105 °C in a hot air oven UFE 700 (Memmert, Germany). One gram of the powder was picked at random from several positions, including the top, center, and bottom of the box. At each sampling site, the samples were tested in triplicate and the mean % moisture content was reported.

The pH of the dissolved Areca seed extract powder in distilled water was measured at room temperature using a pH meter model 3510 (Jenway, The United Kingdom). The samples were examined in triplicate, and the mean value obtained was reported.

The water solubility of Areca seed extract powder was evaluated by dissolving it in 10 ml of distilled water at room temperature with a vortex mixer Genie 2 (Scientific, USA). Areca seed extract was shaken in a water tube with a screw top. The dissolving and subsequent precipitate were visually observed, and the amount of soluble extract powder at room temperature that yielded the maximum amount was recorded.

The Folin-Ciocalteu technique was used to determine the total phenolic content of Areca seed extract powder (Chanda and Dave 2009). Initially, a 10% v/v Folin-Ciocalteu reagent was added to the phenolic compound-containing sample solution and allowed to react for 5 minutes while covered with aluminum foil. Following that, a 700 millimolar sodium bicarbonate solution was added, and the mixture was incubated in a dark room for 2 hours while remaining covered with aluminum foil. Following the incubation period, the resultant solution was carefully pipetted into a 96-well plate in exactly 200 microliters. The absorbance of this solution was then measured at 765 nanometers using a microplate reader EON model (BioTek, USA). These absorbance values were then compared to those obtained from a standard gallic acid solution dissolved in deionized water. This standard gallic solution has a concentration range of 20 to 100 micrograms per milliliter and was used to create a calibration curve. Finally, the amount of Areca seed extract solution in deionized water was estimated using the absorbance measurements and the calibration curve, and the total phenolic content was expressed as milligrams of Gallic Acid Equivalent per gram of extract (mg GAE/g extract).

The reaction between the sample and a DPPH solution was evaluated to determine free radical inhibition activity in Areca seed extract. Initially, 25–250 microgram per milliliter Areca seed extract powder and a 0.5–3.0 microgram per milliliter gallic acid standard were dissolved in water to make solutions. To begin the reaction, 100 microliters of these solutions were pipetted into a 96-well plate, followed by 100 microliters of absolute ethanol-based 225.2 molar DPPH solution. The reaction was allowed to run for 30 minutes in the dark with the plate covered with aluminum foil. After that, absorbance was measured at 517 nanometers using a microplate reader EON model (BioTek, USA). The experiment was carried out in triplicate, and the results were used to compute the percentage of radical scavenging activity.

The total number of microorganisms in the samples was determined using the AOAC Official Method (AOAC 900.12 (2015), which employs PetrifilmTM agar plates containing nutrients and 2,3,5-triphenyl tetrazolium chloride, both of which are appropriate for microbial growth. The sample solution was pipetted onto 1 ml of PetrifilmTM and cultured at 20 to 25 °C for five days before counting colony forming units per gram (cfu/g).

The AOAC Official Method 2014.05 was used to determine the yeast and mold count in samples. 3MTM PetrifilmTM Rapid Yeast and Mold Count Plate First Action (AOAC 2014) using 3M PetrifilmTM Rapid Yeast and Mold Count Plates. The sample solution was pipetted onto 1 ml of PetrifilmTM and incubated for five days at 20 to 25 °C. The colony counts were then expressed as colony forming units per gram (cfu/g).

A determined amount of finely crushed Areca microbeads was poured into a screw-cap sample tube filled with water to ascertain the hue. After that, the mixture was violently agitated for 5 minutes with a Vortex mixer Genie 2 (Scientific, USA). The suspension was then allowed to stay at room temperature for 24 hours, during which time the observed color was recorded and compared to a reference color band with a score level of 2–6.

The total phenolic components in Areca seed extract powder were determined to estimate the amount of Areca seed extract necessary for the desired formulations before preparing the gel formulation. The total phenolic compounds in the formula should be no less than 0.005% w/w, which falls between 0.00001 to 5.0% w/w.

Nine body scrub gel compositions comprising one gram of Areca extract powder were created. Following the master recipe, the formulations were developed using various types and amounts of gelling agents such as carbomer and polyvinyl alcohol, as indicated in Table 1. The gel formulations were created with Areca extract powder and different carbomers and polyvinyl alcohol (code-N) or without Areca extract (code-C), and the body gel was prepared without Areca extract powder (Table 2).

The samples were subjected to varied storage conditions during the stability analysis of the body gel formulation. For 30 days, samples were held at two distinct temperatures: 4 °C in a Refrigerator MPR-214 (Sanyo, Japan) and 30 °C in a Stability Chamber oven HPP260 (Memmert, Germany). Furthermore, an accelerated heating-cooling cycle was carried out, which included holding the samples at 4 °C for 48 hours, followed by another 48-hour storage period at 40 °C in a Stability Chamber oven HPP749 (Memmert, Germany). Over the course of 24 days, this cycle was repeated six times. The body gel scrub was constantly inspected for any changes in color, pH, odor, and antioxidant activity over these storage periods and cycles, and the results were painstakingly documented.

A pH meter Model 3510 (Jenway, The United Kingdom) was used to determine the pH of the body gel scrub. A 5-gram quantity of the material was precisely weighed before being distributed in 50 ml of distilled water. For each formulation, this measuring technique was repeated three times, and the resulting pH values were reported and then averaged.

The viscosity was measured using a Brookfield viscometer DV-III Ultra (Brookfield, USA) with a cone and plate attachment. The gel was put on the P42 plate, and the torque was adjusted to be as near to 100% as possible. The viscosity was then measured, and the average viscosity for each formula was computed.

The homogeneity of the body gel was assessed visually using a three-level grading system. A score of 0 indicates that there was more than 50% separation of the gel layer in the formulation, a score of 1 indicates that there was less separation of the gel layer, and a score of 2 indicates that there was no separation in the formulation.

The dispersion of Areca microbeads was evaluated using a scoring system. A score of 0 showed that the scrubbing beads had more than 50% formulation sedimentation, while a score of 1 suggested that the scrubbing beads had less than 50% formulation sedimentation. A score of 2 showed that there was no scrubbing bead sedimentation in the preparation.

The antioxidant activity of the body gel was determined using the DPPH radical scavenging test. The body gel scrub compositions were tested in water at concentrations ranging from 25 to 250 micrograms per milliliter, and the results were compared to a standard gallic acid solution of 5–150 micrograms per milliliter. To begin, 100 microliters of each of these solutions were dispensed into a 96-well plate, followed by 100 microliters of a 225.2 molar DPPH solution in absolute ethanol to start the reaction. This reaction was allowed to run for 30 minutes in a light-protected atmosphere with the plate covered with aluminum foil. Following this incubation time, the absorbance of the solutions was measured at a wavelength of 517 nanometers using a microplate reader EON model (BioTek, USA). Each formulation’s free radical scavenging capability was then determined as a percentage of radical scavenging.

The retention time for Gallic acid at position (1) was 4.807 min, which matched the reference Gallic acid position. Furthermore, the retention durations at locations (2) and (3), which correspond to catechin and epicatechin, were 10.853 min and 11.793 min, respectively. Figs 3, 4 show the results of the HPLC analysis.

Figure 3. 

HPLC Chromatograms of 0.2% Gallic acid at 280 nanometer.

Figure 4. 

HPLC Chromatograms of 2% Areca seed in ethanolic extract at 280 nanometer

The ethanolic Areca seed extract powder is brown and has a moisture content of 4.82 ± 0.46% on average. A pH meter was used to perform acid-base analysis on extract concentrations ranging from 1–5% w/v. At 25 °C, the pH of the solution slightly decreased as the content of Areca seed extract increased, ranging from 4.92 to 5.07. These findings suggest that the concentration of Areca seed extract in ethanol in the aforementioned concentration range has no effect on pH alteration.

The DPPH radical scavenging assay findings show that the antioxidant activity of the Areca seed extract is concentration-dependent. The IC50 values for gallic acid, employed as a standard, and Areca seed extract were 1.35 µg/ml and 183.31 µg/ml, respectively, showing that the extract had lesser antioxidant efficacy than the standard reference. Numerous studies have been conducted to investigate the polyphenolic content of Areca nut, taking into account various geographical origins and extraction techniques. As established in the research (Gurumurthy et al. 2017; Gurumurthy 2018; Sari et al. 2020; Yang et al. 2023), the variance in polyphenol content is controlled by regional characteristics and environmental circumstances. Furthermore, Meutia (2021) note that the choice of Areca nut species and its intrinsic properties have a major influence on the quality and quantity of phytochemical contents within the nut.

Combining the main component, Areca seed extract powder, with polyvinyl alcohol and Carbomer Ultrez 21 using various preparation factors results in a dark brown gel, as shown in Figs 5, 6. Areca seed extract powder and Areca microbeads were used in equal amounts in each gel composition. The composition and quantity of Carbomer Ultrez 21 and polyvinyl alcohol, however, differed between formulations. Surprisingly, the gel with the deepest brown hue had the least amount of gelling agent. The intensity of the color reduced as the amount of gelling ingredient in the formulations rose. Every formulation’s gel has a homogeneous distribution and good dispersion of Areca scrub microbeads.

Figure 5. 

Appearance of gel scrub containing extract and microbeads from Areca seed with different component.

Figure 6. 

Appearance of the formulations containing Areca microbeads scrub, C-formula contain only Areca microbeads, N-formula contain with Areca seed extract and Areca microbeads.

According to the findings, increasing the volume of Carbomer Ultrez 21 and polyvinyl alcohol resulted in a greater formulation viscosity. Table 4 compares the viscosity values in Areca gel containing 1% w/w Areca seed extract powder, a Carbomer Ultrez 21 content of 0.5% w/w and a polyvinyl alcohol content of 0, 2.5, and 5.0% w/w (NS1, NS2, and NS3), Areca gel containing 1% w/w Areca seed extract powder, a Carbomer Ultrez 21 content of 1.0% w/w, and a polyvinyl alcohol content of 0, 2.5, and 5.0% w/w (NM1, NM2, and NM3), and Areca gel containing 1% w/w Areca seed extract powder, a Carbomer Ultrez 21 content of 2.0% w/w, and a polyvinyl alcohol content of 0, 2.5, 5.0 % w/w (NL1, NL2, and NL3). When the carbomer or polyvinyl alcohol percentage was increased, the viscosity increased from 719.86 cP to 224,974.69 cP.

The viscosity of gels containing Carbomer Ultrez 21 was affected by the formulation’s pH. When the viscosity of Areca gel (NS1, NS2, NS3, NM1, NM2, NM3, NL1, NL2, and NL3) was compared to the viscosity of non-extracted seeds gel (CS1, CS2, CS3, CM1, CM2, CM3, CL1, CL2, and CL3), higher viscosity was linked with lower pH. Given the changes in polyvinyl alcohol content within the formulations despite employing the same concentration of triethanolamine for neutralization, additional research into the rheological behavior is required to help in the creation of these formulations.

Due to the gelling qualities of Carbomer Ultrez 21, which are impacted by the pH of the formulation, the formulation without Areca seed extract had a lower viscosity than the formulation with Areca seed extract powder. The data in Table 4 also show that the pH and viscosity values in the NS2 and NS3 formulations were similar to human skin (Saryanti and Zulfa 2017) and recommended for semi-solid cosmetic product viscosity (Badan Standarisasi Nasional 1996 (SNI 16-3499-1996; Ervina et al. 2020). It indicates that these formulations are ideal for further development as an Areca seed extract body scrub gel for skin care products.

The physicochemical stability of the Areca gel scrub containing 1% w/w of Areca seed extract powder, 0.5% w/w of Carbomer Ultrez 21, and 2.5% w/w of polyvinyl alcohol (NS2) and the Areca gel scrub containing 5.0% w/w of polyvinyl alcohol (NS3), packed in 100 g plastic jars, was evaluated under various conditions. The formulations were kept for 30 days under accelerated conditions at 4 °C and 30 °C. The NS2 and NS3 formulations were found to be similar after testing. As seen in Fig. 7, the gel exhibited a brown color with high homogeneity and even dispersion of microbead particles.

Figure 7. 

Physical characteristics of the gel scrub containing 1% w/w Areca seed extract powder, 0.5% w/w of Carbomer Ultrez 21, and 2.5 % w/w of polyvinyl alcohol (NS2) at the test condition A = 4 °C, B= 30 °C, C = heating-cooling.

The stability of the body gel formulation comprising seed extract components was examined, and the pH values for both formulations were found to be between 5–7. Under all storage settings, the pH values for the seed extract formula (NS2, NS3) were consistently lower than the control (CS2, CS3). Notably, the pH was lower when held at 30 °C with a heating-cooling cycle compared to 4 °C, which might be ascribed to the harsher storage circumstances. Fig. 8 depicts this information.

Figure 8. 

pH chart of body gel scrub tested for stability. NS2, containing 1% Areca seed extract powder, 0.5% w/w Carbomer Ultrez 21, and 2.5% w/w Polyvinyl alcohol. NS3, consisting of 1% Areca seed extract powder, 0.5% w/w Carbomer Ultrez, and 5% w/w Polyvinyl alcohol. CS2 with no Areca seed extract powder, 0.5% w/w Carbomer Ultrez 21, and 2.5% w/w Polyvinyl alcohol. CS3 with no Areca seed extract powder, 0.5% w/w Carbomer Ultrez 21, and 5% w/w Polyvinyl alcohol.

The NS2 and NS3 body gel formulations were found to have high viscosity and varied viscosity variations during storage conditions of 30 °C and a heating-cooling cycle, as illustrated in Fig. 9. Those held at 4 °C, on the other hand, remained identical to those made in the original preparation. It was also discovered that the viscosities of the NS2 and NS3 formulations held at 30 °C and under fast heating-cooling circumstances exceeded the initial. In terms of the formulation’s homogenous acid-base and scrubber distribution, the accelerated condition was shown to be the most significant modification among the three sample conditions. Nonetheless, samples held in all three settings satisfied the established acceptability requirements of gel viscosity 2,500–6,000 mPa.s, semi-solid cosmetic product viscosity (Badan Standarisasi Nasional 1996 (SNI 16-3499-1996; Ervina et al. 2020).

Figure 9. 

Viscosity chart of body gel tested for stability. NS2, containing 1%w/w Areca seed extract powder, 0.5% w/w Carbomer Ultrez 21, and 2.5% w/w Polyvinyl alcohol. NS3, consisting of 1% w/w Areca seed extract powder, 0.5% w/w Carbomer Ultrez, and 5% w/w Polyvinyl alcohol. CS2 with no Areca seed extract powder, 0.5% w/w Carbomer Ultrez 21, and 2.5% w/w Polyvinyl alcohol. CS3 with no Areca seed extract powder, 0.5% w/w Carbomer Ultrez 21, and 5% w/w Polyvinyl alcohol.

The antioxidant activity of the gel formed from seed extract was assessed using the DPPH radical scavenging assay, and the body gel formulations NS2 and NS3 showed radical scavenging values of 61.609% and 62.187%, respectively. The stability test revealed that the antioxidant activity of the body gel formulation was stable. Furthermore, under the test condition, the product developed from NS2 seed extract and NS3 formula showed an enhanced% radical scavenging activity. The antioxidant activity of the formula increased in the stability test at different storage temperatures, which might be ascribed to the increased quantity of extract in the formulation due to the dissolution of granules generated from finely crushed powder.

Figure 10. 

% Radical scavenging chart of body scrub at various storage conditions of NS2, containing 1% w/w Areca seed extract powder, 0.5% w/w Carbomer Ultrez 21, and 2.5% w/w Polyvinyl alcohol. NS3, consisting of 1% w/w Areca seed extract powder, 0.5% w/w Carbomer Ultrez 21, and 5% w/w Polyvinyl alcohol. CS2 with no Areca seed extract powder, 0.5% w/w Carbomer Ultrez 21, and 2.5% w/w Polyvinyl alcohol. CS3 with no Areca seed extract powder, 0.5% w/w Carbomer Ultrez 21, and 5% w/w Polyvinyl alcohol.

The appearance of antioxidant activity may be related to a noticeable dramatic color change and an increase in heating temperature. The study also found that raising the heating temperature boosted the DPPH radical scavenging capacity and antioxidant property, which conforms to the temperature rise described in Kim (2018) study. According to Molaveisi et al. (2019), relationships between antioxidant activity and brown pigment were identified, with the highest phenol concentration associated with the darkest sample. The effect of heat processing on flavonoids’ antioxidant activity was demonstrated by the observation of an increase in the breakdown of phenolic acid components with increasing temperature (Chaaban et al. 2017; Che Sulaiman et al. 2017; Fei Zhou et al. 2017; ElGamal et al. 2023). The impact of thermal treatments on phenolics, including phenolic and flavonoid contents and antioxidant properties, is dependent on the characteristics of phenolic compounds and the processing conditions (Li et al. 2020; Zapata et al. 2021). Studies have investigated the thermal degradation of visual color of gallic and protocatechuic acids, detectable increases in polymeric color and browning indexes were observed (Sinela et al. 2017; Oliveira and Antelo 2020). Furthermore, the effect of heat processing on the color and molecular structure was investigated, at higher pH values, changes in both color and molecular structure was reported (Ngamwonglumlert et al. 2020).

The NS3 formulation was found to be stable and acceptable for generating a body gel scrub for skin products after analyzing the stability of the NS2 and NS3 body gel formulations, as shown in Tables 5, 6. With Areca seed extract and Areca microbeads scrub, this mixture had 1% w/w Areca seed extract powder, 0.5% w/w Carbomer Ultrez, and 5% w/w polyvinyl alcohol.