Formulation And Evaluation of Anti Acne Gel

Figure 1

Ideal Properties of Anti-Acne Gel

An ideal anti-acne gel should have the following properties:

a.    Antibacterial Activity:

Effective against Propionibacterium acnes (now known as Cutibacterium acnes), the bacteria involved in acne development.

b.    Anti-inflammatory Effects:

Reduces redness, swelling, and inflammation associated with acne lesions.

c.    Comedolytic and Keratolytic Actions:

Helps unclog pores and remove dead skin cells (e.g., salicylic acid, retinoids).

d.    Sebum Regulation:

Controls excessive oil production without over-drying the skin.

e.    Non-comedogenic:

Should not block pores or worsen acne.

f.     Hydrating but non-greasy:

Maintains skin moisture balance, especially important when using drying agents like Benzoyl peroxide.

g.    Fast Absorbing and lightweight:

Gels should be easy to apply, quickly absorbed, and leave no residue.

h.    Safe for Daily Use:

Minimal irritation or allergic reactions, suitable for long-term use.

i.     Compatible with Other Treatments:

Can be used alongside other acne treatments without adverse interactions.

j.     Stability and Shelf Life:

Chemically stable with a reasonable shelf life, resistant to oxidation and degradation. [4][5]

MATERIALS AND METHODS

A.        Materials

a.         Azadirachta Indica

b.         Carbapol 940

c.         Propylene Glycol

d.         Methyl Paraben

e.         Sodium Hydroxide

1.         AZADIRACHTA INDICA

Azadirachta indica A. Juss (Neem)

Azadirachta Indica (Neem) is a tree in the mahogany family Meliaceae... For thousands of years the beneficial properties of Neem (Azadirachta indica A. Juss) have been recognized in the Indian tradition [7].Anti-bacterial activity of Azadirachta indica against P. acne... Thus, results of the study revealed that Barg-e-Neem has potential antibacterial activity and both aqueous and ethanolic extract are equally significant against acnes [6].

Neem twigs are used for brushing teeth in India and Pakistan. This practice is perhaps one of the earliest and most effective forms of dental care.

All parts of the tree (seeds, leaves, flowers and bark) are used for preparing many different medical preparations.

Neem oil is useful for skin care such as acne and keeping skin elasticity. Traditionally, patients suffering from Chicken Pox sleep on the leaves in India owing to its medicinal value.

In Ayurvedic, Unani and folklore traditional medicine, different parts of neem-were-preferred in the treatment of a wide range of afflictions. [6]

Taxonomy of Azadirachta Indica

Kingdom – Plantae Division - Magnoliophyta Class - Dipsacales

Order- Rutales Sub-order- Rutinae

Genus - Azadirachta Species – indica. [7]

Figure 2

Chemical Constituents:

•      Limonoids: Such as azadirachtin, nimbin, Nimbidin, nimbolide, and gedunin, which exhibit insecticidal, antifungal, and anticancer activities.

•      Flavonoids: Including quercetin and B-sitosterol, known for antioxidant and anti-inflammatory properties.

•      Terpenoids: Such as nimbolide, contributing to anticancer and antimicrobial effects.

•      Steroids, Alkaloids, and Fatty Acids: These contribute to neem's broad-spectrum pharmacological activities [8][9][10].

Pharmacological Action:

•      Antidiabetic lowers blood glucose

•      Antioxidant - scavenges free radicals

•      Antimicrobial effective against bacteria, fungi, and viruses

•      Anti-inflammatory and antipyretic

•      Hepatoprotective and anticancer particularly due to nimbolide

•      Immunomodulatory enhances immune response [8][9]

2.         Carbapol 940

Carbopol 940 is a high molecular weight, cross-linked polyacrylic acid polymer widely used in pharmaceutical and cosmetic formulations. It serves primarily as a thickening, suspending, and emulsifying agent. Its ability to form clear, stable gels upon neutralization makes it ideal for topical applications such as gels, creams, and ointments [11].

Chemical Information

•      Chemical Name: Carbomer 940

•      CAS Number: 9003-01-4

•      Appearance: White, fluffy powder

•      Molecular Weight: Approx. 4 × 10⁶ Da (dependent on grade)

•      Solubility: Dispersible in water, swells to form a hydrogel upon neutralization with bases like triethanolamine or sodium hydroxide [12].

Figure 3

Sources

Carbopol 940 is synthetically produced by polymerizing acrylic acid with a polyalkenyl polyether crosslinker. It is manufactured by Lubrizol under the trademark Carbopol® [11].

Properties

pH Range (after neutralization): 6.0 – 7.0

Viscosity (at 0.5% w/w solution): 40,000 to 60,000 cP Clarity: Excellent for aqueous gels

Thickening Efficiency: High at low concentrations

Shear-thinning Behavior: Exhibits pseudoplasticity—ideal for topical formulations Stability: Compatible with a wide range of excipients; sensitive to electrolytes [11][13].

3.         PROPYLENE GLYCOL

Propylene glycol (PG), also known by its chemical name 1,2-propanediol, is a colorless, odorless, and tasteless liquid commonly used in a wide range of industrial, food, cosmetic, and pharmaceutical applications. Its chemical formula is C₃H₈O₂.

Chemical Information

•      IUPAC Name: Propane-1,2-diol

•      Chemical Formula: C₃H₈O₂

•      Molar Mass: 76.09 g/mol

•      CAS Number: 57-55-6[18]

Figure 4

Physical Properties

•      Appearance: Clear, colorless, viscous liquid

•      Odor: Slightly sweet

•      Boiling Point: ~188°C

•      Solubility: Miscible with water, ethanol, acetone, and chloroform

•      pH: Neutral (6–8 in aqueous solution)

•      Density: 1.036 g/cm³ [18]

Preparation and Synthesis

Propylene glycol is typically produced via the hydration of propylene oxide, a petroleum-derived compound. There are two primary methods:

•           Non-catalytic high-temperature process

•           Catalytic low-temperature process using ion exchange resins [19]

Toxicology and Safety

•           Toxicity: Generally recognized as safe (GRAS) by the U.S. FDA.

•           LD50 (oral, rat): 20 g/kg (17)

4.         METHYL PARABEN

Pharmaceutical Profile: Methyl Paraben

Introduction

Methyl paraben, chemically known as methyl 4-hydroxybenzoate, is one of the most widely used paraben esters. It functions primarily as an antimicrobial preservative in cosmetic, pharmaceutical, and food products. Owing to its efficacy and ease of formulation, methyl paraben has attracted significant attention both for its preservative benefits and for ongoing discussions about its safety profile [20][21].

Chemical Information

•      IUPAC Name: Methyl 4-hydroxybenzoate

•      Molecular Formula: C₈H₈O₃

•      Molecular Weight: Approximately 152.15 g/mol

•      CAS Number: 99-76-3 [20]

Figure 5

Source

 Methyl           paraben           is predominantly         synthesized     via       the     esterification  ofp-hydroxybenzoic acid with methanol. Although it can occasionally be detected as a natural component in certain fruits such as blueberries, the commercial product is primarily synthesized to ensure consistency and purity.[21]

Physical Properties

•           Appearance: White to off-white crystalline powder

•           Melting Point: Typically reported in the range of approximately 120–125 °C (reports may vary slightly among sources) [20]

•           Solubility:

Water: Slightly soluble

Organic Solvents: Highly soluble in alcohols and other organic media

•           Boiling/Decomposition: Methyl paraben does not have a well-defined boiling point because it tends to decompose upon strong heating.

•           pKa: Around 8.4, which influences its behavior in different pH environments [20]

5.         SODIUM HYDROXIDE

Introduction

Sodium hydroxide (NaOH), commonly known as caustic soda or lye, is a highly caustic base and alkali widely used in industrial and laboratory settings. A 10% sodium hydroxide solution is a dilute aqueous preparation commonly employed for titrations, pH adjustment, cleaning, and various chemical processes due to its strong alkalinity and reactivity [39].

Chemical Information

•      Chemical Name: Sodium Hydroxide

•      Molecular Formula: NaOH

•      Molecular Weight: 40.00 g/mol

•      CAS Number: 1310-73-2

•      IUPAC Name: Sodium hydroxide

•      Reactivity: Strong base; reacts exothermically with water, acids, and some metals [22][23].

Figure 6

Source

Sodium hydroxide is industrially produced primarily by the electrolysis of sodium

chloride (NaCl) solution (brine) using membrane cell technology. This process also yields chlorine gas and hydrogen gas as co-products. The 10% solution is made by dissolving solid NaOH pellets or flakes into distilled water under controlled conditions [23].

Physical Properties (10% Solution)

•      Appearance: Clear, colorless liquid

•      pH: ~13–14

•      Density: Approximately 1.109 g/mL at 20°C

•      Boiling Point: Slightly above that of water due to dissolved solute (~102–104°C)

•      Melting Point (solid NaOH): 318°C

•      Solubility: Highly soluble in water with strong exothermic reaction

•      Odor: Odorless

•      Corrosivity: Strongly corrosive to skin, eyes, and mucous membranes [24]

B.        Extraction Method

1.         Collection of Leaves

i.     Collect mature, healthy green leaves, preferably in the early morning to minimize moisture loss.

ii.    Avoid leaves that are diseased, damaged, or yellowing.

iii.   Choose leaves from trees growing in clean, pollution-free environments to prevent contamination.

iv.   Use clean, sterilized scissors or pruning shears to cut the leaves and reduce mechanical damage. [25]

2.         Drying of Leaves

Leaf Washing and Preparation:

Rinse freshly collected leaves with clean distilled water to remove dust, dirt, and debris. Gently blot the leaves dry using clean paper towels to eliminate surface moisture.

Arrange the leaves in a single, even layer on stainless steel trays—ensure they do not overlap for consistent drying.

Oven Drying Conditions:

Temperature:  Maintain         between           40°C    and      50°C. (Avoid temperatures above 60°C, as they may degrade heat-sensitive compounds like azadirachtin.)

Oven Type: Use a hot air oven (forced air convection) to ensure even airflow and uniform drying.

Drying Process:

Dry for 6 to 24 hours, depending on the initial moisture content of the leaves and the oven’s efficiency.

Check periodically and weigh small test samples at intervals—when the weight remains constant, drying is complete.

If needed, gently turn the leaves halfway through to promote even drying.

Post-Drying Steps:

Allow the dried leaves to cool to room temperature inside a desiccator to prevent moisture absorption from the air.

Store the dried leaves in airtight containers (e.g., glass jars or aluminum foil pouches). Keep the containers in a cool, dry, and dark place to maintain quality and shelf life.[26]

3.         Extraction of Leaves

Water-Based Extraction (Aqueous Extraction)

1.         Powdering:

Grind the dried leaves into a coarse or fine powder using a clean, dry grinder.

2.         Extraction Procedure:

i.     Weigh an appropriate amount of the powdered leaves (e.g., 50 g).

ii.    Add the powder to a measured volume of distilled water (e.g., 500 mL).

iii.   Heat the mixture and simmer gently for 30–60 minutes.

iv.   Allow the mixture to cool to room temperature.

v.    Filter the extract using muslin cloth or Whatman No. 1 filter paper.

vi.   Collect the filtrate this is your aqueous leaf extract. (27)

C.   Formulation Process

Materials:

Azadirachta indica (Neem) extract or powder Carbapol 940

Propylene glycol (humectant/solvent) Methyl paraben (preservative)

Sodium hydroxide (10% w/v solution) (for pH adjustment) Distilled water

Rose Water

Procedure:

1.         Base Preparation:

Carbopol 940 was dispersed in distilled water and mixed thoroughly using a high-speed mechanical mixer.

A 10% sodium hydroxide solution was added vigorously to initiate gel formation. The mixture was placed in a water bath at a temperature not exceeding 50 °C.

pH was adjusted dropwise using 10% sodium hydroxide until the desired consistency and gel clarity were achieved.

2.         Volume Adjustment:

The final weight of the gel base was adjusted to 100 g using distilled water (q.s. – quantum satis).

3.         Incorporation of Plant Extract:

Azadirachta indica (Neem) extract was added in concentrations of:

1          g for Gel-I (1% w/w)

2          g for Gel-II (2% w/w)

3          g for Gel-III (3% w/w)

4.         Preservative Addition:

Methyl paraben, previously dissolved in propylene glycol, was added to the gel mixture as a preservative.

5.         Final Adjustment:

The remaining amount of purified water was added to bring the formulation to the desired volume and consistency (3).

Table 1: Composition of Formulations for 100 g

Evaluation and Observation of Gel Formulations Evaluation

Physical appearance

The gel formulations were evaluated for their physical, parameters like color, odor, consistency, transparency, and homogeneity.

Spreadability of Gel Formulations

A glass slide with standard dimensions was used, where 0.5 g of the gel was placed in a circle 1 cm in diameter on the glass slide, over which another glass slide was placed. A weight of 125 g was set for 5 min so that the gel was sandwiched between the two slides to form a thin layer. Then, the weight was removed, and the extra gel was removed. Then the slides were adjusted so that the upper slide was fixed with a weight of about 20 g. The time was noted for the slides to separate from each other. The spreadability was recorded using the

following formula. S = M / T

Where:

S – Spreadability in grams/seconds. M – Mass in grams.

T – Time in seconds.

Viscosity

A Brookfield DV-E viscometer (RVDVE) was used to determine the viscosity of the gels. Spindle No. 07 was inserted in each formulation and was sheared at 3.3, 9.9, and 16.5 g at 24 ± 1 °C. The gel formulations were prepared in distilled water.

pH Determination of Gel Formulations

The pH of the gels was detected with a digital pH meter. An amount of 0.5 g of gel was dissolved in 50 ml of distilled water and stored for two hours. Each formulation’s pH was measured in triplicate and the average values were taken.

Antibacterial Activity of Gel Formulations

Each formulation was assessed for its antimicrobial effects against the microorganisms on a nutrient agar using a suitable diffusion method. About 0.2 ml of the bacterial test strain was inoculated over a nutrient agar plate with a sterile cotton swab and was allowed to dry. With the help of a cork borer, 6 mm diameter wells were created. Half a milliliter of the Azadirachta indica extract was introduced into the wells. The plates were placed at room temperature for about one hour. Then the plates were placed in an incubator at 37 °C for 24 hours. Then, the zone of inhibition was checked and recorded. Clindamycin was used as standard.

Acne Healing Activity of Gel Formulations

Adults aged from 17 to 22-year-old were divided into three groups, having 4 adults each. Group I, II, and III received Gel-I containing 1% w/w of the Azadirachta indica extract, Gel-II containing 2% w/w of the Azadirachta indica extract, and Gel-III containing 3% w/w of the Azadirachta indica extract. No other medicine was given to the adults during the entire study. The study was evaluated for 15 days.

Grittiness

The grittiness test is conducted to detect the presence of coarse particles or undissolved material in the gel, which may affect its texture and user acceptability. A small quantity of the gel (approximately 0.5 g) is taken on a clean glass slide or between the fingers and gently rubbed to assess its smoothness

RESULTS AND DISCUSSION

This study evaluated the anti-acne potential of herbal gels. Three different concentrations of an Azadirachta indica extract were used to prepare gel formulations with Carbopol 940. The formulations were evaluated for the physical parameters like the pH, viscosity, and spread ability. A pharmacological evaluation, like a skin irritation test, revealed that the herbal gels were safe to apply on the skin. The antibacterial activity of these gels against Propionibacterium acne bacteria was also tested and confirmed. An anti-acne study was carried out to show that herbal gels can heal the acne without severe

adverse effects.All the formulations were green. The spreadability indicates the extent to which the gel readily spreads on application to the skin or the affected part. The bioavailability efficiency of a gel formulation also depends on its spreading value. All the formulations had very slightly alkaline pH which was compatible with normal skin physiology. The results of the viscosity are also shown in Table 2

Table 2 Evaluation parameters data