Formulation, Optmization and Evaluation of Curcuma longa and Piper nigrum Hydrogel  

Mohammed Aslam Mohammed Azam*, Dr. Sandeep A. Wathore,

Dr. Umesh T Jadhao

Department of Pharmaceutics, SVP College of Pharmacy, Hatta TQ Basmat Dist. Hingoli (M.S) India

Correspondence:  mohammedaslambagban@gmail.com  
DOI: https://doi.org/10.71431/IJRPAS.2026.5615    

INTRODUCTION

Herbal medicines have been the basis of traditional medical systems throughout Asia, Africa and other regions for centuries and they remain an important part of primary healthcare today globally.[1] The World Health Organization indicates that a large proportion of the world relies on herbal medicines because they are often easily obtainable, inexpensive, and culturally acceptable, particularly in low- and middle-income countries.[2-3] In addition to their historical importance, medicinal plants harbour a large pool of bioactive secondary metabolites that directly or indirectly contributed to the identification and development of novel drugs such as artemisinin and other plant-derived cytotoxic and anti-inflammatory agents.[2,4] The effective integration of herbal medicines into evidence-based healthcare continues to be limited by aspects like species and geography-specific variability in phytochemical composition as well as processing conditions, lack of standardized extraction and quality-control protocols, potential herb–drug interactions, and poor availability of adequate high-quality clinical data. However, conventional forms of delivery for phytoconstituents yield distinctly suboptimal bioavailability and therapeutic responses due to inadequate solubility, membrane permeability and plasma half-lives, as well as high rates of metabolism.[3-4] These limitations highlight the importance of scientific validation, standardization, and rational formulation design to ensure their safety, efficacy and reproducibility. [4].

Curcuma longa L. (family Zingiberaceae), commonly known as turmeric, is a rhizomatous perennial herb widely cultivated in India and other tropical regions and extensively used as a culinary spice, colouring agent, and traditional remedy.[5,6] The dried rhizomes of C. longa contain a characteristic yellow pigment fraction composed predominantly of curcuminoids, including curcumin, dimethoxy curcumin, and bisdemethoxycurcumin, along with essential oils rich in turmerones and other volatile constituents.[5,6] Curcumin, the principal polyphenolic curcuminoid, has been extensively investigated and shown to possess broad pharmacological activities, including potent antioxidant, anti-inflammatory, antimicrobial, wound-healing, hepatoprotective, and immunomodulatory effects.[5-7] In the context of dermatology and cutaneous health, curcumin modulates multiple cellular pathways related to oxidative stress, inflammatory cytokine production, collagen synthesis, and melanogenesis, supporting its potential utility in conditions such as acne, psoriasis, atopic dermatitis, photodamage, and wound repair.[6,8] These pleiotropic effects, combined with a generally favourable safety profile, have made turmeric and curcumin attractive candidates for incorporation into pharmaceutical and cosmeceutical formulations, particularly for topical and localized therapy.[6,8]

Fig. 1. Curcuma Longa

Although curcumin displays an interesting pharmacological profile, there are many biopharmaceutical limitations preventing its clinical use. [7-9] It shows highly poor aqueous solubility, low stability in physiological media, high pre-systemic metabolism and fast systemic clearance leading to very low oral and systemic bioavailability.[7,9,10]  Various formulation strategies—including solid dispersions, lipid-based carriers, nanoparticles, and phospholipid complexes—have been explored to enhance curcumin solubility, permeability, and therapeutic efficacy.[9-11] In the topical domain, advanced delivery systems such as hydrogels and nanoparticulate carriers have been reported to improve the retention, controlled release, and local effectiveness of curcumin for the management of skin disorders.[12,6,8] Nevertheless, there remains a need for simple, patient-friendly, and stable topical dosage forms capable of enhancing the local availability of curcuminoids at the site of application.

Piper nigrum L. (family Piperaceae) is commonly known as black pepper. It is another widely used spice and medicinal plant with a long history of use in traditional medicine as a digestive stimulant, carminative, and general health-promoting agent.[13,14] Its principal pungent alkaloid, piperine, is responsible for its characteristic taste of black pepper and has been recognized as the major bioactive constituent.[13,14] Pharmacological studies have shown piperine to possesses diverse biological activities, with antioxidant, anti-inflammatory, antimicrobial, immunomodulatory, hepatoprotective, and anticancer effects.[13,14] Piper nigrum extracts and piperine-containing formulations have also been investigated for their analgesic and anti-nociceptive properties, including in transdermal and topical delivery systems designed for pain relief.[15]

Fig. 2. Piper nigrum

One of the most vital trait of piperine is that it works as a bioavailability enhancer for diverse medicinal drugs and phytoconstituents.[14,16] As such, piperine has been shown to alter membrane dynamics, inhibit efflux transporters (e.g., P-glycoprotein), and inhibit drug metabolizing enzymes which can increase the absorption and systemic exposure of co-administered agents.[14,16] Multiple studies have documented the enhancement of curcumin bioavailability and pharmacokinetic profiles after co-treatment with piperine, along with therapeutic response to other poorly absorbed molecules. [17,14] To exploit this bio enhancing effect, a number of solid dispersion-based microparticles or other delivery systems containing Curcuma longa as well as Piper nigrum extracts have been formulated with improved dissolution and release characteristics for both curcumin and piperine.[18,17,19] These findings strongly substantiates the scientific foundation of rational combinations with curcumin.

Polyherbal formulations of Curcuma longa and Piper nigrum are similarly gaining interest in current phytopharmaceutical research and plays an integral role in traditional medical systems such as Ayurveda and Traditional Chinese Medicine and are increasingly being revisited within modern phytopharmaceutical research.[2-3] With a view towards utilizing the synergistic or additive effects of the different plant constituents to achieve multiple molecular targets and pathways, expanding the therapeutic spectrum and minimizing the dosage requirement for these individual components.[4,2] Polyherbal combinations can also provide complementary pharmacological activities, such as simultaneous antioxidant, anti-inflammatory, antimicrobial, and wound-healing effects, which are particularly advantageous for complex, multifactorial conditions.[4,20] With the specific case of Curcuma longa and Piper nigrum, curcumin contributes strong antioxidant and anti-inflammatory actions, while piperine not only exerts similar pharmacological effects but can also enhance the bioavailability and penetration of curcumin and other curcuminoids.[5,17,14] Altogether, these plants may provide a complementary and potentially synergistic approach in the management of inflammation, oxidative stress, microbial contamination, and tissue repair in skin-related disorders, especially when delivered directly to the affected site.

Topical drug delivery is attractive for the delivery of herbal actives for the treatment of the topical skin conditions, wounds, infections or inflammatory disorders.[21,22] Since they provide direct access for their action on the target site, reducing systemic exposure and allow the minimization of systemic adverse effects.[21-23] From a patient's convenience point of view, topical formulation are often non-invasive and convenient to use, and are associated with good compliance with the topical delivery, particularly for topical oral and skin diseases, which need long term daily treatment. [21-23]

A variety of topical dosage forms are available, including creams, ointments, lotions, gels, and hydrogels, each with distinct rheological and sensory properties.[21,22] The high water contents and the advantageous physiological factors of hydrogels, like their soothing and cooling effects, skin compatibility, and ease of application, have made hydrogels a growing field of interest in the delivery of herbals and synthetic drugs applied to inflamed or irritated skin, where comfort to the patient and ease of application are crucial factors to consider when designing a drug delivery system.[21,22]

Hydrogels are 3D, cross-linked polymeric networks, which are capable of absorbing and retaining large quantities of water or biological fluids while maintaining their structural integrity.[24,22] Their high water content and tunable network structure also enable them to mimic the properties of soft tissues and to provide a moist microenvironment, which is beneficial for wound healing and epithelial regeneration.[21,22] From a drug-delivery perspective, hydrogels can function as controlled-release systems, allowing modulation of drug loading, diffusion, and release kinetics by altering the polymer composition, cross-linking density, and network architecture.[24,22]

Different types of natural and synthetic polymers were used for the formulation of hydrogels, including carbopol (carbomer), hydroxypropyl methylcellulose (HPMC), sodium alginate, and chitosan, among others.[21,24,25] Such gelling agents differ in their swelling behavior, viscosity, bioadhesiveness, mechanical strength, and permeability, and hence influence the critical topical performance parameters such as spreadability, extrudability, residence time, and drug-release profile.[21,23,26] Hydrogels formulated using alginate and chitosan, often in combination, have shown promising outcomes as wound dressings and drug carriers, offering biocompatibility, intrinsic antimicrobial activity, and the ability to provide sustained release of incorporated agents.[24,25,26] Consequently, hydrogel-based systems are being widely explored in contemporary pharmaceutical research for applications in wound healing, antimicrobial therapy, anti-inflammatory treatment, and broader dermatological indications.[21,24,22]

Incorporation of herbal extracts into the formulations could be a good approach for enhanced topical delivery and local bioavailability of phytoconstituents. [21-22] Methanolic extracts of Curcuma longa have been observed to possess a wide diversity of secondary metabolites in different phytochemical classes such as curcuminoids and phenolic compounds and other secondary metabolites with strong antioxidant and anti-inflammatory properties.[5-6] Similarly, Piper nigrum extracts are also rich in piperine and other phenolic and alkaloidal constituents that play a role in antioxidant, antimicrobial, analgesic actions as well as bioavailability enhancement.[13,27] Topical hydrogels of turmeric extracts were evaluated for phytoconstituents, and qualitative and quantitative evaluations show that multiple classes of phytoconstituents such as flavonoids, tannins, steroids, terpenoids, saponins, and glycosides, which may work synergistically to provide multi-targeted effects [5-6]

Recent studies using Curcuma longa-derived hydrogels demonstrated the incorporation of methanolic turmeric extracts into controlled-release hydrogel systems with favourable physicochemical properties and encouraging antioxidant, anti-inflammatory, photoprotective, and wound-healing activities.[6] These findings encourage the need for developing topical formulations based on turmeric-loaded hydrogels to be utilized in skin care products and dermatological therapy efforts. [6-8] Nonetheless, although piperine is well-known for is bioenhancing properties and both these extracts have shown compatibility in oral as well as solid dispersion systems, relatively lesser studies has reported the use of polyherbal hydrogel containing Curcuma longa along with Piper nigrum. [18-19] Therefore, a new hydrogel formulation containing methanolic extracts of both plants could represent an efficient vector for efficiently delivering several classes of phytoconstituents directly to the skin and potentially enhancing local therapeutic activity through complementary antioxidant, antiseptic effects while taking advantage of the permeation-enhancing and bioavailability-modulating properties of piperine.

Both Curcuma longa and Piper nigrum have been analysed separately for various pharmacological activity including antioxidant, anti-inflammatory, antimicrobial, wound-healing bioavailability-enhancing potential but development of combined topical hydrogel system with P. nigrum and C. longa methanolic extracts remains relatively unexplored. [5,6,13,14] Most of these studies have dealt with oral or systemic formulations, solid dispersions and nanocarriers for better dissolution and systemic bioavailability of curcumin both in the presence of piperine but relatively few that may lead to localized skin-targeted delivery. [18,17,19,14] Hence, systematic formulation development and compatibility evaluation, as well as complete characterization of the physicochemical properties of a hydrogel containing Curcuma longa and Piper nigrum extracts with in vitro assessment of their relevant biological activities for topical therapy is clearly warranted. [6,22]

Therefore, this study was aimed to formulate and develop a herbal hydrogel of methanolic extracts of Curcuma longa and Piper nigrum for topical application. The work aims to optimize a suitable polymeric hydrogel base for the incorporation of these extracts with respect to key physicochemical parameters such as appearance, pH, viscosity, spreadability and extrudability and drug content as well as their in vitro antioxidant, anti-inflammatory and antimicrobial properties. The current study aims to investigate the possibility of a herbal topical product that may contain offer enhanced local therapeutic efficacy for skin-related disorders through combined and possibly synergistic pharmacological actions.

MATERIALS AND METHODOLOGY

The plant materials, Curcuma longa and Piper nigrum, used as active herbal ingredients were obtained from the locality of Hatta Tal. Basmat Dist. Hingoli, (M.S), India and the voucher specimen were stored for future use. Sodium alginate, Carbopol 934, and HPMC K100M were procured from Research-Lab Fine Chem Industry, while chitosan, methyl paraben, and propyl paraben were obtained from Loba Chemie Pvt. Ltd., India. Propylene glycol was purchased from Merck Life Science Pvt. Ltd., India, and sodium hydroxide was procured from Fisher Scientific, India. All chemicals and reagents used in the study were of analytical grade and used without further purification.

Extraction of Curcuma longa and Piper nigrum

The dried rhizomes of Curcuma longa and dried fruits of Piper nigrum were washed with distilled water and shade dried and ground into powder separately in a mechanical grinder. A total of 100 g of each powdered material was macerated with 500 mL of methanol for 72 h with intermittent shaking for good phytoconstituents extraction. The extracts were filtered through Whatman No. 1 filter paper and concentrated under reduced pressure using rotary vacuum evaporator below 40°C. The concentrated extracts were subsequently dried under water bath to produce semi-solid extracts and kept in a closed, air-tight, amber coloured containers at 4°C until used. [33-34]

Preliminary Phytochemical Screening

The methanolic extracts of Curcuma longa and Piper nigrum were subjected to qualitative phytochemical screening using standard procedures to determine various phytoconstituents such as alkaloids, carbohydrates, glycosides, flavonoids, tannins, phenolic compounds, saponins, steroids, terpenoids, proteins, and amino acids. The presence or absence of these constituents was determined based on characteristic colour changes and/or precipitate formation.[35]

FTIR Study

The compatibility of extracts of Piper nigrum and Curcuma longa with the selected excipients was evaluated using Fourier-transform infrared (FTIR) spectroscopy. The spectra of the individual extracts and their corresponding extract–excipient mixtures were recorded in the range of 4000–400 cm⁻¹ at room temperature. The characteristic functional group peaks were compared for significant shift, disappearance or appearance of new peaks which might be occurring due to interaction between the herbal extracts and formulation excipients. [36]

Formulation of Herbal Hydrogel

Herbal hydrogel was prepared by dispersion of the selected polymer into distilled water and stirring for 24 hours until a uniform gel base form. Propylene glycol was used to dissolve methanolic extract of Curcuma longa and Piper nigrum and added to the hydrated polymeric dispersion. Methyl paraben and propyl paraben were added as preservatives and mixed for evenly dispersion with all the ingredients by stirring continuously for 10 min. An appropriate pH modifier was used to adjust the pH and distilled water was used to adjust the volume. The formulation was then homogenized to achieve a smooth, homogeneous and lump-free hydrogel. [37-38]

Table 1. Formulation table for Hydrogel

Appearance and Homogeneity

The prepared hydrogel formulations were evaluated visually for colour, consistency, transparency, grittiness, and phase separation. Homogeneity and smoothness were done by allowing the formulation to be gently rubbed between the fingers to check for the presence of coarse particles or lumps.

pH Determination

A calibrated digital pH meter was used to measure the pH of the hydrogel formulations. The appropriate amount of gel was suspended in distilled water and allowed to stand until uniform. The electrode of the pH meter was dipped into the sample and the reading on the pH meter was noted. Triplicate measurements were made and the mean obtained. The pH values were kept on physiological range of skin to reduce possible skin irritation after topical application. [39]

Viscosity Measurement

The viscosity of the formulations of hydrogel was measured by using AMETEK Brookfield DV-E™ viscometer using spindle model RV No.4 with 20rpm working rate and temperature of 25°C ± 1. The spindle was immersed in the beaker containing the sample of the hydrogel, and equilibrium readings were taken when the system was in a state of equilibrium. Triplicate measurements were done for all samples, and the resulting values in terms of viscosity was determined. [40]

Spreadability Study

The spreadability of the prepared hydrogels was analysed by the glass slide method. Equal amount of gel itself was positioned between two glass slides and standard weight was applied for a fixed amount of time to promote even dispersion. The distance traversed by the upper slide was then measured and spreadability determined according to the equation; S = M × L/T, where S is spreadability, M is applied weight, L is distance moved by slide and T is the time taken. The higher the spreadability values the efficient of application of the hydrogel on the skin surface was. [41]

Determination of Swelling Index

The swelling behaviour of the hydrogels was evaluated by placing approximately 1 g of the formulation in 10 mL of 0.1 N sodium hydroxide solution. The swollen gel was removed at pre-determined intervals, the surface was soaked with water to drain off excess water and then weighed. The swelling index was calculated using the ratio of the increase in weight of the swollen gel to its initial weight and expressed as percentage swelling. [42]

Extrudability Test

The extrudability of the hydrogel formulations was evaluated by filling the prepared gels into collapsible tubes and applying a specified pressure to extrude the contents. The volume of gel extruded in a specified time period was measured and the ease of extruding the gel was evaluated. Each formulation underwent three replicate tests and was calculated to determine the suitability of the product for convenient dispensing from the container.

In Vitro Antioxidant Activity

The antioxidant activity of the hydrogel formulations was evaluated using the DPPH free radical scavenging assay. DPPH solution was mixed with equal volume of the test samples and allowed to stand in the dark at room temperature for 30 min. The absorbance was taken at 517 nm using UV-visible spectrophotometer with ascorbic acid as reference drug. The percentage inhibition of DPPH radicals was determined using the decreasing in absorbance value of the control and sample and expressed as the scavenging activity of the radicals. [43]

In Vitro Anti-Inflammatory Activity

Egg albumin denaturation method was used to determine the anti-inflammatory activity of the herbal hydrogel. Fresh egg albumins fresh were used for the reaction with phosphate buffers pH 6.4 and different concentrations of test sample. Distilled water was used as negative control and Diclofenac Sodium used as standard drug. The protein mixture was incubated at 37°C for 15 min and heated at 70°C for 5 min to denature the protein. The absorbance was spectrophotometrically measured after the cooling process and percentage inhibition of protein denaturation was calculated according to the value of absorbance of the control and sample solutions. [44] DPPH radical inhibition percentages were determined with the following formula:

% Inhibition = [(Absorbance of control − Absorbance of sample) / Absorbance of control] × 100

The antioxidant potential was expressed as percentage radical scavenging activity, and the IC₅₀ value, if required, was determined from the graph plotted between concentration and percentage inhibition

In Vitro Antibacterial Activity

The antibacterial activity of the hydrogel formulation prepared from methanolic extracts of Curcuma longa and Piper nigrum was tested by agar well diffusion method. Sterile nutrient agar plates were prepared and wells, using a sterile cork borer were made, were inoculated with test microorganisms. The test formulation was added to the wells, and an antibiotic as positive control and plain gel base as negative control. The plates were incubated for 24 h at 37°C and the zone of inhibition was in measured in millimetres for the assessment of antibacterial activity. [44]

3. RESULT AND DISCUSSION

 Preliminary Phytochemical Screening

Alkaloids, carbohydrates, glycosides, flavonoids, tannins, phenolics, steroids and terpenoids were identified in methanolic extracts of both Curcuma longa and Piper nigrum; however proteins and amino acids were not present in either of the two extracts as saponins was detected only in C. longa (Table 02). This confirms that both extracts contain a wide variety of secondary metabolites which may have increased the bioactive properties like antioxidant, anti-inflammatory and antimicrobial potential of the final hydrogel formulation.

Table 2. Preliminary Phytochemical Screening of Methanolic Extracts

(+): Present

(−): Absent

Total Phenolic Content (TPC)

The total phenolic content of Curcuma longa extract and Piper nigrum extract was found to be 86.42 ± 1.18 mg GAE/g  and 71.36 ± 1.05 mg GAE/g, respectively. This indicated that C. longa was found richer in terms of phenolic compounds in the present study. The higher level of phenolics is due to their contribution towards free-radical scavenging as phenolic compounds are strong antioxidant potential. The gallic acid calibration curve showed excellent linearity (Fig 03), confirming the reliability of the assay.

Fig. 3. Calibration curve for Galic acid

Total Flavonoid Content (TFC)

The total flavonoid content of the extracts of C. longa was higher at 64.78 ± 0.94 mg QE/g than that of P. nigrum at 52.63 ± 0.88 mg QE/g, which indicates that more flavonoid-rich phytoconstituent to the formulation. Because flavonoids are known for their antioxidant and anti-inflammatory activities, this result further supports the biological relevance of the plant extracts used in the hydrogel. The quercetin calibration curve showed good linearity (Fig 04), validating the assay.

Table 3. TPC of the extract

Fig. 4. Calibration curve for Quercetin

FTIR Study

FTIR analysis of the extracts was performed using ALPHA II FTIR spectrophotometer (BRUKER, Japan). When analysed alone (fig 05and 07) and with excipients (Fig 06 and 08) it showed retention of the characteristic absorption peaks with no significant shifting or disappearance or appearance of new peaks employed in FTIR studies. This suggested excellent compatibility between the herbal extracts and the chosen excipients with no significant chemical interaction while also revealing that active phytoconstituents remained chemically stable during formulation development.

Fig. 5. FTIR of C. Longa extract

Fig. 6. FTIR of C. Longa extract with excipients

Fig. 7. FTIR of P. Nigrum extract

Fig. 8. FTIR of P. Nigrum extract with excipients

Organoleptic Evaluation

Visual inspections of the hydrogel batches showed no signs of phase separation, confirming physical stability of developed formulations (Table 04). It transitions from yellowish brown to dark yellowish brown, and varies in consistency from smooth to thick and smooth, with no grit or separation. These results suggest successful gel formation and that herbal extracts and excipients dispersed uniformly throughout the gels whereas texture changes observed between formulated samples, indicating that polymer type and concentration had a significant impact on the final features of the formulation.

Table 4. Organoleptic Evaluation of Hydrogel Formulations

pH of Formulations

The pH of all hydrogel formulations was observed using LI-120 digital pH meter (Labindia Instruments Pvt. Ltd., India). It was observed between 6.21 and 6.51 (Table 05), indicating suitable compatibility with physiological conditions within the upper layers of skin. Formulation F1 had the lowest pH (6.21 ± 0.05), whereas F9 showed the highest pH (6.51 ± 0.03). The narrow pH range indicates good stability of the formulation and compatibility between the incorporated herbal extracts and polymers in the hydrogel system.

Viscosity of Formulations

The viscosity was determined using DV-E Brookfield viscometer (AMETEK Brookfield, USA). It varied with respect to the strength of each polymer and formulation composition (Table 05), whereby F1 exhibited the lowest viscosity of 4210 ± 42 cP, whereas, F9 has the highest of 6246 ± 51 cP. Chitosan and other formulations including Carbopol showed higher viscosity than sodium alginate based batches, whereas HPMC based batches also showed relatively high viscosity. This suggests that stronger gel networks resulted in better retention at the site of application, but may also limit drug diffusion to some extent.

Spreadability of Formulations

Spreadability was inversely correlated to viscosity with F1 exhibiting the highest spreadability (18.45 ± 0.31 g·cm/sec) and F9 the lowest (12.85 ± 0.19 g·cm/sec). This confirms that more structured and viscous gels are less easily spread, whereas less viscous gels spread more readily. A moderate spreadability is desirable for topical hydrogel application because it ensures ease of application without excessive flow from the skin surface.

Swelling Index of Formulations

The swelling index increased across all batches, with F9 exhibiting the highest swelling (148.3 ± 3.2%) and F1 the lowest (112.4 ± 2.1%). Importantly, this illustrates how polymer composition governs liquid absorption and an extension of the matrix, which can promote hydration and enable active constituents to be released from the gel. The greater swelling of the batches containing Carbopol could be indicative of greater water-binding capacity and possibly an improved drug release profile.

Extrudability of Formulations

Extrudability values ranged from 91.5 ± 1.6 g/cm² for F1 to 76.4 ± 1.5 g/cm² for F9, indicating that higher-viscosity formulations were more resistant to extrusion from the tube. Although the stronger gel structure can improve residence time but acceptable extrudability is necessary for the patient convenience and ease of application. The F9 batch showed the best balance of gel strength and dispensability among the tested formulations.

Table 5. physicochemical parameters

In Vitro Antioxidant Activity (DPPH Assay)

The DPPH radical scavenging activity increased from 62.4 ± 1.2% in F1 to 78.5 ± 1.5% in F9, indicating that the optimized formulation has maximum antioxidant potential. This increased activity could be based on the prolonged retention and better release of herbal actives from the polymeric matrix, along with are rich in phenolic and flavonoid content of the plant extracts. Therefore, F9 may be a good candidate for antioxidant topical hydrogel.

Table 6. In vitro antioxidant activity and anti inflammatory activity

Fig. 9. DPPH study of Formulation F1–F12

In Vitro Anti-Inflammatory Activity

The egg albumin denaturation assay showed a similar trend to the antioxidant study, with F1 exhibiting 58.4 ± 1.1% inhibition and F9 showing the highest anti-inflammatory activity at 74.2 ± 1.4%. Thus, this indicates that the formulation successfully minimized the denaturation of proteins and hence inflammatory process. The best performance of F9 signifies the optimum bioavailability from bioactive compounds and suitable polymeric matrix.

Fig. 10. In-Vitro anti- Inflammatory activity study of Formulation F1–F12

In Vitro Antibacterial Activity of F9 Optimized Batch

The optimized F9 formulation demonstrated clear antibacterial activity against both Staphylococcus aureus and Escherichia coli, with zones of inhibition of 16.5 ± 0.3 mm and 18.5 ± 0.4 mm, respectively, compared with the standard values of 18.9 ± 0.4 mm and 21.1 ± 0.2 mm. Although the activity was slightly lower than the standard antibiotic, the hydrogel still showed appreciable antimicrobial potential, which may be due to the combined effect of Curcuma longa and Piper nigrum and effective delivery of active compounds from the gel matrix.

Fig. 11. In Vitro Antibacterial Activity of F9 Optimized Batch

Overall Interpretation

In general, the herbal hydrogel formulations were stable from a physical point of view in terms of skin compatibility and possessed significant antioxidant, anti-inflammatory and antimicrobial activities. Of all batches, F9 is the most successful formulation due to its elevated swelling index, significant antioxidant and anti-inflammatory activity and strong antibacterial property; however, higher viscosity, lower spreadability and low extrudability suggest a compact polymer network, probably responsible for adhesion and more permanent residence at the site of application.

CONCLUSION

The present study successfully formulated a stable and skin-compatible polyherbal hydrogel from Curcuma longa and Piper nigrum extracts. The optimized F9 formulation showed the best overall balance of physicochemical properties and biological activity that indicated strong antioxidant, anti-inflammatory, and antimicrobial potential. The results support the use of this herbal hydrogel as a suitable topical formulation for further preclinical and clinical investigation.

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