Development and Evaluation of Emulgel Loaded with Pongamia pinnata Seed Oil and Wrightia tinctoria Leaf Extract for the Treatment of Skin Disorders

Abstract

The present study aimed to develop and evaluate an emulgel loaded with Pongamia pinnata seed oil and Wrightia tinctoria leaf extract for the treatment of skin disorders, with a particular focus on antimicrobial activity. Pongamia pinnata seed oil was extracted by mechanical pressing, while Wrightia tinctoria leaves were subjected to hot aqueous extraction. Four O/W type emulgel formulations (F1–F4) were prepared by incorporating a herbal emulsion into a gel base and evaluated for their physicochemical properties. All formulations exhibited good appearance, suitable pH, spreadability, extrudability, and stability without phase separation, with F4 showing the most favorable characteristics. Antimicrobial studies revealed that Wrightia tinctoria leaf extract showed strong antifungal activity with a MIC of 25 µl/ml against Candida albicans. In comparison, Pongamia pinnata seed oil and its combination showed moderate inhibition at 50 µl/ml. Against Staphylococcus aureus, both extracts were effective at 50 µl/ml, whereas the mixture showed reduced efficacy (MIC 100 µl/ml). The results suggest that topical emulgel formulations containing these extracts may offer dual antifungal and antibacterial effects, though further in vivo and extended antimicrobial studies are warranted to confirm therapeutic potential.

Keywords

Introduction

                 

 

Pongamia pinnata                                Wrightia tinctoria

Figure 1: Authentication letter

Method of Preparation of Plant Extracts: ^{6, 7}

Wrightia tinctoria leaf extract: Healthy leaves of Wrightia tinctoria were collected and shade-dried at room temperature to prevent degradation of bioactive constituents. The dried leaves were then powdered using a mixer, sieved to obtain uniform particle size, and stored in a well-closed container in a dry place until use. A hot aqueous extract was prepared by mixing 10 g of the leaf powder with 100 mL of distilled water (10% w/v) and maintaining the mixture at a constant temperature of 60?°C. The extract was then filtered through Whatman filter paper to obtain a clear solution for further use.

Pongamia pinnata seed oil: Mature seeds of Pongamia pinnata were collected and thoroughly cleaned to remove dust, debris, and damaged seeds. The seeds were shade-dried (or sun-dried if necessary) to reduce moisture content. Further drying was performed, if required, to achieve an optimal moisture content of approximately 8–10%, which is ideal for efficient oil extraction. The dried kernels were then ground into a coarse powder or crushed to increase the surface area, thereby enhancing the extraction efficiency of the oil.

Figure 2: Extraction Process

Preliminary Phytochemical Screening of plant extracts:^{8, 11}

Hot aqueous extract of Wrightia tinctoria leaves was subjected to preliminary phytochemical screening to detect the presence of various classes of phytoconstituents, including alkaloids, flavonoids, tannins, saponins, glycosides, and phenolic compounds, following standard qualitative procedures. The extracted oil from Pongamia pinnata seeds was similarly analyzed for the presence of phytoconstituents such as fatty acids, flavonoids, phenolic, terpenoids, and other bioactive compounds using standard phytochemical screening methods as given in table 1 and 2.

Table 1. Phytochemical Screening of Wrightia Tinctoria Leaf Extract

Phytochemical constituent	test	Inference
Flavonoids	Shinoda test	++
Alkaloids	Hager’s test	+++
	Wagner’s test	+++
Tannins	Ferric Chloride Test	++
	Lead Acetate	++

Phytochemical screening of Wrightia tinctoria leaf extract. The intensity of phytoconstituents is expressed as (+++) highly present, (++) moderately present

Table 2: Phytochemical screening of Pongamia pinnata seed oil

Phytochemical constituent	Test	Inference
Alkaloids	Wagner’s test	+++
Steroids	Liebermann–Burchard test	++
Tannins and Phenolics	Ferric chloride test	++
Fixed oil and fats	Spot test	+++
Flavonoids	Shinoda test	+++

Phytochemical screening of Pongamia pinnata seed oil. The intensity of phytoconstituents is expressed as (+++) highly present, (++) moderately present

Preparation of Emulgel loaded with Pongamia pinnata seed oil and Wrightia tinctoria leaf extract: The emulgel formulation was prepared using a two-phase system: an aqueous phase and an oil phase. The aqueous phase consisted of Carbopol 934, methyl paraben, and distilled water. Oil phase: Contained Pongamia pinnata seed oil, Wrightia tinctoria leaf extract, liquid paraffin, and isopropyl myristate. The aqueous and oil phases were separately prepared and then mixed. Triethanolamine was added to the mixture to neutralize Carbopol 934, resulting in the formation of a stable gel base.^12-14

Formulation composition of emulgels (F1–F4) loaded with Wrightia tinctoria leaf extract and Pongamia pinnata seed oil. Propylene glycol serves as a co-solvent in F1 and F2, while PEG 400 is incorporated in F3 and F4. Distilled water is added q.s. to make up the final weight to 50 g.

Figure 3: Prepared formulation of Emulgel loaded with plant extracts (F1- F4)

The results of the evaluation tests confirmed the stability and effectiveness of the developed emulgel. All the formulations were evaluated for their Colour and appearance. The physical appearances of all the formulations were found to be yellow in color, with a pleasant odor and smooth texture. The pH of all the formulations that is F1, F2, F3 and F4 were found to be in range of 6.5 to 6.7 which is good for skin pH. All the formulation of emulgel were shown pH nearer to skin required that is 5-7 pH. Spreadability study is one of the criteria for an emulgel to meet the ideal qualities that it should possess good Spreadability. If Spreadability value is more, it would be properly spread over the skin which is more beneficial as per patient compliance concern. All the formulations were checked for the Spreadability and Extrudability. The data were given in the table 4. Among all the formulations, F4 showed better Spreadability and Extrudability. The antimicrobial activity of Wrightia tinctoria leaf extract, Pongamia pinnata seed oil, and their combination was evaluated against Candida albicans and Staphylococcus aureus using the Minimum Inhibitory Concentration (MIC) method. The results are presented in Table 5.

Antimicrobial activity of Wrightia tinctoria leaf extract, Pongamia pinnata seed oil, and their mixture against Candida albicans and Staphylococcus aureus at different concentrations. “S” indicates sensitivity and “R” indicates resistance. B + C = Blank control, B + O = Blank ointment.

The results indicate that Wrightia tinctoria leaf extract exhibited the highest antifungal activity with a MIC of 25 µl/ml against Candida albicans, while Pongamia pinnata seed oil and the mixture showed moderate inhibition at 50 µl/ml. Against Staphylococcus aureus, both Wrightia tinctoria leaf extract and Pongamia pinnata seed oil were effective at 50 µl/ml, whereas the mixture showed a higher MIC of 100 µl/ml, suggesting reduced antibacterial efficacy in combination. Since Wrightia tinctoria showed better antifungal activity and both extracts were moderately effective against Staphylococcus aureus, incorporating them into topical formulations such as gels or emulsions may provide dual action against fungal and bacterial skin infections. Further evaluation through time-kill assays, zone of inhibition, and in vivo studies will be necessary to confirm their therapeutic relevance.

     

 

Figure 4:  MIC dilution test of plant extracts against E. coli and C. albicans

CONCLUSION

The present study successfully developed and evaluated a stable and effective emulgel formulation incorporating Pongamia pinnata seed oil and Wrightia tinctoria leaf extract for potential topical application in the treatment of skin disorders. All prepared formulations (F1–F4) exhibited desirable physicochemical characteristics such as appropriate pH, smooth texture, good spreadability, and excellent extrudability without phase separation. Among them, formulation F4 demonstrated the most favorable performance in terms of spreadability and stability.

Phytochemical analysis confirmed the presence of bioactive constituents including flavonoids, alkaloids, tannins, and fatty acids, which are responsible for the antimicrobial and anti-inflammatory activities of the extracts. Antimicrobial studies revealed that Wrightia tinctoria exhibited strong antifungal activity against Candida albicans (MIC 25 µl/ml), while Pongamia pinnata oil showed moderate antifungal and antibacterial activity. The combination of both extracts provided a balanced spectrum of antimicrobial effects, supporting their synergistic therapeutic potential.

Overall, the findings indicate that the developed herbal emulgel is a promising formulation for managing fungal and bacterial skin infections with good patient acceptability. Further in vivo studies and clinical evaluations are recommended to establish its safety, efficacy, and mechanism of action for potential pharmaceutical application.

ACKNOWLEDGEMENT

The authors would like to thank KRET’s Rani Chennamma College of Pharmacy, Belagavi, for providing the necessary facilities and support for this research work. We would also like to acknowledge Dr. Harsha V. Hegde (ICMR-NITM, Belagavi) and Dr. Ulka Idate (Maratha Mandal’s Central Research Laboratory, Belagavi) for their valuable assistance during this work.

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