Formulation of a Novel Emulgel Incorporated with <i>Alpinia calcarata</i> Essential Oil and Assessment of Its Anti-inflammatory Activity

Alpinia calcarata (A. calcarata) Roscoe (Family: Zingiberaceae) is a rhizomatous perennial herb used in traditional medicine to treat inflammatory conditions. This study aimed to develop a topical emulgel dosage form by incorporating the essential oil of A. calcarata rhizome and to investigate it’s in vitro anti-inflammatory activity. A thin-layer chromatographic fingerprint of the essential oil of A. calcarata rhizome was developed. Then, an emulsion base containing plant oil was formulated and incorporated within a Carbopol gel base. The physical characteristics of this formulation were evaluated subsequently. The anti-inflammatory mechanism of the emulgel was determined by in vitro blood cell membrane stabilization assay and thrombolytic activity assay. The results were statistically analyzed by one-way analysis of variance. The thin-layer chromatographic fingerprint of the test oil demonstrated several bands with unique retention factor values. The formulated herbal emulgel was white, viscous, and homogeneous in appearance. The spreadability was 118 g·cm/M, and the pH of the emulgel was 6.30 at 25°C. The A. calcarata emulgel significantly (p < 0.05) inhibited heat-induced in vitro hemolysis, with the highest activity at a 50 µg/mL dose (87.68 ± 0.35%) compared to the placebo. Furthermore, this activity was found to be dependent on the essential oil concentration (r2 = 0.99) of the emulgel. Therefore, it was concluded that the essential oil of A. calcarata rhizome is an effective active ingredient to be used in a topical emulgel formulation, whereas the diverse phytochemicals present in the essential oil would be the underlying source of its anti-inflammatory activity.