Formulation and Evaluation of Herbal Based Immunomodulatory Gel Prepared from the Leaf Extract of Hippophae rhamnoides L.

Background: Hippophae rhamnoides L. (sea buckthorn) is a medicinal plant containing phenolic acids, flavonoids and other bioactive constituents. The leaves are of particular interest because they can contain substantial phenolic and flavonoid fractions. Objective: The present work aimed to develop and evaluate a topical herbal gel containing ethanolic leaf extract of Hippophae L., with emphasis on formulation quality, antioxidant activity, preliminary anti-inflammatory activity, analytical characterization and in-vitro release. Methods: Leaves collected from Sissu, Lahaul and Spiti, Himachal Pradesh, were shade-dried and extracted with ethanol using Soxhlet extraction. Five formulations (F1–F5) were prepared using Carbopol 940 with increasing extract concentrations and evaluated for appearance, homogeneity, washability, pH, viscosity and spreadability. The optimized formulation was examined by UV-visible spectroscopy and HPLC. Antioxidant activity was assessed by DPPH radical-scavenging assay, and preliminary anti-inflammatory activity by egg albumin denaturation. In-vitro release was studied using a membrane diffusion setup. Results: The extract yield was 12.80%. F3 was selected as the optimized formulation, showing pH 6.0, viscosity 7725 cps and spreadability 4.0 cm. The extract produced 91.6% DPPH inhibition at 100 µg/mL, with an IC50 of 27.7 µg/mL. F3 produced 58.0% inhibition of protein denaturation. UV-visible scanning showed a major absorption maximum at 260 nm, while HPLC showed a major peak at approximately 5.6 min under the reported chromatographic conditions. Cumulative release reached 96.3% at 360 min. Conclusion: The findings support the feasibility of incorporating Hippophae rhamnoides L. leaf extract into a Carbopol-based topical gel with satisfactory physicochemical properties and preliminary antioxidant/anti-inflammatory activity. The work should be considered a formulation and screening study; validated cell-based immunomodulatory, permeation, safety and stability studies are needed before therapeutic claims are made.