Qualitative Analysis of Solid Capsules Containing Lyophilized Proanthocyanidins Extracted from Dry Pelargonium sidoides DC. Root Extract

Abstract

Background: Pelargonium sidoides DC. is a perennial plant that belongs to the Geraniaceae plant family and is primarily found in Southern Africa [1]. It‘s secondary metabolites are mostly proanthocyanidins that are linked to antioxidant, anti-inflammatory, immunomodulatory, antitumor and DNA-protective properties [2]. In this study, qualitative analysis of solid capsules containing lyophilized proanthocyanidins extracted from the dry Pelargonium sidoides DC. root extract was performed. Aim: To perform qualitative analysis of solid capsules containing lyophilized proanthocyanidins extracted from the dry Pelargonium sidoides DC. root extract. Methods: Dry Pelargonium sidoides DC. root extract was obtained from International Flavors & Fragrances Inc. (Switzerland). Proanthocyanidins were isolated and purified using Sephadex LH – 20 column chromatography with methanol (50 %) and acetone (70 %) as eluting solvents sequentially. Proanthocyanidin samples were prepared by acetone evaporation followed by lyophilization. For proanthocyanidin quantification spectrophotometric DMAC method was used with epicatechin solution as a standard. Capsule quality was evaluated by uniformity of mass and disintegration tests, as well as an in vitro release study in methanol (50 %) and hydrochloric acid medium (pH = 1.2). The statistical analysis was performed using “Microsoft Excel 2025” (Microsoft Corporation, USA). Results: The average capsule weight, determined by the uniformity of mass test, was 0.370 (0.004) g. Capsules disintegrated after 16 minutes. In methanol (50 %) medium maximum release was 8.72 mg EE/g (87.06 %) and in pH 1.2 medium maximum release was 6.22 mg EE/g (62.03 %). Conclusions: Fewer than 2 capsules out of 20 showed a mass deviation greater than 7.5 %, indicating consistent capsule filling. All capsules disintegrated in less than 30 minutes, demonstrating acceptable disintegration performance. The in vitro release study showed that release of epicatechin equivalents was dependent on the test medium: in 50 % methanol, proanthocyanidin - like compounds were released from capsules almost completely, whereas in a pH 1.2 medium the maximum release was lower, indicating limited release of epicatechin – equivalent compounds under acidic conditions.