Development and Formulation of Anti-diabetic Capsules Containing Extract of E. denticulatum: Physicochemical Study, Encapsulation, and Release Kinetics

Abstract

Background

Eucheuma denticulatum has been widely used to treat diabetes mellitus due to its several antidiabetic components. The current study aimed to formulate capsules containing the crude extract of E. denticulatum.

Methods

The dry granulation method was used, with microcrystalline starch, corn starch, and the crude extract of E. denticulatum to produce granules. The granules were encapsulated, and the formulations were evaluated for weight uniformity, disintegration time, and in vitro drug release.

Results

The formulated capsules rapidly disintegrated (≤ 4 min), with a pH of 6.9 ± 0.15, a moisture content of 5 ± 0.01%, and weight uniformity within ±7.5%. Organoleptic and physicochemical properties of the extracts demonstrated their suitability for use in oral capsule formulation. Fourier transform infrared spectroscopy results showed that the active substance and the excipients were compatible. The final formulation spectrum retained most of the characteristic peaks of microcrystalline starch, corn starch, and the extract, but with noticeable shifts in peak positions and variations in intensity, particularly in the O–H, C–O, and C=O vibration bands, which signify that encapsulation of the E. denticulatum extract was successful. In vitro drug release showed almost 98% cumulative drug release and followed non-Fickian (anomalous) transport, Higuchi diffusion, and polymer swelling or erosion. In addition, the encapsulation efficiency was approximately 98%, and the drug-loading capacity was approximately 84%.

Conclusion

This study has demonstrated that the E. denticulatum capsule has ideal properties, a favorable release profile, and a suitable mechanism for antidiabetic activity. However, this study lacks stability tests and recommends their implementation, which are essential to determine the formulation’s long-term physicochemical stability, potency, and shelf-life.

Introduction

Type 2 diabetes, also known as type 2 diabetes mellitus (T2DM), is currently a serious public health concern estimated to affect approximately 537 million adults worldwide [1]. At the country level, Tanzania has about 2.9 million (12.3%) people currently living with diabetes, and is among the top five countries with the largest number of diabetic patients in Africa [2].

The increase of diabetes in Tanzania is related to risk factors such as obesity, physical inactivity, unhealthy dietary patterns, smoking, and alcohol consumption [3]. Currently available conventional antidiabetic therapies, such as metformin, sulfonylureas, and α-amylase and α-glycosidase inhibitors like acarbose and miglitol, have been used to treat type 2 diabetes. The major challenges associated with these treatments over long-term use include hypoglycemia, weight gain, hepatotoxicity, cardiovascular diseases, and drug resistance [4], [5]. Therefore, in order to reduce the consequences of synthetic treatments, there is an urgent need to search for natural sources for natural antidiabetic therapies that are safe and affordable.

The natural sources in focus are plants and algae. Natural products from macroalgae are reported to have the strongest hypoglycemic effects. Generally, natural therapies are considered less harmful and have fewer adverse effects than synthetic ones. E. denticulatum, a red alga in the class Rhodophyceae that grows in the ocean, has traditionally been used as a natural therapy for type 2 diabetes. Despite this species’ health and nutritional value as a valuable resource for functional foods in Tanzania, its full potential has yet to be tapped. The algae have been found to exhibit antidiabetic, antioxidant, and anti-inflammatory activities, suggesting their potential to regulate blood glucose levels [6], [7].

The phytochemical composition, antidiabetic activity, and safety profile of Eucheuma denticulatum extracts have all been documented in earlier research [6], [7], [8], [9]. However, the formulation of a standardized oral dosage form for therapeutic use has not been documented, as most research has focused on the biological evaluation of the crude extract. Therefore, this study aimed to investigate the integration of E. denticulatum extract into granules, a step of paramount importance for improving its bioavailability and thereby enhancing its effectiveness in the treatment of diabetes [10]. This study evaluated the formulated capsules containing E. denticulatum granules for their extract-excipient compatibility, organoleptic and physicochemical characteristics, and capsule quality, including the disintegration test, in vitro dissolution test, and weight uniformity.

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Materials

The red seaweed E. denticulatum was collected from the shores of Fumba in Zanzibar from 1^st April to 24^th April 2026, using the handpicking method, placed in a cool box at – 4°C, and transported to the University of Dar es Salaam laboratory for extraction procedures. To ensure optimal temperature for further processing and analysis, the seaweeds were placed in plastic bags that are designed to minimize exposure to sunlight and stored at –20°C. A small sample of the seaweed was taken to the Tanzania Plant Health and Pesticides Authority (TPHPA) for authentication. The identified macroalgae were deposited in the herbarium at TPHPA in Arusha with voucher specimen number Muze, M.00.

Mary Muze, Clara Mollay, Emmanuel Abraham Mpolya, Clarence Rubaka, Development and Formulation of Anti-diabetic Capsules Containing Extract of E. denticulatum: Physicochemical Study, Encapsulation, and Release Kinetics, Current Pharmaceutical Analysis, 2026, ISSN 1573-4129, https://doi.org/10.1016/j.cpan.2026.08.002.