Lysosomal Berberine: Intracellular Targeting and Therapeutic Advancements

Berberine is a bioactive isoquinoline alkaloid extracted from various medicinal plants, including Berberis aristata, long used in traditional medicine systems such as Ayurveda and Chinese medicine. Over the past two decades, its therapeutic potential has been increasingly supported by modern pharmacological research. Berberine exhibits a wide range of biological effects including antidiabetic, antihyperlipidemic, anti-inflammatory, antioxidant, antimicrobial, and anticancer properties [1–3]. It exerts these effects through modulation of multiple intracellular pathways such as AMP-activated protein kinase (AMPK), nuclear factor-kappa B (NF-κB), mitogen-activated protein kinases (MAPKs), and insulin signaling cascades [2, 4, 5]. Despite these promising properties, the clinical utility of berberine has been significantly limited by its poor oral bioavailability (<1%), low intestinal permeability, rapid metabolism in the liver, and strong P-glycoprotein (P-gp) efflux [6, 7]. These pharmacokinetic drawbacks hinder its systemic absorption and intracellular availability, leading to suboptimal therapeutic concentrations at the target site [8, 9]. Various formulation strategies have been proposed to overcome these limitations. Among them, lipid-based systems such as phytosomes and nanoemulsions have achieved modest improvements in bioavailability [10, 11]. However, these approaches often fail to ensure intracellular targeting, which is crucial for achieving therapeutic efficacy in diseases driven by cellular dysfunction such as type 2 diabetes, atherosclerosis, NAFLD, and certain cancers [3, 12, 13]. This growing awareness has led to the exploration of lysosomal-targeted delivery as an emerging and more rational strategy to enhance berberine’s intracellular pharmacodynamics. Lysosomes are acidic, enzyme-rich organelles that play a central role in autophagy, macromolecule degradation, and immune responses [14]. They serve as critical intracellular destinations for many endocytosed nanocarriers, making them a strategic target for drug delivery [15, 16]. In lysosomal delivery systems, berberine is encapsulated within nanocarriers engineered to release their payload under the lysosomal environment’s low pH or specific enzymatic conditions [17–19]. These nanocarriers—comprising pH-sensitive micelles, biodegradable polymers, or peptide-based constructs—are typically internalized via receptor-mediated endocytosis and trafficked through endosomal pathways to the lysosome [20, 21]. Once inside the lysosome, the acidic microenvironment triggers the breakdown of the carrier, allowing berberine to be released where it can interact with intracellular targets such as AMPK and PPAR-γ [1, 5, 22]. This targeted approach enhances intracellular retention, improves drug bioactivity, and bypasses efflux mechanisms like P-gp, thereby overcoming one of the primary pharmacological barriers of berberine [7, 23]. Preclinical studies have consistently demonstrated the superiority of lysosome-targeted berberine formulations over conventional oral berberine in improving glycemic control, reducing hepatic steatosis, modulating lipid metabolism, and suppressing inflammatory markers [4, 6, 9, 24]. In animal models of diabetes and fatty liver disease, lysosome-directed nanocarriers have shown more potent activation of metabolic pathways and reduction of histological damage compared to unmodified berberine [25, 26]. Moreover, early clinical studies employing advanced delivery forms such as self-nanoemulsifying drug delivery systems (SNEDDS), phytosomes, and chitosan nanoparticles have reported improved therapeutic outcomes, including lower fasting glucose, improved insulin sensitivity, and better lipid profiles with reduced side effects [3, 11, 27]. Given the growing burden of chronic, intracellularly-driven diseases and the limitations of conventional berberine formulations, the need for targeted delivery systems is clear. This review provides a comprehensive overview of lysosomal berberine delivery systems, discussing their underlying mechanisms, formulation strategies, pharmacokinetic advantages, and emerging clinical applications. It also highlights existing gaps and potential directions for future research to facilitate translation into clinical practice.

Mechanisms of Lysosomal Targeting in Berberine Delivery

Targeting berberine to lysosomes represents an innovative strategy to overcome its limited oral bioavailability and insufficient intracellular activity. The central goal of lysosomal delivery is to ensure that berberine reaches its intended site of action within the cell, particularly where signaling modulation, metabolic regulation, or cytotoxic effects are required. This is achieved by using nanocarriers engineered to exploit the natural process of endocytosis and lysosomal trafficking within cells [5, 14, 15].

Figure 1. Mechanism of lysosomal berberine delivery. Nanocarriers encapsulating berberine are internalized via endocytosis, trafficked through early endosomes, and reach lysosomes where the acidic pH triggers berberine release. Intracellular berberine activates AMPK and related signalling pathways involved in metabolic regulation.

Most lysosomal-targeting drug delivery systems rely on endocytic uptake to enter the cell. Nanoparticles are typically internalized through clathrin-mediated or caveolae-mediated endocytosis, depending on their size, surface charge, and functionalization [15, 16]. Following endocytosis, carriers are first enclosed in early endosomes, then mature into late endosomes, and eventually fuse with lysosomes—organelles rich in hydrolytic enzymes and acidic pH (4.5–5.5) [14, 16]. By designing nanocarriers that remain intact during early endosomal transport and become destabilized in the acidic lysosomal environment, berberine can be selectively released inside lysosomes, thereby maximizing its intracellular availability [17, 18].

2. pH-Responsive and Enzyme-Sensitive Nanocarriers

Lysosomal targeting is largely enabled by smart drug delivery systems that respond to the physicochemical conditions inside the lysosome. Among the most widely used are:

• pH-sensitive polymers that destabilize and release the drug at low pH [17, 18]
• Enzyme-responsive linkers, such as those cleaved by cathepsins or β-glucuronidase [19, 20]
• Proton sponge effect polymers, which create osmotic swelling and rupture endosomal membranes, enhancing berberine release into the cytoplasm [21]

Materials such as poly(lactic-co-glycolic acid) (PLGA), polyethylene glycol (PEG), chitosan, and polypeptides have been effectively used to create these systems. Their biodegradability and safety profiles make them suitable for clinical development [6, 7, 18].

3. Receptor-Mediated Targeting

To enhance the specificity of lysosomal accumulation, surface modifications such as ligand conjugation or peptide functionalization are often employed. These ligands (e.g. transferrin, folic acid, mannose) bind to cell-surface receptors that are actively internalized and trafficked toward the lysosome [19, 20]. This approach is particularly relevant in targeting diseased cells such as hepatocytes, cancer cells, or activated immune cells that overexpress certain uptake receptors [22].

4. Bypassing Efflux and Metabolic Barriers

Lysosomal-targeted delivery also allows berberine to bypass common pharmacokinetic barriers such as:

• First-pass metabolism, by enabling uptake in the intestinal lymphatics
• Efflux transporters like P-glycoprotein (P-gp), which actively remove berberine from cells [7, 23]

Once released into the lysosome, berberine escapes rapid elimination and maintains higher intracellular retention, which is critical for activating AMPK, downregulating lipogenic enzymes, and modulating immune signaling cascades [1, 4, 22].

5. Enhanced Therapeutic Precision

By delivering berberine directly to its intracellular site of action, lysosomal systems reduce the systemic dose required, lower the risk of off-target effects, and enable more consistent pharmacological responses—especially in metabolic diseases, chronic inflammation, and intracellular infections [3, 5, 24].

Types of Nanocarriers Used for Lysosomal Berberine Delivery

The effectiveness of lysosomal berberine delivery is closely tied to the type of nanocarrier system employed. These carriers are designed to optimize intracellular uptake, enhance lysosomal accumulation, and release berberine in response to specific lysosomal triggers such as pH or enzymes. The following are the major classes of nanocarriers utilized in lysosomal-targeted delivery systems for berberine.

Figure 2: Types of nanocarriers designed for lysosomal delivery of berberine. Each system utilizes unique physicochemical triggers—such as acidic pH or lysosomal enzymes—to enable intracellular release. The diagram compares materials, triggering mechanisms, disease targets, and release strategies for micelles, enzyme-responsive nanoparticles, chitosan-based systems, dendrimers, and peptide-functionalized carriers

Micelles constructed from block copolymers like PEG-PLA or PEG-PCL exhibit disassembly under acidic conditions found in lysosomes (pH 4.5–5.5). This pH sensitivity allows for rapid drug release upon lysosomal localization, improving berberine’s intracellular bioavailability in tissues affected by metabolic dysfunction [5].

2. Enzyme-Responsive Nanoparticles

These systems utilize biodegradable polymers such as PLGA linked with enzyme-sensitive moieties that respond to lysosomal enzymes like cathepsin B or cathepsin L. Berberine release is triggered upon enzymatic cleavage within the lysosome, which is particularly beneficial in targeting tumor or inflamed cells that overexpress such enzymes [7].

3. Chitosan-Based Nanoparticles

Chitosan, often crosslinked with tripolyphosphate (TPP) or alginate, offers mucoadhesive properties and pH sensitivity. Its amino groups become protonated under lysosomal pH, enhancing endosomal escape and enabling targeted delivery in hepatic and intestinal inflammatory disorders [17].

4. Dendrimer-Based Carriers

Dendrimers such as PAMAM or PPI offer high surface functionality, enabling fine-tuned lysosomal release profiles. These nanostructures can be engineered for pH-triggered swelling or endosomal escape, and are being explored for chronic inflammation and neurodegenerative conditions [18].

5. Peptide-Functionalized Nanocarriers

Peptide-ligand conjugation (e.g., transferrin, RGD peptides) allows for receptor-mediated endocytosis. These nanocarriers selectively target diseased cells and facilitate precise lysosomal delivery, making them promising for cancer and diabetic organ damage [19].

The clinical translation of berberine has long been constrained by its limited cellular uptake and systemic exposure. Lysosomal delivery systems, by facilitating intracellular accumulation and controlled release, have shown marked improvements in preclinical and early clinical studies. These systems enhance berberine’s pharmacological engagement with molecular targets and result in superior therapeutic outcomes in metabolic and inflammatory diseases.

1. Preclinical Studies: In Vitro and In Vivo

Several animal and cellular models have demonstrated that lysosome-targeted formulations of berberine significantly enhance its pharmacological effects compared to unencapsulated forms. In high-fat diet-induced diabetic mice, pH-sensitive micellar berberine formulations activated AMPK more efficiently and reduced fasting glucose, triglycerides, and insulin resistance markers [5, 6]. Similarly, in hepatocyte cell lines and NAFLD mouse models, chitosan-based and dendrimeric carriers facilitated berberine release in lysosomes, resulting in stronger inhibition of lipogenesis and pro-inflammatory cytokine expression [17, 18]. Lysosomal delivery has also been linked to effective suppression of NF-κB activation, reduced oxidative stress, and decreased macrophage infiltration in inflamed tissues [7, 9]. These intracellular effects are crucial in chronic conditions such as obesity, metabolic syndrome, and fatty liver disease where systemic delivery alone may be insufficient.

2. Pharmacokinetics and Cellular Retention

Comparative pharmacokinetic studies have shown that lysosome-targeted berberine remains in the intracellular compartment significantly longer than free berberine or traditional lipid-based formulations. Nano-formulated berberine using enzyme-sensitive carriers achieved higher intracellular drug retention and increased tissue-to-plasma concentration ratios [6, 12]. Moreover, these carriers bypass efflux by P-glycoprotein, allowing berberine to persist at therapeutic levels within target cells [7, 13].

3. Early Clinical Observations and Pilot Trials

Although limited in number, emerging clinical studies using advanced delivery systems provide encouraging evidence of enhanced efficacy with improved tolerability. For instance, a double-blinded pilot study using SNEDDS-berberine formulations showed greater improvements in HbA1c, lipid profiles, and liver enzyme levels compared to conventional tablets in patients with type 2 diabetes and NAFLD [3, 11]. Another open-label trial utilizing chitosan–berberine complexes reported better patient adherence due to reduced gastrointestinal side effects and more stable glycemic control [24]. Table 2 below summarizes representative clinical outcomes associated with lysosomal berberine delivery across various formulations.

While lysosomal delivery systems offer promising therapeutic advantages over traditional formulations, their safety, tolerability, and translational applicability require careful consideration. Several preclinical and early-phase clinical studies have assessed these parameters across various carrier systems.

1. General Safety and Biocompatibility

Nanocarriers used for lysosomal delivery—such as chitosan, PLGA, PEG, dendrimers, and micellar structures—are generally regarded as safe and have been used in multiple pharmaceutical products [5, 7]. Their controlled drug release mechanisms help reduce systemic toxicity by concentrating berberine at intracellular sites of action. In animal models, lysosome-targeted systems demonstrated good tissue compatibility and minimal signs of immunogenicity or inflammation [18].

2. Gastrointestinal Tolerability

Conventional berberine formulations are known to cause gastrointestinal discomfort, including cramping and diarrhea. Lysosomal-targeted versions—particularly those based on mucoadhesive polymers like chitosan or oil-in-water nanoemulsions like SNEDDS—appear to mitigate these effects. Improved retention and slower release in the gastrointestinal tract reduce peak plasma spikes and lower irritation, contributing to better patient compliance [9, 11].

3. Formulation-Specific Risks

Despite the advantages, several formulation-specific concerns have been identified. pH-sensitive micelles may exhibit burst release in the stomach or lysosomes, leading to off-target effects if poorly designed [5]. Enzyme-responsive systems pose potential immunogenicity risks with chronic use, particularly in individuals with autoimmune sensitivity [7]. Dendrimer-based systems, though effective, require comprehensive toxicological profiling due to concerns regarding renal clearance and long-term retention [18].