The utilization of plants in treating both human and animal diseases dates back to ancient times. In the developing countries of the world, plants have continued to be a rich source of medicine where about 80 % of the population depend on medicinal plants (herbal remedies) for their survival [1], [2], [3], [4], [5]. Herbal medicines from plants are cheaply available, conveniently accessible, and satisfy some cultural and traditional beliefs, in addition to their little or no side effects. Different parts of the plant (seed, fruit, stem bark, root, leaves, etc) have over the years shown activity for various diseases [6]. Therefore, screening of herbal (medicinal) plants has continued to be a potential source of compounds of high therapeutic value. A typical example is Artemisinin (Qinghaosu), a sesquiterpene 1, 2, 4-trioxane (sesquiterpene lactone endoperoxide) isolated from the Chinese medicinal herb Qing Hao (Artemisia annua L.) and is an effective antimalarial against chloroquine-resistant strains of Plasmodium falciparum [7], [8]. This has necessitated many studies into extraction, isolation, purification, and chemical characterization of plant extracts for possible lead molecules for drug development from their bioactive secondary metabolites [9], [10], [11].

The genus Pentaclethra (Fabacaea) is represented by only three species (P. macrophylla, P. macroloba and P. eetveldeana [12], [13]. The Zairian traditional medicine (in tropical African forests) recognizes P. eetveldeana as a remedy for the treatment of hemorrhoids, malaria, and epilepsy [14] while local Brazilian people use P. macroloba as an antidote against snakebite [12], [15] due to the action of its triterpenoid saponins [12]. P. macrophylla is the only member of the genus occurring naturally in the lowlands of West Africa. Nearly all parts of the P. macrophylla plant (fruits, seeds, stem bark, leaves, and roots) are used for various human and animal ailments. P. macrophylla has been shown to have a variety of pharmacological effects [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26]. The plant has also many nutritional benefits [26]. The therapeutic efficacy of medicinal plants lies in the presence of phytoconstituents present in them which may include alkaloids, steroids, saponins, and flavonoids [1], [20], [25], [27].

Bergenin (BGN) is a bioactive natural compound that is isolated from the traditional African tree, Pentaclethera macrophylla [1]. BGN is a C-glycoside of 4-O-methylgallic acid that is isolated from many other medicinal plants such as Flueggea leucopyrus, Mallotus philippensis, Corylopsis spicata, Mallotus japonicus, Sacoglottis gabonensis, the traditional Chinese herb, Bergenia crassifolia [28], Securinega virosa (Euphorbiaceae) commonly marketed in Ghana for medicinal purposes [29], the Japanese Pulmonaria officinalis as well as Caesalpinia digyna in the Himalayas [30]. BGN has been reported to have pharmacological effects that range from anti-inflammatory [27], antioxidant [31], antimicrobial [32], anti-HIV [33], hepatoprotective [34], [35], to anti-malarial effects [36]. BGN has low solubility in water (1.37 ± 0.02 mg/mL) and permeability (Log P = −1.02) [37], [38], [39] and is therefore classified as a class IV drug based on the Biopharmaceutics Classification System (BCS). It has poor oral absorption due to low solubility which hampers its clinical relevance. Scientists have reported many techniques to improve the solubility and bioavailability of BGN. These include structural modification, poly(lactic acid) polymers and the application of absorption enhancers [28], [40], [41], [42]. However, there have been few studies evaluating the nanostructured lipid carrier (NLC) of BGN. NLCs are third-generation solid lipid nanoparticles credited to handle low solubility and poor permeability by occluding the drug in the lipid core of its constitution [8]. Liquid crystalline nanoparticles are also suitable for encapsulation of hydrophobic drugs [43]. In this study, 75 % of the liquid lipid Transcutol® HP was melted with 15 % of Phospholipon® 90H and 10 % Gelucire® 43/01 as the lipid phase, altogether giving a lipid matrix of 5 % to which was added the surfactant aqueous phase consisting of Tween® 80, sorbitol and sorbic acid. BGN was extracted from P. macrophylla stem bark extract, purified by HPLC, and used as a drug to formulate and evaluate NLCs as an anti-inflammatory preparation on inflamed macrophages. Macrophages are the main component of the innate immune system that senses pathogens and quickly promote an inflammatory phenotype to reduce damage and support tissue homeostasis [43], [44], [45]. Inflammation is a complicated defense process involving extensive signaling-dependent changes in gene expression [46], [47]. Lipopolysaccharides (LPS) are endotoxin molecules that come from the cell walls of gram-negative bacteria [43]. LPS administration to cells or animals induces strong immune responses (IL-6 and TNF-α); hence it is commonly used as a stimulus to develop and study inflammation. By this study therefore, the cytotoxicity of BGN, BGN-NLC formulation and plant extract (PE) will be studied as well as their anti-inflammatory effects on IL-6 levels, secreted by dTHP-1 macrophages and/or reduction of TNF-α in vitro. To the best of our knowledge, this is the first study analyzing the anti-inflammatory activity of the BGN-NLC formulation and/or as PE.