Self-assembled renewable nano-sized pentacyclic triterpenoid maslinic acids in aqueous medium for anti-leukemic, antibacterial and biocompatibility studies: An insight into targeted proteins-compound interactions based mechanistic pathway prediction through molecular docking

Maslinic acid is a naturally occurring dihydroxy, mono-carboxy bioactive triterpenoid. Its bulky structure was the main hindrance in the path of biological activity. Sodium and potassium salts of nano-sized triterpenoid maslinic acid were prepared from maslinic acid and its self-assembly property was studied in aqueous and aqueous-organic binary liquid mixtures. Morphology of the compounds studied by Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), High Resolution Transmission Electron Microscopy (HRTEM), Optical Microscopy, Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) revealed vesicular morphology of the self-assemblies. Selective cytotoxicity was performed in leukemic (K-562 and KG-1a) and PBMC cells. Among the three self-assemblies (maslinic acid 1, sodium maslinate 2 and potassium maslinate 3), sodium maslinate 2 showed better antileukemic efficacy. Sodium maslinate 2 induced apoptosis in leukemic cells by elevating ROS levels and disrupting the cellular antioxidant system. From the in-silico studies, it was confirmed that 2 interacted with extrinsic and intrinsic apoptotic proteins of leukemic cells and killed those cells by inducing apoptotic pathways. The compounds 1, 2 and 3 showed significant antibacterial efficacy against E.coli strain through binding with several periplasmic membrane fusion protein (MFP) and limiting the efflux system leading to arrestation of antimicrobial resistance.

Saponins of Selected Triterpenoids as Potential Therapeutic Agents: A Review

Saponins represent important natural derivatives of plant triterpenoids that are secondary plant metabolites. Saponins, also named glycoconjugates, are available both as natural and synthetic products. This review is focused on saponins of the oleanane, ursane, and lupane types of triterpenoids that include several plant triterpenoids displaying various important pharmacological effects. Additional convenient structural modifications of naturally-occurring plant products often result in enhancing the pharmacological effects of the parent natural structures. This is an important objective for all semisynthetic modifications of the reviewed plant products, and it is included in this review paper as well. The period covered by this review (2019–2022) is relatively short, mainly due to the existence of previously published review papers in recent years.

Natural Small-Molecule-Based Carrier-Free Self-Assembly Library Originated from Traditional Chinese Herbal Medicine

The carrier-free self-assembly of small molecules opens a new window for the development of nanomaterials. This study is dedicated to developing binary small-molecular self-assemblies derived from phytochemicals in traditional Chinese herbal medicine. Among them, Rhei Radix et Rhizoma and Coptidis Rhizoma are a common pair used in clinics for thousands of years. Here, we found that there were numerous spherical supramolecular nanoparticles (NPs) originated from Rhei Radix et Rhizoma and Coptidis Rhizoma decoction. Ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) was used to analyze the composition of the supramolecules, and a total of 119 phytochemicals were identified (23 anthraquinones, 31 alkaloids, 24 organic acids, 8 tannins, and other components). Isothermal titration calorimetry (ITC) showed that the interaction between Rhei Radix et Rhizoma and Coptidis Rhizoma was a spontaneous exothermic reaction, indicating that their phytochemicals had the property of self-assembly and interacted to form supramolecules in the decocting process. Furthermore, scanning electron microscopy (SEM), UV, IR, NMR, and ITC were used to verify that rhein and coptisine could self-assemble into nanofibers (Rhe-Cop NFs), while emodin and coptisine could self-assemble into nanoparticles (Emo-Cop NPs). The formation mechanism analysis of the self-assemblies revealed that they were induced by electrostatic attraction, hydrogen bonding, and π-π stacking, forming nanospheres of about 50 nm and nanofibers. The current study not only provides an idea of discovering carrier-free self-assemblies from traditional herbal medicine decoction but also supplies a reference for the design of binary self-assembly of small molecules in the future.

Self-assembly of the monohydroxy triterpenoid lupeol yielding nano-fibers, sheets and gel: environmental and drug delivery applications

Lupeol is a medicinally important naturally abundant triterpenoid having a 6-6-6-6-5 fused pentacyclic backbone and one polar secondary "-OH" group at the C3 position of the "A" ring. It was extracted from the dried outer bark of Bombax ceiba and its self-assembly properties were investigated in different neat organic as well as aquous-organic binary liquid mixtures. The triterpenoid having only one polar "-OH" group and a rigid lipophilic backbone self-assembled in neat organic non-polar liquids like n-hexane, n-heptane, n-octane and polar liquids like DMSO, DMF, DMSO-H₂O, DMF-H₂O, and EtOH-H₂O yielding supramolecular gels via formation of nano to micrometre long self-assembled fibrillar networks (SAFINs). Morphological investigation of the self-assemblies was carried out by field emission scanning electron microscopy, high resolution transmission electron microscopy, atomic force microscopy, optical microscopy, concentration dependent FTIR and wide angle X-ray diffraction studies. The mechanical properties of the gels were studied by concentration dependent rheological studies in different solvents. The gels were capable of removing toxic micro-pollutants like rhodamine-B and 5,6-carboxyfluorescein as well as the toxic heavy metal Cr(vi) from contaminated water. Moreover release of the chemotherapeutic drug doxorubicin from a drug loaded gel in PBS buffer at pH 7.2 has also been demonstrated by spectrophotometry.

Garland, Flower, and Petals via a Hierarchical Self-Assembly of Ursane-Type Triterpenoid Uvaol

Uvaol, a 6-6-6-6-6 pentacyclic dihydroxy ursane-type triterpenoid, is isolable from different parts of plants Plumeria rubra, Olea europaea, Nerium oleander, Lavandula pedunculta, and Malus domestica. It is also obtained by a one-step reduction of naturally occurring triterpenoid ursolic acid. Herein, we report the first self-assembly properties of uvaol in different neat organic liquids and aqueous organic binary liquid mixtures. Spontaneous self-assembly of uvaol in different neat liquids and binary liquid mixtures yielded garland, flower, and petal-like porous superstructures of nano- to micrometer dimensions. Utilization of self-assemblies has been demonstrated in generation of anticancer drug conjugates and the removal of carcinogenic and toxic chemicals.

Flower- and Grass-like Self-Assemblies of an Oleanane-Type Triterpenoid Erythrodiol: Application in the Removal of Toxic Dye from Water

Erythrodiol (3β-olean-12-ene-3, 28-diol) (C30H50O2) 1 is a nanosized oleanane-type fused 6-6-6-6-6 pentacyclic triterpeneoid extractable from the dried leaves of olive (Olea europia). One step reduction of oleanolic acid extracted from Lantana camara also yields the same compound. The triterpenoid has one secondary -OH group attached at C3 of the "A" ring and one primary -OH group at C28 present at the junction of the "D" and "E" rings. Here, we report the spontaneous self-assembly of erythrodiol in different neat organic liquids and aqueous-organic liquid mixtures. The nanosized dihydroxy triterpenoid having an oleanane-type lipophilic rigid skeleton self-assembled in liquids, yielding nanosized fibrils, microsized flowers, and grass-like architectures via formation of densely assembled fibrils and petals or 2D sheets. The microstructures of the self-assemblies have been characterized by different techniques like optical microscopy, electron microscopy, atomic force microscopy, FTIR, and wide angle X-ray diffraction studies. The porous self-assemblies having a large surface area obtained from 1 were capable of adsorbing toxic fluorophores like rhodamine-B, rhodamine-6G, methylene blue, and crystal violet (CV). Moreover, removal of the aforementioned toxic pigments has also been demonstrated from their aqueous solutions by using UV-visible spectrophotometry and epifluorescence microscopy.

Self-assembly of naturally occurring stigmasterol in liquids yielding a fibrillar network and gel

Stigmasterol extracted from the leaves of Roscoea purpurea spontaneously self-assembled in liquids yielding a fibrillar network and gel.