Synthesis and evaluation of andrographolide derivatives as potent anti-osteoporosis agents in vitro and in vivo

The Nexus Between Traditional Chinese Medicine and Immunoporosis: Implications in the Treatment and Management of Osteoporosis

Osteoporosis (OP) is a globally prevalent bone disease characterized by reduced bone mass and heightened fracture risk, posing a significant health and economic challenge to aging societies worldwide. Osteoimmunology-an emerging field of study-investigates the intricate relationship between the skeletal and the immune systems, providing insights into the immune system's impact on bone health and disease progression. Recent research has demonstrated the essential roles played by various immune cells (T cells, B cells, macrophages, dendritic cells, mast cells, granulocytes, and innate lymphoid cells) in regulating bone metabolism, homeostasis, formation, and remodeling through interactions with osteoclasts (OC) and osteoblasts (OB). These findings underscore that osteoimmunology provides an essential theoretical framework for understanding the pathogenesis of various skeletal disorders, including OP. Traditional Chinese medicine (TCM) and its active ingredients have significant clinical value in OP treatment. Unfortunately, despite their striking multieffect pathways in the pharmacological field, current research has not yet summarized them in a comprehensive and detailed manner with respect to their interventional roles in immune bone diseases, especially OP. Consequently, this review addresses recent studies on the mechanisms by which immune cells and their communication molecules contribute to OP development. Additionally, it explores the potential therapeutic benefits of TCM and its active components in treating OP from the perspective of osteoimmunology. The objective is to provide a comprehensive framework that enhances the understanding of the therapeutic mechanisms of TCM in treating immune-related bone diseases and to facilitate the development of novel therapeutic strategies.

Synthesis and Pesticidal Activities of Ester Derivatives of the Labdane Diterpenoid Andrographolide at the C-3 Position Containing the Isoxazoline Fragment and Their Toxicology Study against Tetranychus cinnabarinus Boisduval

Due to the long-term overuse of chemical pesticides, serious resistance and negative problems on human health and the ecological environment have appeared. To develop plant-product-based pesticide candidates, a series of novel andrographolide ester derivatives containing the isoxazoline skeleton were prepared at the C-3 position. Their pesticidal activities were evaluated against three typical pests such as Mythimna separata Walker, Aphis citricola Van der Goot, and Tetranychus cinnabarinus Boisduval. Against M. separata, compounds Ik, IIf, IIg, and IIk showed 1.6-1.8 times insecticidal activity compared to that of andrographolide; against A. citricola, compounds 6, Ih, and IIh possessed 3.7-3.9-fold aphicidal activity compared to that of andrographolide; against T. cinnabarinus, compounds Ib, Ig, and IIk exhibited 7.4-9.1-fold promising acaricidal activity compared to that of andrographolide. It is worth mentioning that effects of IIk on morphological changes of the treated mite cuticle layer structures were observed by the scanning electron microscope imaging method. Compound IIk can be studied as a pesticidal lead for further structural modification.

Identification of novel RANKL inhibitors through in silico analysis

Receptor activator of nuclear factor-κB ligand (RANKL) is considered the principal regulator of osteoclast differentiation. Therefore, strategies interfering with the RANKL-RANK signaling pathway may effectively inhibit osteoclast differentiation and mitigate bone resorption. Consequently, RANKL has become a promising target for new drug design strategies. Despite extensive research on specific drugs and antibodies, only a few have shown efficacy in treating osteoporosis. To address this challenge, we aimed to explore new approaches for designing drugs for osteoporosis. In this study, a 3D quantitative structure-activity relationship (QSAR) pharmacophore model was built for RANKL with reference to known inhibitor IC50 values. The optimal pharmacophore model was then employed as a 3D query to screen databases for novel lead compounds. The obtained compounds were subjected to ADMET and TOPKAT analyses to predict drug pharmacokinetics and toxicity. Molecular docking and de novo evolution approaches were applied to verify the docking binding affinities of the compounds. Five candidate compounds were subjected to further in vitro analyses to assess their anti-osteoporotic effects, among which compound 4 demonstrated significant inhibitory activity, achieving an inhibitory rate of 92.6 % on osteoclastogenesis at a concentration of 10 μM. Subsequent molecular dynamics (MD) simulations to assess the stability and behavior of compound 4 and its evolved variant, ZINC00059014397_Evo, within the RANKL binding site revealed that the variant is a potential therapeutic agent for targeting osteoclasts. This study offers valuable insights for developing next generation RANKL inhibitors for osteoporosis treatments.

Discovery of Novel Neo-Clerodane Derivatives as Potent Dual-Functional Antiosteoporosis Agents through Targeting Peroxisome Proliferator-Activated Receptor-γ

A library of 31 natural neo-clerodanes isolated from Ajuga decumbens was assayed for antiosteoporosis. This results in 18 neo-clerodane osteoclastogenesis inhibitors, and compound 3 prevents bone loss in vivo. Further mechanistic studies demonstrated that these compounds inhibit osteoporosis by antagonizing peroxisome proliferator-activated receptor-γ (PPARγ). We designed and synthesized 17 compounds by chemically modifying the natural neo-clerodane 19 (highly potent and the major composition of A. decumbens extract) by means of structure-based drug design techniques. Among these neo-clerodane derivatives, compound 34 is the most potent osteoporosis inhibitor with a 46-fold improvement in inhibiting osteoclastogenesis (IC50 = 0.042 vs 1.92 μM), 11-fold increased activity in PPARγ antagonism (EC50 = 0.75 vs 8.35 μM), 66-fold enhancement in receptor affinity (KD = 0.27 vs 17.7 μM), and enhanced osteogenic promotion compared to 19. This underscores the potential of neo-clerodane diterpenoids as promising leads for osteoporosis treatment by targeting PPARγ.

Formononetin Derivative for Osteoporosis by Simultaneous Regulating Osteoblast and Osteoclast

Seven new formononetin derivatives (1-7) were designed and prepared from formononetin (phase II phytoestrogen). The derivatives 9-butyl-3-(4-methoxyphenyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]oxazin-4-one (2) and 9-(furan-3-ylmethyl)-3-(4-methoxyphenyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]oxazin-4-one (7) promoted significant osteoblast formation by modulating the BMP/Smad pathway. Compound 7 exhibited potent antiosteoclastogenesis activity in RANKL-induced RAW264.7 cells and ovariectomy (OVX)-induced osteoporosis in mice by regulation of the RANK/RANKL/OPG pathway. Compound 7 regulated osteoblast and osteoclast simultaneously and showed better effect than the well-known drug ipriflavone in vivo, suggesting 7 as a patented antiosteoporosis candidate.

Synthesis and evaluation of 2-NMPA derivatives as potential agents for prevention of osteoporosis in vitro and in vivo

Abnormal osteoclast differentiation causes various bone disorders such as osteoporosis. Targeting the formation and activation of osteoclasts has been recognized as an effective approach for preventing osteoporosis. Herein, we synthesized eleven 2-NMPA derivatives which are (2-(2-chlorophenoxy)-N-(4-alkoxy-2-morpholinophenyl) acetamides, and evaluated their suppression effects on osteoclastogenesis in vitro by using TRAP-staining assay. Among the synthesized eleven novel 2-NMPAs, 4-(2-(2-chlorophenoxy)acetamido)-3-morpholinophenyl trifluoromethanesulfonate (11b), 4-(2-(2-chlorophenoxy) acetamido)-3-morpholinophenyl-3-(N-(2-oxo-2-((2-(phenylthio) phenyl) amino) ethyl)methylsulfonamido)benzoate (11d), and 4-(2-(2-chlorophenoxy) acetamido)-3-morpholinophenyl 4-acetamidobenzenesulfonate (11h) displayed highly inhibitory bioactivity on the differentiation of primary osteoclasts. 11h was selected for further investigation of the inhibitory effects and potential mechanism involved in the suppression of osteoclastogenesis. In vitro analysis suggested that 11h inhibited osteoclastogenesis with an IC50 of 358.29 nM, decreased the formation of F-action belts and bone resorption, without interfering cell viability and osteoblast differentiation. Furthermore, the mRNA expressions of osteoclast-specific genes such as Acp5, Nfatc1, Dc-stamp, Atp6v0d2, Mmp9, and Ctsk significantly decreased following 11h treatment. RANKL-induced osteoclast-specific proteins analysis demonstrated that 11h suppressed osteoclast differentiation by downregulating of RANKL-mediated TRAF6 expression, followed by inactivation of PI3K/AKT and IκBα/NF-κB signaling pathways. Finally, 11h inhibited ovariectomy-induced bone loss in vivo. Therefore, the current work highlighted the therapeutic potential of 11h as an anti-osteoporosis lead compound.

Evolving Roles of Natural Terpenoids From Traditional Chinese Medicine in the Treatment of Osteoporosis

Osteoporosis (OP) is a systemic metabolic skeletal disease which can lead to reduction in bone mass and increased risk of bone fracture due to the microstructural degradation. Traditional Chinese medicine (TCM) has been applied in the prevention and treatment of osteoporosis for a long time. Terpenoids, a class of natural products that are rich in TCM, have been widely studied for their therapeutic efficacy on bone resorption, osteogenesis, and concomitant inflammation. Terpenoids can be classified in four categories by structures, monoterpenoids, sesquiterpenoids, diterpenoids, and triterpenoids. In this review, we comprehensively summarize all the currently known TCM-derived terpenoids in the treatment of OP. In addition, we discuss the possible mechanistic-of-actions of all four category terpenoids in anti-OP and assess their therapeutic potential for OP treatment.

An insight into the pharmacological and analytical potential of Andrographolide

Andrographis paniculata is an annual medicinal herb from the family Acanthaceae. Andrographolide is generally considered an essential bioactive component of plant A. paniculata. Since ancient times, it has been widely recognized for its therapeutic qualities and has attracted the scientific and medical communities' attention. This review summarizes the molecular, clinical, and in vitro research of compound andrographolide and its mechanism of action. Andrographolide, when combined with other enhancing agents, offers a wide variety of health benefits. The therapeutic potential of andrographolide has been exemplified and exhibited by directly regulating genes and indirectly interacting with small molecules and different enzymes. This review compiles and consolidates the pharmacological action of andrographolide and its analogs and deciphers the gaps that have hindered its use in medicinal research.

Advances in ameliorating inflammatory diseases and cancers by andrographolide: Pharmacokinetics, pharmacodynamics, and perspective

Andrographolide, a well-known natural lactone having a range of pharmacological actions in traditional Chinese medicine. It has long been used to cure a variety of ailments. In this review, we cover the pharmacokinetics and pharmacological activity of andrographolide which supports its further clinical application in cancers and inflammatory diseases. Growing evidence shows a good therapeutic effect in inflammatory diseases, including liver diseases, joint diseases, respiratory system diseases, nervous system diseases, heart diseases, inflammatory bowel diseases, and inflammatory skin diseases. As a result, the effects of andrographolide on immune cells and the processes that underpin them are discussed. The preclinical use of andrographolide to different organs in response to malignancies such as colorectal, liver, gastric, breast, prostate, lung, and oral cancers has also been reviewed. In addition, several clinical trials of andrographolide in inflammatory diseases and cancers have been summarized. This review highlights recent advances in ameliorating inflammatory diseases as well as cancers by andrographolide and its analogs, providing a new perspective for subsequent research of this traditional natural product.

Euphoesulatin A prevents osteoclast differentiation and bone loss via inhibiting RANKL-induced ROS production and NF-κB and MAPK signal pathways

Euphoesulatin A (Eup A), a new jatrophane diterpenoid isolated from the Euphorbia esula L. (Euphorbiaceae), was reported to inhibit RANKL-induced osteoclastogenesis. However, the underlying mechanism and the effect in osteoporosis mouse model are still unclear. This study is the first to demonstrate that Eup A inhibits osteoclastogenesis in vitro and in vivo. Mechanistic analysis suggested that Eup A (3, 6, 12 μM) dose-dependently inhibited osteoclastogenesis by down-regulating the activation of NFATc1 and NF-κB and MAPKs signal pathways. Moreover, Eup A (10 mg/kg) significantly prevented bone loss in ovariectomized mice. This work provides in vitro and in vivo evidence that Eup A could be a potential candidate for the development of anti-osteoporosis agents.

Andrographolide and its derivatives: Current achievements and future perspectives

Natural product andrographolide isolated from the plant Andrographis paniculata shows a plethora of biological activities, including anti-tumor, anti-bacterial, anti-inflammation, anti-virus, anti-fibrosis, anti-obesity, immunomodulatory and hypoglycemic activities. Based on extensive chemical structural modifications, a series of andrographolide derivatives with improved bioavailability and druggability has been developed. Moreover, greater understanding of their mechanisms of action at the molecular and cellular level has been thoroughly investigated. In this review, we give an outlook for the therapeutical potential of andrographolide and its derivatives in diverse diseases and highlighted the drug design, pharmacokinetic and mechanistic studies for the past ten years, together with a brief overview of the pharmacological effects. Notably, we focused to provide a critical enlightenment of the area of andrographolide and its derivatives with the intent of indicating the future perspectives, challenges and limitations. We believe that this review paper will benefit drug discovery where andrographolide was used as a template, shed light on the identification of drug targets for andrographolide and its analogs, as well as increase our knowledge for using them for therapeutic application, including the treatment for various forms of cancers.