Identification of cryptolepine metabolites in rat and human hepatocytes and metabolism and pharmacokinetics of cryptolepine in Sprague Dawley rats

Unravelling the pharmacological properties of cryptolepine and its derivatives: a mini-review insight

Cryptolepine (1,5-methyl-10H-indolo[3,2-b]quinoline), an indoloquinoline alkaloid, found in the roots of Cryptolepis sanguinolenta (Lindl.) Schltr (family: Periplocaceae), is associated with the suppression of cancer and protozoal infections. Cryptolepine also exhibits anti-bacterial, anti-fungal, anti-hyperglycemic, antidiabetic, anti-inflammatory, anti-hypotensive, antipyretic, and antimuscarinic properties. This review of the latest research data can be exploited to create a basis for the discovery of new cryptolepine-based drugs and their analogues in the near future. PubMed, Scopus, and Google Scholar databases were searched to select and collect data from the existing literature on cryptolepine and their pharmacological properties. Several in vitro studies have demonstrated the potential of cryptolepine A as an anticancer and antimalarial molecule, which is achieved through inhibiting DNA synthesis and topoisomerase II. This review summarizes the recent developments of cryptolepine pharmacological properties and functional mechanisms, providing information for future research on this natural product.

A combinatorial approach to screen structurally diverse acetylcholinesterase inhibitory plant secondary metabolites targeting Alzheimer's disease

Alzheimer's disease (AD) is a form of Dementia known to diminish the brain's function by perturbating its structural and functional components. Though cholinesterase inhibitors are widely used to treat AD, they are limited by numbers and side effects. Hence, present study aims to identify structurally diverse Acetylcholinesterase (AChE) inhibitory plant secondary metabolites (PSM) by employing high throughput screening and computational studies. AChE inhibitory activity was performed using 390 crude extracts from 63 plant parts belongs to 58 plants. The lowest IC₅₀ value was recorded by acetone extract of Cyperus rotundus rhizome at 0.5 mg/ml, followed by methanol extract of Terminalia arjuna bark (0.95 mg/ml) and water extract Acacia catechu stem (0.95 mg/ml). A virtual library containing 487 PSM belongs to 18 plants found positive for AChE inhibition (IC₅₀≤5 mg/ml) was prepared. Through ADMET analysis, 78 PSM fulfilling selected drug-likeness parameters were selected for further analysis. Molecular docking studies of selected PSM against AChE recorded a wide range of binding energy from -3.40 to -10.90 Kcal/mol. Further molecular dynamics simulation studies also recorded stabilized interactions of AChE-ligand complexes in the term of RMSD, RMSF, Rg, SASA, and hydrogen bond interaction. MMPBSA analysis revealed the binding energy of selected PSM ranging from -123.757 to -261.697 kJ/mol. Our study demonstrated the potential of 12 PSM (Sugiol, Margolone, 7-Hydroxy-3',4'-(Methylenedioxy) flavan, Beta-cyprone, Ethenone, Isomargolonone, Serpentine, Cryptolepine, Rotundone, Strictamin, Rotundenol and Nootkatone) as AChE inhibitors. Further in vitro and in vivo experimental evaluations with pure PSM could be beneficial for therapeutic uses.

A Review of the Toxicity and Phytochemistry of Medicinal Plant Species Used by Herbalists in Treating People Living With HIV/AIDS in Uganda

Introduction: Despite concerns about toxicity, potentially harmful effects and herb-drug interactions, the use of herbal medicines remains widely practiced by people living with HIV/AIDS (PLHIV) in Uganda. Objective: The objective of the paper was to comprehensively review the literature on the toxicity and chemical composition of commonly used medicinal plant species in treating PLHIV in Uganda. Methods: We reviewed relevant articles and books published over the last sixty years on ethnobotany, antiviral/anti-HIV activity, toxicity, phytochemistry of Vachellia hockii, Albizia coriaria, Bridelia micrantha, Cryptolepis sanguinolenta, Erythrina abyssinica, Gardenia ternifolia, Gymnosporia senegalensis, Psorospermum febrifugium, Securidaca longipendunculata, Warburgia ugandensis and Zanthoxylum chalybeum and their synonyms. We searched PubMed, Web of Science, Scopus, Science Direct and Google Scholar. Discussion: Most of the plant species reviewed apart from P. febrifugium, S. longipedunculata and C. sanguinolenta lacked detailed phytochemical analyses as well as the quantification and characterization of their constituents. Crude plant extracts were the most commonly used. However, purified/single component extracts from different plant parts were also used in some studies. The U87 human glioblastoma was the most commonly used cell line. Water, ethanol, methanol and DMSO were the commonest solvents used. In some instances, isolated purified compounds/extracts such as Cryptolepine and Psorospermin were used. Conclusion: Cytotoxicity varied with cell type, solvent and extract type used making it difficult for direct comparison of the plant species. Five of the eleven plant species namely, A. coriaria, C. sanguinolenta, G. ternifolia, P. febrifugium and Z. chalybeum had no cytotoxicity studies in animal models. For the remaining six plant species, the crude aqueous and ethanol extracts were mainly used in acute oral toxicity studies in mice. Herbalists reported only A. coriaria and W. ugandensis to cause toxic side effects in humans. However, selective cytotoxic plant extracts can potentially be beneficial as anticancer or anti-tumour drugs.

Botanical Medicines Cryptolepis sanguinolenta, Artemisia annua, Scutellaria baicalensis, Polygonum cuspidatum, and Alchornea cordifolia Demonstrate Inhibitory Activity Against Babesia duncani

Human babesiosis is a CDC reportable disease in the United States and is recognized as an emerging health risk in multiple parts of the world. The current treatment for human babesiosis is suboptimal due to treatment failures and unwanted side effects. Although Babesia duncani was first described almost 30 years ago, further research is needed to elucidate its pathogenesis and clarify optimal treatment regimens. Here, we screened a panel of herbal medicines and identified Cryptolepis sanguinolenta, Artemisia annua, Scutellaria baicalensis, Alchornea cordifolia, and Polygonum cuspidatum to have good in vitro inhibitory activity against B. duncani in the hamster erythrocyte model. Furthermore, we found their potential bioactive compounds, cryptolepine, artemisinin, artesunate, artemether, and baicalein, to have good activity against B. duncani, with IC₅₀ values of 3.4 μM, 14 μM, 7.4 μM, 7.8 μM, and 12 μM, respectively, which are comparable or lower than that of the currently used drugs quinine (10 μM) and clindamycin (37 μM). B. duncani treated with cryptolepine and quinine at their respective 1×, 2×, 4× and 8× IC₅₀ values, and by artemether at 8× IC₅₀ for three days could not regrow in subculture. Additionally, Cryptolepis sanguinolenta 90% ethanol extract also exhibited no regrowth after 6 days of subculture at doses of 2×, 4×, and 8× IC₅₀ values. Our results indicate that some botanical medicines and their active constituents have potent activity against B. duncani in vitro and may be further explored for more effective treatment of babesiosis.

Recent Advances in the Chemistry and Pharmacology of Cryptolepine

Cryptolepine, the principal constituent of the West African climbing shrub Cryptolepis sanguinolenta, continues to be of interest as a lead to new therapeutic agents, especially for the treatment of protozoal infections and cancer. This contribution reviews the research published in the last decade, highlighting new synthesis routes to cryptolepine and to analogs of this alkaloid, as well as their pharmacology. Studies relating to the use of C. sanguinolenta as an herbal medicine for the treatment of malaria are discussed, as well as the development of analogs of cryptolepine as leads to new agents for the treatment of malaria, trypanosomiasis, and cancer with an emphasis on the pharmacological mechanisms involved. Other potential therapeutic applications include antimicrobial, antidiabetic, and anti-inflammatory activities; the pharmacokinetics and toxicity of cryptolepine are also reviewed.

In vitro and in vivo growth inhibitory activities of cryptolepine hydrate against several Babesia species and Theileria equi

Piroplasmosis treatment has been based on the use of imidocarb dipropionate or diminazene aceturate (DA), however, their toxic effects. Therefore, the discovery of new drug molecules and targets is urgently needed. Cryptolepine (CRY) is a pharmacologically active plant alkaloid; it has significant potential as an antiprotozoal and antibacterial under different in vitro and in vivo conditions. The fluorescence assay was used for evaluating the inhibitory effect of CRY on four Babesia species and Theileria equi in vitro, and on the multiplication of B. microti in mice. The toxicity assay was evaluated on Madin–Darby bovine kidney (MDBK), mouse embryonic fibroblast (NIH/3T3), and human foreskin fibroblast (HFF) cell lines. The half-maximal inhibitory concentration (IC₅₀) values of CRY on Babesia bovis, B. bigemina, B. divergens, B. caballi, and T. equi were 1740 ± 0.377, 1400 ± 0.6, 790 ± 0.32, 600 ± 0.53, and 730 ± 0.025 nM, respectively. The toxicity assay on MDBK, NIH/3T3, and HFF cell lines showed that CRY affected the viability of cells with a half-maximum effective concentration (EC₅₀) of 86.67 ± 4.43, 95.29 ± 2.7, and higher than 100 μM, respectively. In mice experiments, CRY at a concentration of 5 mg/kg effectively inhibited the growth of B. microti, while CRY–atovaquone (AQ) and CRY–DA combinations showed higher chemotherapeutic effects than CRY alone. Our results showed that CRY has the potential to be an alternative remedy for treating piroplasmosis.

The development and evaluation of new treatment strategies against Babesia and Theileria parasites have become increasingly urgent due to the emergence of parasite resistance and unwanted toxicity side effects by current chemotherapies. On the other hand, vaccination is a cheaper, reliable and sustainable option. Unfortunately, it has not worked well for the protozoan diseases because they possess ingenious mechanisms to evade the host immune system, rendering treatment the most suitable approach for their control. Sadly, only diminazene aceturate (DA) and imidocarb dipropionate have passed clinical trials for the treatment of piroplasmosis. However, these drugs cause many adverse effects and not approved yet for human medicine. Cryptolepine (CRY) is a pharmacologically active indoloquinoline alkaloid isolated from the roots of the shrub Cryptolepis sanguinolenta. CRY is reported to possess various pharmacological activities, including antifungal, anti-mycobacterial, and potent antiplasmodial activities. In the present study we evaluated the effects of CRY against the growth of Babesia bovis, B. bigemina, B. divergens, B. caballi and Theileria equi in vitro and its chemotherapeutic potential on Babesia microti in mice. Furthermore, we investigated the effect of combination between CRY with the current babesiocidal drugs such as DA, atovaquone (AQ) and clofazimine (CF) in vitro and in vivo.

Evaluation of Disulfiram Drug Combinations and Identification of Other More Effective Combinations against Stationary Phase Borrelia burgdorferi

Lyme disease, caused by Borrelia burgdorferi, is the most common vector-borne disease in USA, and 10-20% of patients will develop persistent symptoms despite treatment ("post-treatment Lyme disease syndrome"). B. burgdorferi persisters, which are not killed by the current antibiotics for Lyme disease, are considered one possible cause. Disulfiram has shown to be active against B. burgdorferi, but its activity against persistent forms is not well characterized. We assessed disulfiram as single drug and in combinations against stationary-phase B. burgdorferi culture enriched with persisters. Disulfiram was not very effective in the drug exposure experiment (survival rate (SR) 46.3%) or in combinations. Clarithromycin (SR 41.1%) and nitroxoline (SR 37.5%) were equally effective when compared to the current Lyme antibiotic cefuroxime (SR 36.8%) and more active than disulfiram. Cefuroxime + clarithromycin (SR 25.9%) and cefuroxime + nitroxoline (SR 27.5%) were significantly more active than cefuroxime + disulfiram (SR 41.7%). When replacing disulfiram with clarithromycin or nitroxoline in three-drug combinations, bacterial viability decreased significantly and subculture studies showed that combinations with these two drugs (cefuroxime + clarithromycin/nitroxoline + furazolidone/nitazoxanide) inhibited the regrowth, while disulfiram combinations did not (cefuroxime + disulfiram + furazolidone/nitazoxanide). Thus, clarithromycin and nitroxoline should be further assessed to determine their role as potential treatment alternatives in the future.