Cytotoxic leuconoxine-type diazaspiroindole alkaloids isolated from Cryptolepis dubia.

Two leuconoxine-type diazaspiroindole alkaloids, the known compound, (+)-melodinine E (1), and its new analogue, (+)-11-chloromelodinine E (2), were isolated from the stems of Cryptolepis dubia (Burm.f.) M.R. Almeida (Apocynaceae), collected in Laos. The chemical structures of these compounds were determined by analysis of their spectroscopic data and by comparison of these data with literature values, of which the molecular structure of 1 has been determined previously by analysis of its single-crystal X-ray diffraction data. The absolute configurations of 1 and 2 have been defined by their experimental and simulated electronic circular dichroism (ECD) spectroscopic data and supported by 1H and 13C NMR-based DP4+ probability analysis and specific rotation calculations. When tested against a small panel of human cancer cell lines, these two compounds exhibited selective cytotoxicity toward OVCAR3 human ovarian cancer cells.

The Cytotoxic Cardiac Glycoside (-)-Cryptanoside A from the Stems of Cryptolepis dubia and Its Molecular Targets.

A cardiac glycoside epoxide, (-)-cryptanoside A (1), was isolated from the stems of Cryptolepis dubia collected in Laos, for which the complete structure was confirmed by analysis of its spectroscopic and single-crystal X-ray diffraction data, using copper radiation at a low temperature. This cardiac glycoside epoxide exhibited potent cytotoxicity against several human cancer cell lines tested, including HT-29 colon, MDA-MB-231 breast, OVCAR3 and OVCAR5 ovarian cancer, and MDA-MB-435 melanoma cells, with the IC50 values found to be in the range 0.1-0.5 µM, which is comparable with that observed for digoxin. However, it exhibited less potent activity (IC50 1.1 µM) against FT194 benign/nonmalignant human fallopian tube secretory epithelial cells when compared with digoxin (IC50 0.16 µM), indicating its more selective activity toward human cancer versus benign/nonmalignant cells. (-)-Cryptanoside A (1) also inhibited Na+/K+-ATPase activity and increased the expression of Akt and the p65 subunit of NF-κB but did not show any effects on the expression of PI3K. A molecular docking profile showed that (-)-cryptanoside A (1) binds to Na+/K+-ATPase, and thus 1 may directly target Na+/K+-ATPase to mediate its cancer cell cytotoxicity.

Four New Pentacyclic Triterpene Glycosides Isolated from the Fruits of Cryptolepis buchananii R.Br. ex Roem. & Schult and Their Inhibition of NO Production in LPS-activated RAW264.7 Cells.

From the methanol extract of the Cryptolepis buchananii fruits, four undescribed pentacyclic triterpenene glycosides (1-4) and five known pentacyclic triterpenenes (5-9) were isolated. Their structures were determined to be uncargenin C 28-O-α-L-rhamnopyranosyl-(1→2)-ß-D-glucopyranosyl ester (1), 3-O-ß-D-glucopyranosyluncargenin C 28-O-α-L-rhamnopyranosyl-(1→2)-ß-D-glucopyranosyl ester (2), 3-O-ß-D-glucopyranosyl-(1→6)-ß-D-glucopyranosyl-6ß,23-dihydroxyursolic acid 28-O-α-L-rhamnopyranosyl-(1→2)-ß-D-glucopyranosyl ester (3), 3-O-ß-D-glucopyranosyl-(1→2)-ß-D-glucopyranosylasiatic acid 28-O-α-L-rhamnopyranosyl-(1→2)-ß-D-glucopyranosyl ester (4), asiatic acid (5), 2α,3ß,23-trihydroxyoleana-11,13(18)-dien-28-oic acid (6), arjunolic acid (7), 6ß-hydroxyarjunolic acid (8), and actinidic acid (9) based on analyses of their HR-ESI-MS, 1D and 2D NMR spectra. All the isolates showed significantly NO production inhibition in LPS-activated RAW264.7 cells with the IC50 values ranging from 18.79 to 37.57 µM, compared to that of the positive control compound, dexamethasone, which showed IC50 value of 14.05 µM.

Medicinal plants used in the treatment of Malaria: A key emphasis to Artemisia, Cinchona, Cryptolepis, and Tabebuia genera.

Malaria is one of the life-threatening parasitic diseases that is endemic in tropical areas. The increased prevalence of malaria due to drug resistance leads to a high incidence of mortality. Drug discovery based on natural products and secondary metabolites is considered as alternative approaches for antimalarial therapy. Herbal medicines have advantages over modern medicines, including fewer side effects, cost-effectiveness, and affordability encouraging the herbal-based drug discovery. Several naturally occurring, semisynthetic, and synthetic antimalarial medications are on the market. For example, chloroquine is a synthetic medication for antimalarial therapy derived from quinine. Moreover, artemisinin, and its derivative, artesunate with sesquiterpene lactone backbone, is an antimalarial agent originated from Artemisia annua L. A. annua traditionally has been used to detoxify blood and eliminate fever in China. Although the artemisinin-based combination therapy against malaria has shown exceptional responses, the limited medicinal options demand novel therapeutics. Furthermore, drug resistance is the cause in most cases, and new medications are proposed to overcome the resistance. In addition to conventional therapeutics, this review covers some important genera in this area, including Artemisia, Cinchona, Cryptolepis, and Tabebuia, whose antimalarial activities are finely verified.

Isobolographic analysis of co-administration of two plant-derived antiplasmodial drug candidates, cryptolepine and xylopic acid, in Plasmodium berghei.

BACKGROUND: Increasing resistance to current anti-malarial therapies requires a renewed effort in searching for alternative therapies to combat this challenge, and combination therapy is the preferred approach to address this. The present study confirms the anti-plasmodial effects of two compounds, cryptolepine and xylopic acid and the relationship that exists in their combined administration determined. METHODS: Anti-plasmodial effect of cryptolepine (CYP) (3, 10, 30 mg kg-1) and xylopic acid (XA) (3, 10, 30 mg kg-1) was evaluated in Plasmodium berghei-infected male mice after a 6-day drug treatment. The respective doses which produced 50% chemosuppression (ED50) was determined by iterative fitting of the log-dose responses of both drugs. CYP and XA were then co-administered in a fixed dose combination of their ED50s (1:1) as well as different fractions of these combinations (1/2, 1/4, 1/8, 1/16 and 1/32) to find the experimental ED50 (Zexp). The nature of interaction between cryptolepine and xylopic acid was determined by constructing an isobologram to compare the Zexp with the theoretical ED50 (Zadd). Additionally, the effect of cryptolepine/xylopic acid co-administration on vital organs associated with malarial parasiticidal action was assessed. RESULTS: The Zadd and Zexp were determined to be 12.75 ± 0.33 and 2.60 ± 0.41, respectively, with an interaction index of 0.2041. The Zexp was significantly (P < 0.001) below the additive isobole indicating that co-administration of cryptolepine and xylopic acid yielded a synergistic anti-plasmodial effect. This observed synergistic antiplasmodial effect did not have any significant deleterious effect on the kidney, liver and spleen. However, the testis were affected at high doses. CONCLUSION: The co-administration of cryptolepine and xylopic acid produces synergistic anti-malarial effect with minimal toxicity.

Inhibition of lipopolysaccharide (LPS)-induced neuroinflammatory response by polysaccharide fractions of Khaya grandifoliola (C.D.C.) stem bark, Cryptolepis sanguinolenta (Lindl.) Schltr and Cymbopogon citratus Stapf leaves in raw 264.7 macrophages and U87 glioblastoma cells.

BACKGROUND: Khaya grandifoliola (C.D.C.) stem bark, Cymbopogon citratus (Stapf) and Cryptolepis sanguinolenta (Lindl.) Schltr leaves are used in Cameroonian traditional medicine for the treatment of inflammatory diseases. Several studies have been performed on the biological activities of secondary metabolites extracted from these plants. However, to the best of our knowledge, the anti-neuro inflammatory and protective roles of the polysaccharides of these three plants have not yet been elucidated. This study aimed at investigating potential use of K. grandifoliola, C. sanguinolenta and C. citratus polysaccharides in the prevention of chronic inflammation. METHODS: Firstly, the composition of polysaccharide fractions isolated from K. grandifoliola stem bark (KGF), C. sanguinolenta (CSF) and C. citratus (CCF) leaves was assessed. Secondly, the cytotoxicity was evaluated on Raw 264.7 macrophages and U87-MG glioblastoma cell lines by the MTT assay. This was followed by the in vitro evaluation of the ability of KGF, CSF and CCF to inhibit lipopolysaccharides (LPS) induced overproduction of various pro-inflammatory mediators (NO, ROS and IL1ß, TNFα, IL6, NF-kB cytokines). This was done in Raw 264.7 and U87-MG cells. Finally, the in vitro protective effect of KGF, CSF and CCF against LPS-induced toxicity in the U87-MG cells was evaluated. RESULTS: CCF was shown to mostly contain sugar and no polyphenol while KGP and CSP contained very few amounts of these metabolites (≤ 2%). The three polysaccharide fractions were non-toxic up to 100 µg.mL- 1. All the polysaccharides at 10 µg/mL inhibited NO production, but only KGF and CCF at 12.5 µg/mL down-regulated LPS-induced ROS overproduction. Finally, 100 µg/mL LPS reduced 50% of U87 cell viability, and pre-treatment with the three polysaccharides significantly increased the proliferation. CONCLUSION: These results suggest that the polysaccharides of K. grandifoliola, C. citratus and C. sanguinolenta could be beneficial in preventing/treating neurodegenerative diseases in which neuroinflammation is part of the pathophysiology.

Synergistic anti-malarial action of cryptolepine and artemisinins.

BACKGROUND: Cryptolepine (CPE) is the major indoloquinoline isolated from the popular West African anti-malarial plant, Cryptolepis sanguinolenta. CPE possesses various pharmacological activities with potent anti-malarial activity against both chloroquine (CQ)-resistant and -sensitive strains. The search for safe and novel anti-malarial agents and combinations to delay resistance development to Plasmodium falciparum directed this work aimed at evaluating the anti-malarial interaction and safety of CPE in combination with some artemisinin derivatives. METHODS: The in vitro SYBR Green I, fluorescent-based, drug sensitivity assay using a fixed ratio method was carried out on the CQ-sensitive plasmodial strain 3D7 to develop isobolograms from three CPE-based combinations with some artemisinin derivatives. CPE and artesunate (ART) combinations were also evaluated using the Rane's test in ICR mice infected with Plasmodium berghei NK-65 strains in a fixed ratio combination (1:1) and fractions of their ED50s in order to determine the experimental ED50 (Zexp) of the co-administered compounds. Isobolograms were constructed to compare the Zexp to the Zadd. RESULTS: CPE exhibited promising synergistic interactions in vitro with ART, artemether and dihydroartemisinin. In vivo, CPE combination with ART again showed synergy as the Zexp was 1.02 ± 0.02, which was significantly less than the Zadd of 8.3 ± 0.31. The haematological, biochemical, organ/body weight ratio and histopathology indices in the rats treated with CPE at all doses (25, 50, 100 mg kg(-1) po) and in combination with ART (4 mg kg(-1)) showed no significant difference compared to the control group. CONCLUSION: The combination of CPE with the artemisinin derivatives were safe in the rodent model and showed a synergistic anti-malarial activity in vivo and in vitro. This study supports the basis for the selection of CPE as a prospective lead compound as the search for new anti-malarial combinations continues.

N10,N11-di-alkylamine indolo[3,2-b]quinolines as hemozoin inhibitors: design, synthesis and antiplasmodial activity.

We recently reported that potent N10,O11-bis-alkylamine indolo[3,2-b]quinoline antimalarials act as hemozoin (Hz) growth inhibitors. To improve access and binding to the target we have now designed novel N10,N11-di-alkylamine bioisosteres. 3-Chloro derivatives (10a-f) showed selectivity for malaria parasite compared to human cells, high activity against Plasmodium falciparum chloroquine (CQ)-resistant strain W2 (IC50s between 20 and 158nM), good correlation with ß-hematin inhibition and improved vacuolar accumulation ratios, thus suggesting inhibition of Hz growth as one possible mechanism of action for these compounds. Moreover, our studies show that Hz is a valid target for the development of new antimalarials able to overcome CQ resistance.

Homodecoupled 1,1- and 1,n-ADEQUATE: Pivotal NMR Experiments for the Structure Revision of Cryptospirolepine.

Cryptospirolepine is the most structurally complex alkaloid discovered and characterized thus far from any Cryptolepis specie. Characterization of several degradants of the original, sealed NMR sample a decade after the initial report called the validity of the originally proposed structure in question. We now report the development of improved, homodecoupled variants of the 1,1- and 1,n-ADEQUATE (HD-ADEQUATE) NMR experiments; utilization of these techniques was critical to successfully resolving long-standing structural questions associated with crytospirolepine.

A review of preclinical evidence of Cryptolepis nigrescens (Wennberg) L. Joubert. and Bruyns., Prosopsis africana (Guill. and Perr.) Taub. and Pterygota macrocarpa K. Schum. traditionally used to manage tumours in Ghana.

ETHNOPHARMACOLOGICAL RELEVANCE: Cancer stands as one of the leading causes of death worldwide according to the World Health Organization (WHO), and it has led to approximately 10 million fatalities in 2020. Medicinal plants are still widely used and accepted form of treatment for most diseases including cancer in Ghana. This review presented Cryptolepis nigrescens (Wennberg) L. Joubert. and Bruyns., Prosopsis africana (Guill. and Perr.) Taub. and Pterygota macrocarpa K. Schum. as medicinal plants that are traditionally used to treat tumour growth, amongst other diseases, in the Ashanti region of Ghana. AIM OF REVIEW: This paper aims to present a comprehensive review on the botanical description, ecological distribution, ethnomedicinal uses, phytochemical composition and ethnopharmacological relevance of C. nigrescens, P. africana and P. macrocarpa. MATERIALS AND METHODS: The review covers works published between 1962 and 2023 from various countries. Published books, thesis, scientific and medical articles on C. nigrescens, P. africana and P. macrocarpa were collected from the following databases: 'Scopus', 'Science Direct', 'Medline', 'PubMed', 'Research Gate' 'Google Scholar, and 'Springer link' using the keywords. RESULTS: Phytochemical analysis of C. nigrescens, P. africana and P. macrocarpa revealed the presence of some prominent bioactive compounds such as convallatoxin, 7,3,4-trihydroxy-3-methoxyflavanone and dioxane, respectively. Plant extracts and isolated compounds of these medicinal plants exhibited a wide range of ethnopharmacological activities including antimicrobial, anti-inflammatory, antioxidant, analgesic, cytotoxic, antimalarial, antipyretic, haematinic, hepato-protective, aphrodisiac and antihypertensive properties. CONCLUSION: The present review on C. nigrescens , P.africana and P. macrocarpa provided a credible summary of the ethnopharmacological research conducted on these medicinal plants till date. The data also highligted the potential therapeutic profiles of these plants in Ghana that could serve as foundation for future studies. Additionally, the information significantly supported the traditional and commercial use of these plants among the people.

Antimicrobial, antioxidant activities, and total phenolic contents of Pycnanthus angolensis Sap and Cryptolepis sanguinolenta root extracts.

The death of many people in tropical countries can be attributed to microbial infection, probably, because synthetic antibiotics are failing in the treatment of most microbial infections, attributed to the ability of the microorganisms to mutate and adapt to harsh conditions. This study evaluated, in vitro, the antimicrobial activities, antioxidant potentials, and the total phenolic as well as phytochemical contents of aqueous and ethanol extracts of the root of Cryptolepis sanguinolenta (Lindl.) and the crude sap of Pycnanthus angolensis (Welw) using selected standard bacteria strains (Staphylococcus aureus (ATCC 25,923), Staphylococcus saprophyticus (ATCC 15,305), Escherichia coli (ATCC 25,922), Salmonella typhi (ATCC 19,430), Pseudomonas aeruginosa (ATCC 27,853), and Proteus mirabilis (ATCC 49,565). The modified agar well diffusion method was used to evaluate the antimicrobial activities of the plant extracts. Chloramphenicol and tetracycline were used as positive controls. The extracts were screened for specific phytochemicals with total phenolic contents were determined using Folin Ciocalteu reagent test. The phytoconstituents observed were alkaloids, cardiac glycosides, and saponins in both Cryptolepis sanguinolenta and Pycnanthus angolensis. For the antimicrobial activities, all the test bacteria were susceptible to the crude sap of Pycnanthus angolensis except Proteus mirabilis. In the case of the Cryptolepis sanguinolenta, only S. aureus was susceptible to both aqueous and ethanol extracts. The total phenolic content, expressed in g/100 g GAE, recorded values of 55.427 ± 4.248 for the crude sap of Pycnanthus angolensis, and 11.642 ± 4.248 and 26.888 ± 4.248 for the aqueous and ethanol extracts of Cryptolepis sanguinolenta, respectively. It is concluded that Cryptolepis sanguinolenta and Pycnanthus angolensis are excellent candidates for further development of antimicrobial agents in the fight against microbial infections given the pressing need for novel efficacious agents.

Impact of Synthesized Indoloquinoline Analog to Isolates from Cryptolepis sanguinolenta on Tumor Growth Inhibition and Hepatotoxicity in Ehrlich Solid Tumor-Bearing Female Mice.

The study evaluated the antitumor efficacy of APAN, "synthesized indoloquinoline analog derived from the parent neocryptolepine isolated from the roots of Cryptolepis sanguinolenta", versus the chemotherapeutic drug etoposide (ETO) in Ehrlich solid tumor (EST)-bearing female mice as well as its protective effect against etoposide-triggered hepatic disorders. APAN showed an ameliorative activity against Ehrlich solid tumor and hepatic toxicity, and the greatest improvement was found in the combined treatment of APAN with ETO. The results indicated that EST altered the levels of tumor markers (AFP, CEA, and anti-dsDNA) and liver biomarker function (ALT, AST, ALP, ALB, and T. protein). Furthermore, EST elevated CD68 and anti-survivin proteins immuno-expressions in the solid tumor and liver tissue. Molecular docking studies were demonstrated to investigate their affinity for both TNF-α and topoisomerase II as target proteins, as etoposide is based on the inhibition of topoisomerase II, and TNF-α is quite highly expressed in the solid tumor and liver tissues of EST-bearing animals, which prompted the authors' interest to explore APAN affinity to its binding site. Treatment of mice bearing EST with APAN and ETO nearly regularized serum levels of the altered parameters and ameliorated the impact of EST on the tissue structure of the liver better than that by treatment with each of them separately.

In vitro antimicrobial activity of ethanolic fractions of Cryptolepis sanguinolenta.

BACKGROUND: Following claims that some plants have antimicrobial activities against infectious microbes, the in vitro antimicrobial activities of different solvent fractions of ethanolic extract of Cryptolepis sanguinolenta were evaluated against eight standard bacteria and clinical isolates. METHODS: The solvent partitioning protocol involving ethanol, petroleum ether, chloroform, ethyl acetate and water, was used to extract various fractions of dried pulverized Cryptolepis sanguinolenta roots. Qualitative phyto-constituents screening was performed on the ethanol extract, chloroform fraction and the water fraction. The Kirby Bauer disk diffusion method was employed to ascertain the antibiogram of the test organisms while the agar diffusion method was used to investigate the antimicrobial properties of the crude plant extracts. The microplate dilution method aided in finding the MICs while the MBCs were obtained by the method of Nester and friends. The SPSS 16.0 version was used to analyze the percentages of inhibitions and bactericidal activities. RESULTS: The phytochemical screening revealed the presence of alkaloids, reducing sugars, polyuronides, anthocyanosides and triterpenes. The ethanol extract inhibited 5 out of 8 (62.5%) of the standard organisms and 6 out of 8 (75%) clinical isolates. The petroleum ether fraction inhibited 4 out of 8 (50%) of the standard microbes and 1 out of 8 (12.5%) clinical isolates. It was also observed that the chloroform fraction inhibited the growth of all the organisms (100%). Average inhibition zones of 14.0 ± 1.0 mm to 24.67 ± 0.58 mm was seen in the ethyl acetate fraction which halted the growth of 3 (37.5%) of the standard organisms. Inhibition of 7 (87.5%) of standard strains and 6 (75%) of clinical isolates were observed in the water fraction. The chloroform fraction exhibited bactericidal activity against all the test organisms while the remaining fractions showed varying degrees of bacteriostatic activity. CONCLUSION: The study confirmed that fractions of Cryptolepis sanguinolenta have antimicrobial activity. The chloroform fraction had the highest activity, followed by water, ethanol, petroleum ether and ethyl acetate respectively. Only the chloroform fraction exhibited bactericidal activity and further investigations are needed to ascertain its safety and prospects of drug development.

Membrane perturbations induced by new analogs of neocryptolepine.

Indoloquinoline alkaloids represent an important class of antimalarial, antibacterial and antiviral compounds. Indolo[2,3-b]quinolines are a family of DNA intercalators and inhibitors of topoisomerase II, synthetic analogs of neocryptolepine, an alkaloid traditionally used in African folk medicine. These cytotoxic substances are promising anticancer agents. Active representatives of indolo[2,3-b]quinolines affect model and natural membranes. The distinct structure and hydrophobicity of the compounds leads to marked differences in the disturbing effects on membrane organization and function. Our results also indicated a strong relationship between the presence of the chain and the Poct of the molecule as well as the capacity for incorporation into carboxyfluorescein-trapped liposomes in the 0.02-0.06 mM range. Moreover, a correlation between binding to neutral dimyristoylphosphatidylcholine (DMPC) or negative charged dimyristoylphosphatidylcholine:dimyristoylphosphatidylglycerol (DMPC:DMPG, 9:1 w/w) liposomes, as well as to erythrocyte ghosts and pKa, was also found. All the compounds cause hemolysis in isotonic conditions with concentration causing 50% hemolysis (HC50) in the 0.12-0.88 mM range. The concentration-dependent inhibitory effect of the tested agents on erythrocyte ghosts' acetylcholinesterase activity was also studied.

Schistosomicidal and molluscicidal activities of aminoalkylamino substituted neo- and norneocryptolepine derivatives.

CONTEXT: The cryptolepines originate from the roots of the climbing shrub Cryptolepis sanguinolenta (Lindi) Schitr(Periplocaeae) which is used in Central and West Africa in traditional medicine for the treatment of malaria. OBJECTIVES: Evaluation for the first time of a series of chloro- and aminoalkylamino derivatives of neo- and norneocryptolepines for potential schistosomicidal and molluscicidal activities. MATERIALS AND METHODS: A series of chloro- and aminoalkylamino substituted neo- and norneocryptolepine derivatives were synthesized. They were tested in vitro against viable Schistosoma mansoni Sambon mature worms in culturemedium with fetal serum and antibiotics and in dechlorinated water against the snail vector Biomphalaria alexandrina Ehrenberg. Active compounds were further subjected to determination of their IC50 values. RESULTS: Results showed that six neocryptolepine and two norneocryptolepine derivatives had in vitro schistosomicidal activity on Egyptian and Puerto Rican strains of S. mansoni. The most effective derivative (2-chloro-5-methyl-N-(2-morpholin-4-ethyl)-5H-indolo[2,3b]quinoline-11-amine) has IC50 and IC90 1.26 and 4.05 µM and 3.54 and 6.83 µM with the Egyptian and Puerto Rican strains of Schistosoma, respectively. All eight derivatives showed molluscicidal activity against the vector snail B. alexandrina. The most active compound (2-chloro-11-(4-methylpiperazin-1-yl)-6H-indolo[2,3-b] quinoline) has LC50 0.6 and LC90 3.9 ppm after 24 h. DISCUSSION AND CONCLUSIONS: The findings demonstrate that introducing chloro- and aminoalkylamino side chain initiated both schistosomicidal and molluscicidal activities in these derivatives. The structure­activity relationship of this series of compounds is discussed.

Improved traditional phytomedicines in current use for the clinical treatment of malaria.

Phytomedicines and "green pharmacies" are promoted by some NGOs and governments as part of their efforts to control malaria. "Improved traditional medicines" (ITMs) are standardised as regards preparation and dose, although not always according to the concentration of active compounds. A systematic literature search revealed that six such phytomedicines are currently government-approved in at least one country and used on a relatively large scale nationally or internationally: Artemisia annua L. (Asteraceae), Cinchona bark (Rubiaceae), Cryptolepis sanguinolenta (Lindl.) Schltr. (Apocynaceae), "Ayush-64", "Malarial-5" and Cochlospermum planchonii Hook. f. ex Planch. (Bixaceae). One further ITM has been developed and is in the process of being approved: Argemone mexicana decoction. Their development, phytochemistry, pharmacology, and clinical trials are reviewed, as well as priorities for future research.

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.

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.

Cryptolepine inhibits hepatocellular carcinoma growth through inhibiting interleukin-6/STAT3 signalling.

BACKGROUND: Diverse signalling pathways are involved in carcinogenesis and one of such pathways implicated in many cancers is the interleukin 6/signal transducer and activator of transcription 3 (IL-6/STAT3) signalling pathway. Therefore, inhibition of this pathway is targeted as an anti-cancer intervention. This study aimed to establish the effect of cryptolepine, which is the main bioactive alkaloid in the medicinal plant Cryptolepis sanguinolenta, on the IL-6/STAT3 signalling pathway. METHODS: First, the effect of cryptolepine on the IL-6/STAT3 pathway in human hepatoma cells (HepG2 cells) was screened using the Cignal Finder Multi-Pathway Reporter Array. Next, to confirm the effect of cryptolepine on the IL-6/STAT3 signalling pathway, the pathway was activated using 200 ng/mL IL-6 in the presence of 0.5-2 µM cryptolepine. The levels of total STAT3, p-STAT3 and IL-23 were assessed by ELISA. RESULTS: Cryptolepine downregulated 12 signalling pathways including the IL-6/STAT3 signalling pathway and upregulated 17 signalling pathways. Cryptolepine, in the presence of IL-6, decreased the levels of p-STAT3 and IL-23 in a dose-dependent fashion. CONCLUSION: Our results demonstrated that cryptolepine inhibits the IL-6/STAT3 signalling pathway, and therefore cryptolepine-based remedies such as Cryptolepis sanguinolenta could potentially be used as an effective immunotherapeutic agent for hepatocellular carcinoma and other cancers.

Solid-lipid nanoparticle formulation improves antiseizure action of cryptolepine.

Following the high treatment gap and massive impact of epilepsy on global health particularly in low- and middle-income countries, our study aims to investigate cryptolepine, the major alkaloid of Cryptolepis sanguinolenta as well as its solid-lipid nanoparticle formulation for potential antiseizure activity. Cryptolepine was isolated and a solid-lipid formulation was prepared. Antiseizure activity of Solid-Lipid Nanoparticle formulation of cryptolepine (SLN-CRYP) was investigated using Pentylenetetrazole (PTZ)-induced model of seizure-like behaviors in Zebrafish with 2.5 and 5 mg/kg each of cryptolepine and SLN-CRYP. Drug receptor binding and permeability of the compound across the Blood Brain Barrier (BBB) were also assessed. SLN formulation of cryptolepine increased its permeability to the BBB from 0.32 × 10-6 cm/s to 10.81 × 10-6 cm/s. 2.5 and 5 mg/kg of SLN-CRYP significantly reduced mean seizure score (P = 0.0018; F(6, 63) = 23.52) and significantly increased (P < 0.0001; F(6, 63) = 65.41) latency to onset of seizures. The total distance swam by fish administered with 2.5 and 5 mg/kg of SLN-CRYP was significantly (P < 0.000; F(6, 63) = 161.9) decreased. 5 mg/kg of cryptolepine also significantly decreased swimming distance. Cryptolepine exhibited inhibitory modulation of human voltage-gated calcium channels (Cav1.2), H1-receptor, Peripheral Benzodiazepine Receptor and Sigma 2 receptor with a high Ki values of 6133.38 nM and 2945.0 nM, indicating less potent antagonism on Cav1.2 and Sigma 2 receptors compared to Nifedipine and Haloperidol respectively. This study reveals that the solid-lipid nanoparticle formulation of cryptolepine improves its BBB permeability and hence antiseizure activity.