Antimicrobial and in silico studies of the triterpenoids of Dichapetalum albidum.

Here we report a new polyhydroxylated triterpene, 2ß,6ß,21α-trihydroxyfriedelan-3-one (4) isolated from the root and stem bark of Dichapetalum albidum A. Chev (Dichapetalaceae), along with six known triterpenoids (1-3, 5, 6, 8), sitosterol-3ß-O-D-glucopyranoside (9), a dipeptide (7), and a tyramine derivative of coumaric acid (10). Friedelan-3-one (2) showed an antimicrobial activity (IC50) of 11.40 µg/mL against Bacillus cereus, while friedelan-3α-ol (1) gave an IC50 of 13.07 µg/mL against Staphylococcus aureus with ampicillin reference standard of 19.52 µg/mL and 0.30 µg/mL respectively. 3ß-Acetyl tormentic acid (5) showed an IC50 of 12.50 µg/mL against Trypanosoma brucei brucei and sitosterol-3ß-O-d-glucopyranoside (9) showed an IC50 of 5.06 µg/mL against Leishmania donovani with respective reference standards of IC50 5.02 µg/mL for suramin and IC50 0.27 µg/mL for amphotericin B. Molecular docking of the isolated compounds on the enzyme glucose-6-phosphate dehydrogenase (G6PDH) suggested 3ß-acetyl tormentic acid (5) and sitosterol-3ß-O-D-glucopyranoside (9) as plausible inhibitors of the enzyme in accordance with the experimental biological results observed.

Dimerized fusion inhibitor peptides targeting the HR1-HR2 interaction of SARS-CoV-2.

Membrane fusion is a critical and indispensable step in the replication cycles of viruses such as SARS-CoV-2 and human immunodeficiency virus type-1 (HIV-1). In this step, a trimer of the heptad repeat 1 (HR1) region interacts with the three HR2 regions and forms a 6-helix bundle (6-HB) structure to proceed with membrane fusion of the virus envelope and host cells. Recently, several researchers have developed potent peptidic SARS-CoV-2 fusion inhibitors based on the HR2 sequence and including some modifications. We have developed highly potent HIV-1 fusion inhibitors by dimerization of its HR2 peptides. Here, we report the development of dimerized HR2 peptides of SARS-CoV-2, which showed significantly higher antiviral activity than the corresponding monomers, suggesting that the dimerization strategy can facilitate the design of potent inhibitors of SARS-CoV-2.

Anti-plasmodial, Cytotoxic and Antioxidant Activities of Selected Ghanaian Medicinal Plants.

Malaria affects about half of the world's population. The sub-Saharan African region is the most affected. Plant natural products have been a major source of antimalarial drugs; the first (quinine) and present (artemisinin) antimalarials are of natural product origin. Some secondary metabolites demonstrate adjuvant antioxidant effects and selective activity. The focus of this study was to investigate the anti-plasmodial activity, cytotoxicities and antioxidant properties of eight (8) Ghanaian medicinal plants. The anti-plasmodial activity was determined using the SYBR green assay and the tetrazolium-based colorimetric assay (MTT) was employed to assess cytotoxicity of extracts to human RBCs and HL-60 cells. Antioxidant potential of plant extracts was evaluated using Folin-Ciocalteu and superoxide dismutase assays. Phytochemical contstituents of the plant extracts were also assessed. All the extracts demonstrated anti-plasmodial activities at concentrations <50 µg/ml. Parkia clappertoniana and Terminalia ivorensis elicited the strongest anti-plasmodial activities with 50% inhibitory concentrations (IC50) of 1.13 µg/ml and 0.95 µg/ml, respectively. This is the first report on anti-plasmodial activities of Baphia nitida, Tabernaemontana crassa and Treculia Africana. T. Africana showed moderate anti-plasmodial activity with IC50 value of 6.62 µg/mL. Extracts of P. clappertoniana, T. Africana and T. ivorensis (0.4 mg/mL) showed >50% antioxidant effect (SOD). The extracts were not cytotoxicity towards RBCs at the concentration tested (200 µg/ml) but were weakly cytotoxic to HL-60 cell. Selectivity indices of most of the extracts were greater than 10. Our results suggest that most of the plant extracts have strong anti-plasmodial activity and antioxidant activity which warrants further investigations.

Digyalipopeptide A, an antiparasitic cyclic peptide from the Ghanaian Bacillus sp. strain DE2B.

During the continued isolation of different bacteria from highly diverse, low human activity environments in Ghana and the subsequent characterization and biological activity studies of their secondary metabolites, we found both Gram-positive and Gram-negative Bacillus strains to be ubiquitous and widespread. One of such strains, the Ghanaian novel Bacillus sp. strain DE2B was isolated from rhizosphere soils collected from the Digya National Park in Ghana. Chromatographic purifications of the fermented culture extract of the strain DE2B, led to the isolation of a cyclic lipopeptide, digyalipopeptide A (1). Using 1D and 2D NMR data, mass spectrometry sequence tagging, advanced Marfey's analysis, and the GNPS molecular networking we solved the full structure of digyalipopeptide A (1). We found that compound 1 is a member of a somewhat homologous series of peptides produced as a mixture by the strain containing the same amino acid sequence in the cyclic peptide backbone but differing only by the length of aliphatic fatty acid side chains. When tested against Trypanosoma brucei subsp. brucei strain GUTat 3.1 and Leishmania donovani (Laveran and Mesnil) Ross (D10), digyalipopeptide A (1) gave IC50 values of 12.89 µM (suramin IC50 0.96 µM) and 4.85 µM (amphotericin B IC50 4.87 µM), respectively. Furthermore, digyalipopeptide A (1) produced IC50 values of 10.07 µM (ampicillin IC50 0.18 µM) and 10.01 µM (ampicillin IC50 1.53 µM) for Staphylococcus aureus and Shigella sonnei, respectively. The selectivity and toxicity profile of compound 1 was investigated using normal cell lines, macrophages RAW 264.7. When tested against normal macrophages, compound 1 gave an IC50 value of 71.32 µM. Selectivity indices (SI) were obtained by calculating the ratio of the IC50 in RAW 264.7 to the IC50 in the respective microbe and neglected parasite. In the presence of RAW 264.7 cell lines, compound 1 was particularly selective towards Leishmania donovani (Laveran and Mesnil) Ross (D10) with an SI value of 14.71. The bioactivity studies conducted confirm the role of these cyclic lipopeptides as defense chemicals in their natural environment and their ability to be biologically active across different species.

Towards understanding antimicrobial activity, cytotoxicity and the mode of action of dichapetalins A and M using in silico and in vitro studies.

Dichapetalum madagascariense Poir (Dichapetalaceae) is traditionally used to treat bacterial infections, jaundice, urethritis and viral hepatitis in Africa. Its root contains a broad spectrum of biologically active dichapetalins. To evaluate the plant's effect on human MCF-7 cells and its' antibacterial and antiparasitic potentials, we isolated and identified the known dichapetalins A and M from the roots. Both dichapetalins were tested on six bacterial strains (Shigella flexneri, Bacillus cereus, Salmonella paratyphi B, Listeria monocytogenes, Escherichia coli, Staphylococcus aureus) and two parasite strains; Trypanosoma brucei brucei, and Leishmania donovani using the Alamar Blue assay system. Dichapetalins A and M were more potent against B. cereus with IC50 values of 11.15 and 3.15 µg/ml, respectively, compared to the positive control ampicillin (IC50 = 19.50 µg/ml). Dichapetalins A (IC50 = 74.22 µg/ml) and M (IC50 = 72.34 µg/ml) were less active against T. b. brucei, compared to the standard Suramin (IC50 = 4.96 µg/ml). Dichapetalin M showed moderate activity against L. donovani (Amphotericin B: IC50 = 0.21 µg/ml) with an IC50 of 16.80 µg/ml. In human MCF-7 cells expressing the NR1I2 receptor, the activity of dichapetalin M was higher (IC50 = 4.71 µM and 3.95 µM) for 48 and 72 h of treatment, respectively compared to Curcumin with IC50 of 17.49 µM and 12.53 µM for 48 and 72 h of treatment, respectively. Results from in vitro expression studies with qPCR confirmed an antagonistic effect of dichapetalin M on PXR (NR1I2) signaling; supporting the PXR signaling pathway as a possible mode of action of dichapetalin M as predicted by in silico results. These findings confirm previous studies that D. madagascariense can be a source of potential lead compounds for development of novel antibiotic, antiparasitic and anticancer medicines, and provide further insights into the mechanism of action of the dichapetalins.

Potent leads based on CA-19L, an anti-HIV active HIV-1 capsid fragment.

Several anti-HIV-1 peptides have previously been found among overlapping fragment peptide libraries that contain an octa-arginyl moiety and cover the whole sequence of an HIV-1 capsid (CA) protein. Several derivatives based on a potent CA fragment peptide CA-19L have been synthesized. CA-19L overlaps with the Helix 9 region of the CA protein, which could be important for oligomerization of the CA proteins. Derivatives of CA-19L in which several amino acid residues were added to the N- and C-termini according to the natural CA sequence, were synthesized and their anti-HIV activity was evaluated. Some potent compounds were found, and these potential new anti-HIV agents are expected to be useful as new tools for elucidation of CA functions.

Exploratory studies on CA-15L, an anti-HIV active HIV-1 capsid fragment.

Utilizing overlapping fragment peptide libraries covering the whole sequence of an HIV-1 capsid (CA) protein with the addition of an octa-arginyl moiety, we had previously found several peptides with anti-HIV-1 activity. Herein, among these potent CA fragment peptides, CA-15L was examined because this peptide sequence overlaps with Helix 7, a helix region of the CA protein, which may be important for oligomerization of the CA proteins. A CA-15L surrogate with hydrophilic residues, and its derivatives, in which amino acid sequences are shifted toward the C-terminus by one or more residues, were synthesized and their anti-HIV activity was evaluated. In addition, its derivatives with substitution for the Ser149 residue were synthesized and their anti-HIV activity was evaluated because Ser149 might be phosphorylated in the step of degradation of CA protein oligomers. Several active compounds were found and might become new anti-HIV agents and new tools for elucidation of CA functions.

Cardiovascular Collapse in a Patient With Parotid Abscess: Dangerous Cross Talk Between the Brain and Heart: A Case Report.

Postsurgical trigeminal neuralgia (TN), although rare, can lead to significant hemodynamic perturbations by triggering the trigeminocardiac reflex (TCR). The combination can lead to diagnostic as well as management challenges for clinicians. We present the case of a patient with a parotid abscess, which developed as a complication of his otolaryngologic surgery, and which led to repeated episodes of symptomatic bradycardia associated with cardiovascular collapse. This case highlights the importance of heightened awareness, early diagnosis, and timely treatment of postsurgical neuropathic pain syndromes to avoid life-threatening complications.

Paenidigyamycin A, Potent Antiparasitic Imidazole Alkaloid from the Ghanaian Paenibacillus sp. DE2SH.

A new alkaloid paenidigyamycin A (1) was obtained from the novel Ghanaian Paenibacillus sp. isolated from the mangrove rhizosphere soils of the Pterocarpus santalinoides tree growing in the wetlands of the Digya National Park, Ghana. Compound 1 was isolated on HPLC at tR = 37.0 min and its structure determined by MS, 1D, and 2D-NMR data. When tested against L. major, 1 (IC50 0.75 µM) was just as effective as amphotericin B (IC50 0.31 µM). Against L. donovani, 1 (IC50 7.02 µM) was twenty-two times less active than amphotericin B (IC50 0.32 µM), reinforcing the unique effectiveness of 1 against L. major. For T. brucei brucei, 1 (IC50 0.78 µM) was ten times more active than the laboratory standard Coptis japonica (IC50 8.20 µM). The IC50 of 9.08 µM for 1 against P. falciparum 3d7 compared to artesunate (IC50 36 nM) was not strong, but this result suggests the possibility of using the paenidigyamycin scaffold for the development of potent antimalarial drugs. Against cercariae, 1 showed high anticercaricidal activity compared to artesunate. The minimal lethal concentration (MLC) and minimal effective concentration (MEC) of the compound were 25 and 6.25 µM, respectively, while artesunate was needed in higher quantities to produce such results. However, 1 (IC50 > 100 µM) was not active against T. mobilensis.

In vitro antiprotozoan activity and mechanisms of action of selected Ghanaian medicinal plants against Trypanosoma, Leishmania, and Plasmodium parasites.

Trypanosomiasis, leishmaniasis, and malaria are protozoan infections of public health importance with thousands of new cases recorded annually. Control of these infection(s) with existing chemotherapy is limited by drug toxicity, lengthy parenteral treatment, affordability, and/or the emergence of resistant strains. Medicinal plants on the other hand are used in the treatment of various infectious diseases although their chemical properties are not fully evaluated. In this study, we screened 112 crude extracts from 72 selected Ghanaian medicinal plants for anti-Trypanosoma, anti-Leishmania, and anti-Plasmodium activities in vitro and investigated their mechanisms of action. Twenty-three extracts from 20 plants showed significant antiprotozoan activity against at least 1 of 3 protozoan parasites screened with IC50 values less than 20 µg/ml. Eleven extracts showed high anti-Trypanosoma activity with Bidens pilosa whole plant and Morinda lucida leaf extracts recording the highest activities. Their IC50 (selectivity index [SI]) values were 5.51 µg/ml (35.00) and 5.96 µg/ml (13.09), respectively. Nine extracts had high anti-Leishmania activity with Annona senegalensis and Cassia alata leaf extracts as the most active. Their IC50 (SI) values were 10.8 µg/ml (1.50) and 10.1 µg/ml (0.37), respectively. Six extracts had high anti-Plasmodium activity with the leaf and stem-bark extracts of Terminalia ivorensis recording the highest activity. Their IC50 (SI) values were 7.26 µg/ml (129.36) and 17.45 µg/ml (17.17), respectively. Only M. lucida at 25 µg/ml induced significant apoptosis-like cell death in Trypanosoma parasites. Anti-Leishmania active extracts induced varying morphological changes in Leishmania parasites such as multiple nuclei and/or kinetoplast, incomplete flagella division, or nuclear fragmentation. Active extracts may be potential sources for developing new chemotherapy against these infections.

In Vitro Assessment of Anthelmintic Activities of Rauwolfia vomitoria (Apocynaceae) Stem Bark and Roots against Parasitic Stages of Schistosoma mansoni and Cytotoxic Study.

Schistosomiasis is a Neglected Tropical Diseases which can be prevented with mass deworming chemotherapy. The reliance on a single drug, praziquantel, is a motivation for the search of novel antischistosomal compounds. This study investigated the anthelmintic activity of the stem bark and roots of Rauwolfia vomitoria against two life stages of Schistosoma mansoni. Both plant parts were found to be active against cercariae and adult worms. Within 2 h of exposure all cercariae were killed at a concentration range of 62.5-1000 µg/mL and 250-1000 µg/mL of R. vomitoria stem bark and roots, respectively. The LC50 values determined for the stem bark after 1 and 2 h of exposure were 207.4 and 61.18 µg/mL, respectively. All adult worms exposed to the concentrations range of 250-1000 µg/mL for both plant parts died within 120 h of incubation. The cytotoxic effects against HepG2 and Chang liver cell assessed using MTT assay method indicated that both plant extracts which were inhibitory to the proliferation of cell lines with IC50 > 20 µg/mL appear to be safe. This report provides the first evidence of in vitro schistosomicidal potency of R. vomitoria with the stem bark being moderately, but relatively, more active and selective against schistosome parasites. This suggests the presence of promising medicinal constituent(s).

In vitro anti-Leishmania activity of tetracyclic iridoids from Morinda lucida, benth.

Leishmaniasis is an infectious disease transmitted by the sand fly. It is caused by over 20 different species of Leishmania and has affected over 14 million people worldwide. One of the main forms of control of leishmaniasis is chemotherapy, but this is limited by the high cost and/or toxicity of available drugs. We previously found three novel compounds with an iridoid tetracyclic skeleton to have activity against trypanosome parasites. In this study, we determined the activity of the three anti-trypanosome compounds against Leishmania using field strain, 010, and the lab strain Leishmania hertigi. The minimum inhibitory concentration (MIC) of the compounds against 010 was determined by microscopy while the IC50 of compounds against L. hertigi was determined by fluorescence-activated cell sorting with Guava viacount analysis. We found two of the three compounds, molucidin and ML-F52, to have anti-Leishmania activity against both strains. The fluor-microscope observation with DAPI stain revealed that both Molucidin and ML-F52 induced abnormal parasites with two sets of nucleus and kinetoplast in a cell, suggesting that compounds might inhibit cytokinesis in Leishmania parasites. Molucidin and ML-F52 might be good lead compounds for the development of new anti-Leishmania chemotherapy.

Antitrypanosomal Activities and Mechanisms of Action of Novel Tetracyclic Iridoids from Morinda lucida Benth.

Trypanosoma brucei parasites are kinetoplastid protozoa that devastate the health and economic well-being of millions of people in Africa through the disease human African trypanosomiasis (HAT). New chemotherapy has been eagerly awaited due to severe side effects and the drug resistance issues plaguing current drugs. Recently, there has been an emphasis on the use of medicinal plants worldwide. Morinda lucida Benth. is a popular medicinal plant widely distributed in Africa, and several research groups have reported on the antiprotozoal activities of this plant. In this study, we identified three novel tetracyclic iridoids, molucidin, ML-2-3, and ML-F52, from the CHCl3 fraction of M. lucida leaves, which possess activity against the GUTat 3.1 strain of T. brucei brucei The 50% inhibitory concentrations (IC50) of molucidin, ML-2-3, and ML-F52 were 1.27 µM, 3.75 µM, and 0.43 µM, respectively. ML-2-3 and ML-F52 suppressed the expression of paraflagellum rod protein subunit 2, PFR-2, and caused cell cycle alteration, which preceded apoptosis induction in the bloodstream form of Trypanosoma parasites. Novel tetracyclic iridoids may be promising lead compounds for the development of new chemotherapies for African trypanosomal infections in humans and animals.

New anti-trypanosomal active tetracyclic iridoid isolated from Morinda lucida Benth.

Human African trypanosomiasis (HAT), commonly known as sleeping sickness has remained a serious health problem in many African countries with thousands of new infected cases annually. Chemotherapy, which is the main form of control against HAT has been characterized lately by the viewpoints of toxicity and drug resistance issues. Recently, there have been a lot of emphases on the use of medicinal plants world-wide. Morinda lucida Benth. is one of the most popular medicinal plants widely distributed in Africa and several groups have reported on its anti-protozoa activities. In this study, we have isolated one novel tetracyclic iridoid, named as molucidin, from the CHCl3 fraction of the M. lucida leaves by bioassay-guided fractionation and purification. Molucidin was structurally elucidated by (1)H and (13)C NMR including HMQC, HMBC, H-H COSY and NOESY resulting in tetracyclic iridoid skeleton, and its absolute configuration was determined. We have further demonstrated that molucidin presented a strong anti-trypanosomal activity, indicating an IC50 value of 1.27 µM. The cytotoxicity study using human normal and cancer cell lines indicated that molucidin exhibited selectivity index (SI) against two normal fibroblasts greater than 4.73. Furthermore, structure-activity relationship (SAR) study was undertaken with molucidin and oregonin, which is identical to anti-trypanosomal active components of Alnus japonica. Overlapping analysis of the lowest energy conformation of molucidin with oregonin suggested a certain similarities of aromatic rings of both oregonin and molucidin. These results contribute to the future drug design studies for HAT.

Impact of immunosuppression minimization and withdrawal in long-term hepatitis C virus liver transplant recipients.

AIM: To investigate the effects of different immunosuppressive regimens and avoidance on fibrosis progression in hepatitis C virus (HCV) liver transplant (LT) recipients. METHODS: We retrospectively compared the liver biopsies of well-matched HCV LT recipients under calcineurin inhibitors (CNI group, n = 21) and mycophenolate (MMF group, n = 15) monotherapy, with those patients who successfully withdrawn immunosuppression (IS) therapy from at least 3 years (TOL group, n = 10). To perform the well-matched analysis, all HCV transplanted patients from December 1993 were screened. Only those HCV patients who reached the following criteria were considered for the analysis: (1) at least 3 years of post-operative follow-up; (2) patients with normal liver graft function under low dose CNI monotherapy (CNI group); (3) patients with normal liver graft function under antimetabolite (Micophenolate Mofetil or coated mycophenolate sodium) monotherapy (MMF group); and (4) recipients with normal liver function without any IS. We excluded from the analysis recipients who were IS free or under monotherapy for < 36 mo, recipients with cirrhosis or with unstable liver function tests. RESULTS: Thirty six recipients were enrolled in the study. Demographics, clinical data, time after LT and baseline liver biopsies were comparable in the three groups. After six years of follow-up, there was no worsening of hepatic fibrosis in the MMF group (2.5 ± 1.5 Ishak Units vs 2.9 ± 1.7 Ishak Units, P = 0.5) and TOL group (2.7 ± 10.7 vs 2.5 ± 1.2, P = 0.2). In contrast, a significant increase in the fibrosis score was observed in the CNI group (2.2 ± 1.7 vs 3.9 ± 1.6, P = 0.008). The yearly fibrosis progression rate was significantly worse in the CNI group (0.32 ± 0.35) vs MMF group (0.03 ± 0.31, P = 0.03), and TOL group (-0.02 ± 0.27, P = 0.02). No differences have been reported in grading scores for CNI group (2.79 ± 1.9, P = 0.7), MMF group (3.2 ± 1.5, P = 0.9) and TOL group (3.1 ± 1.4, P = 0.2). Twenty four patients were treated with low dose ribavirin (8 TOL, 7 MMF, 9 CNI). The hepatitis C titers were comparable in the three groups. No episodes of rejection have been reported despite differences of liver function test in the three groups during the observational period. CONCLUSION: IS withdrawal and MMF monotherapy is safe and seems to be associated with the slowest fibrosis progression in HCV LT recipients.

Changing prognostic factors in osteosarcoma: analysis of 381 cases from two institutions.

Osteosarcoma occurs most commonly in children and young adults, with a historic second incidence peak in the elderly. Most studies have focused on those occurring in adolescence. Detailed information on descriptive features and prognostic factors in patients of different age groups is lacking. We analyzed 381 osteosarcomas diagnosed between 1973 and 2012 to identify factors significantly associated with survival in various age groups. The peak incidence was seen in patients age <25, followed by a steady incidence rate thereafter until the sixth decade, when it started to decline. In the early onset diseases, significant factors for recurrence-free survival (RFS) were tumor site and size; whereas those for overall survival (OS) were gender, tumor site, type, grade and size. In patients age 25 to 54, tumor type and grade were significant for RFS, and the pathologic type was significant for OS. In those age ≥55, race and tumor size were significant for RFS; tumor site and size were significant for OS. In multivariate analysis, tumor size remained significant for RFS; gender, tumor site and size maintained their significance for OS in patients age <25. While no independent factor was identified in patients age 25 to 54, tumor size remained significant for RFS in those age ≥55. Chemotherapy-induced tumor necrosis was a prognosticator for RFS in patients age 25 to 54 by univariate analysis, but not as an independent factor in any stratified age group. Our data indicate that the distinctive prognostic factors differed significantly among different age groups, thus providing a rationale for age-based management strategies.

Extracellular Matrix Scaffold Technology for Bioartificial Pancreas Engineering: State of the Art and Future Challenges.

Emergent technologies in regenerative medicine may soon overcome the limitations of conventional diabetes therapies. Collaborative efforts across the subfields of stem cell technology, islet encapsulation, and biomaterial carriers seek to produce a bioengineered pancreas capable of restoring endocrine function in patients with insulin-dependent diabetes. These technologies rely on a robust understanding of the extracellular matrix (ECM), the supportive 3-dimensional network of proteins necessary for cellular attachment, proliferation, and differentiation. Although these functions can be partially approximated by biosynthetic carriers, novel decellularization protocols have allowed researchers to discover the advantages afforded by the native pancreatic ECM. The native ECM has proven to be an optimal platform for recellularization and whole-organ pancreas bioengineering, an exciting new field with the potential to resolve the dire shortage of transplantable organs. This review seeks to contextualize recent findings, discuss current research goals, and identify future challenges of regenerative medicine as it applies to diabetes management.