Enhancing of cerebral Abeta clearance by modulation of ABC transporter expression: a review of experimental approaches

Clearance of amyloid-beta (Aβ) from the brain is impaired in both early-onset and late-onset Alzheimer's disease (AD). Mechanisms for clearing cerebral Aβ include proteolytic degradation, antibody-mediated clearance, blood brain barrier and blood cerebrospinal fluid barrier efflux, glymphatic drainage, and perivascular drainage. ATP-binding cassette (ABC) transporters are membrane efflux pumps driven by ATP hydrolysis. Their functions include maintenance of brain homeostasis by removing toxic peptides and compounds, and transport of bioactive molecules including cholesterol. Some ABC transporters contribute to lowering of cerebral Aβ. Mechanisms suggested for ABC transporter-mediated lowering of brain Aβ, in addition to exporting of Aβ across the blood brain and blood cerebrospinal fluid barriers, include apolipoprotein E lipidation, microglial activation, decreased amyloidogenic processing of amyloid precursor protein, and restricting the entrance of Aβ into the brain. The ABC transporter superfamily in humans includes 49 proteins, eight of which have been suggested to reduce cerebral Aβ levels. This review discusses experimental approaches for increasing the expression of these ABC transporters, clinical applications of these approaches, changes in the expression and/or activity of these transporters in AD and transgenic mouse models of AD, and findings in the few clinical trials which have examined the effects of these approaches in patients with AD or mild cognitive impairment. The possibility that therapeutic upregulation of ABC transporters which promote clearance of cerebral Aβ may slow the clinical progression of AD merits further consideration.

Recent developments of P-glycoprotein inhibitors and its structure-activity relationship (SAR) studies

P-glycoprotein (P-gp) over-expression is a key factor in multi-drug resistance (MDR), which is a major factor in the failure of cancer treatment. P-gp inhibitors have been demonstrated to have powerful pharmacological properties and may be used as a therapeutic approach to overcome the MDR in cancer cells. Combining clinical investigations with biochemical and computational research may potentially lead to a clearer understanding of the pharmacological properties and the mechanisms of action of these P-gp inhibitors. The task of turning these discoveries into effective therapeutic candidates for a variety of malignancies, including resistant and metastatic kinds, falls on medicinal chemists. A variety of P-gp inhibitors with great potency, high selectivity, and minimal toxicity have been identified in recent years. The latest advances in drug design, characterization, structure-activity relationship (SAR) research, and modes of action of newly synthesized, powerful small molecules P-gp inhibitors over the previous ten years are highlighted in this review. P-gp transporter over-expression has been linked to MDR, therefore the development of P-gp inhibitors will expand our understanding of the processes and functions of P-gp-mediated drug efflux, which will be helpful for drug discovery and clinical cancer therapies.

Investigating the Antibacterial Properties of Prospective Scabicides

Scabies is a dermatological disease found worldwide. Mainly in tropical regions, it is also the cause of significant morbidity and mortality due to its association with potentially severe secondary bacterial infections. Current treatment strategies for scabies do not consider the role of opportunistic bacteria, and here we investigate whether current and emerging scabicides can offer any anti-bacterial protection. Using the broth microdilution method, we examined antimicrobial potential of the current scabicide ivermectin and emerging scabies treatments: abametapir, mānuka oil, and its individual β-triketones. Our results demonstrate that the two novel scabicides abametapir and mānuka oil have antimicrobial properties against common scabies-associated bacteria, specifically Staphylococcus aureus, Streptococcus pyogenes, Streptococcus dysgalactiae subsp. equisimilis and Acinetobacter baumannii. The current scabicide ivermectin offers some antimicrobial activity and is capable of inhibiting the growth aforementioned bacteria. This research is important as it could help to inform future best treatment options of scabies, and scabies-related impetigo.

Colupulone, colupone and novel deoxycohumulone geranyl analogues as larvicidal agents against Culex pipiens

BACKGROUND

As climate change proceeds, the management of the population of mosquitoes becomes more and more challenging. Insect adulticides and larvicides constitute significant control techniques, with the latter being considered the leading mosquito control method. However, the development of mosquito resistance development and the adverse side effects caused by the extensive use of synthetic insecticides have turned research towards the discovery of environmentally-friendly solutions. Plants and bacteria have historically proven to be a good source of insecticidally active compounds, which may possess novel modes of action to overcome current resistance mechanisms and could also possess favorable human and environmental safety profiles. A previous study demonstrated that the naturally occurring prenylated acyl phloroglucinol deoxycohumulone is a potent larvicidal agent against Culex pipiens. Herein the structural characteristics that improve it are explored by evaluating colupulone and novel geranylated analogues.

RESULTS

Colupulone, a prenylated acyl phloroglucinol isolated from Humulus lupulus, colupone, and novel geranylated acyl phloroglucinol congeners, were synthesized and evaluated against Cx. pipiens larva. Results indicated that selected derivatives exhibited superior potency than deoxycohumulone (LC₅₀ 43.7 mg L^-1 ). Thus, strong activity was observed for colupulone (LC₅₀ 19.7 mg L^-1 ), and some novel geranyl analogues of deoxycohumulone reaching at LC₅₀ 17.1 mg L^-1 , while colupone and similar compounds were almost inactive.

CONCLUSION

The results determined the relationship between the target activity and the chemical structure of the tested compounds, and they revealed significantly improved larvicidal candidates. These results highlight the potential of the acyl phloroglucinol chemistry for further development of mosquito larvicides. © 2022 Society of Chemical Industry.

Estrogenic Plants: to Prevent Neurodegeneration and Memory Loss and Other Symptoms in Women After Menopause

In mammals, sexual hormones such as estrogens play an essential role in maintaining brain homeostasis and function. Estrogen deficit in the brain induces many undesirable symptoms such as learning and memory impairment, sleep and mood disorders, hot flushes, and fatigue. These symptoms are frequent in women who reached menopausal age or have had ovariectomy and in men and women subjected to anti-estrogen therapy. Hormone replacement therapy alleviates menopause symptoms; however, it can increase cardiovascular and cancer diseases. In the search for therapeutic alternatives, medicinal plants and specific synthetic and natural molecules with estrogenic effects have attracted widespread attention between the public and the scientific community. Various plants have been used for centuries to alleviate menstrual and menopause symptoms, such as Cranberry, Ginger, Hops, Milk Thistle, Red clover, Salvia officinalis, Soy, Black cohosh, Turnera diffusa, Ushuva, and Vitex. This review aims to highlight current evidence about estrogenic medicinal plants and their pharmacological effects on cognitive deficits induced by estrogen deficiency during menopause and aging.

Discovery of aromatic amides with triazole-core as potent reversal agents against P-glycoprotein-mediated multidrug resistance

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) is a major impediment for clinical cancer therapy. 19 novel aromatic amides with triazole-core as MDR reversal agents were designed and synthesized via click chemistry to reverse MDR. Among them, compound 42 was identified as the most promising candidate with high potency (EC₅₀ = 78.1 ± 5.4 nM), low cytotoxity (SI > 1282) and persistent duration in reversing doxorubicin (DOX) resistance in K562/A02 cells. 42 also enhanced the potency of other P-gp associated cytotoxic agents with different structures. In further study, remarkably increased intracellular accumulation of Rh123 and DOX in K562/A02 cells was achieved by compound 42, while CYP3A4 activity had no change by compound 42. These results indicate that compound 42 as a relatively safe modulator of P-gp-mediated MDR has good potential for further development.

Identification of embelin, a 3-undecyl-1,4-benzoquinone from Embelia ribes as a multitargeted anti-Alzheimer agent

Beta-secreatse (BACE-1) and cholinesterases are clinically validated targets of Alzheimer's disease (AD), for which natural products have provided immense contribution. The multifaceted nature of AD signifies the need of multitargeted agents to tackle this disease. In the search of new natural products as dual BACE-1/cholinesterase inhibitors, a library of pure natural products was screened for inhibition of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and BACE-1. The screening efforts have identified 1,4-benzoquinone "embelin," a natural product derived from Embelia ribes displaying inhibition of all three enzymes, with IC₅₀ values of 2.5, 5.4, and 2.1 μM, respectively. This screen has also identified isoquinoline alkaloids papaverine and L-tetrahydropalmatine as AChE inhibitors. Kinetic study has shown that embelin inhibits EeAChE and EqBChE with ki values of 4.59 and 0.57 μM, in an uncompetitive and noncompetitive manner, respectively. The interactions of embelin with allosteric peripheral anionic site of cholinesterases, has further supported the results of kinetic study. Embelin has also enhanced the activity of P-gp in LS-180 cells, the efflux pump which is involved in the clearance of amyloid-β from AD brain. Further, the cell viability study in neuronal cell line has indicated the excellent therapeutic window of embelin. These results are indicative of the fact that embelin is a multitargeted agent playing role in stopping the formation of amyloid-β oligomers (via inhibition of BACE-1), improves cholinergic-transmission (via inhibition of AChE/BChE) and increases amyloid-β clearance (via P-gp induction).

Preclinical Development of Crocus sativus-Based Botanical Lead IIIM-141 for Alzheimer's Disease: Chemical Standardization, Efficacy, Formulation Development, Pharmacokinetics, and Safety Pharmacology

Crocus sativus L. (family: Iridaceae) has been documented in traditional medicine with numerous medicinal properties. Recently, we have shown that C. sativus extract (IIIM-141) displays promising efficacy in a genetic mice (5XFAD) model of Alzheimer's disease (AD) (ACS Chem. Neurosci. 2017, 16, 1756). To translate the available traditional knowledge and the scientifically validated results into modern medicine, herein we aimed to carry out its preclinical development. IIIM-141 is primarily a mixture of crocins containing trans-4-GG-crocin (36 % w/w) as the principal component. The in vitro studies show that IIIM-141 has protective as well as therapeutic properties in assays related to AD. It induces the expression of P-gp, thereby enhancing the amyloid-β clearance from an AD brain. It also inhibits NLRP3 inflammasome and protects SH-SY5Y cells against amyloid-β- and glutamate-induced neurotoxicities. In behavioral models, it decreased the streptozotocin-induced memory impairment in rats and recovered the scopolamine-induced memory deficit in Swiss albino mice at 100 mg/kg dose. The acute oral toxicity study shows that IIIM-141 is safe up to the dose of 2000 mg/kg, with no effect on the body weight and on the biochemical/hematological parameters of the rats. The repeated oral administration of IIIM-141 for 28 days at 100 mg/kg dose did not cause any preterminal deaths and abnormalities in Wistar rats. The pharmacokinetic analysis indicated that after oral administration of IIIM-141, the majority of crocin gets hydrolyzed to its aglycone crocetin. The sustained release (SR) capsule formulation was developed, which showed an improved in vitro dissolution profile and a significantly enhanced plasma exposure in the pharmacokinetic study. The SR formulation resulted in 3.3-fold enhancement in the area under the curve of crocetin and doubling of the crocetin/crocin ratio in plasma compared with the extract. The data presented herein will serve as the benchmark for further research on this botanical candidate.

Drug interactions in HIV treatment: complementary & alternative medicines and over-the-counter products

INTRODUCTION

Use of complementary and alternative medicines (CAMs) and over-the-counter (OTC) medications are very common among HIV-infected patients. These products can cause clinically significant drug-drug interactions (DDIs) with antiretroviral (ARV) medications, thereby increasing risk for negative outcomes such as toxicity or loss of virologic control. Areas covered: This article provides an updated review of the different mechanisms by which CAM and OTC products are implicated in DDIs with ARV medications. Expert commentary: Much of the literature published to date involves studies of CAMs interacting with older ARV agents via the cytochrome P450 (CYP450) system. However, the HIV treatment and prevention arsenal is continually evolving. Furthermore, our elucidation of the role of non-CYP450 mediated DDIs with ARV medications is greatly increasing. Therefore, clinicians are well served to understand the various mechanisms and extent by which new ARV therapies may be involved in drug interactions with CAMs and OTC medications.

Functional induction of P-glycoprotein efflux pump by phenyl benzenesulfonamides: Synthesis and biological evaluation of T0901317 analogs

N-(2,2,2-Trifluoroethyl)-N-[4-[2,2,2-trifluoro-1-hydroxy-1-(trifluoromethyl)ethyl]phenyl]-benzenesulfonamide (T0901317, 6) is a potent activator of pregnane-X-receptor (PXR), which is a nuclear receptor controlling P-gp expression. Herein, we aimed to investigate P-gp induction activity of T0901317 and establish its structure-activity relationship. T0901317 along with a series of N-triazolyl-methylene-linked benzenesulfonamides were synthesized and screened for P-gp induction activity using a rhodamine-123 based efflux assay in the P-gp overexpressing human adenocarcinoma LS-180 cells, wherein several compounds showed potent P-gp induction activity at 5 μM. Treatment with benzene sulphonamides led to the decrease in intracellular accumulation of a fluorescent P-gp substrate rhodamine-123 up to 48% (control 100%). In the western-blot studies, T0901317 (6) and its triazole linked analog 26e at 5 μM displayed induction of P-gp expression in LS180 cells. These compounds were non-toxic in LS-180 and human neuroblastoma SH-SY5Y cells (IC50 > 50 μM). The compound 26e showed significant P-gp induction even at 0.3 μM, indicating an excellent therapeutic window. These results clearly indicate promise of this class of compounds as potential agents to enhance amyloid-β clearance in Alzheimers patients.

Design, synthesis and P-gp induction activity of aryl phosphonate esters: identification of tetraethyl-2-phenylethene-1,1-diyldiphosphonate as an orally bioavailable P-gp inducer

The P-gp induction activity of SR12813 and its analogs has been reported.