Acinetobacter baumannii: An overview of emerging multidrug-resistant pathogen

The emergence of infections caused by Acinetobacter baumannii, a multidrug-resistant bacterium, has been a concern worldwide. This bacterium is an important hospitalacquired pathogen that causes several diseases including ventilator-associated pneumonia, bloodstream infections, and meningitis. This study aimed to determine antibioticresistant mechanisms in the pathogenesis of A. baumannii and the alternative treatment strategies against it. The combined actions of outer membrane protein A, formation of a biofilm on biotic and abiotic surfaces, phospholipases C and D, metal homeostatic system, lipopolysaccharides, and verotoxins are relevant for virulence and pathogenesis. A. baumannii resists the broad-spectrum antibiotics by its mechanisms of resistance, such as β-lactamases, efflux pump, aminoglycoside modifying enzymes, permeability changes, and alternation of targets. In an attempt to overcome the resistance mechanisms, plant-derived compounds and a combination of the antibiotics and the plant phytocompounds have been focused. Nanoparticles synthesised with the plant extract have been studied extensively. Furthermore, we projected modern methods, including multi-omics analysis, to study insight into mechanisms of actions of antibiotics. The information suggested that the potential antibiotic mechanisms of A. baumannii could lead to an alternative treatment against A. baumannii infections.

Can Costus afer be used for co-treatment of COVID-19, its symptoms and comorbidities? A novel approach for combating the pandemic and implications for sub-Saharan Africa

Despite the huge loss of lives and massive disruption of the world economy by the COVID -19 pandemic caused by SARS -CoV-2, scientists are yet to come out with an effective therapeutic against this viral disease . Several vaccines have obtained 'emergency approval ', but difficulties are being faced in the even distribution of vaccines amongst high- and low- income countries . On top of it, comorbidities associated with COVID -19 like diabetes, hypertension and malaria can seriously impede the treatment of the main disease, thus increasing the fatality rate . This is more so in the context of sub -Saharan African and south Asian countries . Our objective was to demonstrate that a single plant containing different phytoconstituents may be used for treatment of COVID -19 and comorbidities . Towards initial selection of a plant, existing scientific literature was scanned for reported relevant traditional uses, phytochemicals and pharmacological activities of a number of plants and their phytoconstituents pertaining to treatment of COVID-19 symptoms and comorbidities. Molecular docking studies were then performed with phytochemicals of the selected plant and SARS-CoV-2 components - Mpro, and spike protein receptor binding domain and hACE2 interface using AutoDock V ina. We showed that crude extracts of an indigenous African plant, Costus afer having traditional antidiabetic and antimalarial uses, has phytochemicals with high binding affinities for Mpro, and /or spike protein receptor binding domain and hACE2 interface; the various phytochemicals with predicted high binding energies include aferoside C, dibutyl phthalate, nerolidol, suginal, and ± -terpinene, making them potential therapeutics for COVID -19. The results suggest that crude extracts and phytochemicals of C. afer can function as a treatment modality for COVID -19 and comorbidities like especially diabetes and malaria .

Potential role of flavonoids against SARS-CoV-2 induced diarrhea

COVID-19, caused by the SARS-CoV-2 virus, can lead to massive inflammation in the gastrointestinal tract causing severe clinical symptoms. SARS-CoV-2 infects lungs after binding its spike proteins with alveolar angiotensin-converting enzyme 2 (ACE2), and it also triggers inflammation in the gastrointestinal tract. SARS-CoV-2 invades the gastrointestinal tract by interacting with Toll-like receptor-4 (TLR4) that induces the expression of ACE2. The influx of ACE2 facilitates cellular binding of more SARS-CoV-2 and causes massive gastrointestinal inflammation leading to diarrhea. Diarrhea prior to COVID-19 infection or COVID-19-induced diarrhea reportedly ends up in a poor prognosis for the patient. Flavonoids are part of traditional remedies for gastrointestinal disorders. Preclinical studies show that flavonoids can prevent infectious diarrhea. Recent studies show flavonoids can inhibit the multiplication of SARS-CoV-2. In combination with vitamin D, flavonoids possibly activate nuclear factor erythroid-derived-2-related factor 2 that downregulates ACE2 expression in cells. We suggest that flavonoids have the potential to prevent SARS-CoV-2 induced diarrhea.

In silico screening of Allium cepa phytochemicals for their binding abilities to SARS and SARS-CoV-2 3C-like protease and COVID-19 human receptor ACE-2

Corona virus SARS-CoV-2-induced viral disease (COVID-19) is a zoonotic disease that was initially transmitted from animals to humans. The virus surfaced towards the end of December 2019 in Wuhan, China where earlier SARS (Severe Acute Respiratory Syndrome) had also surfaced in 2003. Unlike SARS, SARS-CoV-2 (a close relative of the SARS virus) created a pandemic, and as of February 24 2021, caused 112,778,672 infections and 2,499,252 deaths world-wide. Despite the best efforts of scientists, no drugs against COVID-19 are yet in sight; five vaccines have received emergency approval in various countries, but it would be a difficult task to vaccinate twice the world population of 8 billion. The objective of the present study was to evaluate through in silico screening a number of phytochemicals in Allium cepa (onion) regarding their ability to bind to the main protease of COVID-19 known as the 3C-like protease or 3CL^pro, (PDB ID: 6LU7), 3CL^pro of SARS (PDB ID: 3M3V), and human angiotensin converting enzyme-2 (ACE-2), [PDB ID: 1R42], which functions as a receptor for entry of the virus into humans. Molecular docking (blind docking, that is docking not only against any target pocket) were done with the help of AutoDockVina. It was observed that of the twenty-two phytochemicals screened, twelve showed good binding affinities to the main protease of SARS-CoV-2. Surprisingly, the compounds also demonstrated good binding affinities to ACE-2. It is therefore very likely that the binding affinities shown by these compounds against both 3CL^pro and ACE-2 merit further study for their potential use as therapeutic agents.

Antibacterial activities of the extracts, fractions and isolated compounds from Canarium patentinervium Miq. against bacterial clinical isolates

Background

Canarium patentinervium leaves are used by the local indigenous people of Malaysia for wound healing. The current study is undertaken to screen the comprehensive antibacterial activity of the leaves and barks extracts, fractions and isolated compounds from this plant. Bioassay guided fractionation was also undertaken to deeply evaluate the antibacterial activity of the water fraction of the leaves extract. This is to provide preliminary scientific evidence to the ethnopharmacology usage of this plant by investigating antibacterial properties of the plant and its isolated constituents.

Methods

Bio-assay guided fractionation and subsequent isolation of compounds using open column chromatography. The antibacterial activity against gram positive and gram negative ATCC strain and resistant clinical strains were evaluated using microtiter broth dilution method to determine minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time-kill assay. The chemical structure of the isolated compounds from the water fraction of the ethanol extract of leaves was elucidated using Nuclear Magnetic Resonance (NMR).

Results

The ethanol extract of the leaves and barks showed antimicrobial activity against all four ATCC and eight clinical isolates. The ethanol extract of the leaves and the corresponding water fraction had good activity against MRSA S. aureus. (MIC: 250 μg/ml) and had bactericidal effect on eight of the clinical strains (MSSA,MRSA, oxacillin-resistant CONS, oxacillin-sensitive CONS, Enterococcus faecalis, Klebsiela species, Kleb pneumoniae ESBL and Candida parapsilosis). Further phytochemical investigation of the water fraction of the crude ethanol extract of leaves afforded compound 7 (hyperin) and compound 8 (cynaroside) that had bactericidal activity against tested bacterial species (MIC 50 μg/ml and 100 μg/ml). The two compounds were isolated from this genus for the first time.

Conclusions

These results may provide a rational support for the traditional use of Canarium patentinervium Miq. in infections and wound healing, since the antimicrobial compounds isolated were also present in the leaves extract.

A preliminary screening of potentially antimalarial plants against Plasmodium falciparum in vitro

Plasmodium is a blood protozoan parasite that is responsible for malaria. To date, Plasmodium falciparum has shown multi-drug resistance, particularly in Thailand, Myanmar and Malaysia. The aim of the study is to screen the plant extracts that can effectively inhibit P. falciparum 3D7, a common lab strain malaria parasite. Nine plants were collected and processed through maceration using hexane, chloroform and ethanol, resulting in 24 crude plant extracts. Of these, extracts from Artabotrys crassifolius, Pericampylus glacus and Leuconotis eugeniifolia showed promising antiplasmodial activities at IC50 of 15.32 to 39.75 µg/mL in a modified schizont maturation assay. Further studies are warranted to explore its efficacies and lead compounds of these three plant extracts for the development of antiplasmodial drugs.

The Medicinal Timber Canarium patentinervium Miq. (Burseraceae Kunth.) Is an Anti-Inflammatory Bioresource of Dual Inhibitors of Cyclooxygenase (COX) and 5-Lipoxygenase (5-LOX)

The barks and leaves extracts of Canarium patentinervium Miq. (Burseraceae Kunth.) were investigated for cyclooxygenase (COX) and 5-lipoxygenase (LOX) inhibition via in vitro models. The corresponding antioxidative power of the plant extract was also tested via nonenzyme and enzyme in vitro assays. The ethanolic extract of leaves inhibited the enzymatic activity of 5-LOX, COX-1, and COX-2 with IC₅₀ equal to 49.66 ± 0.02 μg/mL, 0.60 ± 0.01 μg/mL, and 1.07 ± 0.01 μg/mL, respectively, with selective COX-2 activity noted in ethanolic extract of barks with COX-1/COX-2 ratio of 1.22. The ethanol extract of barks confronted oxidation in the ABTS, DPPH, and FRAP assay with EC₅₀ values equal to 0.93 ± 0.01 μg/mL, 2.33 ± 0.02 μg/mL, and 67.00 ± 0.32 μg/mL, respectively, while the ethanol extract of leaves confronted oxidation in β-carotene bleaching assay and superoxide dismutase (SOD) assay with EC₅₀ value of 6.04 ± 0.02 μg/mL and IC₅₀ value of 3.05 ± 0.01 μg/mL. The ethanol extract acts as a dual inhibitor of LOX and COX enzymes with potent antioxidant capacity. The clinical significance of these data is quite clear that they support a role for Canarium patentinervium Miq. (Burseraceae Kunth.) as a source of lead compounds in the management of inflammatory diseases.

Anti-Inflammatory, Anticholinesterase, and Antioxidant Potential of Scopoletin Isolated from Canarium patentinervium Miq. (Burseraceae Kunth)

Bioassay guided fractionation of an ethanol extract of leaves of Canarium patentinervium Miq. (Burseraceae Kunth.) led to the isolation of scopoletin. The structure of this coumarin was elucidated based on spectroscopic methods including nuclear magnetic resonance (NMR-1D and 2D) and mass spectrometry. Scopoletin inhibited the enzymatic activity of 5-lipoxygenase and acetyl cholinesterase with an IC50 equal to 1.76 ± 0.01  μ M and 0.27 ± 0.02 mM, respectively, and confronted oxidation in the ABTS, DPPH, FRAP, and β -carotene bleaching assay with EC50 values equal to 5.62 ± 0.03  μ M, 0.19 ± 0.01 mM, 0.25 ± 0.03 mM and 0.65 ± 0.07 mM, respectively. Given the aforementioned evidence, it is tempting to speculate that scopoletin represents an exciting scaffold from which to develop leads for treatment of neurodegenerative diseases.

Acalypha wilkesiana extracts induce apoptosis by causing single strand and double strand DNA breaks

ETHNOPHARMACOLOGICAL RELEVANCE

The seeds of Acalypha wilkesiana have been used empirically by traditional healers in Southwest Nigeria together with other plants as a powder mixture to treat patients with breast tumours and inflammation.

AIM OF THE STUDY

There is an increasing interest among researchers in searching for new anticancer drugs from natural resources, particularly plants. This study aimed to investigate the anticancer properties of Acalypha wilkesiana extracts and the characteristics of DNA damage against brain and lung cancer cells.

MATERIALS AND METHODS

The antiproliferative activity of Acalypha wilkesiana extracts (ethyl acetate, hexane, and ethanol) was examined on human glioma (U87MG), human lung carcinoma (A549), and human lung fibroblast (MRC5) cells.

RESULTS

Cell viability MTT assay revealed that ethyl acetate extract of the plant possessed significant antiproliferative effects against both U87MG (GI(50)=28.03 ± 6.44 μg/ml) and A549 (GI(50)=89.63 ± 2.12 μg/ml) cells (p value<0.0001). The hexane extract was found to exhibit crucial antiproliferative effects on U87MG (GI(50)=166.30 ± 30.50 μg/ml) (p value<0.0001) but not on A549 cells. Neither plant extract possessed noticeable antiproliferative effects on the non-cancerous MRC5 cells (GI(50)>300 μg/ml). The ethanol extract showed no antiproliferative effects on any cell line examined. Haematoxylin & Eosin (H & E) staining and single cell gel electrophoresis (SCGE) comet assay confirmed that plant extract-treated cells underwent apoptosis and not necrosis. SCGE comet assays confirmed that plant extracts caused both single strand (SSB) and double strand (DSB) DNA breaks that led to the execution of apoptosis.

CONCLUSION

The extracts (especially ethyl acetate and hexane) of Acalypha wilkesiana possess valuable cytotoxic effects that trigger apoptosis in U87MG and A549 cancer cells through induction of DNA SSBs and DSBs.

In Vitro Antimicrobial, Antioxidant Activities and Phytochemical Analysis of Canarium patentinervium Miq. from Malaysia

Six different extracts of Canarium patentinervium Miq. (Burseraceae) leaves and barks were screened for their phytochemical composition, and antimicrobial and free radical scavenging activities. Among the different extracts tested, the ethanol extract of leaves showed significant antimicrobial and radical scavenging activities. The most susceptible micro-organisms were found to be Gram-positive bacteria (Staphylococcus aureus, methicillin-resistant Staphylococcus aureus or MRSA) and Gram-negative bacteria (Pseudomonas aeruginosa). Phytochemical analysis of the extracts revealed that the antimicrobial and the radical scavenging activities are mainly due to the presence of tannins and flavonoids. The results obtained suggest that Canarium patentinervium Miq. could be exploited in the management of various infectious diseases.

Antiviral properties of ent-labdene diterpenes ofAndrographis paniculata nees, inhibitors of herpes simplex virus type 1

Andrographolide, neoandrographolide and 14-deoxy-11,12-didehydroandrographolide, ent-labdene diterpenes isolated from Andrographis paniculata showed viricidal activity against herpes simplex virus 1 (HSV-1). None of these compounds exhibited significant cytotoxicity at viricidal concentrations.

Growth inhibition of foodborne and nosocomial pathogens by aqueous fraction of bearded Argostemma (Argostemma involucratum Hemsl., Rubiaceae)

The crude methanol extract of Bearded Argostemma (Argostemma involucratum Hemsl., Rubiaceae) showed a good and broad spectrum of antibacterial activity against both Gram-negative and Gram-positive bacteria. The activity was increased on fractionation (hexane, dichloromethane and water), particularly in the aqueous fraction which was more active than the methanol extract and streptomycin (no activity was shown against tested moulds). Both the hexane and dichloromethane fractions were inactive. The objective of this experiment was to investigate the antibacterial activity of hexane, dichloromethane, and aqueous fractions of Argostemma involucratum Hemsl. The aqueous fraction of Bearded Argostemma may be a possible new option for the treatment of bacterial infections.

Antimicrobial activity of tiger's betel (Piper porphyrophyllum N.E. Br., Piperaceae)

The ethanol extract of leaves of Piper porphyrophyllum N.E. Br. showed a broad spectrum of antibacterial activity. The activity was increased on fractionation (hexane, dichloromethane and aqueous), particularly in the aqueous fraction. No activity was shown against tested Candida albicans.

Antimicrobial activity of Acalypha siamensis Oliv. ex Gage

The hexane, dichloromethane, ethyl acetate and methanol fractions of leaves of Acalypha siamensis Oliv. ex Gage were evaluated for antibacterial and antifungal activity. The antibacterial activity was more pronounced in the ethyl acetate and methanol extracts. No activity was shown against tested moulds.

Antimicrobial screening of plants used for traditional medicine in the state of Perak, Peninsular Malaysia

Seventy-two extracts (methanol) obtained from the leaves, barks, and roots of 50 plant species used in the traditional medicine of Perak, Peninsular Malaysia, have been screened for antibacterial and antifungal activities. Peristrophe tinctoria, Polyalthia lateriflora, Knema malayana, Solanum torvum, Celosia argentea, Eclipta prostrata, Ancistrocladus tectorius, Dillenia suffruticosa, Piper stylosum and Rafflesia hasseltii displayed the broadest spectrum of activity.

Sesquiterpenes and alkaloids from Scorodocarpus borneensis

A new sesquiterpene, scodopin, and a mixture of three tryptamine-type alkaloids, scorodocarpines A-C, were isolated from the fruits of Scorodocarpus borneensis, together with a known hemisynthetic sesquiterpene, cadalene-beta-carboxylic acid, which was isolated from the bark. The structures of the new compounds were elucidated by interpretation of spectral data, especially tandem mass spectrometry for the alkaloid mixture.