Anti-infective activities of 11 plants species used in traditional medicine in Malaysia

Sucrose esters of aryldihydronaphthalene-type lignans, and antitumor activity of extracts of Moltkiopsis ciliata (Forssk.) aerial parts

One new compound (3f-[(7'R,8'R)-4,4'-dihydroxy-5-methoxy-2,7'-cycloligna-7-en-9-methoxycarbonyl, 9'-carbonyl-O-] -β- D-fructofuranosyl- (2→1)-α- D-glucopyranoside) (Moltkiopsin A) (2) was isolated and identified from the extract of aerial parts of the wild Egyptian plant Moltkiopsis ciliata (Frossk.), family Boraginaceae, for the first time, along with two aryldihydronaphthalene lignans 3f→9':6f→9-[(7'R,8'R)-4,4'- dihydroxy-3,3',5-trimethoxy-2,7'-cycloligna-7-en-9,9'-dicarbonyl]-6g-acetyl-α-D-gluco pyranosyl-(1→2) -β-D-fructofuranoside (Trigonotin A) (1) which was reported for the first time from this plant species and a known compound 3f→9':6f→9-[(7'R,8'R)-4,4'- dihydroxy-3,3',5-trimethoxy-2,7'-cycloligna-7-en-9,9'-dicarbonyl]-α-D-gluco pyranosyl - (1→2)- β-D- fructofuranoside (Trigonotin C) (3). These compounds were separated and purified using different chromatographic techniques and their structures were elucidated by extensive 1D (1H and 13C NMR), and 2D NMR (COSY, HSQC, and HMBC), besides ESI-MS spectral methods. Extracts were screened as antioxidant, antitumor and antibacterial. The different extracts showed moderate to strong antioxidant capacities in DPPH assays. Ethyl acetate, methylene chloride and crude methanol extracts exhibited the most significant free radicals scavenging activity when compared to the standard antioxidant vitamin C. Hexane and butanol fractions showed the highest cytotoxicity against the cancer cell lines HepG2 and MCF-7.

Potential medicinal plants to combat viral infections: A way forward to environmental biotechnology

The viral diseases encouraged scientific community to evaluate the natural antiviral bioactive components rather than protease inhibitors, harmful organic molecules or nucleic acid analogues. For this purpose, medicinal plants have been gaining tremendous importance in the field of attenuating the various kinds of infectious and non-infectious diseases. Most of the commonly used medicines contains the bioactive components/phytoconstituents that are generally extracted from medicinal plants. Moreover, the medicinal plants offer many advantages for the recovery applications of infectious disease especially in viral infections including HIV-1, HIV-2, Enterovirus, Japanese Encephalitis Virus, Hepatitis B virus, Herpes Virus, Respiratory syncytial virus, Chandipura virus and Influenza A/H1N1. Considering the lack of acceptable drug candidates and the growing antimicrobial resistance to existing drug molecules for many emerging viral diseases, medicinal plants may offer best platform to develop sustainable/efficient/economic alternatives against viral infections. In this regard, for exploring and analyzing large volume of scientific data, bibliometric analysis was done using VOS Viewer shedding light on the emerging areas in the field of medicinal plants and their antiviral activity. This review covers most of the plant species that have some novel bioactive compound like gnidicin, gniditrin, rutin, apigenin, quercetin, kaempferol, curcumin, tannin and oleuropin which showed high efficacy to inhibit the several disease causing virus and their mechanism of action in HIV, Covid-19, HBV and RSV were discussed. Moreover, it also delves the in-depth mechanism of medicinal with challenges and future prospective. Therefore, this work delves the key role of environment in the biological field.

A review on new natural and synthetic anti-leishmanial chemotherapeutic agents and current perspective of treatment approaches

Leishmaniases are considered among the most neglected yet dangerous parasitic diseases worldwide. According to the recent WHO report (Weekly Epidemiological Record, Sep, 2021), 200 countries and territories reported leishmanises cases in 2020; of which 89 (45%) for CL, and 79 (40%) for VL were endemic. Indian subcontinent (India, Bangladesh and Nepal), one of the three eco-epidemiological hotspots of VL, currently reported 18% of the total cases of VL worldwide. Eastern Mediterranean region and the Region of the Americas together reported >90% of the new CL cases, of which >80% were from Afghanistan, Algeria, Brazil, Colombia, Iraq, Pakistan and the Syrian Arab Republic. While considering the current therapeutic options, conventional anti-leishmanial drugs have long been proved to be toxic and/or expensive and have resulted in extensive drug resistance in India. Recent searches for novel anti-leishmanial drugs have led to find out the prime cellular targets and metabolic pathways to bridge the gap between the known facts and unexplored data. Cutting edge knowledge based drug designing has simplified the search for novel molecules with leishmanicidal efficacy by identifying ligand-receptor interactions and has accelerated the cost effective primary discovery of molecules through computational validation against Leishmaniases. This review focuses on the limitations of conventional drugs, and discusses the chemotherapeutic potential of many novel natural and synthetic anti-leishmanial agents reported since the last decade. It is also interpreted that some of the reported molecules might be tested singly or as a part of combinatorial therapy on pre-clinical and clinical level.

Potent Anti-amoebic Effects of Ibogaine, Voacangine and the Root Bark Alkaloid Fraction of Tabernaemontana arborea

Plants of Tabernaemontana species have several pharmacological activities including antimicrobial effects. Amoebiasis continues to be a public health problem, with increasing evidence of resistance to metronidazole. In this study, we assessed the effect of the alkaloid fraction of T. arborea root bark and the alkaloids ibogaine and voacangine on the viability and infectivity of Entamoeba histolytica trophozoites. Cultures were exposed to 0.1 - 10 µg/mL for 24, 48 and 72 h, and viability was then determined using a tetrazolium dye reduction assay and type of cellular death analyzed by flow cytometry. Results showed that the alkaloid fraction, but mainly ibogaine and voacangine alkaloids, exhibited potent dose-dependent anti-amoebic activity at 24 h post-exposure (IC₅₀ 4.5 and 8.1 µM, respectively), comparable to metronidazole (IC₅₀ 6.8 µM). However, the effect decreased after 48 and 72 h of exposure to concentrations below 10 µg/mL, suggesting that the alkaloids probably were catabolized to less active derivatives by the trophozoites. The treatment of trophozoites with the IC_50 s for 24 h induced significant morphological changes in the trophozoites, slight increase in granularity, and death by apoptonecrosis. The capacity of T. arborea alkaloids to inhibit the development of amoebic liver abscesses in hamsters was evaluated. Results showed that even when the treatments reduced the number of amoebic trophozoites in tissue sections of livers, they were unable to limit the formation of abscesses, suggesting their rapid processing to inactive metabolites. This work leaves open the possibility of using Tabernaemontana alkaloids as a new alternative for amoebiasis control.

Functional Characterization of UDP-Glycosyltransferases Involved in Anti-viral Lignan Glycosides Biosynthesis in Isatis indigotica

Isatis indigotica is a popular herbal medicine with its noticeable antiviral properties, which are primarily due to its lignan glycosides such as lariciresinol-4-O-β-D-glucoside and lariciresinol-4,4'-bis-O-β-D-glucosides (also called clemastanin B). UDP-glucose-dependent glycosyltransferases are the key enzymes involved in the biosynthesis of these antiviral metabolites. In this study, we systematically characterized the UGT72 family gene IiUGT1 and two UGT71B family genes, IiUGT4 and IiUGT71B5a, with similar enzymatic functions. Kinetic analysis showed that IiUGT4 was more efficient than IiUGT1 or IiUGT71B5a for the glycosylation of lariciresinol. Further knock-down and overexpression of these IiUGTs in I. indigotica's hairy roots indicates that they play different roles in planta: IiUGT71B5a primarily participates in the biosynthesis of coniferin not pinoresinol diglucoside, and IiUGT1 primarily participates in the biosynthesis of pinoresinol diglucoside, while IiUGT4 is responsible for the glycosylation of lariciresinol and plays a dominant role in the biosynthesis of lariciresinol glycosides in I. indigotica. Analysis of the molecular docking and site-mutagenesis of IiUGT4 have found that key residues for its catalytic activity are H373, W376, E397, and that F151 could be associated with substrate preference. This study elucidates the biosynthetic route of anti-viral lignan glycosides in I. indigotica, and provides the foundation for the production of anti-viral lignan glycosides via synthetic biology under the heterologous model.

Targeting NF-κB pathway by dietary lignans in inflammation: expanding roles of gut microbiota and metabolites

Inflammation is a major factor affecting human health. Nuclear factor-kappa B (NF-κB) plays a vital role in the development of inflammation, and the promoters of most inflammatory cytokine genes have NF-κB-binding sites. Targeting NF-κB could be an exciting route for the prevention and treatment of inflammatory diseases. As important constituents of natural plants, lignans are proved to have numerous biological functions. There are growing pieces of evidence demonstrate that lignans have the potential anti-inflammatory activities. In this work, the type, structure and source of lignans and the influence on mitigating the inflammation are systematically summarized. This review focuses on the targeting NF-κB signaling pathway in the inflammatory response by different lignans and their molecular mechanisms. Lignans also regulate gut microflora and change gut microbial metabolites, which exert novel pathway to prevent NF-κB activation. Taken together, lignans target NF-κB with various mechanisms to inhibit inflammatory cytokine expressions in the inflammatory response. It will provide a scientific theoretical basis for further research on the anti-inflammatory effects of lignans and the development of functional foods.

Plant-Based Natural Products and Extracts: Potential Source to Develop New Antiviral Drug Candidates

Viral infections are among the most complex medical problems and have been a major threat to the economy and global health. Several epidemics and pandemics have occurred due to viruses, which has led to a significant increase in mortality and morbidity rates. Natural products have always been an inspiration and source for new drug development because of their various uses. Among all-natural sources, plant sources are the most dominant for the discovery of new therapeutic agents due to their chemical and structural diversity. Despite the traditional use and potential source for drug development, natural products have gained little attention from large pharmaceutical industries. Several plant extracts and isolated compounds have been extensively studied and explored for antiviral properties against different strains of viruses. In this review, we have compiled antiviral plant extracts and natural products isolated from plants reported since 2015.

Compounds isolated from hexane fraction of Alternanthera brasiliensis show synergistic activity against methicillin resistant Staphylococcus aureus

Methicillin resistant Staphylococcus aureus (MRSA) has been classified as a “serious threat” by the centre for Disease Control, USA. Alternanthera brasiliensis plant, usually found on wasteland, belongs to the family Amaranthaceae. It is traditionally used for wound healing and has shown antimicrobial effect. Yet, this plant has not been fully explored for its antibacterial activity. Hence, this study evaluated isolated compounds from this plant for its activity against MRSA infections. The leaves extracts and fractions were prepared and concentrated in vacuo using a rotatory evaporator. Isolated compounds were obtained through vacuum liquid chromatographic (VLC) techniques and structurally elucidated with various spectroscopic techniques. Anti-MRSA assay of the fraction and compounds were evaluated by agar-well diffusion and broth-dilution methods while checkerboard assay was used to determine the fractional inhibitory concentration index (FICi). The Gas Chromatography-Mass Spectrometry (GCMS) and High Performance Liquid Chromatography (HPLC) analysis revealed fatty acid and carboxylic acid components like hexadecanoic acid, bis (2-ethylhexyl) phthalate and Fettsäure. The compounds AbHD1 and AbHD5 were identified as hexadecanoic acid and di (ethylhexyl) phthalate. Anti-MRSA assay shows that A. brasiliensis hexane fraction (AbHF) and the compounds had zones of inhibitions (Zi) ranging from 7.3 ± 0.5 to 17.5 ± 0.5 mm with minimum inhibitory concentrations (MIC) between 1.22 × 10−5 – 2.5 mg/mL. Synergistic effects were observed between AbHF and erythromycin, AbHF and ampicillin and AbHF and ciprofloxacin with FICi 0.208–0.375 in K1St4 strain while amoxicillin revealed antagonistic effects against M91 strain (4.67). Similarly, hexadecanoic acid and di (ethylhexyl) phthalate showed synergistic behaviour only with ampicillin against K1St4 while the rest were antagonistic. The study revealed that hexadecanoic acid and di (ethylhexyl) phthalate isolated from A. brasiliensis showed synergistic activity in variations against MRSA isolate and strains.

Potential of the natural products against leishmaniasis in Old World - a review of in-vitro studies

Leishmaniasis is a vector-borne disease among the 10 most Neglected Tropical Diseases with diverse clinical manifestations caused by protozoan parasites of the Leishmania genus. Around 80% of leishmaniasis cases are found in the Old World affecting populations mainly in low and middle-income countries. Its control relies mostly on chemotherapy which still presents many drawbacks. Natural products may offer an inexhaustible source of chemical diversity with therapeutic potential. Despite the lack of knowledge on traditional products with activity against Leishmania parasites, many reports describe the search for natural extracts and compounds with antileishmanial properties against promastigote and amastigote parasite forms. This review summarizes the research of 74 publications of the last decade (2008-2018) focused on the identification of endemic plant-derived products that are active against Old World Leishmania parasites responsible for cutaneous and visceral leishmaniasis. The present review combines data on antileishmanial activity of 423 plants species, belonging to 94 different families, including a large range of crude extracts which lead to the isolation of 86 active compounds. Most studied plants came from Asia and most promising plant families for antileishmanial activity were Asteraceae and Lamiaceae. From the chemical point of view, terpenoids were the most frequently isolated natural products. These studies suggest that natural products isolated from Old World flora are a rich source of new chemical scaffolds for future leishmaniasis treatment as well as for other Neglected Tropical Diseases warranting further investigation.

Naturally Lignan-Rich Foods: A Dietary Tool for Health Promotion?

Dietary guidelines universally advise adherence to plant-based diets. Plant-based foods confer considerable health benefits, partly attributable to their abundant micronutrient (e.g., polyphenol) content. Interest in polyphenols is largely focused on the contribution of their antioxidant activity to the prevention of various disorders, including cardiovascular disease and cancer. Polyphenols are classified into groups, such as stilbenes, flavonoids, phenolic acids, lignans and others. Lignans, which possess a steroid-like chemical structure and are defined as phytoestrogens, are of particular interest to researchers. Traditionally, health benefits attributed to lignans have included a lowered risk of heart disease, menopausal symptoms, osteoporosis and breast cancer. However, the intake of naturally lignan-rich foods varies with the type of diet. Consequently, based on the latest humans' findings and gathered information on lignan-rich foods collected from Phenol Explorer database this review focuses on the potential health benefits attributable to the consumption of different diets containing naturally lignan-rich foods. Current evidence highlight the bioactive properties of lignans as human health-promoting molecules. Thus, dietary intake of lignan-rich foods could be a useful way to bolster the prevention of chronic illness, such as certain types of cancers and cardiovascular disease.