Antimicrobial activities of saponins from Melanthera elliptica and their synergistic effects with antibiotics against pathogenic phenotypes
TL;DR: The present study showed significant antimicrobial activity of compounds 1, 2, 3 and 4 against the tested microorganisms, which could lead to new options for the treatment of infectious diseases and emerging drug resistance.
Abstract: Resistance of bacteria and fungi to antibiotics is one of the biggest problems that faces public health. The present work was designated to evaluate the antimicrobial activities of saponins from Melanthera elliptica and their synergistic effects with standard antibiotics against pathogenic phenotypes. The plant extract was prepared by maceration in methanol. The methanol extract was partitioned into ethyl acetate and n-butanol extracts. Column chromatography of the n-butanol extract followed by purification of different fractions led to the isolation of four saponins. Their structures were elucidated on the basis of spectra analysis, and by comparison with those from the literature. The antimicrobial activities of the extracts/compounds alone and their combinations with tetracycline and fluconazole were evaluated using the broth microdilution method through the determination of minimum inhibitory concentration (MIC) and minimum microbicidal concentration. Four compounds: 3-O-β-d-glucuronopyranosyl-oleanolic acid (1), 3-O-β-d-glucuronopyranosyloleanolic acid 28-O-β-d-glucopyranosyl ester (2), 3-O-β-d-glucopyranosyl(1 → 2)-β-d-glucuronopyranosyl oleanolic acid (3) and 3-O-β-d-glucopyranosyl(1 → 2)-β-d-glucuronopyranosyl oleanolic acid 28-O-β-d-glucopyranosyl ester (4) were isolated. Compounds 1, 2 and 3 showed the largest antibacterial activities (MIC = 8–128 μg/mL) whereas compound 4 displayed the highest antifungal activities (MIC = 8–16 μg/mL). The antibacterial activities of compounds 1 and 2 (MIC = 16–32 μg/mL) against multi-drug-resistant Escherichia coli S2 (1) and Shigella flexneri SDINT are equal to those of vancomycin (MIC = 16–32 μg/mL) used as reference antibiotic. The present study showed significant antimicrobial activity of compounds 1, 2, 3 and 4 against the tested microorganisms. The saponins act in synergy with the tested standard antibiotics. This synergy could lead to new options for the treatment of infectious diseases and emerging drug resistance.
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TL;DR: Key findings on the antibacterial potential of plant NPs are brought to the forefront for consideration in future antibiotic discovery and development efforts.
Abstract: The crisis of antibiotic resistance necessitates creative and innovative approaches, from chemical identification and analysis to the assessment of bioactivity. Plant natural products (NPs) represent a promising source of antibacterial lead compounds that could help fill the drug discovery pipeline in response to the growing antibiotic resistance crisis. The major strength of plant NPs lies in their rich and unique chemodiversity, their worldwide distribution and ease of access, their various antibacterial modes of action, and the proven clinical effectiveness of plant extracts from which they are isolated. While many studies have tried to summarize NPs with antibacterial activities, a comprehensive review with rigorous selection criteria has never been performed. In this work, the literature from 2012 to 2019 was systematically reviewed to highlight plant-derived compounds with antibacterial activity by focusing on their growth inhibitory activity. A total of 459 compounds are included in this Review, of which 50.8% are phenolic derivatives, 26.6% are terpenoids, 5.7% are alkaloids, and 17% are classified as other metabolites. A selection of 183 compounds is further discussed regarding their antibacterial activity, biosynthesis, structure-activity relationship, mechanism of action, and potential as antibiotics. Emerging trends in the field of antibacterial drug discovery from plants are also discussed. This Review brings to the forefront key findings on the antibacterial potential of plant NPs for consideration in future antibiotic discovery and development efforts.
123 citations
01 Mar 2021
TL;DR: In this paper, the authors investigated the antioxidant and antimicrobial effects of the peel, rind, pulp and seeds of C. lanatus (watermelon) as well as their respective phytochemical composition.
Abstract: This study investigated the antioxidant and antimicrobial effects of the peel, rind, pulp and seeds of C. lanatus (watermelon) as well as their respective phytochemical composition. The antioxidant effect was investigated using the DPPH and ABTS assay whereas the antimicrobial activity was evaluated using the well diffusion and broth dilution methods. The results revealed that the peel possessed the highest antioxidant activity whereas the pulp demonstrated the lowest. The peels demonstrated the highest antimicrobial effect, which was followed by the seed and then the rind. The pulp, however, demonstrated the least antimicrobial activity. A strong correlation was observed between total phenolic contents and biological activity. The peels were found to possess the highest content of total phenolics (0.087±0.002 mgGAE/g), which was followed by the seed (0.042±0.003 mgGAE/g) and the rind (0.026±0.003 mgGAE/g). The pulp did not only demonstrate the lowest antioxidant and antimicrobial activities but also had the lowest phenolic content (0.010±0.001 mgGAE/g). The peel and the seed show the presence of flavonoids whereas alkaloids and free reducing sugars were present in all parts of the watermelon fruit. From the results of the current study, it can, therefore, be concluded that among the various parts of the watermelon fruit, the peel has the highest antioxidant and antimicrobial activity whereas the pulp has the least. The peels and seeds are not only potent in their antioxidant and antimicrobial effects but also possess appreciable levels of phenolic compounds relative to the other parts.
30 citations
TL;DR: A review of nano-drug delivery system (nano-DDS) of existing anti-leishmanials, phyto-nano DDS, surface modified and nano-adjuvants can be found in this paper.
Abstract: As a neglected tropical disease, Leishmaniasis is significantly instigating morbidity and mortality across the globe. Its clinical spectrum varies from ulcerative cutaneous lesions to systemic immersion causing hyperthermic hepato-splenomegaly. Curbing leishmanial parasite is toughly attributable to the myriad obstacles in existing chemotherapy and immunization. Since the 1990s, extensive research has been conducted for ameliorating disease prognosis, by resolving certain obstacles of conventional therapeutics viz. poor efficacy, systemic toxicity, inadequate drug accumulation inside the macrophage, scarce antigenic presentation to body’s immune cells, protracted length and cost of the treatment. Mentioned hurdles can be restricted by designing nano-drug delivery system (nano-DDS) of extant anti-leishmanials, phyto-nano-DDS, surface modified—mannosylated and thiolated nano-DDS. Likewise, antigen delivery with co-transportation of suitable adjuvants would be achievable through nano-vaccines. In the past decade, researchers have engineered nano-DDS to improve the safety profile of existing drugs by restricting their release parameters. Polymerically-derived nano-DDS were found as a suitable option for oral delivery as well as SLNs due to pharmacokinetic re-modeling of drugs. Mannosylated nano-DDS have upgraded macrophage internalizing of nanosystem and the entrapped drug, provided with minimal toxicity. Cutaneous Leishmaniasis (CL) was tackling by the utilization of nano-DDS designed for topical delivery including niosomes, liposomes, and transfersomes. Transfersomes, however, appears to be superior for this purpose. The nanotechnology-based solution to prevent parasitic resistance is the use of Thiolated drug-loaded and multiple drugs loaded nano-DDS. These surfaces amended nano-DDS possess augmented IC50 values in comparison to conventional drugs and un-modified nano-DDS. Phyto-nano-DDS, another obscure horizon, have also been evaluated for their anti-leishmanial response, however, more intense assessment is a prerequisite. Impoverished Cytotoxic T-cells response followed by Leishmanial antigen proteins delivery have also been vanquished using nano-adjuvants. The eminence of nano-DDS for curtailment of anti-leishmanial chemotherapy and immunization associated challenges are extensively summed up in this review. This expedited approach is ameliorating the Leishmaniasis management successfully. Alongside, total to partial eradication of this disease can be sought along with associated co-morbidities.
27 citations
TL;DR: Saponins are secondary metabolic compounds produced in healthy plants with potential anti-pathogenic activity and serve as potential chemical barriers against pathogens as mentioned in this paper, and they are classified into two major groups the steroidal and terpenoid saponins.
25 citations
TL;DR: To have a systematic overview of saponin compounds, this review will describe the main aspects related to their structure, bioactivities and potential applications.
Abstract: Saponins are an important group of plant secondary metabolites that are widely distributed throughout the plant kingdom. These biomolecules can be divided into two main classes represented by triterpenoid and steroid glycosides whose structure varies according to the number of sugar units attached in different positions. Despite saponins have been historically considered as anti-nutritional factors, recent studies have indicated that some saponin stereoisomers may show a number of pharmacological activities, such as anti-tumor, antioxidative, antiinflammatory, antidiabetic, and neuro-protective activities. Nerveless, more attention in studying this group is necessary due to the fact that many active mechanisms are not fully elucidated. To have a systematic overview of saponin compounds, this review will describe the main aspects related to their structure, bioactivities and potential applications.
17 citations
Additional excerpts
...(Tamokou et al., 2017; Tagousop et al., 2018)....
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TL;DR: A six-volume revision of J.M. Dalziel's 1937 encyclopaedic work, to supplement the 2nd edition of the Flora of West Tropical Africa, was published in this paper.
Abstract: A six-volume revision of J.M. Dalziel's 1937 encyclopaedic work, to supplement the 2nd edition of the Flora of West Tropical Africa. In volumes one to five 5260 plants are described, each with its geographical range, habitat and economic attributes. Volume 6 is an aggregation of all the indices in the previous five volumes.
686 citations
"Antimicrobial activities of saponin..." refers background in this paper
...3 m high, commonly found in tropical West and Central Africa [23]....
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...Melanthera elliptica O. Hoffm., belonging to Asteraceae family, is a perennial bushy herb to 1.3 m high, commonly found in tropical West and Central Africa [23]....
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TL;DR: Despite the recent emphasis on gram-negative causes, sepsis resulting from gram-positive sources is increasingly common, as can be evidenced by the emergence of streptococcal toxic shock syndrome and the resurgence of acute rheumatic fever.
Abstract: In recent years, the importance of gram-negative organisms in the genesis of sepsis has been emphasized. However, this emphasis may no longer be correct; recent studies show an increasing incidence of gram-positive sources of sepsis, and it is possible that these cases may predominate in the coming years. This increase results from more than just a greater prevalence of infection—it appears that gram-positive organisms may also be more virulent in fomenting the disease, as can be evidenced by the emergence of streptococcal toxic shock syndrome and the resurgence of acute rheumatic fever. This may result from the ability of gram-positive organisms to produce more inflammation-causing cell wall constituents, as well as unbound exotoxins. Despite the recent emphasis on gram-negative causes, sepsis resulting from gram-positive sources is increasingly common. Research on these causes of sepsis should be encouraged. (Arch Intern Med. 1994;154:26-34)
315 citations
TL;DR: Extracts from Bupleurum fruticescens were examined for oral and topical anti-inflammatory activities and the BuOH extract proved to be active against carrageenan and tetradecanoylphorbol acetate acute edemas and allowed the isolation of three saponins identified by spectroscopic techniques.
Abstract: Extracts from Bupleurum fruticescens were examined for oral and topical anti-inflammatory activities. The BuOH extract proved to be active against carrageenan and tetradecanoylphorbol acetate acute edemas and allowed the isolation of three saponins identified by spectroscopic techniques as 3 beta-O-(O-alpha-L-rhamnopyranosyl-(1-->4)-O-[beta-D-glucopyranosyl- (1-->6)]-O-beta-D-glucopyranosyl)lup-20(29)-ene-23,28-dioic acid (fruticesaponin A), 3 beta-O-(O-alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl) lup-20(29)-ene-23,28-dioic acid 28-O-beta-D-glucopyranosyl ester (fruticesaponin B), and 3 beta-O-(O-alpha-L-rhamnopyranosyl-(1-->4)-O-[beta-D-glucopyranosyl- (1-->6)]-O-beta-D-glucopyranosyl)-lup-20(29)-ene-23,28-dioic acid 28-O-beta-D-glucopyranosyl ester (fruticesaponin C). These compounds were studied against carrageenan, tetradecanoylphorbol acetate, arachidonic acid and ethyl phenylpropiolate acute edemas. Fruticesaponin B, a bidesmosidic saponin with an unbranched saccharide moiety was the most active in all the tests applied.
252 citations
TL;DR: Both bidesmosides and derived monodesmosides showed little or no antifungal activity, whereas a comparatively higher degree of hemolytic activity could be determined for monodesMosides.
Abstract: At least 16 saponins were detected in the seeds of Chenopodium quinoa. The 5 previously isolated major saponins, 3-O-beta-D-glucuronopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl ester, 3-O-alpha-L-arabinopyranosyl hederagenin 28-O-beta-D-glucopyranosyl ester, 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl hederagenin 28-O-beta-D-glucopyranosyl ester, 3-O-alpha-L-arabinopyranosyl phytolaccagenic acid 28-O-beta-D-glucopyranosyl ester, 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl phytolaccagenic acid 28-O-beta-D-glucopyranosyl ester, and the new saponin 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl phytolaccagenic acid were isolated and characterized using mainly NMR spectroscopy, mass spectrometry, and chemical methods. The antifungal activity against Candida albicans and hemolytic activity on erythrocytes of these compounds and derived monodesmosides were evaluated. Both bidesmosides and derived monodesmosides showed little or no antifungal activity, whereas a comparatively higher degree of hemolytic activity could be determined for monodesmosides.
184 citations
TL;DR: The overall results demonstrates the potential of phytochemicals to control the growth of E. coli and S. aureus resistant strains and to act synergistically with antibiotics, contributing to the recycling of old antibiotics that were once considered ineffective due to resistance problems.
Abstract: Bacteria can be resistant to multiple antibiotics and we are fast approaching a time when antibiotics will not work on some bacterial infections. New antimicrobial compounds are urgently necessary. Plants are considered the greatest source to obtain new antimicrobials. This study aimed to assess the antimicrobial activity of four phytochemicals—7-hydroxycoumarin (7-HC), indole-3-carbinol (I3C), salicylic acid (SA) and saponin (SP)—against Escherichia coli and Staphylococcus aureus, either as planktonic cells or as biofilms. These bacteria are commonly found in hospital-acquired infections. Some aspects on the phytochemicals mode of action, including surface charge, hydrophobicity, motility and quorum-sensing inhibition (QSI) were investigated. In addition, the phytochemicals were combined with three antibiotics in order to assess any synergistic effect. 7-HC and I3C were the most effective phytochemicals against E. coli and S. aureus. Both phytochemicals affected the motility and quorum-sensing (QS) activity, which means that they can play an important role in the interference of cell-cell interactions and in biofilm formation and control. However, total biofilm removal was not achieved with any of the selected phytochemicals. Dual combinations between tetracycline (TET), erythromycin (ERY) and ciprofloxacin (CIP) and I3C produced synergistic effects against S. aureus resistant strains. The overall results demonstrates the potential of phytochemicals to control the growth of E. coli and S. aureus in both planktonic and biofilm states. In addition, the phytochemicals demonstrated the potential to act synergistically with antibiotics, contributing to the recycling of old antibiotics that were once considered ineffective due to resistance problems.
167 citations