Quinone Derivatives as Promising Anti-Helicobacter pylori Agents from Aerial Parts of Mitracarpus hirtus

Chemical constituents of the aerial parts of Mitracarpus hirtus (L.) DC (Rubiaceae)

A phytochemical investigation of the aerial parts of Mitracarpus hirtus afforded thirteen compounds, including a new naphthoquinone di-glycoside (1), three isopentenyl isoflavones (2-4), four flavonoids (5-8), three iridoid glycosides (9 - 11) and two coumarins (12 and 13). Their structures were elucidated based on extensive spectroscopic analyses, chemical methods, and the comparison with the literature. Among them, compound 1 possesses a 2-(3-methylnaphthalen-2-yl)acetic acid core with two glucosyl groups, compounds 2-4 are the first three representatives from the Rubiaceae family, and compounds 9-11 and 13 were isolated from Mitracarpus genus for the first time. Additionally, compounds 2-4 displayed potent antibacterial activities against Helicobacter pylori G27/HP159/JRES00015 (MIC = 4-16 μg/mL) , comparable to metronidazole. To date, wighteone (2) is the most active isoflavone with favourable predicted ADMET properties reported against H. pylori.

Helicobacter pylori infection in humans and phytotherapy, probiotics, and emerging therapeutic interventions: a review

The global prevalence of Helicobacter pylori (H. pylori) infection remains high, indicating a persistent presence of this pathogenic bacterium capable of infecting humans. This review summarizes the population demographics, transmission routes, as well as conventional and novel therapeutic approaches for H. pylori infection. The prevalence of H. pylori infection exceeds 30% in numerous countries worldwide and can be transmitted through interpersonal and zoonotic routes. Cytotoxin-related gene A (CagA) and vacuolar cytotoxin A (VacA) are the main virulence factors of H. pylori, contributing to its steep global infection rate. Preventative measures should be taken from people's living habits and dietary factors to reduce H. pylori infection. Phytotherapy, probiotics therapies and some emerging therapies have emerged as alternative treatments for H. pylori infection, addressing the issue of elevated antibiotic resistance rates. Plant extracts primarily target urease activity and adhesion activity to treat H. pylori, while probiotics prevent H. pylori infection through both immune and non-immune pathways. In the future, the primary research focus will be on combining multiple treatment methods to effectively eradicate H. pylori infection.

Discovery of pyranonaphthoquinones and an eighteen-membered ring macrolide from the rhizospheric soil-derived fungus Phialocephala sp. YUD18001 by OSMAC strategy

Two new pyranonaphthoquinones, phialoyxinones A (1) and B (2), a new eighteen-membered ring lactone, phialoyxtone (3), and five known pyranonaphthoquinone derivatives were identified from the fungus Phialocephala sp. YUD18001, which was isolated from the rhizospheric soil associated with Gastrodia elata. Their structures were unequivocally established by a comprehensive interpretation of the spectroscopic data, with the stereochemistry for 1-3 was defined by a combination of TDDFT calculations, and the DP4+ probability analysis based on NMR chemical shift calculations. All of the new compounds 1-3 were evaluated for cytotoxicity and acetylcholinesterase inhibitory, compound 2 exhibited in vitro cytotoxic activities against five human cancer cell lines (HL-60, SMMC-7721, A549, MCF-7 and SW480) with IC50 values ranging from 11.80 to 19.32 μM. Compounds 2 and 3 exhibited moderate AChE inhibitory activities. A putative biosynthetic pathway for the pyranonaphthoquinones was proposed.

Structurally diverse (9β-H)-pimarane derivatives with six frameworks from the leaves of Icacina oliviformis and their cytotoxic activities

Thirteen previously undescribed (9β-H)-pimarane derivatives, icacinolides A-G (1-7) and oliviformislactones C-H (8-13), together with four known analogs (14-17), were isolated from the leaves of Icacina oliviformis. Their structures were constructed by extensive spectroscopic analysis, 13C NMR-DP4+ analysis, ECD calculation, single-crystal X-ray diffraction, and chemical methods. These structurally diverse isolates were classified into six framework types: rearranged 3-epi-17-nor-(9β-H)-pimarane, rearranged 17-nor-(9β-H)-pimarane, 16-nor-(9β-H)-pimarane, 17-nor-(9β-H)-pimarane, 17,19-di-nor-(9β-H)-pimarane, and (9β-H)-pimarane. Among them, compounds 1, 5, and 7 were the first examples of three rearranged 3-epi-17-nor-(9β-H)-pimaranes featuring a unique (11S)-carboxyl-9-oxatricyclo[5.3.1.02,7]dodecane motif with contiguous stereogenic centers, whereas their C-3 epimers, compounds 2-4 and 6 were the second examples of four rearranged 17-nor-(9β-H)-pimaranes. Additionally, compounds 8 and 12/13 represented the second examples of a 16-nor-(9β-H)-pimarane and two 17,19-di-nor-(9β-H)-pimaranes, respectively. In cytotoxic bioassay, compound 2 exhibited significant cytotoxic against HT-29 with IC50 values of 7.88 μM, even stronger than 5-fluorouracil, and 15 showed broad-spectrum cytotoxic activities against HepG2, HT-29, and MIA PaCa-2 with IC50 values of 11.62, 9.77, and 4.91 μM, respectively. Meanwhile, a preliminary structure-activity relationship suggested that 3,20-epoxy, 6,19-lactone, 2-OH, 7-OH, and 8-OH in (9β-H)-pimarane derivatives might be active groups, whereas ring C aromatization may decrease the cytotoxic activities.

The Quinone-Derived Small Molecule M5N32 Is an Effective Anti-Helicobacter pylori Agent Both In Vivo and In Vitro

BACKGROUND

Helicobacter pylori has become increasingly resistant to all commonly used clinical antibiotics. Therefore, new anti-H. pylori drugs need to be identified. Recently, quinones were found to inhibit growth of H. pylori with quinone-derived small-molecule compounds identified as having antitumor effects.

METHODS

The minimum inhibitory concentrations of the compounds against H. pylori were measured by agar plate dilution method. The inhibition of biofilm formation by the compounds was assessed by SYTO9-PI double staining. The reactive oxygen species induced by the compounds were detected by DCFH-DA stain. The clearance effects of the compounds for H. pylori in mouse were evaluated by counting colony-forming units and hematoxylin and eosin staining.

RESULTS

Our results revealed strong inhibition of M5N32 in vitro against H. pylori in both the planktonic and biofilm-forming states. Resistance to M5N32 was not developed in successive generations of the bacteria. In vivo, the combination of M5N32 and omeprazole showed enhanced effects in comparison to the standard triple therapy. M5N32 was nontoxic to normal tissues.

CONCLUSIONS

M5N32 is effective in the treatment of H. pylori infections, providing potential development of anti-H. pylori medicines in the treatment of H. pylori infections.

Recent Advancements in Enhancing Antimicrobial Activity of Plant-Derived Polyphenols by Biochemical Means

Plants are a reservoir of phytochemicals, which are known to possess several beneficial health properties. Along with all the secondary metabolites, polyphenols have emerged as potential replacements for synthetic additives due to their lower toxicity and fewer side effects. However, controlling microbial growth using these preservatives requires very high doses of plant-derived compounds, which limits their use to only specific conditions. Their use at high concentrations leads to unavoidable changes in the organoleptic properties of foods. Therefore, the biochemical modification of natural preservatives can be a promising alternative to enhance the antimicrobial efficacy of plant-derived compounds/polyphenols. Amongst these modifications, low concentration of ascorbic acid (AA)–Cu (II), degradation products of ascorbic acid (DPAA), Maillard reaction products (MRPs), laccase–mediator (Lac–Med) and horse radish peroxidase (HRP)–H2O2 systems standout. This review reveals the importance of plant polyphenols, their role as antimicrobial agents, the mechanism of the biochemical methods and the ways these methods may be used in enhancing the antimicrobial potency of the plant polyphenols. Ultimately, this study may act as a base for the development of potent antimicrobial agents that may find their use in food applications.