Composition, Antibacterial Efficacy, and Anticancer Activity of Essential Oil Extracted from Psidium guajava (L.) Leaves

Antidiarrheal effect of Psidium guajava L. extract in acute diarrhea: a systematic review

Acute diarrheal diseases are a leading cause of childhood mortality and morbidity worldwide. Psidium guajava has been globally used for its antidiarrheal potential. We conducted a systematic review of scientific articles published up to the year 2021, which included in vivo pre-clinical tests and clinical trials involving patients with acute infectious diarrhea to verify the antidiarrheal, antibacterial and antispasmodic effects of galenic preparations or phytopharmaceuticals from P. guajava. PRISMA and Rayyan were used as tools for the selection of studies collected in four databases (Pubmed, Scopus, Web of Science and Science Direct). The keywords used to carry out the search were: 'Psidium guajava', 'guava', 'antidiarrhe*' and 'diarrhe*', joined by Boolean operators 'OR' or 'AND'. The characteristics of studies in animal models of acute diarrhea induction, as well as in vivo and in vitro motility and microbiological tests linked with its main pathophysiological mechanisms, were collected. Twenty-three articles were included. Twenty (87%) of these reported heterogenic preclinical studies, predominating pharmacological studies of efficacy against conventional antidiarrheal agents, which utilized relevant outcomes and models of infectious diarrhea from the top pathogens in the clinic along with classical castor oil-induced diarrhea associated with motility tests. Only three articles (13%) corresponded to clinical trials investigating the efficacy, dose and safety of these preparations. Most studies reported positive results and significant mechanistic evidence from antibacterial, anti-motility, anti-secretory and protective/anti-inflammatory perspectives. However, further studies are needed to define the clinical significance and safety treatment with P. guajava extracts. © 2024 Society of Chemical Industry.

Plant Essential Oil with Biological Activity (II)

Essential oils (EOs) are concentrated hydrophobic liquids that originate from plants and contain different bioactive chemicals and volatile substances. Several plant essential oils (PEOs) are obtained from a variety of medicinal plants and have been utilized in folk medicine and traditional pharmacopoeia. They have a long history of usage as antibacterial medicines to treat various human, animal, and plant diseases. The extraction of essential oils frequently involves fractional distillation with a variety of organic solvents. EOs can be used successfully in the food and cosmetics industries in addition to their traditional use as antimicrobial agents. This Special Issue covers various significant PEOs and their individual chemical constituents and biological-pharmaceutical functions. Further information focused on the chemical characterizations, modes of action, and biopharmaceutical properties of PEOs. This Special Issue includes seventeen research papers from different geographical zones.

Chemical Composition, Larvicidal and Molluscicidal Activity of Essential Oils of Six Guava Cultivars Grown in Vietnam

Diseases transmitted by mosquitoes and snails cause a large burden of disease in less developed countries, especially those with low-income levels. An approach to control vectors and intermediate hosts based on readily available essential oils, which are friendly to the environment and human health, may be an effective solution for disease control. Guava is a fruit tree grown on a large scale in many countries in the tropics, an area heavily affected by tropical diseases transmitted by mosquitoes and snails. Previous studies have reported that the extracted essential oils of guava cultivars have high yields, possess different chemotypes, and exhibit toxicity to different insect species. Therefore, this study was carried out with the aim of studying the chemical composition and pesticide activities of six cultivars of guava grown on a large scale in Vietnam. The essential oils were extracted by hydrodistillation using a Clevenger-type apparatus for 6 h. The components of the essential oils were determined using gas-chromatography-mass-spectrometry (GC-MS) analysis. Test methods for pesticide activities were performed in accordance with WHO guidelines and modifications. Essential oil samples from Vietnam fell into two composition-based clusters, one of (E)-β-caryophyllene and the other of limonene/(E)-β-caryophyllene. The essential oils PG03 and PG05 show promise as environmentally friendly pesticides when used to control Aedes mosquito larvae with values of 24 h LC50-aegypti of 0.96 and 0.40 µg/mL while 24 h LC50-albopictus of 0.50 and 0.42 µg/mL. These two essential oils showed selective toxicity against Aedes mosquito larvae and were safe against the non-target organism Anisops bouvieri. Other essential oils may be considered as molluscicides against Physa acuta (48 h LC50 of 4.10 to 5.00 µg/mL) and Indoplanorbis exustus (48 h LC50 of 3.85 to 7.71 µg/mL) and with less toxicity to A. bouvieri.

Exploring the Potent Anticancer Activity of Essential Oils and Their Bioactive Compounds: Mechanisms and Prospects for Future Cancer Therapy

Cancer is one of the leading causes of death worldwide, affecting millions of people each year. Fortunately, the last decades have been marked by considerable advances in the field of cancer therapy. Researchers have discovered many natural substances, some of which are isolated from plants that have promising anti-tumor activity. Among these, essential oils (EOs) and their constituents have been widely studied and shown potent anticancer activities, both in vitro and in vivo. However, despite the promising results, the precise mechanisms of action of EOs and their bioactive compounds are still poorly understood. Further research is needed to better understand these mechanisms, as well as their effectiveness and safety in use. Furthermore, the use of EOs as anticancer drugs is complex, as it requires absolute pharmacodynamic specificity and selectivity, as well as an appropriate formulation for effective administration. In this study, we present a synthesis of recent work on the mechanisms of anticancer action of EOs and their bioactive compounds, examining the results of various in vitro and in vivo studies. We also review future research prospects in this exciting field, as well as potential implications for the development of new cancer drugs.

Essential Oils: Chemistry and Pharmacological Activities

In this review, we provide an overview of the current understanding of the main mechanisms of pharmacological action of essential oils and their components in various biological systems. A brief introduction on essential oil chemistry is presented to better understand the relationship of chemical aspects with the bioactivity of these products. Next, the antioxidant, anti-inflammatory, antitumor, and antimicrobial activities are discussed. The mechanisms of action against various types of viruses are also addressed. The data show that the multiplicity of pharmacological properties of essential oils occurs due to the chemical diversity in their composition and their ability to interfere with biological processes at cellular and multicellular levels via interaction with various biological targets. Therefore, these natural products can be a promising source for the development of new drugs.

Aegle marvels (L.) Correa Leaf Essential Oil and Its Phytoconstituents as an Anticancer and Anti-Streptococcus mutans Agent

Aegle mamelons (A. marmelos) or Indian Bael leaves possess anti-cancerous and antibacterial properties and are used in the traditional medicine system for the treatment of oral infections. In the present study, the essential oil of the leaves of A. marmelos was explored for its anticancer, antioxidant, and anti-cariogenic properties. The hydro-distilled oil of A. marmelos leaves was analyzed using gas chromatography coupled with mass spectrometry (GC-MS). Monoterpene limonene (63.71%) was found to have the highest percentage after trans-2-Hydroxy-1,8-cineole and p-Menth-2,8-dien-1-ol. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay was used to investigate the anticancer activity of the extracted oil against human oral epidermal carcinoma (KB), and the results showed significantly higher (**** p < 0.0001) anticancer activity (45.89%) in the doxorubicin (47.87%) when compared to the normal control. The antioxidant activity of the essential oil was evaluated using methods of DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)). The results showed a significant (*** p < 0.001) percentage of inhibition of DPPH-induced free radical (70.02 ± 1.6%) and ABTS-induced free radical (70.7 ± 1.32%) at 100 µg/mL with IC50, 72.51 and 67.33 µg/mL, respectively, comparatively lower than standard compound ascorbic acid. The results of the molecular docking study of the significant compound limonene with the receptors tyrosinase and tyrosine kinase 2 supported the in vitro antioxidant potential. The anti-cariogenic activity was evaluated against Streptococcus mutans (S. mutans). Results showed a significant minimum inhibitor concentration of 0.25 mg/mL and the killing time was achieved at 3 to 6 h. The molecular-docking study showed that limonene inhibits the surface receptors of the S. mutans c-terminal domain and CviR protein. The study found that A. marmelos leaves have potential anti-carcinoma, antioxidant, and anti-cariogenic effects on human oral epidermal health, making them a valuable natural therapeutic agent for managing oral cancer and infections.

Design and Synthesis of Novel Antimicrobial Agents

The necessity for the discovery of innovative antimicrobials to treat life-threatening diseases has increased as multidrug-resistant bacteria has spread. Due to antibiotics' availability over the counter in many nations, antibiotic resistance is linked to overuse, abuse, and misuse of these drugs. The World Health Organization (WHO) recognized 12 families of bacteria that present the greatest harm to human health, where options of antibiotic therapy are extremely limited. Therefore, this paper reviews possible new ways for the development of novel classes of antibiotics for which there is no pre-existing resistance in human bacterial pathogens. By utilizing research and technology such as nanotechnology and computational methods (such as in silico and Fragment-based drug design (FBDD)), there has been an improvement in antimicrobial actions and selectivity with target sites. Moreover, there are antibiotic alternatives, such as antimicrobial peptides, essential oils, anti-Quorum sensing agents, darobactins, vitamin B6, bacteriophages, odilorhabdins, 18β-glycyrrhetinic acid, and cannabinoids. Additionally, drug repurposing (such as with ticagrelor, mitomycin C, auranofin, pentamidine, and zidovudine) and synthesis of novel antibacterial agents (including lactones, piperidinol, sugar-based bactericides, isoxazole, carbazole, pyrimidine, and pyrazole derivatives) represent novel approaches to treating infectious diseases. Nonetheless, prodrugs (e.g., siderophores) have recently shown to be an excellent platform to design a new generation of antimicrobial agents with better efficacy against multidrug-resistant bacteria. Ultimately, to combat resistant bacteria and to stop the spread of resistant illnesses, regulations and public education regarding the use of antibiotics in hospitals and the agricultural sector should be combined with research and technological advancements.

Caraway Nanoemulsion Gel: A Potential Antibacterial Treatment against Escherichia coli and Staphylococcus aureus

Novel antibiotics are needed due to the rise of antibiotic-resistant pathogens. Traditional antibiotics are ineffective due to antibiotic-resistant microorganisms, and finding alternative therapies is expensive. Hence, plant-derived caraway (Carum carvi) essential oils and antibacterial compounds have been selected as alternatives. In this, caraway essential oil as an antibacterial treatment was investigated using a nanoemulsion gel. Using the emulsification technique, a nanoemulsion gel was developed and characterized in terms of particle size, polydispersity index, pH, and viscosity. The results showed that the nanoemulsion had a mean particle size of 137 nm and an encapsulation efficiency of 92%. Afterward, the nanoemulsion gel was incorporated into the carbopol gel and was found to be transparent and uniform. The gel had in vitro cell viability and antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The gel safely delivered a transdermal drug with a cell survival rate of over 90%. With a minimal inhibitor concentration (MIC) of 0.78 mg/mL and 0.78 mg/mL, respectively, the gel demonstrated substantial inhibition for E. coli and S. aureus. Lastly, the study demonstrated that caraway essential oil nanoemulsion gels can be efficient in treating E. coli and S. aureus, laying the groundwork for the use of caraway essential oil as an alternative to synthetic antibiotics in the treatment of bacterial infections.