Current Topics in Medicinal Chemistry - Volume 18, Issue 9, 2018

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, which has high levels of mortality worldwide and has already gained resistance to first- and second-line drugs. The study by new chemical entities with promising activities becomes paramount to broaden the therapeutic strategies in the cure of the patients affected with this disease. In this context, in this review we report the discovery of 3 classes of compounds that can simultaneously interact with more than one target of Mycobacterium tuberculosis.

Increased incidences of Candida infection have augmented morbidity and mortality in human population, particularly among severely immunocompromised patients and those having a long stay in hospitals (nosocomial infections). Many virulence factors and fitness attributes are reported to be associated with the pathogenicity of Candida sp. It can cause infections ranging from easily treatable superficial type to life-threatening invasive infections. Additionally, it has the capability to infect humans of all age groups. Indeed, overutilization of broad-spectrum antibiotics has further complicated the scenario by leading the emergence of less sensitive Candida strains especially non-albicans. Despite our developed armamentarium, the diagnosis and treatment of human fungal infections remain a challenge. This review focuses on the prevalence of Candida spp. as human pathogens with emerging resistance to existing anti-fungal drugs. Furthermore, factors and mechanisms contributing to the pathogenicity of Candida spp. and the challenges being faced in combating the devastating infections associated with these pathogens have been discussed. Moreover, pros and cons of the current and future anti-mycotic drugs have been analyzed.

Background: Antimicrobial drug resistance is an emerging problem, which leads to a failure in the control of infectious diseases thereby, adversely affecting patient care and reducing effective management of infectious diseases globally. Thus, search for new and more effective alternatives is needed. Daphne retusa Hemsl. (Daphne) has medicinal values and is reported to be widely used in curing a variety of human ailments. Objective: Current study assesses in-vitro antimicrobial activity of the crude extract of D.retusa (whole plant) and its derived fractions against clinically isolated human pathogenic bacteria and fungi. Materials and Methods: Whole plant of D.retusa was powder dried and then extracted with methanol (E1). The resultant was fractionated to give Chloroform fraction (E2), Butanol fraction (E3) and Ethyl acetate fraction (E4). The crude extract and derived fractions were assessed for antimicrobial and antifungal activity by using agar well diffusion method and their MICs were found following Clinical and Laboratory Standard Institute (CLSI) guidelines. Result: Our study shows that D.retusa has very good inhibitory action against different bacterial and fungal strains. All of the extracts were active against almost every microorganism used in the study. E2 has the maximum percent of inhibition against bacterial growth while E1 has themaximum percent of inhibition against fungal growth. Streptococcus pneumonia was the most susceptible bacteria while among fungi, Gongronella butleri showed highest susceptibility. Conclusion: Results justify the use of D. retusa in the treatment of microbial infections. For the development of a novel antibiotic, the crude extract and its derived fractions need further exploration; with emphasis to isolate and identify the active constituents that are responsible for antibacterial and antifungal activity.

Introduction: Onion (Allium cepa L.) and garlic (Allium sativum L.) extracts are traditionally used in many cultures as antimicrobial agents. Nonetheless, there is still a dearth of scientific validation pertaining to the antibacterial and possible antibiotic potentiating activity of these plants. Methods: Decoction as traditionally used and methanol, ethanol, ethyl acetate, and acetone extracts of onion and garlic were evaluated for their antibacterial activity against 15 bacterial strains (6 ATCC strains and 9 clinical isolates) using the broth microdilution method to establish the minimum inhibitory concentration. The bacteriostatic and bactericidal actions were determined as compared to conventional antibiotics (streptomycin and chloramphenicol). Fractional Inhibitory Concentration (FIC) was determined to establish any synergistic interaction between the extracts and antibiotics using a modified checkerboard assay. Results: The ethyl acetate extract of garlic showed bactericidal effect against 1 ATCC (E. coli) and 2 clinical isolates. Streptomycin produced only indifferent effect (FIC 1< and ≤ 4) when combined with ethyl acetate extract of onion. Chloramphenicol showed synergism with ethyl acetate extract of onion against ATCC S. aureus (FIC 0.27-0.30) and Micrococci species (FIC 0.27-0.32). Streptomycin showed mostly antagonism whereas chloramphenicol showed synergism effects with the ethyl acetate extract of garlic. The observed antibacterial activity might be justified due to the presence of high concentration of phenolic compounds in the extracts. Conclusion: This study has provided an opportunity to establish valuable baseline information on the antibiotic potentiating activity of onion and garlic which can be further exploited for the treatment and/or management of infectious diseases.

Background: Some research studies have shown that Lippia pedunculosa essential oil (EOLP) has interesting biological activities. However, its low water solubility is the main challenge to achieve its therapeutic potential. In this context, Cyclodextrins (CDs) have been widely used in order to overcome this problem due to your capability to improve the physicochemical properties of drugs. Objective: In this perspective, the main goal of this study was to investigate how the improvement of the physicochemical properties of inclusion complexes (EOLP and β-CD) enhance the antinociceptive effect in mice. Methods: To achieve that, we prepared samples by Physical Mixture (PM), Paste Complexation (PC) and Slurry Complexation (SC) methods, followed by their physicochemical characterization. In addition, it was evaluated if the use of β-CD enhances the antinociceptive effect of EOLP in mice. Results: The analysis showed that rotundifolone (72.02%) was the major compound of EOLP and we found out based on DSC results that β-CD protected it from oxidation. In addition, TG techniques demonstrated that the best inclusion methods were PC and SC, due to their greater weight loss (10.8 and 11.6%, respectively) in the second stage (171-312°C), indicating that more complexed oil was released at the higher temperature than oil free. Other characteristics, such as changes in the typical crystalline form, and reduced particle size were observed by SEM and laser diffraction, respectively. The SC was the most effective complexation method, once the presence of rotundifolone was detected by FTIR. Based on that, SC method was used in all mice tests. In this regard, the number of paw licks was reduced for both compounds (all doses), but EOLP was more effective in reducing the nociceptive behavior. Conclusion: Therefore, CDs seem not to be a good tool to enhance the pharmacological properties of EOs rich in peroxide compounds such as rotundifolone.