Current Chinese Science - Volume 1, Issue 3, 2021

Background: Typhoid fever is a major health burden in Sub-Saharan Africa. Conventional anti-typhoid drugs are becoming more and more unavailable to most patients in Africa due to the increased costs and emerging drug resistance. Therefore, there is a need for the discovery of new antimicrobial agents to combat typhoid fever. Objective: This work aimed to investigate the bioactive components in Cyperus sphacelatus Rottb. (Cyperaceae) and test the antisalmonellal activity of the isolated compounds. Methods: Compound purification was done through column chromatography. Structure elucidation was accomplished based on the 1D and 2D NMR, IR and mass spectra. The biological assay was done using five bacterial strains, including Salmonella enterica subsp. enterica sérovars Typhi ATCC 6539 (STS), S. enterica subsp. enterica sérovars Typhi (ST), S. enteritidis (STE), S. enterica subsp. enterica sérovars Typhimurim (STM), and a resistant isolate of S. enterica subsp. enterica sérovars Typhi (ST566). Results: Three natural products were isolated from the methylene chloride extract of the rhizomes of C. sphacelatus, including a new furanoquinone, scabequinon-6(14)-ene (1) and two known compounds, cyperotundone (2) and vanillin (3). Compound 1 showed moderate antisalmonellal activity, with a minimal inhibitory concentration (MIC) of 32 μg/mL against STM and STS. The best inhibitory result was obtained with compound 2 on STM with a MIC of 8 μg/mL. Compound 2 also gave the best minimum bactericidal concentration (MBC) of 32 μg/mL on the STM strain. Conclusion: The discovery of the three antisalmonellal compounds from C. sphacelatus supports the addition of this plant to typhoid fever preparations.

Background: All-optical processing has a huge superiority in speed and efficiency than traditional optical-electrical-optical signal processing. Four-wave-mixing is an important nonlinear parametric process to achieve all-optical processing. Objective: We proposed the photonic crystal waveguide to enhance the conversion efficiency of four-wave-mixing significantly in practical application. Methods: We demonstrated a waveguide composed of silicon with mono-layer graphene-coated as core and Si-Ge distributed periodically on both sides as cladding. By the introduction of the slow light effect of Si-Ge photonic crystal and the localization effect of graphene, the conversion efficiency of four-wave-mixing had enhanced dramatically. Results: The conversion efficiency can be increased by 16dB compared with a silicon waveguide. The maximum efficiency as high as -9.1dB can be achieved in the Si-Ge-Graphene photonic crystal waveguide (SGG-PhCWG). The propagation loss can be decreased to 0.032dB/cm. Conclusion: Numerical results of the proposed SGG-PhCWG matched well with nonlinear coupled- mode theory. This configuration offered a new physical mechanism and solution for alloptical signal processing and high-efficiency nonlinear nanoscale devices.

Background: although solution-processed small molecular organic semiconductors have attracted great attention for organic electronic applications, the intrinsic crystal misorientation of the organic semiconductors still remains a challenging issue. Objective: two benzoic acid-based additives, i.e. 4-propylbenzoic acid (RBA) and 4-octylbenzoic acid (OBA), were employed to regulate the crystal growth and charge transport of organic semiconductors. Methods: RBA and OBA were mixed with a π-conjugated organic semiconductor 6,13- bis(triisopropylsilylethynyl) pentacene (TIPS pentacene), respectively. Organic thin-film transistors (OTFTs) with different bottom-gate, top-contact and bottom-gate, bottom-contact configurations were fabricated to investigate charge transport. Results: RBA and OBA share a similar benzoic acid structure with the same hydrophilic head but differ in the length of the hydrophobic tail. The benzoic acid-based additive forms a stratified selfassembled interfacial layer and maneuvers nucleation seed distribution via synergetic interactions with the silanol groups on silicon dioxide and with the bulky side chains of the semiconductor. The TIPS pentacene film with OBA additive exhibited a 10-fold reduction in misorientation angle as compared to the counterpart with RBA. Conclusion: Distinct thin film morphology in terms of crystal alignment and grain width was observed and correlated to the hydrophobic tail length. In particular, OTFTs incorporating the TIPS pentacene/benzoic acid mixture as the active layer showed a mobility of up to 0.15 cm2/Vs.

Background: Unmanned systems have been widely used in multiple fields. Many algorithms have been proposed to solve path planning problems. Each algorithm has its advantages and defects and cannot adapt to all kinds of requirements. An appropriate path planning method is needed for various applications. Objective: To select an appropriate algorithm swiftly in the given application. This could be helpful for improving the efficiency of path planning for unmanned systems. Methods: This paper proposes to represent and quantify the features of algorithms based on the physical indicators of results. At the same time, an algorithmic collaborative scheme is developed to search the appropriate algorithm according to the requirement of the application. As an illustration of the scheme, four algorithms, including the A-star (A*) algorithm, reinforcement learning, genetic algorithm, and ant colony optimization algorithm, are implemented in the representation of their features. Results: In different simulations, the algorithmic collaborative scheme can select an appropriate algorithm in a given application based on the representation of algorithms. Hence, the algorithm could plan a feasible and effective path. Conclusion: An algorithmic collaborative scheme is proposed, which is based on the representation of algorithms and requirement of the application. The simulation results prove the feasibility of the scheme and the representation of algorithms.

Background and Aim: This study aims at the advancement of extra-ordinary biomedical data (genomics, proteomics, metabolomics, drug libraries, and patient care data), evolution of supercomputers, and continuous development of new algorithms that lead to a generous revolution in artificial intelligence (AI). Currently, many biotech and pharmaceutical companies made reasonable investments in and have co-operation with AI companies increasing the chance of better healthcare tools development, includes biomarker and drug target identification, designing a new class of drugs and drug repurposing. Thus, the study is intended to project the pros and cons of AI in the application of drug repositioning. Methods: Using the search term “AI” and “drug repurposing” the relevant literature retrieved and reviewed from different sources includes PubMed, Google Scholar, and Scopus. Results: Drug discovery is a lengthy process; however, leveraging the AI approaches in drug repurposing via quick virtual screening may enhance and speed-up the identification of potential drug candidates against communicable and non-communicable diseases. Therefore, in this mini-review, we have discussed different algorithms, tools and techniques, advantages, limitations on predicting the target in repurposing a drug. Conclusions: AI technology in drug repurposing with the association of pharmacology can efficiently identify drug candidates against pandemic diseases.

Background: The genus Tripos, formerly known as marine species of Ceratium, is the dinoflagellate with the greatest number of species and infraspecific taxa (~800) due to the high morphological intraspecific variability of numerous species. In the past, the species of Tripos were proposed into distinct genera. Objective: To propose an infrageneric classification and to review the taxonomy and nomenclature of each taxon in order to establish the correct species and synonymy. Methods: Observations from the Mediterranean Sea, and Atlantic and Pacific Oceans, a review of the original descriptions and further literature, and the available molecular data. Results: A re-instatement of this generic split is not justified due to the difficulties to circumscribe the basal subgenera Amphiceratium and Archaeceratium, and the polyphyletic character of Biceratium. The subgenus Amphiceratium is dismembered after the classification of the sections Inflata and partially Fusiformia into Archaeceratium. The subgenus Tripos (autonym) replaces other names such as Tripoceratium or Orthoceratium. Based on the original descriptions, the records of T. furca and T. lineatus correspond to T. eugrammus and T. furca, respectively, and T. macroceros has been reported as T. contrarius. The names T. belone and T. carriensis have been misapplied for T. pacificus and T. volans, respectively. Tripos arcuatus, T. gracilis, T. inclinatus, T. scapiformis and T. subcontortus are revived to replace T. euarcuatus, T. declinatus, T. horridus, T. longirostrum and T. contortus, respectively. The species T. ramakrishnae and T. fusus var. schuettii were described from individuals infected by endoparasites. Tripos rotundatus comb. nov. is proposed for C. digitatum var. rotundatum. Conclusion: Tripos is restricted to 57 correct species, although the speciation and synonymy are incomplete due to lack of studies in the life cycle and molecular data.

Background: Ancestral recapitulation of the Zika virus from Uganda, Africa, an epidemic in American territories since 2015, was reported by CDC, 2016. To date, there is no specific vaccine or drug for the Zika virus. Objective: The study aims to identify the potential inhibitors that have the capability to be effective against Zika virus. Natural and FDA-approved anti-viral drug molecules are utilized through the drug repurposing approach to screen the lead compounds. Methods: Molecular docking approach was utilized to screen the best hit compounds. The identified compounds were further evaluated through binding free energy calculations and physiochemical properties. Density functional theory calculations were calculated for the best hit compounds to observe the structural properties and electrophilic/nucleophilic attack at the quantum level. Furthermore, molecular dynamic simulation studies provide insight into structural stability and conformational analysis of the protein and ligand molecules. Result: Non-covalent interactions observed between the molecules are Gly199, Lys200, Thr201, Arg202, Asn417, Glu231, Glu286, and Arg459. Telaprevir, a Hepatitis C virus (NS3/4 protease) inhibitor, and Curcuma Longa, a natural drug, are found to be more potent druggable candidates among the screened leads for the Zika virus. Conclusion: The results of the study suggest Telaprevir and Curcuma Longa to be considered as the lead agents for experimental studies on Zika virus. The outcome of the study may provide much knowledge in designing anti-zika drugs in the future.

Natural products have always been used in medicine for the discovery of new biological molecules against different types of human disorders. Crude drugs have been used in different systems of medicine, including Traditional Chinese Medicine and the Ayurvedic System of Medicine. From ancient time to this modern age, special emphasis has been given to the traditional knowledge of plants based products for the development of newer and better modern drugs. Traditional medicines are always better choices in the medicine and healthcare system by the people of developing countries for the treatment of human disorders. Polyphenolic compounds have been used in medicine due to their vast medicinal application and pharmacological activities. Flavonoidal class chemicals are the better examples of polyphenolic compounds, which have a 15- carbon skeleton chemical structure. Salvigenin is a pure flavonoid class phytochemical found to be present in the Salvia lachnocalyx, Salvia hydrangea and Plectranthus amboinicus and other medicinal plants and vegetables. Pharmacologically salvigenin has been found to have cytotoxic effects on various forms of cancer cells, such as colon adenocarcinoma, breast adenocarcinoma and glioblastoma. Further salvigenin has beneficial potential in the medicine for the treatment of diabetes and protects cells against oxidative stress. In order to know the therapeutic benefit of salvigenin in the medicine, here in the present study, all the scientific research data of salvigenin have been collected and analyzed for their biological significance in medicine. Extensive pharmacological investigation has been performed to know the better medicinal properties of the salvigenin in modern medicine. Analytical techniques used in the separation, isolation and identification of salvigenin have also been searched and presented in the present work. From the above-presented data, it was found that salvigenin has significant biological potential in medicine and could be used for the development of newer and better molecule or drugs against various forms of human disorders, including cancerous disorders.