Bauhinoxepins A and B: New Antimycobacterial Dibenzo[b,f]oxepins from Bauhinia saccocalyx

Two new antimycobacterial dibenzo[b,f]oxepins, bauhinoxepins A (=3,3,5‐trimethylbenzo[b]pyrano[g][1]benzoxepin‐6,11‐diol; 1 ) and B (=6‐methoxy‐7‐methyl‐2‐(3‐methylbut‐2‐enyl)dibenzo[b,f]oxepine‐1,8‐diol; 2 ), were isolated from the roots of Bauhinia saccocalyx, and their structures were elucidated by analysis of spectroscopic data. Bauhinoxepins A and B exhibited antimycobacterial activities with respective minimum‐inhibitory concentrations (MIC) of 6.25 and 12.5 μg/ml. They were inactive (at 20 μg/ml) against the malarial parasite, and also inactive (at 20 μg/ml) towards the Vero, KB, and BC cell lines.     

Non-Covalent Reactions Supporting Antiviral Development

Viruses are the current big enemy of the world’s healthcare systems. As the small infector causes various deadly diseases, from influenza and HIV to COVID-19, the virus continues to evolve from one type to its mutants. Therefore, the development of antivirals demands tremendous attention and resources for drug researchers around the world. Active pharmaceutical ingredients (API) development includes discovering new drug compounds and developing existing ones. However, to innovate a new antiviral takes a very long time to test its safety and effectiveness, from structure modeling to synthesis, and then requires various stages of clinical trials. Meanwhile, developing the existing API can be more efficient because it reduces many development stages. One approach in this effort is to modify the solid structures to improve their physicochemical properties and enhance their activity. This review discusses antiviral multicomponent systems under the research phase and has been marketed. The discussion includes the types of antivirals, their counterpart compound, screening, manufacturing methods, multicomponent systems yielded, characterization methods, physicochemical properties, and their effects on their pharmacological activities. It is hoped that the opportunities and challenges of solid antiviral drug modifications can be drawn in this review as important information for further antiviral development.     

A Numerical Evaluation of Several Stochastic Algorithms on Selected Continuous Global Optimization Test Problems

There is a need for a methodology to fairly compare and present evaluation study results of stochastic global optimization algorithms. This need raises two important questions of (i) an appropriate set of benchmark test problems that the algorithms may be tested upon and (ii) a methodology to compactly and completely present the results. To address the first question, we compiled a collection of test problems, some are better known than others. Although the compilation is not exhaustive, it provides an easily accessible collection of standard test problems for continuous global optimization. Five different stochastic global optimization algorithms have been tested on these problems and a performance profile plot based on the improvement of objective function values is constructed to investigate the macroscopic behavior of the algorithms. The paper also investigates the microscopic behavior of the algorithms through quartile sequential plots, and contrasts the information gained from these two kinds of plots. The effect of the length of run is explored by using three maximum numbers of function evaluations and it is shown to significantly impact the behavior of the algorithms.     

Caesalpinia sappan L. wood fiber: bio-reinforcement for polybutylene succinate-based biocomposite film

Caesalpinia sappan L. wood fiber (CSWF), a novel advanced bio-reinforcement for polybutylene succinate (PBS) composite films, has shown significant promise ranging from 0 to 15 part per hundred of resin (phr). The functional groups and interactions, morphology, thermal stability, mechanical characteristics, and biodegradability were all investigated. Without treatment or any compatibilizers, CSWF could be well-dispersed in the PBS matrix. The PBS/CSWF10 composite film had highest mechanical strength, with a tensile strength of 12.21 N/mm² and a break elongation of 21.01%. Biodegradability studies indicated that the PBS/CSWF10 composite films degraded completely in three months. Furthermore, the E_a of degradation resulting from TGA and the shift of wavenumber resulting from FTIR revealed that the addition of CSWF has a greater interaction between additive and martix than conventional cellulose. The PBS/CSWF10 composite has the potential to be environmentally friendly, with promising short-term degradation and rising mechanical characteristics. Therefore, it is the optimum concentration of a certain biocomposite film. As a result, a novel advanced natural-based cellulose for biopolymer composites film was discovered, as well as other benefits for bio-reinforcement of the green plastic composite film industry.

Graphical abstract

     

Using liquid chromatography-mass spectrometry based metabolomics to discriminate between cold pressed rice bran oils produced from two different cultivars of Oryza sativa L. ssp. indica in Thailand

A newly developed liquid chromatography-mass spectrometry (LC-MS) method for the analysis of cold pressed rice bran oil (RBO) was established and used to discriminate between RBOs produced from two different cultivars of major Thai fragrant rice species. The cold pressed RBO was prepared using the screw compression method. The LC-MS data were preprocessed with MZmine 2.10 program before evaluating with principal component analysis using SIMCA 13 software. The LC-MS method was able to detect and quantify several kinds of valuable constituents such as fatty acids, vitamin E, and γ-oryzanol. The chromatographic condition was feasible; short time for analysis and simple method were achieved. From score plot and loading plot of principle component analysis (PCA), two rice cultivar samples were clearly separated, and it was revealed that Khao-Hom-Pathum was more suitable than Khao-Hom-Mali for cold pressed RBO production since it contained high total γ-oryzanol and less saturated free fatty acids. As with the fixed price of all the rice brans, this information can be used in order to, if possible, preserve the price of rice brans from different cultivars.     

New Organic Salt from Levofloxacin-Citric Acid: What Is the Impact on the Stability and Antibiotic Potency?

This research dealt with the composition, structure determination, stability, and antibiotic potency of a novel organic salt composed of levofloxacin (LF) and citric acid (CA), named levofloxacin-citrate (LC). After a stoichiometric proportion screening, the antibiotic-antioxidant reaction was conducted by slow and fast evaporation methods. A series of characterizations using thermal analysis, powder X-ray diffractometry, vibrational spectroscopy, and nuclear magnetic resonance confirmed LC formation. The new organic salt showed a distinct thermogram and diffractogram. Next, Fourier transform infrared indicated the change in N-methylamine and carboxylic stretching, confirmed by ¹H nuclear magnetic resonance spectra to elucidate the 2D structure. Finally, single-crystal diffractometry determined LC as a new salt structure three-dimensionally. The attributive improvements were demonstrated on the stability toward the humidity and lighting of LC compared to LF alone. Moreover, the antibiotic potency of LF against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) enhanced ~1.5–2-fold by LC. Hereafter, LC is a potential salt antibiotic-antioxidant combination for dosage formulas development.     

Stopping and restarting strategy for stochastic sequential search in global optimization

Two common questions when one uses a stochastic global optimization algorithm, e.g., simulated annealing, are when to stop a single run of the algorithm, and whether to restart with a new run or terminate the entire algorithm. In this paper, we develop a stopping and restarting strategy that considers tradeoffs between the computational effort and the probability of obtaining the global optimum. The analysis is based on a stochastic process called Hesitant Adaptive Search with Power-Law Improvement Distribution (HASPLID). HASPLID models the behavior of stochastic optimization algorithms, and motivates an implementable framework, Dynamic Multistart Sequential Search (DMSS). We demonstrate here the practicality of DMSS by using it to govern the application of a simple local search heuristic on three test problems from the global optimization literature.     

Solving fractional problems with dynamic multistart improving hit-and-run

Fractional programming has numerous applications in economy and engineering. While some fractional problems are easy in the sense that they are equivalent to an ordinary linear program, other problems like maximizing a sum or product of several ratios are known to be hard, as these functions are highly nonconvex and multimodal. In contrast to the standard Branch-and-Bound type algorithms proposed for specific types of fractional problems, we treat general fractional problems with stochastic algorithms developed for multimodal global optimization. Specifically, we propose Improving Hit-and-Run with restarts, based on a theoretical analysis of Multistart Pure Adaptive Search (cf. the dissertation of Khompatraporn (2004)) which prescribes a way to utilize problem specific information to sample until a certain level α of confidence is achieved. For this purpose, we analyze the Lipschitz properties of fractional functions, and then utilize a unified method to solve general fractional problems. The paper ends with a report on numerical experiments. This work was initiated while Mirjam Dür was spending a three-month research visit at the University of Washington. She would like to thank the Fulbright Commission for financial support and the optimization group at UW for their warm hospitality. The work of C. Khompatraporn and Z.B. Zabinsky was partially supported by the NSF grant DMI-0244286.