K-Nearest Neighbor and Random Forest-Based Prediction of Putative Tyrosinase Inhibitory Peptides of Abalone Haliotis diversicolor

Skin pigment disorders are common cosmetic and medical problems. Many known compounds inhibit the key melanin-producing enzyme, tyrosinase, but their use is limited due to side effects. Natural-derived peptides also display tyrosinase inhibition. Abalone is a good source of peptides, and the abalone proteins have been used widely in pharmaceutical and cosmetic products, but not for melanin inhibition. This study aimed to predict putative tyrosinase inhibitory peptides (TIPs) from abalone, Haliotis diversicolor, using k-nearest neighbor (kNN) and random forest (RF) algorithms. The kNN and RF predictors were trained and tested against 133 peptides with known anti-tyrosinase properties with 97% and 99% accuracy. The kNN predictor suggested 1075 putative TIPs and six TIPs from the RF predictor. Two helical peptides were predicted by both methods and showed possible interaction with the predicted structure of mushroom tyrosinase, similar to those of the known TIPs. These two peptides had arginine and aromatic amino acids, which were common to the known TIPs, suggesting non-competitive inhibition on the tyrosinase. Therefore, the first version of the TIP predictors could suggest a reasonable number of the TIP candidates for further experiments. More experimental data will be important for improving the performance of these predictors, and they can be extended to discover more TIPs from other organisms. The confirmation of TIPs in abalone will be a new commercial opportunity for abalone farmers and industry.     

Prediction of Antibacterial Peptides against Propionibacterium acnes from the Peptidomes of Achatina fulica Mucus Fractions

Acne vulgaris is a common skin disease mainly caused by the Gram-positive pathogenic bacterium, Propionibacterium acnes. This bacterium stimulates the inflammation process in human sebaceous glands. The giant African snail (Achatina fulica) is an alien species that rapidly reproduces and seriously damages agricultural products in Thailand. There were several research reports on the medical and pharmaceutical benefits of these snail mucus peptides and proteins. This study aimed to in silico predict multifunctional bioactive peptides from A. fulica mucus peptidome using bioinformatic tools for the determination of antimicrobial (iAMPpred), anti-biofilm (dPABBs), cytotoxic (ToxinPred) and cell-membrane-penetrating (CPPpred) peptides. Three candidate peptides with the highest predictive score were selected and re-designed/modified to improve the required activities. Structural and physicochemical properties of six anti-P. acnes (APA) peptide candidates were performed using the PEP–FOLD3 program and the four previous tools. All candidates had a random coiled structure and were named APAP-1 ori, APAP-2 ori, APAP-3 ori, APAP-1 mod, APAP-2 mod, and APAP-3 mod. To validate the APA activity, these peptide candidates were synthesized and tested against six isolates of P. acnes. The modified APA peptides showed high APA activity on three isolates. Therefore, our biomimetic mucus peptides could be useful for preventing acne vulgaris and further examined on other activities important to medical and pharmaceutical applications.     

Characterization of prehistorical glass beads excavated from Khao Sam Kaeo (Chumphon, Thailand) using PIXE and SEM–EDS

It was proved that non-destructive and non-sampling methods were used to analyze the composition of the archaeological glasses. Glass has been used in ornaments and decoration in Thailand for thousands of years. In this study, glass bead fragments found from the archaeological site at Khao Sam Kaeo, Chumphon Province, southern Thailand were analyzed by the proton induced X-ray emission spectroscopy (PIXE) and scanning electron microscope coupled with energy dispersive X-ray fluorescence spectroscopy (SEM?CEDS). The composition analysis showed that copper was mainly presence as the colorant. Titanium, common impurity in sand, was all present in the glass bead samples. Furthermore, this type of glass almost spread over the various sites in this region that demonstrated the long distance or exchange connections. Finally, PIXE and SEM?CEDS have been used to be the efficient techniques to analyze the archaeological objects, especially the glassy materials, to understand their characteristics and how they were produced in ancient times.     

Nuclear analytical methods on ancient Thai rice

For more than half of humanity, rice is life. Rice is a grain which has shaped the history, culture, diet and economy of billions of people in Asia. In Thailand, it is the essence of life. Archaeological evidence revealed that rice had been planted in northeastern area of Thailand more than 5,500 years ago which is earlier than in China and India. The ancient rice grains were found in various archaeological sites in Thailand such as Nakhon Nayok, Suphan Buri and Prachin Buri Provinces. In this work, the ancient black rice from Nakhon Nayok Province was elementally analyzed using scanning electron microscope coupled with energy dispersive X-ray fluorescence spectroscopy, proton induced X-ray emission spectroscopy and micro-beam energy dispersive X-ray fluorescence spectroscopy. Infrared (IR) spectroscopy was also used to study the chemical composition and bio-molecular structure. The grains were oblique in shape with a rough surface. Three major elements (Si, Ca and Al) and other trace elements were detected. The IR spectra provided some information about the presence of molecular bonds.     

Raman spectroscopic study on archaeological glasses in Thailand: ancient Thai glass

Glasses have been used as ornamental and decorative objects in Thailand for several hundred years as seen in archaeological artifacts, such as glass beads found throughout the regions. Decorative glasses can generally be seen as architectural components in Buddhist temples and old-styled palaces. They came in various colors ranging from transparent to amber, blue, green and red of different shades and tones. Fragments of archaeological glass samples were characterized for the first time using Raman spectrophotometer with the aim of obtaining information that would lead to the identification of the glass samples by means of laser scattering. The samples were also investigated using other techniques, such as proton induced X-ray emission spectroscopy, scanning electron microscopy cooperated with energy dispersive X-ray fluorescence spectrometer and synchrotron radiation to induced X-ray fluorescence. The results showed that they were mostly lead-silica based glasses whose colors were induced by metal ions. The differences in chemical compositions were confirmed by Raman signature spectra.     

PIXE study on Thai amulet: Phra Somdej Wat Rakhang

Phra Somdej Wat Rakhang amulets which were one of the most famous Thai amulets created in an image of Lord Buddha meditation. They were made to explain the Dharma of Buddha and to bless every life in this world for good karma. Their compositions contained with both inorganic and organic materials such as shell lime, assorted flowers, ashes from incense urns, etc. Various molds were differed both types and compositions. In this work, it was the first time on advanced structural analysis using non-destructive x-ray fluorescence spectrometry methods; particle induced x-ray emission. Samples were selected by various molds to analyze theirs composition. Results revealed the presence of Ca, Al, K, Si and others such as Fe, Cu, Mn and Zn. It was also found that there were differences in concentration of composition. It can be concluded that their matrices were heterogeneous. Each mold may be characterized using the differences in its composition.     

Anti-Inflammatory Comparison of Melatonin and Its Bromobenzoylamide Derivatives in Lipopolysaccharide (LPS)-Induced RAW 264.7 Cells and Croton Oil-Induced Mice Ear Edema

The pineal gland is a neuroendocrine organ that plays an important role in anti-inflammation through the hormone melatonin. The anti-inflammatory effects of melatonin and its derivatives have been reported in both in vitro and in vivo models. Our previous study reported the potent antioxidant and neuroprotective activities of bromobenzoylamide substituted melatonin. In silico analysis successfully predicted that melatonin bromobenzoylamid derivatives were protected from metabolism by CYP2A1, which is a key enzyme of the melatonin metabolism process. Therefore, the anti-inflammatory activities of melatonin and its bromobenzoylamide derivatives BBM and EBM were investigated in LPS-induced RAW 264.7 macrophages and croton oil-induced ear edema in mice. The experiments showed that BBM and EBM significantly reduced production of the inflammatory mediators interleukin-6 (IL-6), prostaglandin E2 (PGE₂), and nitric oxide (NO) in a dose-dependent manner, but only slightly affected TNF-α in LPS-induced RAW 264.7 macrophages. This suggests that modifying melatonin at either the N1-position or the N-acetyl side chain affected production of NO, PGE₂ and IL-6 in in vitro model. In the croton oil-induced mouse ear edema model, BBM, significantly decreased ear edema thickness at 2–4 h. It leads to conclude that bromobenzoylamide derivatives of melatonin may be one of the potential candidates for a new type of anti-inflammatory agent.     

Inhibitory Effects of Erythrosine/Curcumin Derivatives/Nano-Titanium Dioxide-Mediated Photodynamic Therapy on Candida albicans

This study focuses on the role of photosensitizers in photodynamic therapy. The photosensitizers were prepared in combinations of 110/220 µM erythrosine and/or 10/20 µM demethoxy/bisdemethoxy curcumin with/without 10% (w/w) nano-titanium dioxide. Irradiation was performed with a dental blue light in the 395–480 nm wavelength range, with a power density of 3200 mW/cm² and yield of 72 J/cm². The production of ROS and hydroxyl radical was investigated using an electron paramagnetic resonance spectrometer for each individual photosensitizer or in photosensitizer combinations. Subsequently, a PrestoBlue^® toxicity test of the gingival fibroblast cells was performed at 6 and 24 h on the eight highest ROS-generating photosensitizers containing curcumin derivatives and erythrosine 220 µM. Finally, the antifungal ability of 22 test photosensitizers, Candida albicans (ATCC 10231), were cultured in biofilm form at 37 °C for 48 h, then the colonies were counted in colony-forming units (CFU/mL) via the drop plate technique, and then the log reduction was calculated. The results showed that at 48 h the test photosensitizers could simultaneously produce both ROS types. All test photosensitizers demonstrated no toxicity on the fibroblast cells. In total, 18 test photosensitizers were able to inhibit Candida albicans similarly to nystatin. Conclusively, 20 µM bisdemethoxy curcumin + 220 µM erythrosine + 10% (w/w) nano-titanium dioxide exerted the highest inhibitory effect on Candida albicans.