In Vitro Antibiotic Activity of red Shallot (Allium ascalonicum), Mulberry (Morus indica), and Marigold (Tagetes erecta) Extracts against Streptococcus pyogenes

Bacterial infection is a major global health concern. One of the critical problems is the widespread of antimicrobial-resistant bacteria from inappropriate and prolonged use of antimicrobial agents in both humans and animals. Plant extracts might afford the chance to replace antibiotic drugs and reduce the emerging of antimicrobial-resistant bacteria. This study aimed to examine the antibiotic activity of ethanolic crude extracts of some Thai medicinal plants grouping in their parts as whole onions of red shallot (Allium ascalonicum), petals of marigold (Tagetes erecta), mulberry leaves, and root barks (Morus indica) to inhibit the growth of Streptococcus pyogenes. The antibiotic activities of the crude extract of three Thai medicinal plants using absolute ethanol were trialed against Streptococcus pyogenes using the disk diffusion method. Erythromycin and Ceftriaxone discs were chosen to be positive control standards as the representative of antibiotic drugs. Each dried plant extracts was prepared to test the inhibition with a concentration at 25, 50, and 75 mg/mL stock solution. The results showed that three groups from all testing groups of Thai medicinal plant extracts had the potential of antibiotic activity against S. pyogenes. The highest antibiotic activity against S. pyogenes was detected from whole onion extract red shallot followed by the extract of the mulberry leaves and root barks of mulberry strain Nakhon Ratchasima 60 (Nak 60) while the extract of marigold petal did not present antibiotic activity. The results revealed that crude extract of those two Thai medicinal plants, including red shallot and mulberry, had antibiotic activity against bacterial growth of S. pyogenes in the experiment and these medical Thai plants had potential benefits for developing as alternative treatment agents for S. pyogenes infections in both humans and animals in the future.

Antifungal Properties of Protein Extracts from Thai Medicinal Plants to Opportunistic Fungal Pathogens

Antifungal proteins or peptides (AFPs) are the natural products produced by several life forms including plants as the first-line defenses to infections. The AFPs from Thai plants can be used as new therapeutic agents in the world with growing resistance to conventional antifungals. This study determined the antifungal activities of protein extracts from Thai medicinal plants against important human opportunistic fungi, Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, and Talaromyces marneffei. Total crude protein supernatants and their precipitated proteins from 10 Thai medicinal plants with the historical usage for treatment of fungal infection were prepared. Most of the protein extracts showed antifungal activities to the tested fungi. The most effective reactivity found in the extracts from Rhinacanthus nasutus, Andrographis paniculata, and Psidium guajava by showing highest activity to T. marneffei ATCC200051 (yeast phase), followed by C. neoformans ATCC90112, C. albicans ATCC90028, T. marneffei ATCC200051 (mold phase), and A. fumigatus NCPF7367. The precipitated proteins from R. nasutus and A. paniculata containing antifungal properties were selected for partial purification by size cut-off membrane centrifugation and tested for antifungal activities. A colorimetric broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) to anti-T. marneffei. The partially purified fractions from A. paniculata, and R. nasutus showed anti-T. marneffei activity with the MIC and MFC values ranged from 2 to 128 μg/mL and 16 to >128 μg/mL, respectively. Therefore, A. paniculata and R. nasutus can be further subjected to the study of the therapeutic antifungals.

MOLECULAR DOCKING STUDY BETWEEN 3 THAI MEDICINAL PLANTS COMPOUNDS AND COVID-19 THERAPEUTIC PROTEIN TARGETS: SARS-COV-2 MAIN PROTEASE, ACE-2, AND PAK-1

Objective: The present study aimed to evaluate those 3 compounds among 122 Thai natural products by using a molecular docking approach to inhibit Main Protease (Mpro) of SARS-CoV-2 (PDB code: 6Y2F), Angiotensin Converting Enzyme (ACE)-2 (PDB code: 1R4L), and PAK-1 kinase (PDB code: 5DEW). Methods: The evaluation was performed on the docking scores calculated using AutoDock Vina as a docking engine and interaction profile analysis through 2-dimensional visualization using LigPlot+. The determination of the docking score was done by selecting the conformation of the ligand that has the lowest binding free energy (best pose). Result: The results of this study indicate that overall, Panduratin A has the best affinity in inhibiting the main protease of SARS-CoV-2, ACE-2, and PAK-1 compared to other compounds. Conclusion: The three thai medicinal plants compound has the potential to be developed as specific therapeutic agents against COVID-19.

In Vitro Wound Healing Activities of Three Most Commonly Used Thai Medicinal Plants and Their Three Markers

Skin ensures that a constant internal environment can be maintained in an ever-changing external environment. When a wound occurs on the skin, the inflammatory and proliferative phases are initiated in response to injury. Thai traditional medicine (TTM), using medicinal plants and ancient knowledge, has been used to treat wounds. Eight Thai medicinal plants, most commonly used to treat wounds, were evaluated for their in vitro biological activities such as antioxidation by NBT assay, anti-inflammation by production inhibition of NO, promoting fibroblast cell proliferation, and wound closure activities. Plant materials were extracted with 95% ethanol or distilled water and then concentrated and dried. Statistical analysis of data was done using one-way ANOVA at p value of 0.05. The ethanolic extracts of Garcinia mangostana L., Glycyrrhiza glabra L., and Nigella sativa L. could inhibit the production of superoxide anion with the IC50 values of 13.97 ± 0.38, 28.62 ± 1.91, and 71.54 ± 3.22 μg/ml and nitric oxide with the IC50 values of 23.97 ± 0.91, 46.35 ± 0.43, and 78.48 ± 4.46 μg/ml, respectively. These extracts could promote cell proliferation and accelerate wound recovery at the rate of 2.02 ± 0.03, 2.12 ± 0.03, and 2.65 ± 0.05% per hour, respectively. Three established markers from these three plants were selected according to the selection criteria. Alpha-mangostin, glycyrrhizin, and thymoquinone were found to be the active markers for wound closure activities. The ethanolic extracts of G. mangostana, G. glabra, and N. sativa could scavenge superoxide anion and inhibit the production of nitric oxide; therefore these extracts could assist in surpassing the inflammatory phase and protected the cells surrounding the wound area. Most importantly, these extracts also increased the proliferation and accelerated wound closure, indicating that these plant extracts could be promoting wound healing processes and support the use of TTM.

High-Content Screening of Thai Medicinal Plants Reveals Boesenbergia rotunda Extract and its Component Panduratin A as Anti-SARS-CoV-2 Agents

Since December 2019, the emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused severe pneumonia, a disease named COVID-19, that became pandemic and created an acute threat to public health. The effective therapeutics are in urgent need. Here, we developed a high-content screening for the antiviral candidates using fluorescence-based SARS-CoV-2 nucleoprotein detection in Vero E6 cells coupled with plaque reduction assay. Among 122 Thai natural products, we found that Boesenbergia rotunda extract and its phytochemical compound, panduratin A, exhibited the potent anti-SARS-CoV-2 activity. Treatment with B. rotunda extract and panduratin A after viral infection drastically suppressed SARS-CoV-2 infectivity in Vero E6 cells with IC50 of 3.62 μg/mL (CC50 = 28.06 µg/mL) and 0.81 μΜ (CC50=14.71 µM), respectively. Also, the treatment of panduratin A at the pre-entry phase inhibited SARS-CoV-2 infection with IC50 of 5.30 µM (CC50=43.47 µM). Our study demonstrated, for the first time, that panduratin A exerts the inhibitory effect against SARS-CoV-2 infection at both pre-entry and post-infection phases. Since B. rotunda is a culinary herb generally grown in China and Southeast Asia, its extract and the purified panduratin A may serve as the promising candidates for therapeutic purposes with economic advantage during COVID-19 situation.

Selection of Thai Medicinal Plants with Anti-Obesogenic Potential via In Vitro Methods

The prevalence of obesity is increasing globally. Despite the availability of a variety of anti-obesogenic drugs, including therapies under clinical development, these treatments are often indicated for patients with severe obesity, making them unsuitable for patients with mild obesity or for preventative use. In Thailand, traditional remedies employing medicinal plants are widely used to maintain health and treat disease. These treatments are generally inexpensive and readily available at markets, making them good treatment options for preventing obesity. To evaluate the anti-obesogenic potential of Thai medicinal plants, we employed three in vitro methods: pancreatic lipase inhibition, lipolysis enhancement, and lipid accumulation reduction assays. Among 70 Thai medicinal plants, Eurycoma longifolia Jack, Tiliacora triandra Diels, and Acacia concinna (Willd.) DC. were selected as the most favorable candidates because they exhibited anti-obesogenic activity in all three assays. These medicinal plants are expected to have efficient anti-obesogenic effects, making them promising candidates for further study.