Thailand has vast areas of tropical forests with many indigenous plants, but limited information is available on their phytochemical profile and in vitro inhibitions of enzymatic and nonenzymatic reactions. This study investigated phenolic profiles using liquid chromatography–electrospray ionization tandem mass spectrometry (LC–ESI-MS/MS), antioxidant activities, and in vitro inhibitory activities of 10 indigenous plants on key enzymes related to obesity (lipase), diabetes (α-amylase and α-glucosidase), and Alzheimer’s disease (cholinesterases and β-secretase). The nonenzymatic anti-glycation reaction was also investigated. The 10 indigenous plants were Albizia lebbeck (L.) Benth, Alpinia malaccensis (Burm.) Roscoe, Careya arborea Roxb., Diplazium esculentum (Retz.) Swartz, Kaempferia roscoeana Wall., Millettia brandisiana Kurz., Momordica charantia, Phyllanthusemblica L., Zingiber cassumunar Roxb, and Zingiber citriodorum J. Mood & T. Theleide. Preparations were made by either freeze-drying or oven-drying processes. Results suggested that the drying processes had a minor impact on in vitro inhibitions of enzymatic and nonenzymatic reactions (80% inhibition using the extract concentration of ≤6 mg/mL), while D. esculentum effectively inhibited β-secretase activity (>80% inhibition using the extract concentration of 10 mg/mL). C. arborea exhibited the highest inhibitory activities against lipase (47–51% inhibition using the extract concentration of 1 mg/mL) and cholinesterases (>60% inhibition using the extract concentration of 2 mg/mL), while Mi. brandisiana dominantly provided α-amylase and α-glucosidase inhibitors (>80% inhibition using the extract concentration of ≤2 mg/mL). Information obtained from this research may support usage of the oven-drying method due to its lower cost and easier preparation step for these studied plant species and plant parts. Furthermore, the information on in vitro inhibitions of enzymatic and nonenzymatic reactions could be used as fundamental knowledge for further investigations into other biological activities such as cell culture or in vivo experiments of these health-beneficial plants.

Sacred lotus (Nelumbo nucifera) has long been used as a food source and ingredient for traditional herbal remedies. Plant parts contain neuroprotective agents that interact with specific targets to inhibit Alzheimer’s disease (AD). Organic solvents including methanol, ethyl acetate, hexane, and n-butanol, are widely employed for extraction of sacred lotus but impact food safety. Seed embryo, flower stalk, stamen, old leaf, petal, and leaf stalk of sacred lotus were extracted using hot water (aqueous extraction). The extractions were analyzed for their bioactive constituents, antioxidant and anti-AD properties as key enzyme inhibitory activities toward acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and β-secretase 1 (BACE-1). Results showed that the sacred lotus stamen exhibited significant amounts of phenolics, including phenolic acids and flavonoids, that contributed to high antioxidant activity via both single electron transfer (SET) and hydrogen atom transfer (HAT) mechanisms, with anti-AChE, anti-BChE, and anti-BACE-1 activities. To enhance utilization of other sacred lotus parts, a combination of stamen, old leaf and petal as the three sacred lotus plant components with the highest phenolic contents, antioxidant activities, and enzyme inhibitory properties was analyzed. Antagonist interaction was observed, possibly from flavonoids–flavonoids interaction. Further in-depth elucidation of this issue is required. Findings demonstrated that an aqueous extract of the stamen has potential for application as a functional food to mitigate the onset of Alzheimer’s disease.

Chrysin (5,7-dihydroxyflavone) is a remarkable flavonoid exhibiting many health-promoting activities, such as antioxidant, anti-inflammatory, and anti-Alzheimer’s disease (AD). Nevertheless, chrysin has been addressed regarding its limited applications, due to low bioaccessibility. Therefore, to improve chrysin bioaccessibility, a colloidal delivery system involving nanoemulsion was developed as chrysin nanoemulsion (chrysin-NE) using an oil-in-water system. Our results show that chrysin can be loaded by approximately 174.21 µg/g nanoemulsion (100.29 ± 0.53% w/w) when medium chain triglyceride (MCT) oil was used as an oil phase. The nanocolloidal size, polydispersity index, and surface charge of chrysin-NE were approximately 161 nm, 0.21, and −32 mV, respectively. These properties were stable for at least five weeks at room temperature. Furthermore, in vitro chrysin bioactivities regarding antioxidant and anti-AD were maintained as pure chrysin, suggesting that multistep formulation could not affect chrysin properties. Interestingly, the developed chrysin-NE was more tolerant of gastrointestinal digestion and significantly absorbed by the human intestinal cells (Caco-2) than pure chrysin. These findings demonstrate that the encapsulation of chrysin using oil-in-water nanoemulsion could enhance the bioaccessibility of chrysin, which might be subsequently applied to food and nutraceutical industries.

Anoectochilus burmannicus is an orchid that contains phenolic compounds and exhibits antioxidant and anti-inflammation properties. This study aimed to investigate whether its ethanolic extract (ABE) can be used as a reducing agent and/or a stabilizer of nano-selenium (SeNP) synthesis. SeNPs exhibited higher antioxidant activity than ABE-SeNPs. In contrast, ABE-SeNP (4 µM Se) had greater anti-inflammatory activity in LPS-induced macrophages than SeNPs. Interestingly, ABE acted as a stabilizer for SeNPs by preventing particle aggregation and preserving its antioxidant activity after long-term storage (90 days). Moreover, after the freeze-drying process, ABE-SeNPs could be completely reconstituted to suspension with significantly stable antioxidant and anti-inflammatory activities compared to freshly prepared particles, suggesting the cryoprotectant and/or lyoprotectant role of ABE. The present study shows the potential of ABE as an effective stabilizer for nanoparticles and provides evidence for the development of ABE-SeNPs as a food supplement or novel functional ingredient for health benefits.