Optimized Conditions for the Extraction of Phenolic Compounds from Aeginetia indica L. and Its Potential Biological Applications.

Aeginetia indica L., a parasitic root in the Orobanchaceae family, is used as a food colorant in traditional Thai desserts. However, scant information is available on its food applications as well as medicinal properties, while overharvesting by the local people has severely depleted wild plant populations. This research, thus, aimed to extract optimized total phenolic content (TPC) in varying extraction conditions using response surface methodology (RSM) and the Box-Behnken design (BBD). Results indicated that an extraction temperature of 90 °C, 80% (v/v) aqueous ethanol, and 0.5% (w/v) solid-to-liquid ratio yielded the highest TPC at 129.39 mg gallic acid equivalent (GAE)/g dry weight (DW). Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) identified the predominant phenolics as apigenin (109.06 mg/100 g extract) and luteolin (35.32 mg/100 g extract) with trace amounts of naringenin and rutin. Under the optimal extraction condition, the plant extract exhibited antioxidant activities of 5620.58 and 641.52 µmol Trolox equivalent (TE)/g DW determined by oxygen radical absorbance capacity (ORAC) and ferric ion reducing antioxidant power (FRAP) assay, while the scavenging capacity of total radicals at 50% (SC50) was determined to be 135.50 µg/mL using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The plant extract also exhibited inhibitory activities against the key enzymes relevant to type II diabetes, obesity, and Alzheimer's disease, suggesting the potential for medicinal applications.

Nutrients, Phytochemicals and In Vitro Disease Prevention of Nephelium hypoleucum Kurz Fruit.

Nephelium hypoleucum Kurz is an evergreen tree in the Sapindaceae family, mostly found in the forests of some Southeast Asia countries, especially Thailand. The lack of biological information regarding this tree has led to inappropriate agricultural management, conservation and utilization. Thus, this study aims to examine the nutritional composition, organic acid and phenolic profiles and in vitro health properties through several key enzyme inhibitions against some civilization diseases including Alzheimer's disease (ß-secretase (BACE-1), butyrylcholinesterase (BChE) and acetylcholinesterase (AChE)), obesity (lipase), hypertension (angiotensin-converting enzyme (ACE)) and diabetes (dipeptidyl peptidase-IV (DPP-IV), α-amylase and α-glucosidase) on the aril (flesh) part of N. hypoleucum Kurz fruit. The remaining fruit parts including the pericarp (peel) and seed were also assessed as sources of potential phenolics as well as key enzyme inhibitors. As results, carbohydrate (17.18 g) was found to be a major source of energy (74.80 kcal) in the aril (100 g fresh weight), with trace amounts of protein (0.78 g) and fat (0.32 g). The fruit aril also contained high insoluble dietary fiber (5.02 g) and vitamin C (11.56 mg), while potassium (215.82 mg) was detected as the major mineral. Organic acid profile indicated that the aril was rich in citric acid, while the phenolic profile suggested predominant quercetin and kaempferol. Interestingly, high gallic acid contents were detected in both pericarp and seed, with the latter 3.2-fold higher than the former. The seed also possessed the highest total phenolic content (TPC, 149.45 mg gallic acid equivalent/g dry weight), while total anthocyanin content (TAC, 0.21 mg cyanidin-3-O-glucoside equivalent/g dry weight) was only detected in pericarp. High TPC also led to high enzyme inhibitory activities in seed including BACE-1, AChE, BChE, ACE, DPP-IV and α-glucosidase. Interestingly, aril with the highest α-amylase inhibition suggested strong inhibitory distribution, predominantly from quercetin and kaempferol. Lipase inhibitory activities were only detected in the aril and pericarp, suggesting the biological function of these two phenolics and possibly anthocyanins.