Liquid chromatography (LC)–nuclear magnetic resonance (NMR) combines the advantage of the outstanding separation power of liquid chromatography (LC) and the superior structural elucidating capability of nuclear magnetic resonance (NMR). NMR has proved that it is a standout detector for LC by providing maximum structural information about plant originated extracts, particularly on the isolating ability of isomeric (same molecular formula) and/or isobaric (same molecular weight) compounds as compared to other detectors. The present review provides an overview of the developmental trends and application of LC–NMR in natural product analysis. The different LC–NMR operational modes are described, and how technical improvements assist in establishing this powerful technique as an important analytical tool in the analysis of complex plant-derived compounds is also highlighted. On-flow, stop-flow and loop-storage modes, as well as the new offline mode LC–solid phase extraction (SPE)–NMR and capillary LC (capLC)–NMR configurations which avoid the ingestion of expensive deuterated solvents throughout the experiment, are mentioned. Utilization of cryogenic probe and microprobe technologies, which are the other important promising approaches for guaranteeing sensitivity, are also described. Concluding remarks and future outlooks are also discussed.

This study aimed to optimize the ultrasound-assisted extraction (UAE) parameters using response surface methodology (RSM) for the determination of ascorbic acid (AA), antioxidant activities/the half maximal effective concentration (EC50), total phenolic contents (TPC), and total flavonoid content (TFC) of Ethiopian wild Syzygium guineense fruit and seed processed under different drying conditions. The optimizations of the UAE methods for the determination of AA, antioxidant activities (EC50 values), TPC, and TFC were evaluated using response surface methodology (RSM). The extraction time of 15 min, the temperature of 35 °C, extraction solvent composition (methanol:water) of 75 to 25%, and solid-to-solvent ratios of 1:15 w/v were the optimum independent parameters. The experimental and the predicted data of TPC, EC50, and AA were in good agreement with the overall error below 0.01%. It also indicated a hypothesized distribution of predicted data fitted with experimental data. The average TPC, EC50, and AA content in S. guineense fruits and the seed varied from 581.25 ± 37.13 to 1917.40 ± 26.15 mg GAE/100 g, 4.02 ± 0.42 to 155.73 ± 5.11 mg/100 g, and 1.96 ± 0.02 to 0.94 ± 0.00 mg/mL, respectively. This study indicated that this underutilized wild fruit and its seeds can be an alternative source of AA and antioxidant compounds.

The study investigated the potential of anchote (Coccinia abyssinica [Lam.] Cogn.) tuber powder as a substitute to commercial pectin. Mixture D-optimal design was used to generate 14 experimental runs using ranges: strawberry fruit (45–55%), sugar (43–53%), and anchote powder (0.75–1.75%). The effect of anchote powder on physicochemical and textural qualities of the jams was evaluated. The parameters measured include: moisture content (30.7–32.8%), total soluble solid (50.7–65.4 ºBrix), water activity (0.73–0.80), pH (2.93–3.13), titratable acidity (0.58–0.72%), gel strength (326.39–440.37 g mm), hardness (26.36–35.09 g), cohesiveness (0.89–0.94), energy of penetration (418.72–489.51 g s), adhesiveness (−25.38 to −103.79 g s) and stickiness (−13.78 to −29.22 g). The jam formulation J₁₃ (50% strawberry, 48.2% sugar, 1.33% anchote) was best performing. Numerical optimization showed the best combination of parameters at 52.4% strawberry, 46.0% sugar, 1.07% anchote. The jam formulated with anchote powder was comparable with the jam made using pectin.

This study aimed to investigate selected bioactive components in three underutilized wild edible exotic fruits (Syzygium guineense Wild. DC, Ziziphus spina-christi L., and Citrus medica L.), using high-performance thin-layer chromatography and ultraviolet-visible spectrophotometry (HPTLC-UV-Vis), treated under three drying conditions. Ultrasound-assisted extraction was used to extract the target bioactive components under specified conditions, i.e., time of 15 min, temperature of 35 °C, methanol and water 75/25, v/v, and fruit powder-to-solvent ratio of 1:15, w/v. The mobile phase ratio for rutin, kaempferol, myricetin, and quercetin was toluene/ethylacetate/methanol/formic acid at 20:12:8:4, whereas, for phenolic acids, the ratio was 10:15:10:5, respectively. The HPTLC plates were scanned to identify and quantify selected compounds (phenolic acids, quercetin, rutin, myricetin, and kaempferol) at their maximum optimized absorption wavelengths. The contents of target bioactive components ranged from 0.64 ± 0.19 mg/100 g for rutin to 320.04 ± 7.10 mg/100 g for chlorogenic acid. Based on the results of this investigation, the phenol content of freeze-dried fruit was significantly (p ≤ 0.05) higher than other drying methods. The calculated average limit of detections and quantifications ranged from 0.37 to 75 ng/spot to 2.5 to 250 ng/spot, respectively. The average recoveries were 99.91 ± 5.65% for quercetin and 99.08 ± 5.96% for rutin. Overall, the validated HPTLC method was simple, selective, sensitive, and stable for the simultaneous identification and determination of phenolic acids and flavonoids. As a result, this study revealed that the contents of phenolic acids and flavonoids in selected exotic edible fruits can be used as effective antioxidants.

Physalis peruviana Linnaeus, also called Cape gooseberry, has been used extensively as a medicinal herb since ancient times. The current study is the very first investigation into the nutrient characteristics of Physalis peruviana L. fruits found in Ethiopia. Its main objective is to investigate the nutritional, antinutritional, and antioxidant capacity of the edible fruit of Physalis peruviana L. Three different drying conditions (shade, sun, and oven drying) were investigated to observe their effects on the chemical composition of the fruit. The antioxidant activities were quantified using DPPH (2,2-diphenylpicrylhydrazyl) and FRAP (ferric reducing antioxidant power) assays. Total flavonoid and total phenol contents were also determined for all dried samples. The shade-dried sample exhibited a better composition with regard to most of the characterized constituents than the other dried samples. From all of the results obtained, the shade-dried sample showed higher antioxidant activity, and, among the investigated minerals, its K content was found to be the highest (313.66 ± 0.05 g/100 g). However, the Fe content (in the oven-dried sample) was found to be the lowest (0.06 ± 0.10 g/100 g) of the investigated minerals. Through fermentation using Saccharomyces cerevisiae, the alcoholic content of the fruit was 9.11%, 9.90%, and 12.34% after 24, 48, and 72 h of fermentation time, respectively. It was also observed that the high temperature used in the drying process led to content loss in the fruit samples. This was evident in the oven-dried samples. It is expected that the analysis of the effects of drying on fruit composition can contribute to a better understanding of fruit storage/preparation and provide useful information on fruit product formulations.