In an attempt to develop a potent, eco-friendly, and selective technique for isolating natural coumarins, this study introduced a novel extraction technique called kinetic thermomagnetic. It involved the application of four different variables: temperature, time interval, magnetic, and rotation speed. Phytochemical analysis was performed on the eighty one crude chloroform extracts of green sweet bell pepper seeds collected, identifying the presence of many botanical categories. Nine extracts were found to have the same two extraction variables—a 90-minute extraction period and a 55 °C extraction temperature—and to have the coumarin chemical class. Two of these extracts with coumarin were selected so that their coumarin contents could be chemically isolated and chromatographically purified. The molecular frameworks of four novel phytocoumarins have been discovered and differentiated by the analysis of their mass, 1H NMR, 13C NMR, and FTIR spectra. These phytocoumarins were found to have anticancer properties against eight malignant populations by MTT probing and to mitigate oxidative stress in human SH-SY5Y populations. Likewise, three and two related enzymes were used to specify the anti-inflammatory and antidiabetic capabilities, respectively. Comparing the isolated phytocoumarins to a positive control, the results showed that they had outstanding oxidative stress-mitigating properties, ranging from 71.51 to 81.48 %. Additionally, they demonstrated excellent cytotoxicity (IC50 values of 46.76–81.45 μg/ml) against the test malignant populations. The isolates also demonstrated an intriguing selective anti-inflammatory action, making them worthy of consideration as dual COX-2/5-LOX antagonists. Ultimately, when they submitted to the test against two blood-controlling enzymes, they showed a moderate antidiabetic effect. The authors concluded that by adjusting its factors, the approach used is effective and adaptable for extraction. Furthermore, natural-B4 in particular and other isolated phytocoumarins in general offer naturally derived remedies for alleviating oxidative stress and its related pathologies.