Influence of Plant Part Selection and Drying Technique: Exploration and Optimization of Antioxidant and Antibacterial Activities of New Guinea Impatiens Extracts

<i>Impatiens</i> L. plants are sources of polyphenols with antioxidant and antimicrobial activities. There are scarce data about these effects in the case of <i>Impatiens hawkeri</i> W. Bull, a relevant species in ornamental plant industry with ethnobotanical backgrounds. The aim of this study is to provide information regarding the antioxidant and the antibacterial properties of the ethanol extracts of <i>I. hawkeri</i> to support new applications. HPTLC was used to estimate the concentration of seven known bioactive metabolites reported among <i>Impatiens</i> plants. Total phenolics, flavonoids, and monomeric anthocyanins were also measured. An orthogonal platform with chemical and biological in vitro assays was used to evaluate the antioxidant activity of the extracts. Antibacterial activity was determined by broth microdilution assay on human pathogenic bacteria. The results were integrated by correlation and principal component analysis to identify the most promissory plant part and drying technique to optimize the evaluated activities. Data suggest the tentative identification of bioactive chemical markers for the antioxidant and antibacterial activities of the extracts (quercetin and rutin). Freeze-dried leaves and flowers are the most promissory parts of <i>I. hawkeri</i> for the development of antioxidant nutraceuticals or preservatives. The results demonstrate that phenolic compounds play a major role in the antioxidant and antibacterial activities of <i>I. hawkery</i> extracts.