<sup>1</sup>H NMR-Based Biochemometric Analysis of <i>Morus alba</i> Extracts toward a Multipotent Herbal Anti-Infective.
Langeder J, Döring K, Schmietendorf H, Grienke U, Schmidtke M, Rollinger JM.
Mulberry Diels-Alder-type adducts (MDAAs) derived from the white mulberry tree were discovered recently as dual inhibitors of influenza viruses and pneumococci. For the development of a natural product based remedy for respiratory infections, the aim was to (i) identify the most prolific natural source of MDAAs, (ii) develop a protocol to maximize the content of MDAAs in <i>Morus alba</i> extracts, (iii) unravel constituents with the highest anti-infective potential within multicomponent mixtures, and (iv) select and characterize a hit extract as a candidate for further studies. Validated quantitative UPLC-PDA analysis of seven MDAAs (<b>1</b>-<b>7</b>) revealed the root bark as the best starting material and pressurized liquid extraction (PLE) as the optimum technique for extraction. Extracts enriched in MDAAs of a total content above 20% exerted a potent dual anti-influenza virus and antipneumococcal activity. For a detailed analysis of the most bioactive chemical features and molecules within the extracts, <sup>1</sup>H NMR-based heterocovariance analysis (HetCA) was used. According to the multivariate statistical analysis procedure conducted, MDAAs exclusively accounted for the in vitro anti-influenza viral effect. The anti-infective profile of one hit extract (MA60) investigated showed a good tolerance by lung cells (A549, Calu-3) and pronounced in vitro activities against influenza viruses, <i>S. pneumoniae</i>, <i>S. aureus</i>, and inflammation.