Circularly polarised light (CPL) interacting with interstellar organic molecules might have imparted chiral bias and hence preluded prebiotic evolution of biomolecular homochirality. The l-enrichment of extra-terrestrial amino acids in meteorites, as opposed to no detectable excess in monocarboxylic acids and amines, has previously been attributed to their intrinsic interaction with stellar CPL revealed by substantial differences in their chiroptical signals. Recent analyses of meteoritic hydroxycarboxylic acids (HCAs) – potential co-building blocks of ancestral proto-peptides – indicated a chiral bias toward the l-enantiomer of lactic acid. Here we report on novel anisotropy spectra of several HCAs using a synchrotron radiation electronic circular dichroism spectrophotometer to support the re-evaluation of chiral biomarkers of extra-terrestrial origin in the context of absolute photochirogenesis. We found that irradiation by CPL which would yield l-excess in amino acids would also yield l-excess in aliphatic chain HCAs, including lactic acid and mandelic acid, in the examined conditions. Only tartaric acid would show “unnatural” d-enrichment, which makes it a suitable target compound for further assessing the relevance of the CPL scenario.

与星际有机分子相互作用的圆偏振光 (CPL) 可能会产生手性偏差，从而阻碍生物分子同手性的生命起源前进化。与未检测到过量的一元羧酸和胺相反，陨石中l-地外氨基酸的富集以前被归因于它们与恒星 CPL 的内在相互作用，这些相互作用通过它们的手性信号的显着差异揭示出来。最近对陨石羟基羧酸 (HCA) 的分析——祖先原肽的潜在共同构建块——表明对l的手性偏向-乳酸的对映体。在这里，我们使用同步辐射电子圆二色谱分光光度计报告了几种 HCA 的新型各向异性光谱，以支持在绝对光手性发生的背景下重新评估地外起源的手性生物标志物。我们发现，在检测条件下，CPL 照射会产生l - 过量的氨基酸，也会产生l - 过量的脂族链 HCA，包括乳酸和扁桃酸。只有酒石酸会显示出“非天然” d-富集，这使其成为进一步评估 CPL 情景相关性的合适目标化合物。