We read with great interest the study by Siyu Chen and colleagues. The authors evaluated the clinical features and outcomes of five pregnant patients with COVID-19 at term, whose delivery was uneventful and led to favorable perinatal outcomes for both mother and neonate. We would like to draw attention to a growing body of evidence that now points towards an under-addressed association between preterm maternal SARS-CoV-2 infection, preterm delivery and adverse neonatal outcomes, which is not reflected in Chen et al.'s small cohort. We also stress that vertical transmission, which was not tested for by Chen et al.,should not be excluded as a potential mechanism for viral spread. Centers should therefore be meticulous in their approach to a SARS-CoV-2+ pregnancy to optimize clinical outcomes for both mother and child.

Calanolides are tetracyclic 4-substituted dipyranocoumarins. Calanolide A, isolated from the leaves and twigs of Calophyllum lanigerum var. austrocoriaceum (Whitmore) P. F. Stevens, is the first member of this group of compounds with anti-HIV-1 activity mediated by reverse transcriptase inhibition. Calanolides are classified pharmacologically as non-nucleoside reverse transcriptase inhibitors (NNRTI). There are at least 15 naturally occurring calanolides distributed mainly within the genus Calophyllum, but some of them are also present in the genus Clausena. Besides significant anti-HIV properties, which have been exploited towards potential development of new NNRTIs for anti-HIV therapy, calanolides have also been found to possess anticancer, antimicrobial and antiparasitic potential. This review article provides a comprehensive update on all aspects of naturally occurring calanolides, including their chemistry, natural occurrence, biosynthesis, pharmacological and toxicological aspects including mechanism of action and structure activity relationships, pharmacokinetics, therapeutic potentials and available patents.

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Taken together, the development of a successful oral formulation may offer relative advantages concerning safety, efficacy, compliance, ease of manufacturing and administration. These factors are essential to consider when developing globally scalable immunisation strategies against SARS-CoV-2.

Purpurogallin (PPG), an orange-red crystalline compound from nutgalls and oak bark, is an exemplar of numerous, ubiquitous natural colorants, biosynthesized through oxidative dimerization-decarboxylation of phenolic compounds. It possesses antioxidant, anticancer, and anti-inflammatory effects. Herein, a robust method is presented to allow students to expediently make this interesting compound that contains a tropolone ring, whose identity initiated a paradigm shift in the understanding of aromaticity. 1D and 2D nuclear magnetic resonance (NMR) spectroscopic data (1H, 13C-DEPT-Q, HSQC, HMBC) were used to identify which protons are connected to carbon atoms. Fourier transform infrared spectroscopy (FT-IR), mass spectrometry, and X-ray diffraction were used to provide complementary information. Importantly, sufficient historical detail is given to provide a useful narrative that highlights the shift from deductive and synthetic proof of structural identity to modern methods of structural elucidation. As a minor, but important, aspect of iron gall inks, PPG links the work of important western historical documents from Da Vinci’s Vitruvian Man to the United States Declaration of Independence. In the experience of the authors, such a pedagogic approach enlivens students with practical exercises which place them within the historical arc and reasoning of notable scientists, adding a sense of scientific discovery.