Discovery of lead natural products for developing pan-SARS-CoV-2 therapeutics.

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a global public health crisis. The reduced efficacy of therapeutic monoclonal antibodies against emerging SARS-CoV-2 variants of concern (VOCs), such as omicron BA.5 subvariants, has underlined the need to explore a novel spectrum of antivirals that are effective against existing and evolving SARS-CoV-2 VOCs.

Antidiabetic and antimicrobial flavonoids from the twigs and roots of (Hassk.) Merr.

The phytochemical investigation of the twig and root extracts of (Hassk.) Merr. (Fabaceae) resulted in the isolation and identification of a new pterocarpan, erythrinocarpan (), along with 27 known compounds (-).

Isolation and crystal structure of lawinal.

The structure of the natural product lawinal [systematic name: (-)-(2)-5,7-dihy-droxy-6-methyl-4-oxo-2-phenyl-chromane-8-carbaldehyde, CHO] at 150 K is reported. The compound crystallizes with monoclinic (2) symmetry and with ' = 2. The absolute configuration could not be determined reliably from X-ray analysis only.

Synthesis and crystal structure of (±)-Goniotamirenone C.

The structure of the racemic version of the natural product Goniotamirenone C [racemic -6-(2-chloro-1-hy-droxy-2-phenyl-eth-yl)-2-pyran-2-one, CHClO] at 150 K is reported. The compound crystallizes with monoclinic (2/) symmetry and with ' = 2. One independent mol-ecule is ordered while the other independent mol-ecule exhibits an inter-esting whole-mol-ecule enanti-omeric disorder with occupancies of 0.

Styryllactones from Goniothalamus tamirensis.

The phytochemical investigation of the twig and leaf extracts of Goniothalamus tamirensis led to the isolation and identification of 15 compounds including three rare previously undescribed styryllactones, goniotamirenones A-C, together with 12 known compounds. (Z)-6-Styryl-5,6-dihydro-2-pyranone and 5-(1-hydroxy-3-phenyl-allyl)-dihydro-furan-2-one are reported here for the first time as previously undescribed natural products. Their structures were elucidated by spectroscopic methods.

α-Glucosidase Inhibitory Flavonoids and Oxepinones from the Leaf and Twig Extracts of Desmos cochinchinensis.

Four new flavonoids (1-4), a new benzyl benzoate derivative (5), five new oxepinones (6-10), and 14 known compounds (11-24) were isolated from the leaf and twig extracts of Desmos cochinchinensis. Their structures were established by spectroscopic methods. The structure of 1 was also confirmed by X-ray diffraction data.

Potent α-glucosidase inhibitory activity of compounds isolated from the leaf extracts of .

The phytochemical investigation of the leaf extracts of (Annonaceae) led to the isolation and identification of ten compounds including a new -cyclohexene () together with nine known compounds (-). Their structures were elucidated by intensive analysis by spectroscopic methods and comparisons of their spectroscopic data with those of compounds reported in the literature. Compounds , , and showed potent -glucosidase inhibitory activity with the IC values ranging from 2.

Xanthones from Garcinia propinqua Roots.

Phytochemical investigation of Garcinia propinqua roots led to the isolation and identification of a new xanthone, doitunggarcinone D (1), together with 15 known compounds (2-16). Their structures were elucidated by intensive analysis of spectroscopic data. Compounds 3, 6, 7, 14, 15 and 16 exhibited strong antibacterial activity against Bacillus subtilis TISTR 088 with MIC values in the range of 1-4 µg/mL.

A New Cytotoxic Clerodane Diterpene from Casearia graveolens Twigs.

The first phytochemical investigation of Casearia graveolens twigs led to the isolation and identification of a new clerodane diterpene, caseariagraveolin (1), together with six known compounds (2-7). Their structures were elucidated by intensive analysis of their spectroscopic data. Compound 1 showed strong cytotoxicity against oral cavity and breast cancer cell lines with IC₅₀ values of 2.