Three pairs of racemic dimers, (±)-cnidimonins A–C (1–3), were isolated from the fruits of Cnidium monnieri. They represent novel hybrid-dimerization patterns of coumarin skeleton with structurally diverse units (flavonol, benzofuran, and chromone) via an unprecedented terminal chiral carbon of prenyl. The absolute configurations of the enantiomers were determined by electronic circular dichroism (ECD). To investigate their bioactivities in depth, (±)-cnidimonins A–C (1–3) were synthesized. The racemic mixture (±)-1 exhibited stronger antiviral activity against HSV-1 (IC50: 1.23 μM) than its corresponding optically pure enantiomers.

Illisimonin A, an unprecedented sesquiterpenoid with a tricyclo[5.2.1.01,6]decane skeleton, was isolated from the fruits of Illicium simonsii. The structure and absolute configuration of 1 were determined using extensive spectroscopic evidence and electronic circular dichroism (ECD) calculations. It was determined that 1 possesses a caged 2-oxatricyclo[3,3,0,14,7]nonane ring system fused to a five-membered carbocyclic ring and a five-membered lactone ring. A plausible biogenetic pathway for 1 was proposed, and 1 showed neuroprotective effects against oxygen-glucose deprivation (OGD)-induced cell injury in SH-SY5Y cells with an EC50 value of 27.72 μM.

Pierisketolide A (1) and pierisketones B and C (2 and 3), three diterpenes with an unusual A-homo-B-nor-ent-kaurane carbon skeleton, were isolated from the roots of Pieris formosa. Their structures were characterized by a series of spectroscopic methods, X-ray diffraction, and electronic circular dichroism (ECD). Pierisketolide A (1) exhibited an analgesic effect with a 45% writhe inhibition rate at a dose of 10.0 mg/kg. The plausible biosynthetic pathways of 1–3 are proposed.

Seventeen new 3,4-secograyanoids (1–17), together with seven known compounds (18–24), were isolated from the roots of Pieris formosa. Their structures with absolute configurations were characterized by a series of spectroscopic methods and X-ray diffraction. Compounds 1, 2, 4–8, 10–13, and 16–24 exhibited significant analgesic activity at 5.0 mg kg−1 (ip) compared to vehicle-injected mice (p < 0.05). In particular, compounds 16 and 17 showed highly potent activities with inhibition rates of 63.5% and 69.9%, respectively.

Two pairs of oligomeric coumarin enantiomers, spirotriscoumarin A [(+)-1 and (−)-1] and spirotriscoumarin B [(+)-2 and (−)-2], with a spirodienone-sesquiterpene fused skeleton were isolated from Toddalia asiatica. Their structures were unambiguously established using spectroscopic data, X-ray diffraction analysis, and the electronic circular dichroism (ECD) method. The racemic mixtures (±)-1 and (±)-2 exhibit 3-to-6-fold stronger antiviral activity against influenza virus A (H3N2) (IC50: 3.13 and 2.87 μM, respectively) than their corresponding optically pure enantiomers.

Eight new grayanane-type diterpenoids, pieristoxin L-S (1–8), and seven known diterpenoids, grayanoside D (9), rhodomolin I (10), pieristoxin H (11), grayanotoxin II (12), pierisformoside B (13), grayanoside C (14) and bis-deacetylkalmitoxin-VI (15), were isolated from the twigs of Pieris formosa. The structures of these compounds were elucidated using extensive spectroscopic analyses, including electronic circular dichroism (ECD). Pieristoxin L (1) is the first example of a 1,7-epoxy-grayanane-type diterpenoid. The analgesic activities of compounds 2–6, 8, and 10–15 were evaluated using an acetic acid-induced writhing test in mice. Compounds 3–6, 8, 10, 12, and 15 exhibited significant analgesic activity at 5 mg/kg (ip) compared to vehicle-injected mice (P<0.01). The writhe inhibition rates of compounds 3, 5, and 6 at 0.08 mg/kg (ip) were 37.6%, 56.8% and 49.8%, respectively. The control drug morphine achieved comparable writhe inhibition at a 10-fold dose.