Two Balkan Peninsula endemics, Nepeta rtanjensis and N. argolica subsp. argolica, both characterized by specialized metabolite profiles predominated by iridoids and phenolics, are differentiated according to the stereochemistry of major iridoid aglycone nepetalactone (NL). For the first time, the present study provides a comparative analysis of antimicrobial and immunomodulating activities of the two Nepeta species and their major iridoids isolated from natural sources—cis,trans-NL, trans,cis-NL, and 1,5,9-epideoxyloganic acid (1,5,9-eDLA), as well as of phenolic acid rosmarinic acid (RA). Methanol extracts and pure iridoids displayed excellent antimicrobial activity against eight strains of bacteria and seven strains of fungi. They were especially potent against food-borne pathogens such as L. monocytogenes, E. coli, S. aureus, Penicillium sp., and Aspergillus sp. Targeted iridoids were efficient agents in preventing biofilm formation of resistant P. aeruginosa strain, and they displayed additive antimicrobial interaction. Iridoids are, to a great extent, responsible for the prominent antimicrobial activities of the two Nepeta species, although are probably minor contributors to the moderate immunomodulatory effects. The analyzed iridoids and RA, individually or in mixtures, have the potential to be used in the pharmaceutical industry as potent antimicrobials, and in the food industry to increase the shelf life and safety of food products.

A molecular networking-based dereplication strategy was applied for the phytochemical investigation of Ainsliaea macrocephala, leading to the isolation of two novel disesquiterpenoid macrocephadiolides A (1) and B (2). Their structures, featuring a rare 5,6-spirocyclic ketal lactone core and a C-15/C-15′ linkage between a guaianolide and a 3,4-seco-guaianolide monomer, respectively, were established by extensive spectroscopic analysis and confirmed further by single-crystal X-ray crystallography. Compounds 1 and 2 showed a potent inhibitory effect on nitric oxide (NO) production, with IC₅₀ values of 0.99 and 6.13 μM, respectively, in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Compound 1 dose-dependently suppressed the expression of inducible NO oxidase (iNOS) through inhibiting nuclear factor-κB (NF-κB) activation.

Tricarabrols A–C (1–3), three sesquiterpene lactone trimers, were identified from Carpesium faberi. Tricarabrols A and B are a pair of stereoisomers possessing a novel C₄₄ skeleton featuring a methylene-tethered linkage among the sesquiterpene scaffolds. Besides the unique linkage of the cyclopentane ring, tricarabrol C also manifests a methylene bridge. Their full structures were established on the basis of spectroscopic data and further confirmed by computational methods. The biosynthetic pathways involving the Alder-ene reaction, [3 + 2] cycloaddition, and Michael addition reaction were proposed. Tricarabrols A and B (1–2) significantly inhibited the nitric oxide production on lipopolysaccaride-stimulated RAW264.7 macrophages with IC₅₀ values of 2.90 and 4.52 μM, respectively, compared with the positive control indomethacin. Further studies indicated that the anti-inflammatory effect of tricarabrol A was mediated through inhibiting the phosphorylation and nuclear translocation of nuclear factor-κB.

Nine new, uncommon humulane-type sesquiterpenoids (1, 2, 4, 6–11), together with two known derivatives, were isolated from extracts of the plant Pilea cavaleriei subsp. crenata. The structures of these compounds were fully elucidated by extensive analyses of spectroscopic data (MS, 1D- and 2D-NMR), use of the Mosher method, and by X-ray crystallographic analysis, in combination with chemical conversions. An ene reaction was discovered during the chemical transformations, which might provide an explanation for the wide distribution of the allylic hydroperoxide group in natural products.

Phytochemical investigation of the roots of Stemona cochinchinensis led to the isolation and structure elucidation of a new pyrido[1,2‐a]azepine‐type alkaloid, stemocochinamine (1), and of four new pyrrolo[1,2‐a]azepine‐type alkaloids, bisdehydrostemocochinine (2), isobisdehydrostemocochinine (3), neostemocochinine (4), and isoneostemocochinine (5), together with six known alkaloids. Their structures were established on the basis of extensive 1D‐ and 2D‐NMR analyses in combination with HR‐MS experiments.