A novel quinic acid derivative, 5-O-trans-o-coumaroylquinic acid methyl ester (1), together with three known ones, chlorogenic acid methyl ester (2), macranthoin F (3) and macranthoin G (4), were isolated from the aerial parts of the invasive plant Ageratina adenophora (Spreng.). The structure of new compound 1 was elucidated on the basis of extensive spectroscopic analysis, including 1D- and 2D-NMR techniques. Compounds 2–4 were isolated from plant A. adenophora for the first time. All the compounds showed in vitro antibacterial activity toward five assayed bacterial strains, especially 3 and 4, which showed in vitro antibacterial activity against Salmonella enterica with MIC values of 7.4 and 14.7 μM, respectively. Compound 1 was further found to display in vitro anti-fungal activity against spore germination of Magnaporthe grisea with an IC₅₀ value 542.3 µM. These four compounds were also tested for their antioxidant activity against DPPH (1,1-diphenyl-2-picrylhydrazyl) radical.

A phytochemical study on the aerial parts of Mikania micrantha led to the isolation of two new phenolic compounds, benzyl 5-O-β-d-glucopyranosyl-2,5-dihydroxybenzoate (1) and (7S,8R)-threo-dihydroxydehydrodiconiferyl alcohol 9-acetate (2), together with twelve known compounds, benzyl 2-O-β-d-glucopyranosyl-2,6-dihydroxybenzoate (3), 4-allyl-2,6-dimethoxyphenol glucoside (4), (+)-isolariciresinol (5), icariol A₂ (6), 9,10-dihydroxythymol (7), 8,9,10-trihydroxythymol (8), caffeic acid (9), p-coumaric acid (10), ethyl protocatechuate (11), procatechuic aldehyde (12), 4-hydroxybenzoic acid (13), and hydroquinone (14). Their structures were elucidated on the basis of extensive spectroscopic analysis. Except 8 and 9, all the other compounds were isolated from this plant species for the first time. The antioxidant activity of those isolated compounds were evaluated using three different assays. Compounds 1, 2, 3, 9, 10, 13, and 14 demonstrated significant 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) free radical cation scavenging activity ranging from SC₅₀ 0.31 to 4.86 µM, which were more potent than l-ascorbic acid (SC₅₀ = 10.48 µM). Compounds 5, 9, 11, and 12 exhibited more potent 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (SC₅₀ = 16.24–21.67 µM) than l-ascorbic acid (39.48 µM). Moreover, the ferric reducing antioxidant power (FRAP) of compounds 2, 5, 9, and 11 were discovered to be also comparable to or even more potent than l-ascorbic acid.

Ten pentacyclic triterpenoids including a new multiflorane triterpene acid, 2α,3β,23-trihydroxymultiflor-7-en-28-oic acid (1), and a new lupane triterpene monoglucoside named akebiaoside C (2), were obtained from the leaves of Akebia trifoliata. Their structures were elucidated by extensive spectroscopic analysis, and they were all isolated from the leaves of A. trifoliata for the first time. These compounds, except 4 and 5, showed in vitro α-glucosidase inhibitory activity much stronger than acarbose. Especially, 2, 3, 6, 8 and 10 displayed in vitro α-glucosidase inhibitory activity with IC₅₀ values from 0.004 to 0.081 mM, which were close or even more potent than corosolic acid (IC₅₀ 0.06 mM). Triterpenoids 1, 8 and 10 were further revealed to show moderate in vitro cytotoxic activity against human tumor A549, HeLa and HepG2 cell lines, with IC₅₀ values ranging from 26.5 to 51.9 μM. Compound 9 selectively showed in vitro cytotoxicity toward HeLa and HepG2 cell lines, with IC₅₀ values of 81.49 and 73.47 μM, respectively. These findings provided new data to support that the leaves of A. trifoliata are a rich source in bioactive triterpenoids highly valuable to be developed for medicinal usage.

The striking rise of methicillin-resistant Staphylococcus aureus (MRSA) infections has become a serious threat to public health worldwide. In an effort to search for new anti-MRSA agents from natural products, a bioassay-guided phytochemical study was conducted on the semi-mangrove plant Myoporum bontioides A. Gray, which led to the isolation of two new sesquiterpene alkaloids (1 and 2) and six known furanosesquiterpenes (3–8). Their structures were elucidated on the basis of extensive analysis of their 1D, 2D NMR and mass spectroscopic data. These two new alkaloids (1 and 2) displayed potent anti-MRSA activity with MIC value of 6.25 μg/mL. This is the first report of sesquiterpene alkaloids from the plants of Myoporum genus and their anti-MRSA activity.

Two new thymol derivatives, 7,9-diisobutyryloxy-8-ethoxythymol (1) and 7-acetoxy-8-methoxy-9-isobutyryloxythymol (2), were isolated from fresh roots of Ageratina adenophora, together with four known compounds, 7,9-di-isobutyryloxy-8-methoxythymol (3), 9-oxoageraphorone (4), (−)-isochaminic acid (5) and (1α,6α)-10-hydroxycar-3-ene-2-one (6). Their structures were established on the basis of detailed spectroscopic analysis, and they were all isolated from the roots of A. adenophora for the first time. All the compounds were tested for their in vitro antibacterial activity toward three Gram-positive and two Gram-negative bacterial strains. Thymol derivatives 1–3 only selectively showed slight in vitro bacteriostatic activity toward three Gram-positive bacteria. The two known carene-type monoterpenes 5 and 6 were found to show moderate in vitro antibacterial activity against all five tested bacterial strains, with MIC values from 15.6 to 62.5 μg/mL. In addition, compounds 5 and 6 were further revealed to show in vitro cytotoxicity against human tumor A549, HeLa and HepG2 cell lines, with IC₅₀ values ranging from 18.36 to 41.87 μM. However, their cytotoxic activities were inferior to those of reference compound adriamycin.