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Salvia castanea (Family Labiatae), a perennial fragrant herb with castaneous flowers, is mainly distributed in areas with an altitude of 2500–3750 m. The roots of this plant were used as a tea drink by local residents to strengthen physical health. The aim of present study was to acquire secondary metabolites of the ethanol extract obtained from the whole plant of S. castanea and to evaluate their potential anti-Alzheimer's disease. Six new sesquiterpene lactones, salcastanins A-F (1–6), together with three known guaiane-type sesquiterpenoids nubiol (7), nubdienolide (8), and nubenolide (9), were separated from the whole plant of S. castanea. The structures of these compounds were determined by HRESIMS and NMR experiments. The absolute configurations of 1–6 were ascertained by electronic circular dichroism (ECD) experiments. The humanized Caenorhabditis elegans AD pathological model was used to evaluate anti-Alzheimer's disease (AD) activities of 1–9. The results showed the compounds 1–3 and 7 significantly delayed AD-like symptoms of worm paralysis phenotype, which could be used as novel anti-AD candidates.

Nine new isoprenoids, named as dictamtrinor-guaianols A (1), B (2), C (3), D (4), and E (5), dictamnorsesquiterpenol A (6), dictamnorsesquiterpenosides B (7) and C (8), as well as dictamtriterpenol A (9), along with eight known compounds (10–17) were obtained from 70% EtOH extract of Cortex Dictamni. Their structures were ascertained based on the extensive spectroscopic methods and ECD data analysis. Moreover, LC-MS analysis result suggested compounds 2 and 3 were natural products. Furthermore, lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage model were used to evaluate nitric oxide production inhibitory activities of them, and compounds 2, 3, 5, 6, 8–11, as well as 15–17 displayed significant activities at 40 μM.

Thirty-one compounds were obtained and identified from the dried roots of Mongolian medicinal and edible plant, Pugionium cornutum L. Gaertn. Eight of them were new ones, and named as pugcornols A (1), B (2), C (3), and D (4), pugcornosides A (5), B (6), C (7), and D (8), respectively. Among them, 1–4 were rare naturally occurring thiohydantoin derivatives. Meanwhile, all the isolates were determined for their activities on isolated mice jejunum contraction, and ten of them increased height of the spontaneous contractions. Moreover, we partly clarified the mechanism of 5-(methylsulfinyl)-pentanenitrile (9), a characteristic compound in P. cornutum by using different kinds of inhibitor.

Caesalpinia decapetala is a versatile medicinal plant belonging to the Fabaceae plant family. In our survey on plant secondary metabolites to obtain bioactive substances for the development of new agricultural anti-TMV agents, the chemical constituents of C. decapetala were investigated. This investigation led to the isolation of three new and ten known diterpenoids. Their structures including absolute configurations were elucidated based on the extensive NMR spectroscopic data analyses and the time-dependent density functional theory calculations. The following biological screenings revealed that most of these diterpenoids possessed anti-TMV activities.

A new cyclopeptide, pulvpeptin A (1), two pairs of norlignan lignanosides, tamariscinosides G and H (2, 3), together with five known compounds (4-8) were isolated from Selaginella pulvinata. The structures were elucidated by spectroscopic data and chemical degradation. The activity of tamariscinoside G (2) was evaluated by stimulating glucose uptake in 3T3-L1 adipocytes. The results showed 1.49-fold increase in glucose uptake in 3T3-L1 cells relative to basal.

A phytochemical investigation to obtain new triglyceride (TG) accumulation inhibitors resulted in the isolation of six new isobenzofuranones, leontopodiols A (1), B (2), leontopodiosides C (3), D (4), E (5), F (6), together with three known ones (7-9) from the aerial parts of Leontopodium leontopodioides (Willd.) Beauv. The structures of these isolates were identified by routine NMR experiments, optical rotation determination, electronic circular dichroism (ECD) calculation, along with chemical reaction. Moreover, compounds 1, 2, 5, and 7-9 displayed TG accumulation inhibitory effects on HepG2 cells.

Nerve growth factor (NGF) and analog reagents to promote the neurite outgrowth of nerve cells against the neuron degeneration are expected to be potentially useful for the medical treatment of Alzheimer's disease. In our focus on the discovery of bioactive diterpenes, we investigated the chemical constituents of the plant Croton yanhuii. This investigation led to the isolation and identification of two novel clerodane diterpenes (1 and 2). Their structures were elucidated on the basis of extensive 1D and 2D NMR (COSY, HMQC, HMBC, and NOESY) and mass (ESIMS and HR-ESIMS) spectroscopic data analyses. Further biological screenings showed that both of the compounds enhanced NGF-mediated neurite outgrowth from PC12 cells.

A phytochemical investigation of the leaves of Callicarpa kwangtungensis led to the isolation of three new diterpenoids (1–3), callipenes A–C, and eleven known analogues (4–14). Their structures were established on the basis of extensive analysis of NMR spectroscopic data, X-ray diffraction data, and experimental and calculated electronic circular dichroism spectra. Compounds 1 and 2 are rare abietane diterpenoids possessing a peroxide bridge. All of the isolates were found to inhibit LPS-induced NO production in BV-2 cells.

Four new sesquiterpenes, myrrhterpenoids K-N (1-4) have been isolated from the resin of Commiphora myrrha. Their structures and relative configurations were elucidated by spectroscopic methods (IR, ESIMS, HR-ESIMS, 1D and 2D NMR). Compounds 1 and 4 showed neuroprotective effects against MPP(+)-induced neuronal cell death in SH-SY5Y cells.

Three new cadinane sesquiterpenes, commiterpenes A-C, were isolated from the resinous exudates of Commiphora myrrha. Their structures and relative configurations were elucidated by spectroscopic methods (IR, ESIMS, HRESIMS, 1D and 2D NMR). All the isolated sesquiterpenes showed neuroprotective effects against MPP+-induced neuronal cell death in SH-SY5Y cells.

From the fruits of Celastrus orbiculatus, a new alkaloid 3-oxo-4-benzyl-3, 4-dihydro-1H-pyrrolo [2, 1-c] oxazine-6-methylal (1), was isolated. The structure was elucidated on the basis of spectroscopic methods.

A phytochemical investigation of the whole plants of Ajuga decumbens led to the isolation of three new (1, 2a, and 2b) and three known (3a-3c) neo-clerodane diterpenes. Their structures were elucidated by spectroscopic data analysis (IR, ESIMS, HR-ESIMS, 1D and 2D NMR), and the structure of 1 was confirmed by X-ray crystallography. The inhibitory activities on LPS-induced NO production of the six diterpenes were evaluated and compounds 2a, 2b, and 3a showed inhibitory effects.

A new lathyrane diterpene (1), an unreported spectroscopic data lathyrane diterpenene (2), and two known analaogues (3 and 4) have been isolated from Euphorbia prolifera. Their structures were elucidated as (12E,2S,3S,4R,5R,6S,9S,11S,15R)-3-butyryloxy-5,15-diacetoxy-6,17-epoxylathyra- 12-en-14-one (1), (12E,2S,3S,4R,5R,6S,9S,11S,15R)-3-propionyloxy-5,15-diacetoxy-6,17- epoxylathyra-12-en-14-one (2), (12E,2S,3S,4R,5R,6S,9S,11S,15R)-3-benzoyloxy-5,15-diacetoxy -6,17-epoxylathyra-12-en-14-one (3), and 15-O-acetyl-17-hydroxyjolkinol (4) by spectroscopic methods (IR, ESIMS, HR-ESIMS, NMR, and X-ray crystallography). The inhibitory activities on LPS-induced NO production of these diterpenes were evaluated and compounds 1, 3 and 4 showed inhibitory effects.

Three new iridoids, valeriandoids A-C (1-3), together with three known analogues (4-6), were isolated from the roots of Valeriana jatamansi. Their structures and relative configurations were elucidated by spectroscopic methods (IR, ESIMS, HRESIMS, 1D and 2D NMR) and by comparison of their NMR data with those of related compounds. All the isolated compounds were evaluated for their neuroprotective effects and compounds 1, 3, 4 and 6 showed moderate neuroprotective effects.

Three new (1-3) and three known (4-6) neo-clerodane diterpenes have been isolated from the whole plants of Ajuga ciliata Bunge. The structures of the new compounds were elucidated as (12S)-1β,6α,19-triacetoxy-18-chloro-4α,12-dihydroxy-neo-clerod-13-en-15,16-olide (1), (12S,2'S)-12,19-diacetoxy-18-chloro-4α,6α-dihydroxy-1β-(2-methylbutanoyloxy)-neo-clerod-13-en-15,16-olide (2), and (12S)-6α,18,19-triacetoxy-4α,12-dihydroxy-1β-tigloyloxy-neo-clerod-13-en-15,16-olide (3), on the basis of spectroscopic data analysis. All the diterpenes were evaluated for the neuroprotective effects against MPP(+)-induced neuronal cell death in dopaminergic neuroblastoma SH-SY5Y cells and compounds 2-5 exhibited moderate neuroprotective effects.

Two new bakkenolides, valerilactones A (1), and B (2), and two known analogues, bakkenolide-H (3) and bakkenolide-B (4), were isolated from the roots of Valeriana jatamansi. Their structures and relative configurations were elucidated by spectroscopic methods (IR, ESIMS, HRESIMS, 1D and 2D NMR) and by comparison of their NMR data with those of related compounds. Compounds 1, 2, and 3 exhibited potent neuroprotective effects against MPP(+)-induced neuronal cell death in human dopaminergic neuroblastoma SH-SY5Y cells.

By bioactivity-guided isolation, two labdane diterpenes (1 and 2) have been isolated from the bulbs of Fritillaria ebeiensis. Their structures were elucidated as 6α,7β-dihydroxy-labda-8(17),12(E),14-triene (1) and 6-oxo-2α-hydroxy-labda-7,12(E), 14-triene (2), on the basis of spectroscopic data analysis (IR, ESI-MS, HR-ESI-MS, 1D and 2D NMR). Both of the isolates showed neuroprotective effects against MPP(+)-induced neuronal cell death in human dopaminergic neuroblastoma SH-SY5Y cells.

As a part of our ongoing search for plant-derived compounds that inhibit nitric oxide production, the methanol extract of the roots of Vladimiria souliei was found to show significant inhibitory effects on INF-γ-induced nitric oxide production in murine macrophage RAW264.7 cells. Bioactivity-guided isolation of the extract yielded two most active sesquiterpenes, including a new compound, named souliene A (1) and alismol (2). Their structures were elucidated by spectroscopic methods (IR, ESIMS, HRESIMS, 1D and 2D NMR). Two isolates showed promising inhibitory effects on INF-γ-induced nitric oxide production in murine macrophage RAW264.7 cells.