Phytochemistry最新文献

Indigo and indirubin are derived from indoxyl molecules, which generally occur as indoxyl glycosides in woad (Isatis tinctoria L.) and other indigo-producing plants. Indoxyl glycosides are biosynthesized from indole via 3-hydroxylation to form indoxyl, followed by one or more glycosylations. Enzymes that attach and remove sugars to and from indoxyl have already been isolated and characterized, while enzymes that convert indole into indoxyl in plants have remained elusive, until the identification of P450s and flavin-containing monooxygenases that hydroxylate indole. A P450 gene from woad (named CYP71B102) was heterologously expressed in E. coli, resulting in the formation of indigo and indirubin, as well as isatin and 2-oxindole, which along with indoxyl are putative precursors of indirubin. The addition of either isatin or 2-oxindole to the recombinant E. coli reduced the levels of indigo and increased the amount of indirubin, whereas coexpression of CYP71B102 with isatin hydroxylase (which degrades isatin) increased the levels of indigo and decreased the amount of indirubin, albeit slightly. The results suggest that CYP71B102 hydroxylates indole at both the 2- and 3- positions to produce 2-oxindole and indoxyl, respectively, and that the coupling of indoxyl with either 2-oxindole or isatin forms indirubin, while dimerization of indoxyl forms indigo. This P450 gene is thus likely involved in the biosynthesis of indirubin in woad, as well as the formation of indigo and its glycosidic precursors, even if other types of enzymes, such as flavin-containing monooxygenases, may be involved in indole hydroxylation in other indigo-producing plants.

Twelve undescribed alkaloids, including eight pyrrolo[3,2-g]isoquinoline alkaloids (+)/(−)-anacyquinoline A (1a/1b), (±)-anacyquinoline B (2), (+)/(−)-anacyquinoline C (3a/3b), (±)-anacyquinoline D (4), (±)-anacyquinoline E (5), and (±)-anacyquinoline F (6), together with four pyrrolo[2,3-g]quinoline alkaloids (+)/(−)-anacyquinoline G (7a/7b), (±)-anacyquinoline H (8), and (±)-anacyquinoline I (9), were isolated from the roots of Anacyclus pyrethrum (L.) DC. Their structures were determined via spectroscopic analyses (UV, IR, NMR), HRESIMS, quantum chemical calculations of ECD, DP4+ analysis, and single-crystal X-ray diffraction analysis (Cu Kα). Furthermore, in bioassay, (+)/(−)-anacyquinoline G (7a/7b) and (±)-anacyquinoline H (8) showed inhibition on nitric oxide production in lipopolysaccharide -induced RAW 264.7 cells with IC₅₀ values of 41.4, 44.1, and 31.4 μM, respectively, indicating their potential anti-inflammatory bioactivity.

In order to elucidate the mass fragmentation patterns and unveil more undescribed ophiobolin analogs, the mass fragmentation patterns of ophiobolins were analyzed based on UPLC-Q-TOF-MS/MS experiments. Different kinds of rearrangements (including McLafferty rearrangement) were the main cleavage patterns. Twenty-six (9–31) analogs were then tentatively characterized based on their mass analysis, and three undescribed ophiobolins (6–8) and a known analogue (5) were isolated in target. Compound 5 possesses a rare polycyclic carbon skeleton only recently reported, and compound 6 contains an undescribed lactone ring system fused with A/B ring at C-3/C-21, whereas compounds 7 and 8 have a peroxyl group in the side chain, which is the first reported in all ophiobolins. Compounds 5 and 7 displayed significant cytotoxicity against MCF-7 cancer cells.

Guided by a probe-based molecular networking strategy, five undescribed cycloheptapeptides, phakefusins A−E (1−5), were isolated from the marine sponge Phakellia fusca. Compounds 1 and 2 contain the nonproteinogenic amino acid residues of dioxindolyalanine (Dioia) and β-3-oxindolylalanine (Oia), respectively. Compound 3 possesses a unique methionine sulfoxide, whereas compound 5 includes a glutamic acid ethyl ester unit. Their structures were elucidated through NMR spectroscopy, HR-MS/MS analysis, and the advanced Marfey's method. By synthesizing the (S, S/R)-Oia standard through tryptophan oxidation, we determined the configuration of this amino acid in compound 2 using the advanced Marfey's method. These cycloheptapeptides were evaluated for their antitumor, antibacterial, and antioxidant activities. Compound 1 showed moderate cytotoxicity against MCF-7 and PC9 cells, with IC₅₀ values of 6.8 and 9.6 μM, respectively, while compounds 2−5 demonstrated potential antioxidant effects by upregulating HO-1, NQO1, and SOD2 levels, as well as inducing Nrf2 activation.

LC-HRMS/MS-based molecular networking was applied to investigate the bioactive sesquiterpene lactones and their analogs contained in Inula helenium, enabling the isolation of four undescribed eudesmane-eudesmane sesquiterpene dimers (1–4), a sesquiterpene-amino acid adduct (5), and 17 known sesquiterpenes (6–22). The structures were determined based on 1D, 2D NMR, and HRESIMS data analysis, as well as DP4+ probability analyses and ECD calculations. The biosynthetic pathway of the sesquiterpene dimers is postulated to proceed via the Diels-Alder reaction as the key step. The inhibitory activity of all isolates on LPS-induced nitric oxide (NO) production in RAW 264.7 macrophages was evaluated. Compounds 4, 17, and 20 exhibited significant inhibitory activity against NO production, with IC₅₀ values of 8.4, 5.5, and 9.1 μM, respectively.

A comprehensive phytochemical investigation of the flower buds and leaves/twigs of Heptacodium miconioides, a cultivated ornamental plant native to China and categorized as ‘vulnerable’, has led to the isolation of 45 structurally diverse compounds, which comprise 18 phenylpropanoids (1–4, 7–20), 11 pentacyclic triterpenoids (5, 6, 21–29), eight secoiridoid glycosides (30–37), three quinic acid derivatives (38–40), and a few miscellaneous components (41–45). Among them, (+)-α-intermedianol (1), (+)-holophyllol A (2), and (−)-pseudolarkaemin A (3) represent previously unreported enantiomeric lignans, while (+)-7′(R)-hydroxymatairesinol (4) is an undescribed naturally occurring lignan. Heptacoacids A (5) and B (6) are undescribed 24-nor-urs-28-oic acid derivatives. Their chemical structures were determined by 2D-NMR, supplemented by evidence from specific rotations and circular dichroism spectra. Given the uncertainty surrounding the systematic position of Heptacodium, integrative taxonomy (ITA), a method utilized to define contentious species, is applied. Chemotaxonomy, a vital aspect of ITA, becomes significant. By employing hierarchical clustering analysis (HCA) and syntenic pattern analysis methods, a taxonomic examination based on the major specialized natural products from the flower buds of H. miconioides and two other Caprifoliaceae plants (i.e., Lonicera japonica and Abelia × grandiflora) could offer enhanced understanding of the systematic placement of Heptacodium. Additionally, compounds 39 and 40 displayed remarkable inhibitory activities against ATP-citrate lyase (ACL), with IC₅₀ values of 0.11 and 1.10 μM, respectively. In summary, the discovery of medical properties and refining systematic classification can establish a sturdy groundwork for conservation efforts aimed at mitigating species diversity loss while addressing human diseases.

Fourteen undescribed diterpenoids, including eleven lathyrane diterpenoids wallathyanes A-K (1–11) and three ent-isopimarane diterpenoids wallisopiranes A-C (12–14), together with fourteen known analogues 15–28, were obtained from the whole plant of Euphorbia wallichii. Their chemical structures were elucidated by spectroscopic data analysis, experimental electronic circular dichroism measurements, and X-ray crystallography. Bioactivity screening indicated that compound 2 exhibited an inhibitory effect on NO generation in LPS-stimulated RAW264.7 macrophage cells with an IC₅₀ value of 4.76 ± 1.08 μM. The network pharmacology and molecular docking studies also revealed that compound 2 can bind with the potential targets GRB, AKT1, MAPK1, MAPK14, HSP90AA1, PIK3R1, PIK3CB, PRKACA, SRC, CASP3, RXRA, PTPNA11, ZAP70, and PRKC of inflammation.

Seven previously undescribed compounds, including one amino acid hybrid sesquiterpene areolatol A (1), two unusual natural sesquiterpenoid skeleton areolatones A-B (2-3) and four benzo[j]fluoranthene areolaranes A-D (4–7) were characterized from Annulohypoxylon areolatum. The structures of the compounds were determined by extensive spectroscopic analysis, X-ray diffraction analysis, and ECD and NMR computational. Notably, areolatol A (1) was the first reported sesquiterpene featuring a 5/7/3-ring system and hybridized with two molecular amino acids. In addition, areolaranes A-D (4–7) were identified as possible chemophenetic markers.

The plant genus Tacca comprises twenty species including Tacca plantaginea, essentially distributed in the Indo-China region. Medicinal preparations from the rhizomes are used traditionally to treat gastrointestinal ailments, stomach aches and inflammatory disorders. A variety of bioactive molecules have been isolated from T. plantaginea, including potent anticancer steroids such as the taccanolides which interfere with microtubules dynamic. Other efficient anticancer natural products have been isolated from the plant, in particular a series of diosgenin/yamogenin-type sapogenins including taccaoside (monodesmosidic) and taccaoside A (bidesmosidic). Taccaoside A displays marked anticancer properties through two complementary mechanisms: a direct action on cancer stem cells via HRas and Pi3K/Akt signaling and an indirect immunomodulatory action via activation of cytotoxic T cells. A similar mechanism of action has been invoked with a total saponin extract from Schizocapsa plantaginea Hance (synonym to T. plantaginea) and the saponin SSPH 1. This saponin reduced tumor growth in mice through stimulation of cytotoxic T lymphocytes. Other bioactive products have been isolated from T. plantaginea, including withanolide-type steroids (plantagiolides, chantriolides), diarylheptanoids (plantagineosides) and different saponins (diosbulbisides, lieguonins). The discussion centers around the mechanism of action of spirostanol saponins, with the objective to promote their study as immuno-active anticancer agents.

Cultivation and extraction of the fungus Stereum hirsutum (Willd.) Pers. yielded 12 isopentenyl benzene derivatives, including six previously undescribed derivatives, named stereuins A–F. Their structures were established based on NMR and mass spectroscopy analyses, supplemented by comparison with previously reported data. Stereuins A–C are unique benzoate derivatives containing fatty acid subunits. Stereuins D and E feature a valylene group and a 6/6/6 ring system. In vitro, stereuin A significantly promoted neurite outgrowth. Several compounds exhibited antibacterial activity against Staphylococcus aureus. Stereuin F has an IC₅₀ value of 5.2 μg/mL against S. aureus, comparable to the positive control, penicillin G sodium (1.4 μg/mL).