Essential Oil from Vietnamese Peperomia leptostachya Hook. & Arn. (Piperaceae): Chemical Composition, Antioxidant, Anti-Inflammatory, Cytotoxic Activities, and In Silico Analysis.

This study is the first to investigate the chemical composition and antioxidant, anti-inflammatory, and cytotoxic activities of Peperomia leptostachya leaf oil. A yellow oil was obtained through hydro-distillation, with a yield of 0.1% (w/w). The GC-MS analysis revealed 66 compounds, constituting 99.6% of the oil. Sesquiterpene hydrocarbons predominated (70.4%), followed by monoterpene hydrocarbons (13.2%), oxygenated sesquiterpenes (12.4%), non-terpenic compounds (2.0%), and oxygenated monoterpenes (1.6%). Major constituents included germacrene D (25.1%), (E)-caryophyllene (17.4%), bicyclogermacrene (6.6%), α-pinene (6.2%), and ß-pinene (4.7%). The assessment of antioxidant capacity via 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay yielded a weak effect, with an IC50 value > 100 µg/mL. The inhibition of lipopolysaccharide-induced nitric oxide production in RAW 264.7 cells was quantified using the MTT assay, showing an IC50 value of 15.15 ± 0.68 µg/mL. Furthermore, cytotoxic effects on SK-LU-1 cell line growth were evaluated using the sulforhodamine B assay, resulting in an IC50 value of 37.45 ± 2.43 µg/mL. The anti-inflammatory activity was notable among the analyzed bioactivities of this oil. By employing a computational model, the predominant secondary metabolites in the essential oil were selected as candidates for interaction analysis with cyclooxygenase-2, an enzyme implicated in the inflammatory response. Our findings suggest that P. leptostachya leaf oil could serve as a potential source of natural compounds with prospective therapeutic effects in treating inflammatory conditions.

Conamonin A and dihydrochalcones from the whole plants of Conamomum rubidum (Lamxay & N.S.Lý) Skornick. & A.D. Poulsen showing anti-inflammatory and cytotoxic activities.

A new compound, conamonin A (1), was isolated from the whole plants of Conamomum rubidum with eight known dihydrochalcones (2-9). Their structures were elucidated by a combination of spectroscopic methods as well as by comparison with previously reported data. The absolute configuration of 1 was assigned by TDDFT-ECD method. Compounds 1 and 8 showed inhibitory activity against LPS-induced NO production in the RAW 264.7 cells, with IC50 values of 58.29 ± 2.88 and 81.77 ± 5.99 µM, respectively. Compounds 3/4 and 5/6 exhibited inhibitory effects, with IC50 values of 28.76 ± 1.16 and 29.89 ± 1.79 µg/mL, respectively. Compounds 2, 7-9 exhibited significant cytotoxic activity against human lung carcinoma (the SK-LU-1 cell line) with IC50 values ranging from 9.87 to 17.99 µM. This study offers valuable insights into the chemical constituents and biological activities of Conamomum rubidum, highlighting its potential as a source for discovering new anti-inflammatory and cytotoxic agents.

Homalolides C-D, two new sesquiterpenoids from the rhizomes of Homalomena pendula.

Two new sesquiterpenoids, homalolides C - D (1‒2), were co-isolated from the rhizomes of Homalomena pendula (Blume) Bakh.f collected in Vietnam with five known ones, aromadendrane-4α,10α-diol (3), bullatantriol (4), 1ß,4ß,6α-trihydroxy-eudesmane (5), 1ß,4ß,6ß-trihydroxyeudesmane (6), and 1ß,4ß,7α-trihydroxy-eudesmane (7). The structures and relative configuration of new compounds were elucidated by 1 D-/2D-NMR, IR, UV and HRESIMS analyses, and by comparisons to the reported data in the literature. Homalolide C presented an unprecedented skeleton with the 4/8 bicyclic system. All isolates did not exhibit appreciable inhibitory effects on LPS-induced NO production in the RAW 264.7 macrophage cell line and on the growth of human lung cancer cell line (SK-LU-1).

Isolation, structural elucidation, and cytotoxic activity investigation of novel styryl-lactone derivatives from Goniothalamus elegans: in vitro and in silico studies.

Two styryl-lactone derivatives (1 and 2) were isolated from the aerial parts of Goniothalamus elegans. Compound 1 is a newly discovered natural product, and compound 2 is reported in this plant for the first time. The absolute configuration of 1 was determined based on the ECD spectrum. The two styryl-lactone derivatives were tested for cytotoxicity activity against five cancer cell lines and human embryonic kidney cells. The newly discovered compound demonstrated potent cytotoxicity, with IC50 values ranging from 2.05 to 3.96 µM. Computational methods were also applied to investigate the mechanism of the cytotoxic activity of the two compounds. Density functional theory and molecular mechanisms were used to assess the interaction between protein targets to compound 1 and 2, respectively, through the EGF/EGFR signaling pathway. The results indicated that 1 showed a strong binding affinity for two proteins EGFR and HER-2. Finally, ADMET predictions were used to validate the pharmacokinetics and toxicity of these compounds. The results showed that both compounds are likely to be absorbed in the gastrointestinal tract and penetrate the blood-brain barrier. Based on our findings, these compounds may have potential for further studies to be developed into active ingredients for cancer treatment.

Structure revision and absolute configuration of 5,7-diepi-2α-hydroxyoplopanone and anti-osteoporotic activities of sesquiterpenoids from the rhizomes of Homalomena pendula.

Five sesquiterpenoids including 2α-hydroxyoplopanone (1), oplopanone (2), 1ß,4ß,6α-trihydroxy-eudesmane (3), 1ß,4ß,7α-trihydroxy-eudesmane (4) and bullatantriol (5) were isolated from Homalomena pendula. The structure of the previously reported compound, 5,7-diepi-2α-hydroxyoplopanone (1a), has been revised to 1 by the spectroscopic evidences (1D-/2D-NMR, IR, UV and HRESIMS) and by comparison between experimental and theoretical NMR data using DP4+ protocol. Furthermore, the absolute configuration of 1 was unambiguously assigned by ECD experiments. Compounds 2 and 4 displayed a potent ability to stimulate osteogenic differentiation of MC3T3-E1 cells at 4 µg/mL (by 123.74% and 131.07%, respectively) and 20 µg/mL (by 112.45% and 126.41%, respectively) whilst 3 and 5 did not show any activities. At 20 µg/mL, 4 and 5 significantly promoted the mineralization of MC3T3-E1 cells with values of 112.95% and 116.37%, respectively, whereas 2 and 3 were inactive. The results indicated that 4 could be an excellent component for anti-osteoporosis studies from the rhizomes of H. pendula.

Sesquiterpenoids from the rhizomes of Homalomena pendula and their anti-inflammatory activities.

Sixteen sesquiterpenoids including two new ones, homalolides A - B (1‒2), were firstly isolated from the methanolic extract of the rhizomes of Homalomena pendula collected in Vietnam. The structures and relative stereochemistry of new compounds were elucidated by 1D-/2D-NMR, IR, UV and HRESIMS analyses. The GCMS experiment demonstrated that homalolide A (1) is an artifact due to the methylation during methanolic extraction process. All isolates (1‒16) were tested for their inhibitory activities against lipopolysaccharide-induced nitric oxide production in the RAW 264.7 macrophage cell line. Compounds 1, 3, 6‒8, 10‒12 displayed moderate inhibitory effect on NO production with IC50 values ranging from 35.41 to 64.06 µM.