Exploring the cytotoxic potential of biflavones of Araucaria cunninghamii: Precise identification combined by LC-HRMS-metabolomics and database mining, targeted isolation, network pharmacology, in vitro cytotoxicity, and docking studies.

The leaves of Araucaria cunninghamii are known to be nonedible and toxic. Previous studies have identified biflavones in various Araucaria species. This study aimed to investigate the in vitro cytotoxicity of the isolated compounds from Araucaria cunninghamii after metabolomics and network pharmacological analysis. Methanol extract of Araucaria cunninghamii leaves was subjected to bioassay-guided fractionation. The active fraction was analyzed using LC-HRMS, through strategic database mining, by comparing the data to the Dictionary of Natural Products to identify 12 biflavones, along with abietic acid, beta-sitosterol, and phthalate. Eight compounds were screened for network pharmacology study, where in silico ADME analysis, prediction of gene targets, compound-gene-pathway network and hierarchical network analysis, protein-protein interaction, KEGG pathway, and Gene Ontology analyses were done, that showed PI3KR1, EGFR, GSK3B, and ABCB1 as the common targets for all the compounds that may act in the gastric cancer pathway. Simultaneously, four biflavones were isolated via chromatography and identified through NMR as dimeric apigenin with varying methoxy substitutions. Cytotoxicity study against the AGS cell line for gastric cancer showed that AC1 biflavone (IC50 90.58 µM) exhibits the highest cytotoxicity and monomeric apigenin (IC50 174.5 µM) the lowest. Besides, the biflavones were docked to the previously identified targets to analyze their binding affinities, and all the ligands were found to bind with energy ≤-7 Kcal/mol.

LCMS-DNP based dereplication of Araucaria cunninghamii Mudie gum-resin: identification of new cytotoxic labdane diterpene.

As a part of natural defense, plants initiate the secretion of gum containing numerous pharmacologically active essential metabolites. A fraction of such gum-resin from Araucaria cunninghamii Mudie, when screened against human cancer cell lines, was found to be active. Further, it was subjected to an LCMS-DNP (Dictionary of Natural Products) based dereplication study followed by a detailed phytochemical investigation to obtain pure metabolites. Also, the gum resin of A. cunninghamii was found to be a rich source of abietanes and labdanes. The LCMS-DNP-based dereplication study identified many known metabolites, which were isolated for the first time from this plant as well as a new labdane diterpenoid (9). The compounds were characterized via spectroscopic techniques, which were subsequently compared with the already existing literature data. The metabolites were screened against seven human cancer cell lines. The anticancer activity was further supported by molecular docking studies.

Phytochemical constituents, antimicrobial and antioxidant activities of Kumaun Himalayan Hoop Pine bark extract.

The chemical composition of the methanol extract obtained from Araucaria cunninghamii Sweet. bark was determined by GC-MS analysis with its antioxidant and antibacterial potential, for the first time. A total of 73 compounds were identified and the extract was strongly characterised by Viridiflorene; Androstan-17-one, 3-ethyl-3-hydroxy-, (5α)-; 8-Isopropenyl-1,3,3,7-tetramethyl-bicyclo[5.1.0]oct-5-en-2-one; 3,6,9-Triethyl-3,6,9-trimethyl-tetracyclo[6.1.0.0 ∼ 2,4∼.0 ∼ 5,7∼]-nonane; Longifolenaldehyde; (-)-Caryophyllen-(I1); 2-hydroxymethyl-5-furfural; Methyl commate B; 3-Ethyl-3-hydroxyandrostan-17-one; 3-Hydroxybenzoic acid as the main components (55.39%). A. cunninghamii extract presents IC50, 53.52 µg/mL and 65.29 µg/mL using DPPH and H2O2 scavenging assay, respectively. The antibacterial activity of the extract was evaluated for eight microorganisms showed that the extract had a remarkable inhibitory potential with a mean zone diameter of inhibition ranging from 09 to 21 mm. The methanol extract of A. cunninghamii showed significant antibacterial activity against X. campestris (21 mm, ZOI) with MIC and MBC values 15.6 and 31.25 µg/mL, respectively.

The complete chloroplast genome of Araucaria cunninghamii (Araucariaceae).

The chloroplast genome of the Araucaria cunninghamii has been completely sequenced. The genome size is 146,337 bp, and the overall GC content is 36.7%. This cp genome does not contain cannonical IRs, it encodes a total 122 genes including 82 protein-coding genes, 36 tRNA genes and four rRNA genes. Among them, eight protein-coding genes (rpl2, rpl16, petB, petD, rpoC1, atpF, ndhA and ndhB) have two exon, and two genes (rps12 and ycf3) have three exons. Also, trnI-CAU and rrn5 has two copies. The Maximum-likelihood tree shows that A. cunninghamii is sister to A. heterophylla.

Drought avoidance and vulnerability in the Australian Araucariaceae.

The Araucariaceae is an iconic tree family. Once globally important, the Araucariaceae declined dramatically over the Cenozoic period. Increasing aridity is thought to be responsible for extinction and range contraction of Araucariaceae in Australia, yet little is known about how these trees respond to water stress. We examined the response to water stress of the recently discovered tree Wollemia nobilis Jones, W.G., Hill, K.D. & Allen, J.M. (Araucariaceae) and two closely related and widespread tree species, Araucaria bidwillii Hook. and Araucaria cunninghamii Mudie, and the island-endemic species, Araucaria heterophylla (Salisb.) Franco. Leaf water potential in all Araucaria spp. remained remarkably unchanged during both dehydration and rehydration, indicating strong isohydry. The xylem tensions at which shoot and stem hydraulic conductances were reduced to 50% (P50shoot and P50stem) were closely correlated in all species. Among the four species, W. nobilis exhibited greater resistance to xylem hydraulic dysfunction during water stress (as indicated by P50shoot and P50stem). Unexpectedly, W. nobilis also experienced the highest levels of crown mortality in response to dehydration, suggesting that this was the most drought-sensitive species in this study. Our results highlight that single traits (e.g., P50) should not be used in isolation to predict drought survival. Further, we found no clear correlation between species' P50 and rainfall across their distributional range. Diversity in drought response among these closely related Araucariaceae species was surprisingly high, considering their reputation as a functionally conservative family.