Phylogenetics of Taxus Using the Internal Transcribed Spacers of Nuclear Ribosomal DNA and Plastid trnL-F Regions

Mycorrhizal symbiosis in Taxus: a review

Taxus, a genus of conifers known for its medicinal significance, faces various conservation challenges with several species classified under different threat categories by the IUCN. The overharvesting of bark and leaves for the well-known chemotherapy drug paclitaxel has resulted in its population decline. Exploring the mycorrhizal relationship in Taxus is of utmost importance, as mycorrhizal fungi play pivotal roles in nutrition, growth, and ecological resilience. Taxus predominantly associates with arbuscular mycorrhizal fungi (AM), and reports suggest ectomycorrhizal (EM) or dual mycorrhizal associations as well. This review consolidates existing literature on mycorrhizal associations in Taxus species, focusing on structural, physiological, and molecular aspects. AM associations are well-documented in Taxus, influencing plant physiology and propagation. Conversely, EM associations remain relatively understudied, with limited evidence suggesting their occurrence. The review highlights the importance of further research to elucidate dual mycorrhizal associations in Taxus, emphasizing the need for detailed structural and physiological examinations to understand their impact on growth and survival.

Assessment of Morphological, Anatomical and Palynological Variation in the Medicinal Plant Disporopsis longifolia Craib (Asparagaceae) for Botanical Quality Control

Disporopsis longifolia Craib is an Asian medicinal plant belonging to the Asparagaceae family. The plants are well known for their steroidal saponins and phenolic compounds and are traditionally used as tonics for back pain, bellyache, cough, diabetes, asthma, pneumonia and rheumatism. However, they are challenging to identify to species level using morphology. This raises a serious concern for their medicinal applications where botanical quality control is essential. The most appropriate morphological, anatomical and pollen characters for species diagnosis were therefore determined. Synonyms were identified and lectotypification provided. The morphological characters were described from 76 fresh and dried specimens to include a broad range of materials from differing habitats and locations. Paraffin and peeling methods were applied for anatomical studies of leaves and stems and a modified acetolysis method was undertaken for pollen morphology. This paper compares the new character data to published data from other species in the genus, namely D. aspersa, D. fuscopicta, D. jinfushanensis, D. pernyi and D. undulata. This is the first report of such anatomical and pollen morphology characters for D. longifolia. The results provide accurate morphological, anatomical and palynological characters for quality control and are best applied in combination with each other.

Flavonoid profile and antioxidant properties of Algerian common yew (Taxus baccata L.)

Background

In humans, various diseases are associated with the accumulation of free radicals. The antioxidants can scavenge free radicals and reduce their impact; thus, the search for effective natural antioxidants of plant origin is indispensable. The present study aims to determine, for the first time, the flavonoid compounds profile and to investigate the free radical scavenging and antioxidant properties of the methanolic extract of Taxus baccata L. from Algeria.

Methods

The determination of the flavonoid compound profile of the methanolic extract of Taxus baccata L. was established using high-performance liquid chromatography with diode-array detection coupled to electrospray ionization tandem mass spectrometry (HPLC–DAD–ESI–MS/MS). The total flavonoid content (TFC) was performed according to the aluminum chloride colorimetric method, while the free radical scavenging and antioxidant activities were carried out using three methods, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay, 2,2'-azino-bis3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical assay and ferric reducing antioxidant power (FRAP) Assay.

Results

A total of 26 compounds including flavon-3-ols, flavanonols, flavones, flavonols and bioflavonoids were characterized and identifiedusing HPLC–DAD–ESI–MS/MS analysis, five were reported for the first time such as taxifolin, apigenin, apigenin 7-O-glucoside, isorhamnetin 3-O-rutinoside and robustaflavone. The plant extract exhibited high total flavonoid content (TFC = 204.26 ± 6.02 mg RE/g dry extract) which corresponded to its strong radical scavenging activities [(DPPH IC50 = 35.31 ± 0.29 µg/ml and ABTS IC50 = 8.27 ± 0.52 µg/ml)] as compared to the synthetic antioxidant BHT [(DPPH IC50 = 78.96 ± 5.70 µg/ml and ABTS IC50 = 13.56 ± 0.06 µg/ml)]. However, the methanolic extract of T. baccata showed the lowest ferric reducing ability as compared to the positive controls (BHT, BHA, ascorbic acid, trolox and quercetin).

Conclusion

Our results imply that the Taxus Baccata L. might be a potential source for the isolation of natural antioxidant compounds.

Taxanes and taxoids of the genus Taxus - A comprehensive inventory of chemical diversity

The pseudoalkaloid diterpene Taxol® (paclitaxel) emerged as a best-selling anti-cancer drug in the mid-1990s. The compound attracted considerable interest because of its unique mechanism to stabilize microtubules, thus reducing dynamicity and ultimately promoting mitotic arrest. Taxol was originally isolated from members of the genus Taxus. Over the last 50 years, close to 600 metabolites with taxane scaffolds were isolated from various Taxus species and their structures reported. The present review article provides an overview of the known chemical diversity of taxanes, with an emphasis on the functionalization of diterpene scaffolds. The implications of the occurrence of chemically diverse taxane metabolites for unraveling Taxol biosynthesis and enabling pathway engineering are discussed as well.

Investigation of bioactivities of Taxus chinensis, Taxus cuspidata, and Taxus × media by gas chromatography-mass spectrometry

Taxus species have attracted much attention for their potency in cancer treatment. However, investigating the bioactivities of Taxus species is a complex task, due to their diversity, slow growth, and endangered state. The most important Taxus species in China are Taxus chinensis (T. chinensis), Taxus cuspidata (T. cuspidata), and Taxus × media (T. media), which mainly grow in the northeastern region. This article probes deep into the differences among the leaves of T. chinensis, T. cuspidata, and T. media, with the aid of gas chromatography-mass spectrometry (GC-MS). Through GC-MS, 162 compounds were detected in the samples and found to contain 35 bioactive metabolites. On this basis, 20 metabolites with significant bioactivities (antibiotic, antioxidant, anticancer, and antiaging effects) were identified via unsupervised learning of principal component analysis and supervised learning of partial least squares-discriminant analysis. The results show that T. media has the most prominent antibiotic, antioxidant, and anticancer effects, while T. cuspidata has the most diverse and abundant metabolites that slow down aging.

Repeated intercontinental migrations and recurring hybridizations characterise the evolutionary history of yew (Taxus L.)

The genus Taxus (Taxaceae) consists of 16 genetically well-defined lineages that are predominantly distributed across the Northern hemisphere. We investigated its biogeographic origin and evolutionary history by sampling 13 chloroplast gene sequences, the nuclear internal transcribed spacers (ITS) and NEEDLY sequences for all 16 lineages. We applied Maximum Parsimony and Bayesian Inference analyses to infer their phylogenetic relationships, time-calibrated phylogenies using BEAST and inferred the ancestral area of occupancy with BioGeoBEARS. We found strong evidence for the hybrid origin of three lineages and dated these events to a rather narrow time window of 6.8-4.9 million years ago (Mya). The dated phylogenies inferred an Upper Cretaceous origin of the genus, with the extant lineages diversifying in North America much later during the Oligocene/early Miocene. Repeated migrations via the Bering land bridge to Eurasia and back were further inferred, with the return to North America as a possible result of vicariance. The diversification in Eurasia (from ~8 Mya onwards) coincided with the orogeny of the Hengduan Mountains, the intensification of the East Asian summer monsoon and the occupancy of ecological niches by lineages that experienced secondary contacts and hybridizations in the Hengduan Mountains and Qinling Mountain, especially around the Sichuan basin. We provide a hypothesis for the evolution of extant lineages of Taxus, a genus with an old and complex evolutionary history. The study highlights that the history of complex species can be unravelled with a careful dissection of phylogenetic signals.