Metabolic and Transcriptomic Approaches of Chitosan and Water Stress on Polyphenolic and Terpenoid Components and Gene Expression in Salvia abrotanoides (Karl.) and S. yangii.

In this research, a HPLC analysis, along with transcriptomics tools, was applied to evaluate chitosan and water stress for the prediction of phenolic flavonoids patterns and terpenoid components accumulation in Salvia abrotanoides Karel and S. yangii. The results indicated that the tanshinone contents under drought stress conditions increased 4.2-fold with increasing drought stress intensity in both species. The rosmarinic acid content in the leaves varied from 0.038 to 11.43 mg/g DW. In addition, the flavonoid content was increased (1.8 and 1.4-fold) under mild water deficit conditions with a moderate concentration of chitosan (100 mg L-1). The application of foliar chitosan at 100 and 200 mg L-1 under well-watered and mild stress conditions led to increases in hydroxyl cryptotanshinone (OH-CT) and cryptotanshinone (CT) contents as the major terpenoid components in both species. The expressions of the studied genes (DXS2, HMGR, KSL, 4CL, and TAT) were also noticeably induced by water deficit and variably modulated by the treatment with chitosan. According to our findings, both the drought stress and the application of foliar chitosan altered the expression levels of certain genes. Specifically, we observed changes in the expression levels of DXS and HMGR, which are upstream genes in the MEP and MVA pathways, respectively. Additionally, the expression level of KSL, a downstream gene involved in diterpenoid synthesis, was also affected. Finally, the present investigation confirmed that chitosan treatments and water stress were affected in both the methylerythritol phosphate pathway (MEP) and mevalonate (MVA) pathways, but their commitment to the production of other isoprenoids has to be considered and discussed.

Variation in Essential Oil Composition, Bioactive Compounds, Anatomical and Antioxidant Activity of Achillea aucheri, an Endemic Species of Iran, at Different Phenological Stages.

In the present research, the essential oil composition, bioactive compounds, anatomical and antioxidant activity of Achillea aucheri were investigated at four phenological stages. The yield of essential oil ranged from 0.1 % (five leaves appearance stage) to 0.7 % (full flowering stage). So, the oils from the plants harvested at the full flowering stage provided higher essential oil contents than those at other stages. The analysis of the essential oils by GC/MS revealed the presence of a large number of components represented mainly by oxygenated monoterpenes (24.36-77.81 %). The compounds revealed high variation at different phenological stages. The major constituents of A. aucheri were carvacrol (1.07-19.17 %), camphor (5.44-9.99 %), δ-cadinene (0.20-13.88 %), thymol (2.15-7.80 %), germacrene D (4.50-7.24 %), 1,8-cineole (1.62-5.54 %) and α-terpineol (1.71-3.42 %). The total phenolic (51.63 mg tannic acid/g DW) and flavonoid (10.88 mg quercetin/g W) contents were more accumulated at the 50 % flowering stage than others. The results revealed that the accumulation of essential oil in A. aucheri increased as the plant grew from the five leaves appearance stage to the 100 % flowering stage with increasing the size and number of secretory structures. Finally, the extracts collected at the 50 % flowering stage showed the highest antioxidant activity as measured based on FTC and DPPH method with the IC50 values ranging from 719.65 µg/mL to 1039.17 µg/mL for the samples.

Variation in Polyphenolic Profiles, Antioxidant and Antimicrobial Activity of Different Achillea Species as Natural Sources of Antiglycative Compounds.

A comparative study was carried out on the methanolic extracts from six Achillea species and the examined polyphenols from these plants on the formation of advanced glycation end-products (AGE) in vitro. A. pachycephala which was richer in flavonoids (15 mg quercetin/g W) and phenolics (111.10 mg tannic acid/g DW) with substantial antioxidant activity (IC50  = 365.5 µg/ml) presented strong anti-AGE properties. Chlorogenic acid, luteolin, quercetin and caffeic acid were identified as the major polyphenols in the extracts by HPLC. In general, polyphenolic content follows the order of A. pachycephalla > A. nobilis > A. filipendulina > A. santolina > A. aucheri > A. millefolium. Most extracts exhibited marked anti-AGE ability in the bovine serum albumin (BSA)/methylglyoxal (MG) system, though A. pachycephala showed the highest potential. The formation of AGEs was assessed by monitoring the production of fluorescent products and circular dichroism (CD) spectroscopy. Diminution in free radical production (assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays) is discussed as potential mechanism for delay or reduced AGE. The results demonstrate the antiglycative, antioxidant and antimicrobial potential of Achillea species which can be attributed to polyphenols content and the effectiveness on generation of AGEs, thus Achillea species can be considered as natural sources for slowing down glycation related diseases.

Mycorrhizal Colonization Modulates the Essential Oil Profile and Enzymatic and Non-Enzymatic Antioxidants to Mitigate the Adverse Effects of Water Deficit in Salvia subg. Perovskia.

Among traditional Iranian herbs, Perovskia species (a subgenus of Salvia), while being valued ornamentals, are also studied for numerous potential pharmacological and therapeutic aspects. The current study was conducted to assess the effectiveness of two species of arbuscular mycorrhizal fungi (AMF), Funneliformis mosseae and Rhizophagus intraradices, separately and in combination, in terms of the essential oil content and compositions along with the enzymatic and non-enzymatic antioxidants in Salvia abrotanoides and S. yangii in response to three levels of irrigation, including 100% FC as well-watered, 75% FC (moderate irrigation deficit), and 50% FC (severe irrigation deficit). In both species, essential oil content, enzyme antioxidant activities, total phenolics, and flavonoids were increased significantly with the severity of stress; this increase was more pronounced in mycorrhizal inoculated herbs. Furthermore, leaf phosphorus concentration, relative water content, chlorophylls a and b, and total carotenoids decreased in parallel with reducing soil moisture; albeit, AMF inoculation improved the stress symptoms under increasing severity of water restriction compared with their control conditions. In addition, the percentage of root colonization was positively correlated with the relative water content (RWC) and leaf phosphorus concentration. Taking into account the essential oil groups, AMF colonization elevated some essential oil components, such as oxygenated monoterpenes, 1,8-cineol, camphor, and borneol, whereas the main sesquiterpenes, including E-ß-caryophyllene and α-humulene, remarkably decreased. Taken together, these findings highlighted the role of symbiosis with AMFs in increasing the tolerance of water deficit stress in S. abrotanoides and S. yangii and improving their essential oil composition.