Search Results (3)

Phlomoides rotata is a traditional Chinese herbal medicine that grows in the Qinghai–Tibet Plateau region at a 3100–5000 m altitude. Iridoid compounds are the main active compounds of the P. rotata used as medical ingredients and display anti-inflammatory, analgesic, and hepatoprotective properties. To better understand the biological mechanisms of iridoid compounds in this species, we performed a comprehensive analysis of the transcriptome and metabolome of P. rotata leaves from four different regions (3540–4270 m). Global metabolome profiling detected 575 metabolites, and 455 differentially accumulated metabolites (DAMs) were detected in P. rotata leaves from the four regions. Eight major DAMs related to iridoid metabolism in P. rotata leaves were investigated: shanzhiside methyl ester, 8-epideoxyloganic acid, barlerin, shanzhiside, geniposide, agnuside, feretoside, and catalpin. In addition, five soil physical and chemical indicators in P. rotata rhizosphere soils were analyzed. Four significant positive correlations were observed between alkaline nitrogen and geniposide, exchangeable calcium and geniposide, available potassium and shanzhiside, and available phosphorus and shanzhiside methyl ester. The transcriptome data showed 12 P. rotata cDNA libraries with 74.46 Gb of clean data, which formed 29,833 unigenes. Moreover, 78.91% of the unigenes were annotated using the eight public databases. Forty-one candidate genes representing 23 enzymes involved in the biosynthesis of iridoid compounds were identified in P. rotata leaves. Moreover, the DXS1, IDI1, 8-HGO1, and G10H2 genes associated with iridoid biosynthesis were specifically expressed in P. rotata. The integration of transcriptome and metabolome analyses highlights the crucial role of soil physical and chemical indicators and major gene expression related to iridoid metabolism pathways in P. rotata from different areas. Our findings provide a theoretical foundation for exploring the molecular mechanisms underlying iridoid compound accumulation in P. rotata. Full article

Nepeta cyrenaica Quézel & Zaffran (Lamiaceae), an endemic species of the Libyan flora, has been scarcely explored until now. Since Nepeta species are proven as pharmacologically active plants rich in iridoid monoterpenes, this study was aimed to quantify the iridoids present in different extracts of in vitro propagated N. cyrenaica. The seeds collected from their natural habitat were germinated. One node stem explant of 5-week-old plants were used for plant micropropagation. After several cycles, the shoots were harvested. The extraction was performed using maceration procedure by dichloromehane, methanol, 96% ethanol, and hot distilled water. Subsequently, the extracts were subjected to UHPLC/(±)HESI-MS2 analysis of iridoids. Two iridoids were identified and quantified, namely epideoxyloganic acid and nepetalactol, as well as their precursor 8-oxogeranial. Iridoid glucoside epideoxyloganic acid was the most abundant in the methanolic and ethanolic extracts (1255.37 and 1262.78 µg/100 g dry extract), followed by aqueous extract. On the other hand, 8-oxogeranial and nepetalactol reached maximal amounts in the dichloromethane extract (476.80 and 1039.52 µg/100 g dry extract, respectively). The results of this study indicate that the high antioxidant and enzyme-inhibiting effects of dichloromethane extract confirmed in our previous study could be attributed to its iridoid content, which was particularly high due to the low polarity of this extraction solvent. In conclusion, endemic N. cyrenaica could be efficiently propagated in vitro as an iridoid-rich plant with great biological potential. Full article

Two Balkan Peninsula endemics, Nepeta rtanjensis and N. argolica subsp. argolica, both characterized by specialized metabolite profiles predominated by iridoids and phenolics, are differentiated according to the stereochemistry of major iridoid aglycone nepetalactone (NL). For the first time, the present study provides a comparative analysis of antimicrobial and immunomodulating activities of the two Nepeta species and their major iridoids isolated from natural sources—cis,trans-NL, trans,cis-NL, and 1,5,9-epideoxyloganic acid (1,5,9-eDLA), as well as of phenolic acid rosmarinic acid (RA). Methanol extracts and pure iridoids displayed excellent antimicrobial activity against eight strains of bacteria and seven strains of fungi. They were especially potent against food-borne pathogens such as L. monocytogenes, E. coli, S. aureus, Penicillium sp., and Aspergillus sp. Targeted iridoids were efficient agents in preventing biofilm formation of resistant P. aeruginosa strain, and they displayed additive antimicrobial interaction. Iridoids are, to a great extent, responsible for the prominent antimicrobial activities of the two Nepeta species, although are probably minor contributors to the moderate immunomodulatory effects. The analyzed iridoids and RA, individually or in mixtures, have the potential to be used in the pharmaceutical industry as potent antimicrobials, and in the food industry to increase the shelf life and safety of food products. Full article