Sustainable Use of Greek Herbs By-Products, as an Alternative Source of Biologically Active Ingredients for Innovative Products

Abstract

The processing of medicinal and aromatic plants (MAPs) results in the production of a significant amount of plant by-products; herbal material of inferior quality and/or unusable plant parts that are not commercially exploitable. An extensive study of Greek native species was performed toward the production of innovative bioactive products using as raw materials the by-products obtained from the processing of cultivated MAPs. Origanum vulgare subsp. hirtum (oregano), Sideritis scardica (Greek mountain tea), Thymus vulgaris (thyme), and Matricaria recutita (chamomile) were selected due to their wide use for the preparation of beverages and culinary purposes. The determination of the percentage of the post-harvest processing by-products was performed for a 3 years period (2018–2020). Results showed that by-products derived from the above-mentioned species' processing constitute 64% (thyme), 54% (oregano), 37% (Greek mountain tea), and 24% (chamomile) of the total processed mass. To value the by-products as a potent source of bioactive ingredients, superior and inferior quality herbal material of the aforementioned plant species were extracted by an ultrasonic assisted extraction method. Hydroalcoholic extracts were chemically investigated using high-performance thin layer chromatography (HPTLC) and liquid chromatography-mass spectrometry (LC-MS) techniques. In addition, their free radical scavenging activity and total phenolic content (TPC) were estimated. Based on the results, herbs by-products revealed similar chemical content to the superior herbal material by the means of HPTLC and LC-MS analysis. In addition, strong free radical scavenging related to a high phenolic content was detected in the case of thyme, oregano, and Greek mountain tea. Moreover, the gas chromatography-mass spectrometry (GC-MS) analyses of the essential oils (EOs) of oregano and thyme by-products revealed the presence of carvacrol, thymol, γ-terpinene, and p-cymene among the major constituents. Finally, the LC-MS analyses of aqueous extracts of Greek mountain tea and chamomile by-products led to the identification of several bioactive compounds, such as flavonoids and phenylpropanoids. Overall, the presence of bioactive constituents in by-products, such as terpenes, phenolic compounds, and flavonoids underly their potent use as food antimicrobial and antioxidant additives, in the preparation of high added-value products, such as enriched aromatic edible oils, and innovative herbal teas, such as instant beverages.

Comparative Study on Assisted Solvent Extraction Techniques for the Extraction of Biologically Active Compounds from Sideritis raeseri and Sideritis scardica

“…Compound 86 also gave characteristic fragments of m / z 145.02838 which correspond to a loss of apigenin and hexose unit [M−H−270−162] − and 413.0878 was produced by the loss of coumaroyl moiety [M−H−164] − , hence it was identified as apigenin-7-O-(6″-O-4-coumaroyl)-beta-glucoside (echinacin). Additionally, this compound was previously reported in S. scardica and S. raeseri [ 23 , 24 ].…”

Sideritis scardica Extracts Demonstrate Neuroprotective Activity against Aβ25–35 Toxicity

“…Specifically, in mice, SS extracts have been shown to decrease soluble Aβ 1-42 and Aβ aggregation by enhancing the phagocytic microglia response of Aβ and inducing the expression of a-secretase ADAM10, which cleaves Aβ [36]. Here, we show that four SS extracts (SSDM, SSM, SSW1, and SSDE) can also reduce the cytotoxic activity of Aβ [25][26][27][28][29][30][31][32][33][34][35] , with SSW1 showing this potential in differentiated cells as well. In addition, for the first time, we present neuroprotectivity in SS extracts generated by using less-polar solvents, such as dichloromethane.…”

“…Sideritis scardica (SS), with the alias "mountain tea", is a medicinal, aromatic plant commonly used in Mediterranean countries to prepare medicinal herbal infusions. Mountain tea has a long tradition of usage in the Balkans ethnomedicine for treating the common cold and gastrointestinal disorders, while it is thought to maintain antioxidant and antiinflammatory properties [24][25][26]. Extracts derived from SS have high contents of flavonoids and phenolics, substances with many pharmacological effects, such as antioxidant, anticancer, and antiviral properties [27][28][29].…”

Physicochemical Characteristics, Antioxidant Properties, Aroma Profile, and Sensory Qualities of Value-Added Wheat Breads Fortified with Post-Distillation Solid Wastes of Aromatic Plants

“…Compounds such as carvacrol in ORE and carvone in SPE were maintained in both the solid waste residues and the respective fortified breads at high levels, thus largely contributing in the total volatile compounds, >40% (Table 5) and providing to the fortified bread products the intense oregano and spearmint odor, respectively [57,58]. It is worth noting that thymoquinone was detected in high concentrations in fortified ORE breads, possibly due to the transformation of carvacrol to thymoquinone, as a result of the selective hydroxylation of the aromatic ring followed by its subsequent oxidation during baking [59].…”