# The Effect of Selected Herbal Extracts on Lactic Acid Bacteria Activity
## 4 Discussion
### TPC and Antioxidant Capacities of Plant Extracts
Their values in chamomile aqueous extract were established as follows: quercetin equivalent per gram of extract--27.65 \(\pm\) 0.007 \(\upmu\)g; GAE per gram of extract--146.97 \(\pm\) 0.046 \(\upmu\)g, and tannic acid equivalent per gram of extract--132.22 \(\pm\) 0.023 \(\upmu\)g. In contrast, analysis of chamomile extract containing many flavonoids and numerous organic acids and their derivatives in this study revealed the low TPC compared to other tested plant extracts tested, as well as one of the lowest antioxidant capacities. [PERSON] et al. [9] determined the content of phenolic acids and flavonoids in cistus (_Cistus_ L) extracts. Their results revealed that aqueous cistus extracts were richer in phenolic compounds and showed strong antioxidant activities. The total amount of polyphenols in the leaf, stalk, and bud extracts of _Cistus incanus_ determined by [PERSON] and [PERSON] [73] varied between 36.26 and 115.32 mg GAE/g dry weight (dw), depending on the time of extraction. After 180 min of _C. incanus_ extraction, the phenolic content was slightly higher than that observed in our study. Such result has also been shown by other studies. Researchers showed that the place of origin is the main factor differentiating the antibacterial activities of cistus samples. [PERSON] et al. [10] found catechins, flavonoids, and gallic and vanillic acids in _Cistus_ extracts. The compounds identified by [PERSON] et al. [80] in crude ethanolic leaf extract of _C. incanus_ included gallic acid derivatives, condensed tannins, and flavonoid glycosides. In total, 19 compounds were identified based on the fragmentation of individual polyphenols and by comparing their retention times and UV/Vis spectra with authentic standards. As in our research, the presence of epicatechin, myricetin hexoside, and quercetin pentoside was found in the C. incanus extract by [PERSON] et al. [80]. In our study, the _Cistus_ extract had the highest TPC among the tested plant extracts, and thus showed the highest antioxidant capacities. Its composition included many organic acids and their derivatives, as well as flavonoids such as catechin, quercetin, kaempfer, and myricetin. Several studies have been performed on linden blossom (_Tilia_ L.) extracts. The results revealed the presence of terpenoids, quercetin, and kaempfer derivatives (such as tilioside), phenolic compounds, esters, aliphatic acids, hydrocarbons, condensed tannins, and a coumarin scopolein in the extracts [11; 16; 81; 82]. [PERSON] et al. [83] stated that TPC and the antioxidant activity were determined in the ethanolic extracts of dried linden blossom leaves (0.3303 \(\pm\) 0.0896 mg/mL calculated as DPPH scavenging activity). In our study, the DPPH value of linden blossom extract was determined as 0.161 \(\pm\) 0.007, but expressed as mmol TE/g extract. This value was the second highest recorded in our experiments. TPC of the linden blossom extract was also one of the largest and resulted from the presence of quercetin, kaempfer, other flavonoids, and their derivatives, as well as many organic acids. In addition, 3,4-dihydroxybenzoic acid, myricetin, rutin, ferulic acid, and 3,4-dihydroxybenzaldehyde were found in abundance in the Tilia momentosa flower [84]. In turn, the major phenolic compound observed in acetone and methanolic extracts of Tilia argentea was protocatechuric acid. The leaf samples of Tilia species were found to contain many compounds similar to those in flower samples, but each of these samples possessed a unique chemical profile including the percentage and type of flavonoid constituents [85]. Some scientists showed that phenolic compounds, mainly flavonoids and hydroxynaminic acids, were the main components of hydrophilic ribport plantain (_P. lanceolata_ L.) extracts [19]. [PERSON] et al. [20] found that luteolin was biologically important among the flavonoids. According to [17], phenylethanoids, especially Aukubin, are responsible for the antimicrobial effects of ribwort plantain extracts.