Akl et al. Bulletin of the National Research Centre (2020) 44:27 Bulletin of the National https://doi.org/10.1186/s42269-020-0280-x Research Centre RESEARCH Open Access Biological activities of phenolic compounds extracted from flaxseed meal Engy M. Akl1* , Samira S. Mohamed1, Ahmed I. Hashem2 and Fakhriya S. Taha1 Abstract Background: There is a worldwide demand for phenolic compounds (PC) because they exhibit several biological activities. The present investigation deals with a comprehensive study on the biological activities of phenolic compounds extracted from flaxseed meal (FM) with the aid of ultrasonic waves. Results: The antioxidant activity of the PC extract of FM is considerably high when measuring it by the three methods (the β-carotene coupled oxidation method, the DPPH free radical scavenging activity method, and measuring the reducing antioxidant power). The toxicity test revealed that the PC extract was nontoxic on normal retina cell line. Also, it has no anticoagulating activity. Evaluation of antimicrobial activity showed that it is effective towards four strains only from seven. FM phenolic extract has been evaluated as chemo-preventive agents by testing the product for any cytotoxic activity against human tumor cell lines. The highest inhibitory effect was achieved on cell lines of colon carcinoma and lung carcinoma with IC50 = 22.3 and 22.6 μ/ml respectively. Conclusion: The PC extracted from FM showed high antioxidant activity, nontoxic on normal retina cell line, no anticoagulating activities, and an antimicrobial effect on some pathogenic bacteria, so the phenolic compounds extracted from flaxseed meal showed significant biological activities. Keywords: Flaxseed meal, Phenolic compounds, Antioxidant, Antimicrobial, Anticoagulant, Cytotoxicity, Anticancer Introduction Flaxseed is particularly rich in lignans, e.g., secoisolari- The components of flaxseed meal were found to have a ciresinol diglucoside (SDG), which are also present in wide spectrum of biological activity. Utilization of flax- flaxseed oil. These components have some antioxidant seed has been shown to exhibit a huge number of advan- activity (Hosseinian et al. 2006). The proved functions of tages to health including the diminishing rate of tumor lignans are related to health benefits and the protection development, lowering serum cholesterol level, and from some types of cancer and heart diseases [Kim and diminishing rate of breast, prostrate, and colon diseases Ilich 2011; Park and Velasquez 2012; Ayella et al. 2010; (Muir et al. 2003; Hemmings et al. 2004; Hosseinian Rodriguez-Leyva et al. 2010]. Besides lignans, flaxseed − et al. 2006; Choo et al. 2007). contains 8:10 gkg 1 of phenolic acids, mainly p- Early research showed that flaxseed possesses a very coumaric, vanillic, sinapic, and ferulic, which are present powerful antioxidant system; ground and whole flax- in the seed as glycosides with ester and ether bonds seeds were stable at room temperature for numerous [Oomah et al. 1995); Johnsson (2004)]. Phenolic acids months [Chen et al. 1994; Malcolmson et al. 2000]. have antioxidant activities, related to the positions of hy- Ground/milled and whole flaxseeds stored showed negli- droxyl groups on the ring [Przybylski and Daun 2005); gible oxidative deterioration at room temperature, which Tuberoso et al. (2007)]. indicates the presence of an efficient antioxidant system, Previous studies demonstrated that the antioxidant where compounds other than tocopherols may play an compounds enhance human health, for example, re- important function [Chen et al. 1994); Malcolmson et al. straint of tumor cells, enhancing the state of cardiovas- (2000); Hosseinian et al. (2006)]. cular sicknesses and diabetes [Żuk et al. 2011], curing human chronic ulceration [Skórkowska-Telichowska * Correspondence: [email protected] et al. (2010)], against allergenic, hostile to atherogenic, 1Fats and Oils Department, National Research Centre, Dokki, Cairo, Egypt Full list of author information is available at the end of the article mitigating against microbial, antioxidant, against © The Author(s). 2020 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Akl et al. Bulletin of the National Research Centre (2020) 44:27 Page 2 of 8 thrombotic, cardioprotective, and vasodilatory impacts tumor development in the later phases of carcinogenesis [Benavente-García et al. 1997]. (Thompson et al. 1996). Essentially, it has been demon- Khouya et al. (2015) evaluated several biological activ- strated that the substitution of corn meal, with flaxseed ities including anticoagulant, anti-inflammatory, and meal (15%) or corn oil with flaxseed oil (15%) in a basal antioxidant from aqueous extracts of thyme varieties. eating routine, diminished tumor generation and size in Wee et al. (2010) extracted active compounds from Ko- the small digestive system and colon of Fischer 344 male rean red ginseng which were identified as phenolic com- rats. The creators presumed that flaxseed meal and oil pounds (namely vanillic, caffeic, ferulic, and p-coumaric are successful chemo-preventive operators (Bommar- acid). These products possess anticoagulant activities. eddy et al. 2009). Daud et al. (2013) stated that the ethanolic extracts from In a recent publication (Akl et al. 2017), the same au- Averrhoa bilimbi even from fruits or leaves showed a thors reported on the extraction of phenolic compounds considerable anticoagulant effect on rats. (PC) from flaxseed meal (FM) using a variety of extrac- Plants produce a large number of organic compounds tion techniques, and then evaluated its phenolic contents that possess antimicrobial activity. The compounds are of each method. The present investigation aims to deal found in various parts of plant such as leaves, bark, with a comprehensive study on the biological activities stems, roots, fruits, flowers, or and seeds. These com- of optimum condition obtained by ultrasonic assisted ex- pounds include alliin/allicins, isothiocyanates, plant pig- traction. Some biological activities of these phenolic ex- ments [Cutter 2000], proteins, hydrolytic enzymes, tracts (antioxidant, antimicrobial, anticoagulation, and essential oils [Smid and LGM 1999], and phytoalexins or anticancer effects) were evaluated. phenolic compounds [Cutter 2000; Smid and LGM 1999]. Materials and methods A huge number of chemical compounds are present in Materials seeds or seed coats, including alkaloids, lectins, and One hundred grams of flaxseed meal were added to 3 l phenolic compounds such as lactones, tannins, and fla- of distilled water and stirred well then transferred to vonoids. These compounds play a role in the seed pro- ultrasonic bath for 2 h at 35 °C then centrifuged to give tection from microbial attack until conditions are the supernatant which contains the phenolic com- improved for germination [Cai et al. 2004; Komutarin pounds. This crude extract was purified then freeze et al. 2004]. dried by Crest Alpha 1-4 LSC plus, Germany, and re- Dietary use of seedcake is effective; it is utilized against served in refrigerator until use. number of diseases, as skin diseases, respiratory tract diseases, and gastrointestinal tract diseases. Secoisolari- Methods ciresinol diglucoside (SDG) is the richest components of β-Carotene coupled oxidation method flaxseed cake, the precursor of lignans, which have many Determination of the AOA of the extracts was based on advantages on human health. SDG is known to possess the coupled oxidation of β-carotene and linoleic acid ac- anticancer properties by reducing cell proliferation and cording to the method of (Taga et al. 1984), with some growth, especially in breast and prostate cancer [Wang modifications. β-Carotene (0.1 g) was dissolved in 20 ml et al. 2005]. SDG, which has also antimicrobial effect in- of CHCl3 solution. Three milliliters of aliquots of the cluding anti-viral, antibacterial, and anti-fungal proper- former solution was added to a round bottom flask along ties, is an antioxidant, and it has been shown to improve with 40 mg of linoleic acid and 400 mg Tween 20. Chloro- immune system functioning [Adolphe et al. 2010]. Be- form was evaporated until dryness under reduced pressure sides that flaxseed cake includes phenolic acids, flavo- at low temperature (less than 30 °C). One hundred millili- noids, and other phenylpropanoids, it is known to have ters distilled water were added to the dried mixture and antioxidative properties and thus having helpful actions mixed well (β-carotene emulsion. Aliquots from the PC on human health [Korkina 2007]. extracts to be examined (500 μl each) were added to 5 ml Intact flaxseed is generally considered as a healthy β-carotene emulsion and incubated in a water bath at 50 food that has anticancer action. Controlled trial diets °C for (60 min). Absorbance of the sample was measured have exhibited various valuable impacts of flaxseed against blank at 470 nm after 60 min. A blank sample utilization [Clark et al. 1995; Cunnane et al. 1993; Jen- formerly prepared (40 mg linoleic acid and 400 mg Tween kins et al. 1999]. Dietary flaxseed cake decreases epithe- 20 in distilled water). Also, an aliquot (500 μlPCextract lial cell generation