NS seeds have a wide range of chemical constituents, such as fixed and volatile (essential) oils, proteins, carbohydrates and other nutrients (vitamins, minerals etc.). TQ, the most abundant and valuable element of an essential oil, offers a variety of medicinal (e.g., antitumoral) properties [9, 10].
TQ may halt the development of cancerous cells at many points in the cell cycle. Upregulation of the transcriptional target p21 and tumor suppressor p53 protein expression is the primary mechanism through which TQ hinders cancer escape from growth suppressors [1, 11]. TQ prevents the growth of several cancer cell lines [12]. Chronic inflammation that promotes tumors also has a significant impact on the development of cancer. In diverse cell types, the inflammatory cytokines (IL-1 alpha and beta, IL-2, IL-4, IL-5, TNF alpha, etc.) were reduced in response to TQ [13]. Nuclear factor-Kappa B (NF-kappa B), which may be triggered by exposing cells to a variety of carcinogen stimuli, is powerfully activated by the pro-inflammatory cytokine TNF alpha. Moreover, it attaches to target DNA sites and triggers the carcinogenesis. NF-kappa B activation brought on by different carcinogens and inflammatory stimuli was also demonstrated to be inhibited by TQ [14]. The majority of cancer cells have active telomerase, which gives them an infinite capacity for reproduction and at long last, a way to avoid aging and apoptosis. In cancerous cell lines, TQ has been found to inhibit telomerase and to cause telomere shortening and apoptosis [15]. TQ also induces apoptosis in a diversty of cancer cell lines and the key initiators of TQ-induced apoptosis in cancer cells include an increment in p53 levels and ROS production [16, 17]. In order to maintain their growth and survival, neoplasia are known to upregulate a number of angiogenesis-related factors. TQ's inhibitory effects on a number of cancer cell lines in vitro allowed researchers to further understand its antiangiogenic capabilities [18]. TQ thus blocks the invasion of several cancer cell types via a variety of biological processes [19, 20].
The growth of malignancies in many organs, including the colon, esophagus, fore stomach, and lung, was shown to be potently inhibited by the administration of NS volatile oil in a study that analyzed the chemo-preventive effects of NS on tumor growth utilizing the rat multi-organ carcinogenesis model. [21]. When essential oil of NS was injected into a solid tumor in a different in vivo mouse model (DBA2/P815), it greatly decreased the tumor's size, decreased the likelihood of liver metastasis and increased the mouse's probability of survival [22]. The aqueous extract of NS dramatically increased splenocyte proliferation and natural killer cytotoxicity against tumor cells in a different investigation examining the immuno-modulatory properties of NS [23]. In comparison to the comparable median fatal dosage, the anticancer activities of TQ are seen in animal experiments at substantially lower doses (5–20 mg/kg), (LD50), [2, 20].
For oral administration in humans, TQ was well tolerated at dosages up to 2600 mg/day without adverse effects for a treatment term varying between 1 to 20 weeks in 21 patients who had relapsed after therapy towards numerous malignant tumors [24]. Numerous studies also demonstrate that TQ increases the anticancer activity of chemotherapeutic drugs and/or decreases their toxicity to normal cells, hence enhancing their therapeutic efficacy. When administered as an adjuvant, TQ can not only target tumor cells with precision but also shield healthy tissues from the harmful effects of chemotherapy [25, 26].
In a pancreatic cancer research, TQ suppressed the expression of MUC4 in pancreatic cancer cells, which increased apoptosis and reduced the motility and immigration of the pancreatic cancer cells [19]. Moreover, prolonged administration of TQ is almost as successful in inducing apoptosis in colon cancer cells as sustained delivery of 5-fluorouracil [17, 27]. It was shown that NS oil administered orally to rats prevented the formation and growth of 1,2-dimethylhydrazine-induced aberrant crypt foci, putative preneoplastic lesions for colon cancer without causing any pathological alterations to the liver, kidneys, spleen or other organs [28]. Similar chemotherapeutic actions of TQ on hepatocellular carcinoma (HepG2) cells have also been described. Additionally, after TQ treatment hepatic metastasis from tumors such mastocytomas is significantly reduced [29, 30, 31]. Nigella sativa supplementation has been shown to protect rats from diethylnitrosamine (DEN)-induced inflammation and carcinogenesis in rat liver [32]. The human cholangiocarcinoma (CCA) cell lines TFK-1 and HuCCT1 have both revealed that TQ can limit the development of these cells [33].
Sadly, there are currently insufficient data on the therapeutic benefits of TQ for stomach cancer [34]. TQ was used in an experiment to decrease the frequency and number of benzopyrene-induced stomach tumors in female Swiss albino mice [35]. Additionally, in a different research, pretreatment with TQ boosted the activation of both caspase-3 and caspase-9 in gastric cancer cell lines, which in turn dramatically rised the apoptotic effect generated by 5 FU in gastric cancer cell lines [36]. Few studies have demonstrated that TQ acts on many genetic signaling pathways to effectively treat cancer [37, 38].
In our investigation, TQ dramatically reduced the viability of AGS cells in a dose-dependent manner; at the highest concentration (200 µmol/L), cell viability was declined to 20%. (Figure-1). Likewise, using two different approaches, we noticed a considerable rise in apopitotic and necrotic AGS cells following TQ treatment. TQ caused apoptosis that reached 80% at the maximal dose, while the number of viable cells considerably dropped (Figure-3 and Figure-4). Additionally, ROS production increased noticeably with TQ concentration and there was a strong negative correlation among ROS production and cell survival (Figure-2). These findings imply that the pro-oxidant activity of TQ, which has a dose-dependent impact on AGS cells, may contribute to ROS production. Another theory for the trigger mechanism of TQ-induced apopitosis is ROS production. Finally, TQ caused AGS cells to experience extremely severe DNA damage depending on the dosage, with DNA damage reaching about 100% at the highest dosage (Figure- 5).
As far as we are aware, this is the first work to describe impact of TQ on cytotoxicity, genotoxicity and apoptosis in human AGS cells, as well as measures of ROS production. TQ dramatically decreased malign cell growth and in a dose-addicted way, also caused apoptosis, necrosis and DNA damage of AGS cells. TQ seams to be a potent and promising drug against gastric cancer as well as many malignancies. In conclusion, these findings demonstrate and suggest the healthful and adjuvant use of natural food components as the new strategy of cancer therapy.