**1. Introduction**

Gastritis is an inflammatory-based pathology which can be classified as acute or chronic. Acute gastritis is provoked by several risk factors which include stress, alcohol abuse, the use of non-steroidal anti-inflammatory drugs (NSAIDs), and bile reflux; chronic conditions are mainly due

to *Helicobacter pylori* (*H. pylori*) infection. Infected people can also develop more severe pathologies, such as peptic ulcer or gastric cancer [1,2]. In 1994, the WHO assessed *H. pylori* as a class I carcinogen for gastric cancer. Several transcription factors are involved in gastric inflammatory conditions, including NF-κB [3]; according to the literature, in vitro studies demonstrate that *H. pylori* and some pro-inflammatory cytokines (i.e., TNF α) are able to induce the activity of this transcription factor in gastric epithelial cells [4,5]. NF-κB plays a pivotal role in the expression and release of some pro-inflammatory mediators, such as IL-8, IL-6 and enzymes such as prostaglandin endoperoxide synthase 2 (PTGS2) (COX-2), which, in turn, lead to the amplification of the gastric phlogistic process [6,7]. IL-8 is considered a key element involved in the development of gastritis. At this regard, Crabtree et al. demonstrated the increased expression of this chemokine in the epithelium of the infected gastric mucosa [8,9]. In this context, an over-production of oxygen reactive species (ROS) leads to increased oxidative stress contributing to exacerbate the inflammatory process [10]. Indeed, it has been demonstrated that several ROS can enhance IL-8 expression in gastric epithelial cells through the NF-κB activation [11].

NSAIDs act on prostaglandin synthesis, through the inhibition of cyclooxygenase enzymes, PTGS1 (COX-1) and PTGS2 (COX-2). The latter is encoded by an NF-κB-dependent gene, strictly involved in the inflammatory process, whose expression can be rapidly up-regulated by cytokines and growth factors; otherwise, *PTGS1* gene is constitutively expressed in human epithelial cells, contributing to preserve the protective mucus layer by cytoprotective prostaglandin production; therefore, the blockage of PTGS1 (COX-1) activity is the main factor responsible for the gastric side e ffects (e.g., peptic ulcers) of NSAID chronic drug treatment [12–14]. These findings underline the importance of selective inhibitor agents for COX-2, able to preserve COX-1 activity.

In Cameroon, the traditional use of natural products for the treatment of several diseases is largely di ffused and constitutes the first health approach among the population [15]. The e fficacy of the traditional use of plants for human health is not generally fully supported by scientific evidence. Many plants are traditionally employed in Cameroon for the treatment of di fferent ailments, such as diabetes, hypertension, malaria, and gastric disorders [16–18]. Nkui and Nahpoh are two traditional soups of the eastern region which contain many spices, among which there are plants used in the present study. These plants are widely distributed in eastern and central Africa, and their fruits and seeds, normally boiled with the help of a thread or a stick of bamboo, are pounded and used in cooked foods or as spices for sauces or beverages. As a traditional remedy, they are mainly employed in association with other botanicals for the treatment of various ailments, including stomach disorders [18–20]. According to the literature, several papers report the potential health benefits of these Cameroonian spices, including anti-microbial, anti-inflammatory, and hypoglycemic properties [19,21–23]. However, no study has investigated the anti-inflammatory activity of Cameroonian spices at the gastric level.

The aim of this study is to investigate the potential anti-inflammatory and antioxidant e ffects of the hydroethanolic extracts from eleven selected Cameroonian spices in human gastric epithelial cells. Human GES-1 and AGS cells are used as reliable in vitro models of human gastric epithelium. The extracts are assessed on the TNF α-induced expression of di fferent NF-κB-dependent mediators, such as IL-8, IL-6 and PTGS2 (COX-2), and the e ffect on the TNF α-induced NF-κB-driven transcription is assessed as well. Among the extracts tested, six showed promising activity as anti-inflammatory agents, confirming their use in Cameroonian traditional medicine for the treatment of gastric disorders.

#### **2. Materials and Methods**

#### *2.1. Preparation of the Hydroethanolic Extracts*

The material from eleven different species of plants was harvested in different areas of the West Cameroon in September 2017, as previously described [24,25]. Plants collected were: *Xylopia aethiopica* (Dunal) A.Rich. (**XA**), *Xylopia parviflora* Spruce (**XP**), *Scorodophloeus zenkeri* Harms (**SZ**), *Monodora myristica* (Gaertn.) Dunal (**MM**), *Tetrapleura tetraptera* (Schum. and Thonn.) Taub. (**TT**), *Echinops giganteus* A. Rich. (**EG**), *Dichrostachys glomerata* (Forssk.) Chiov. syn. *Dichrostachys cinerea* (L.) Wight and Arn. (**DG**), *Afrostyrax lepidophyllus* Mildbr. (**AL**), *Aframomum melegueta* K.Schum. (**AM**), *Aframomum citratum* (C. Pereira) K. Schum. (**AC**), and *Zanthoxylum leprieurii* Guill. and Perr. (**ZL**).

Selected samples consisted of di fferent fruits, seeds, or roots, and were identified in the National Herbarium of Cameroon (http://irad.cm/national-herbarium-of-cameroun/) in Yaoundè (Cameroon), by comparison with preserved specimens [24,25]. The plant material (100 g) of each species was powdered and extracted, under stirring, with 100 mL of an hydroalcoholic (ethanol:water, 70:30) mixture for 4 h at room temperature, in dark conditions. Then, the extract was filtered, and the plant material was recovered and subjected to a second overnight extraction with fresh solvent. The solvent was removed through rotary evaporator (Laborota 4000 e fficient, Heidolph Instruments, Schwabach, Germany), and subjected to lyophilization. All the extracts were dissolved in pure DMSO, aliquoted, and stored at −80 ◦C. Parts used, aspect, color, and extraction yield were previously reported in [25]. The extracts were characterized by gas chromatography coupled with mass spectrometry, as previously reported [24].
