Archive \ Volume.14 2023 Issue 3

Uses, Phytochemistry, and Pharmacological Properties of Scorodophloeus zenkeri

Clément Mutunda Mbadiko^{1, 2}, Koto-te-Nyiwa Ngbolua¹, Gédéon Ngiala Bongo^{1, 2*}, Nadège Ngombe Kabamba³, Paulin Mutwale Kapepula³, Sylvie Ngwadi Kasongo^{1, 2}, Marie Claire D’Alesthu Yandju¹, Pius Tshimankinda Mpiana⁴, Théophile Fundu Mbemba^{1, 2}

¹Department of Biology, Faculty of Sciences, University of Kinshasa, Kinshasa XI, Democratic Republic of the Congo. ²Research Laboratory of Food and Nutrition (LARAN), Department of Biology, Faculty of Science, University of Kinshasa, Kinshasa XI, Democratic Republic of the Congo. ³Centre d’Etudes des Substances Naturelle d’Origine Végétale (CESNOV), Faculty of Pharmaceutical Sciences, University of Kinshasa, Kinshasa XI, Democratic Republic of Congo. ⁴Department of Chemistry, Faculty of Sciences, University of Kinshasa, Kinshasa XI, Democratic Republic of the Congo.

Abstract

Scorodophloeus zenkeri is an aromatic plant of the Caesalpiniaceae family distributed exclusively in a few countries in tropical Africa. The literature provides little information on S. zenkeri. Hence the idea to list in this mini-review the scientific data of ethnobotanical, phytochemical, and biological activity studies published on this plant. The majority of the ethnobotanical data collected reveals that S. zenkeri is used in the food, medicinal, stimulant, condiment, construction, and carpentry sectors. Furthermore, phytochemical studies show that S. zenkeri is a source of phytoconstituents and/or nutrients (proteins, amino acids, essential fatty acids, mineral salts, antioxidants, etc.) that are essential in nutrition and/or can be used in food (as a food additive), pharmaceutical and cosmetic industries. However, most phytochemical studies carried out on S. zenkeri focus only on its essential oils and show that the latter is composed mainly of sulfur compounds which are responsible for the aromatic potential (flavor and odor) of extracts from this plant. In addition, various scientific data from biological screenings carried out on S. zenkeri indicate that the extracts of this plant have antimicrobial, antioxidant, and anticancer activities. The essential oils of S. zenkeri are considered to be responsible for most of the pharmacological actions reported on this plant. S. zenkeri has, in addition to the flavor it imparts to foods, an interesting nutritional potential and is a source of proteins, essential fatty and amino acids, antioxidants, and minerals. It also has interesting functional properties and pharmacological virtues.

Keywords: Scorodophloeus zenkeri, Uses, Phytochemistry, Bioactivities, DRC

The table below shows some of the constituents of essential oils from the seed and sulfur compounds contained in S. zenkeri oils.

Bahati [16], showed that the bark of S. zenkeri has a large amount of alkaloids, tannins, saponins, terpenes, and sterols; however, he revealed a small amount of quinones. Fongang et al. [3], isolated sulfur compounds, flavonoids, and tannins from S. zenkeri seeds and barks. The study of Tchiégang et al. [12], revealed that the fruits of S. zenkeri fruits have high contents of lipids (4.59 ± 0.10 g/100 g DM), proteins (17.87 ± 0.04 g/100 g DM), total carbohydrates (71.75 ± 1.40 g/100 g DM) and phosphorus (8.88 ± 0.0 mg/100 g DM) compared to those of the bark (lipids: 1.18 ± 0.05 g/100 g DM; protein: 15.17 ± 0.01 g/100 g DM g/100 g DM, total carbohydrates: 16.57 ± 1.02 g/100 g DM and phosphorus (1.36 ± 0.0 mg/100 g DM). Although the peels showed high contents of fibres (54.73 ± 0.20 mg/100 g DM), total ash (9.04 ± 0.16 g/100 g DM), iron (4.66 ± 0.30 mg/100 g DM), Ca (2789.35 ± 0.92 mg/100 g DM) and Magnesium (2800.65 ± 0.57 mg/100 g) compared to those of the fruits (crude fiber: 4.17 ± 0.01 g/100 g DM; total ash: 2.50 ± 0.01 g/100 g DM; Iron: 0.29 ± 0.01 mg/100 g DM; Ca: 89.13 ± 0.21 mg/100 g DM; Magnesium: 228.28 ± 0.35 mg/100 g.

Other studies, including that of Abdou [10], have shown that the bark of S. zenkeri bark has the following contents: water (11.1± 1.1%), calcium (223.6±10 mg/100g), potassium (367.8 ± 14.7 mg/100g), manganese (20.5 ± 1.1 103 μg/100g), total polyphenols (13.4±0.14 g gallic acid/100g), flavonoids (1.75±0.09 mg rutin/100g); tannins (125.17±0.68 mg tannic acid/100g) and vitamin C (2.41±0.24 g/100g) high compared to fruit (water: 4.4±1.2%), calcium: 87.0±3.4 mg/100g, potassium: 288.8±11.0 mg/100g, manganese: 10.1±0.5 103μg/100g), total polyphenols: 4.46±0.10 g gallic acid/100g, flavonoids: 0.44±0.01 mg rutin/100g, ; tannins: 101.69±0.79 mg tannic acid/100g) and Vitamin C (1.40±0.16 g/100g).

In addition, the work of Abdou [10], revealed that the contents of ash (9.5 ± 0.05%), magnesium (145.2± 6.7 mg/100g), sodium (31.1 ± 1.4 mg/100g), selenium (310.0 ± 15.5 μg/100g), zinc (6.7 ± 0.3 103 μg/100g), copper (0.25 ± 0.01 103μg/100g) aluminum (10.1 ± 0.4 103μg/100g), iron (44.8 ± 2.1 103 μg/100g), vitamin A (11.45±0.03 mg/100g), vitamin E (1.65±0.10 mg/100g) and proanthocyanidins (9.21±0.25 in mg leucoantrhocynidin/100g), are higher in the fruit compared to the rind (ash: 9.2 ± 0.09%, magnesium: 22.5 ± 0.9 mg/100g, sodium: 6.5 ± 0.2 mg/100g, selenium: 110.0 ± 5.5 μg/100g, zinc: 0.8 ± 0.05 103μg/100g, copper: 0.07 ± 0.00 103μg/100g, aluminum: 4.1 ± 0.2 103μg/100g, iron:5.9 ± 0.3 103 μg/100g, vitamin A: 4.56±0.06 mg/100g, vitamin E: 0.51±0.01 mg/100g and proanthocyanidins: 7.69±0.29 in mg leucoantrhocynidin/100g).

Furthermore, Abdou [10], showed in his study that the rind and fruit of S. zenkeri constitute a good source of protein and essential amino acids. The author showed that the fruit of S. zenkeri has a content of total protein (13.97±0.12%) and essential amino acids (79.81±0.14% of total protein) compared to the bark of the plant (protein: 12.17±0.74%, total essential amino acids: 45.62±0.28%). Regarding the characterization of essential amino acids, Abdou [10], revealed the presence of histidine (10.7±0.06%), isoleucine (8.76±0.03%), leucine (9.79±0.03%), Phe + Tyr (4.04±0.03%), lysine (12.33±0.06%) in S. zenkeri fruits and also, the presence of histidine in the bark of the plant. S. zenkeri fruits and also, the presence of histidine (3.18±0.04%), Meth + Cysteine (11.11±0.03%), threonine (39.41±0.04%), isoleucine (13.59±0.04%), leucine (6.64±0.04%) and lysine (5.88±0.06%), in the peels. These essential amino acids are not synthesized by the body and are essential for its proper functioning. A diet rich in essential amino acids is strongly recommended by dieticians [10, 17].

In addition, Abdou [10], determined the fatty acid composition of S. zenkeri oils and showed that the oils of this plant consist of fatty acids with chains ranging from 8 to 24 carbons and particularly unsaturated fatty acids. In general, unsaturated fatty acids belong dietary to three main series: ω-3 and ω-6 and ω-9. The ω-3 are found mainly in fish oils and some vegetable oils, while the ω-6 are found mainly in vegetable oils. S. zenkeri fruits are rich in ω-3 fatty acids (35.65%) while the bark of S. zenkeri is rich in ω-6 fatty acids (13.03%) also called linoleic acid (C18:2n6C) [10]. The ω-3 are of the series of fatty acids that play an important role in the development and maintenance of the different organs in general, precisely the brain, and intervene in the prevention of various pathologies such as cardiovascular, psychiatric, neurological, dermatological diseases and rheumatological disorders [10, 18-20]. Oils with linoleic acid reduce atherosclerosis through interaction with HDL in the blood and cholesterol levels by about 10% [10, 20]. Some polyunsaturated fatty acids such as linoleic acid, linolenic acid (ω-6) and arachidonic acid known as vitamin F are necessary for skin growth and protection and are incorporated, at about 5%, in some dermatological creams, especially in tanning lotions [10].

Lemmens et al. [1] and Malumba et al. [5], reported that S. zenkeri seeds have about 12% of lipids or fat. According to Bayala et al. [21], the seed oils of S. zenkeri are mainly composed of sulfur-containing compounds, accounting for 91.0 to 96.1% of them which provide typical garlic- and onion-like odors of spices. They are principally represented by 2,4,5,7-tetrathiaoctane (51.5%), 2,3,5-Trithiahexane (24.2%), 2,4,5,6,8-pentathianonane (9.0%), and 2,3,4,6-tetrathiaheptane (6.2%). Phenylpropanoids (1.6%) and monoterpene hydrocarbons (0.5%) were present only in small amounts. However, Fongang et al. [3], revealed that some volatile compounds detected in the seed sample used in their studies: 2,4-dithiapentane (trace amount), 2,3,4-trithiapentane (0.6%), 1,3,5-trithiacyclohexane (trace amount), 3-methyl-2,4,5-trithiahexane (0.1%), 3,6-dimethyl- 2,4,5,7-tetrathiaoctane (0.3%), and 2,4,6,8,10-pentathiaundecane (2.3%), were missing in the bark oil.

Moreover, Kouokan et al. [11, 22] highlighted some alkylthiosulphides reported by previous studies (2,3,5-trithiahexane, 2,4,5,7-tetrathiaoctane, etc.) and other new sulfurous or non-sulfurous compounds (pentathianonanes, hexathiaundecanes, etc.). They also identified oxygenated compounds containing sulfur (sulphoxides), like 1,3,5-trithiahexane 5-oxide and 2,4,5,7-tetrathiaoctane 2-oxide; three new sulphones: S-(methylthiomethyl)-methanesulfonothioate, methylthio(methylthio-methyl) sulfone and 2,3,5,7-tetrathiaoctane 3,3-dioxide as well as four already known compounds belonging to the sulphone family: methyl-sulphonylmethylthiomethane, methylmethanethiosulfonate, bis-methyl-sulphonyl methane and bis-(methylthiomethyl) sulfone. These molecules (S-compounds) extracted in S. zenkeri, play an important role in determining the flavor and odor properties of many foodstuffs such as garlic and onion, in which they also constitute a source of antioxidants. According to the literature, some of these compounds have anti-cancer properties [1, 3, 5, 10, 11, 16, 22].

Dimethyldisulfide (C₂H₆S₂), found in the species from DRC, is commonly used as an additive in the food industry and is used in the preparation of cheeses, soups, fruit juices, and meat. It is also used as a sulphidizing agent in refineries and as a pesticide in the United States of America (USA). Then, 3,5-dimethyl-1,2,4-tritiolane (C₄H₈S₃) is used as a meat flavoring agent in the food industry, while tris(methylthio)methane (C₄H₁₀S₃) is used as a reaction intermediate in the pharmaceutical industry and in the synthesis of sulfur compounds used in pharmaceuticals [5]. Different studies using samples of S. zenkeri collected in DRC and Cameroon have shown the presence of different sulfur compounds. The profile and distribution of chemical compounds also vary according to the organ [1, 3, 5, 10, 11, 16, 22].

Biological Activities

The data concerning the biological actions of S. zenkeri are recorded in the table below:

In addition to the antifungal, antibacterial, antiparasitic, and antioxidant actions of S. zenkeri extracts, the literature also informs us that the essential oils of this plant have an action against several types of cancers [10, 21, 24]. The study of Bayala et al. [21] and Fongang et al. [3], revealed that S. zenkeri oils have a strong inhibitory effect on the growth of human cancer cells, namely, T98G (human glioblastoma multiforme cell line), MDA-MB 231 (human breast adenocarcinoma cell line), A375 (human malignant melanoma cell line), and HCT116 (human colon carcinoma cell line) cells.

Moreover, sulfur-containing compounds have been proven to exert cancer chemopreventive effects by induction of apoptosis in tumor cells [21]. So, 2,4,5,7-tetrathiaoctane; 2,3,5-trithiahexane; 2,4,5,6,8-pentathianonane; 2,3,4,6-tetrathiahepta were mentioned by Sharma et al. [25], as having an anti-cancer activity (human breast). Abdou [10], showed in his study that S. zenkeri extracts had a low antioxidant potential. Oils extracted from the bark of S. zenkeri have shown activity against fungi and bacteria. The antioxidant activity of extracts from the bark, fruit, or seeds has also been reported [1, 10].

Badawe et al. [26], showed that methanolic extracts of S. zenkeri seeds exhibit activity against resistant strains of S. aureus. Methanolic extracts of S. zenkeri are likely to optimize the action of certain antibiotics on resistant phenotypes of S. aureus. S. zenkeri could be used in combination with some antibiotics to combat bacterial resistance to antibiotics (tetracycline, chloramphenicol, ceftriaxone, etc.) [26]. Moreover, organosulfur compounds possess antioxidant activity (good DPPH and ABTS-scavenging activity); this is due to their S-atoms, which can appear in up to ten different oxidation states [16].

Kouokan et al. [27], identified several sulfur compounds with antibacterial or antifungal potential such as 2,4,5,7-Tetrathiaoctane; 2,4,5,6,8-pentathianonane; 2,3,4,6,8,pentathianonane; 2,3,5,6,8,10-hexathiaundecane, 2,3,5-trithiahexane 5-oxide; 2,4,5,7-tetrathiaoctane 2-oxide; 2,3,5,7-tetrathiaoctane 3,3-dioxyde and 2,3,5-trithiahexane 3,3-dioxyde. These compounds have effects not only on the growth of microorganisms but also on the synthesis of cellular ATP.

CONCLUSION

S. zenkeri is a tropical African plant commonly used by the population of Gabon, Cameroon, DRC, and the Republic of Congo in food as a condiment, in traditional medicine (alone or in combination with other plants) to relieve various ailments such as colds, coughs, headaches, rheumatism, bronchitis and genito-urinary problems, measles, constipation, wounds, enlargement of the spleen, nasal instillation, stomach aches, hemorrhoids, long and painful periods, anemia, or as an antihelminthic and purgative. Besides the food and medicinal sector, S. zenkeri is also used in construction for its wood and as an aphrodisiac.

Data from phytochemical studies inventoried in this mini-review show the presence of some secondary metabolites (alkaloids, tannins, saponins, flavonoids, terpenes, and sterols) as well as macros and micronutrients that are essential in nutrition and the prevention of chronic non-communicable diseases (cancers, cardiovascular diseases, etc.). These essential oils are mostly composed of sulfurous phytoconstituents and can be used in the pharmaceutical, agri-food, or cosmetics industries. However, further phytochemical and biological studies are needed to: (i) scientifically justify the above-mentioned uses of S. zenkeri, (ii) characterize the secondary metabolites (alkaloids, flavonoids, tannins, essential oils, etc.) of S. zenkeri, (iii) identify the active ingredients of S. zenkeri, apart from the essential oils, and highlight their synergistic action or mechanism of action, and (iv) evaluate the toxicity of S. zenkeri extracts. We also recommend that scientists promote the use of S. zenkeri by local populations in African countries because of its nutritional potential (source of proteins, essential fatty and amino acids, micronutrients, and antioxidants) and its pharmacological virtues.

ACKNOWLEDGMENTS: None

CONFLICT OF INTEREST: None

FINANCIAL SUPPORT: None

ETHICS STATEMENT: None