1 Introduction

From old civilization, plants have been used traditionally as medicines by mankind due to their medicinal value. Nature is considered a creative source of therapeutic agents since more than thousands of years and a huge number of remedies with significant values have been isolated from exiting natural sources. Among them, some were uses of the agents in traditional medicine system. Plant-derived bacteriostatic, have added substantial importance due to their possible health benefits. bacteriostatic from nature, mostly the demands of bacteriostatic contains fruit and leafy vegetables have growing attention among the buyers and researchers because pharmacological studies indicated that everyday intake of natural antidiabetic and bacteriostatic is allied with a lesser risk of infections and different diseases [1]. The self-protective effects from fruit and vegetables as sources of natural bacteriostatic are linked to the foremost groups; vitamin, derivatives of phenolics and β-carotene and carotenoids. Both ascorbic acid and derivatives of phenolics are considered as water-soluble bacteriostatic compounds, whereas carotenoids are known as fats soluble bacteriostatic compounds [2]. Majority of the fruits are considered a highly nutritive because they contain extraordinary level of various vitamin, antidiabetic that might be inhibited the progress of major medical conditions plus cardiac diseases [3]. The fruits and vegetables also contain various phenolic derivatives and β-carotene [4, 5], which constitute natural sources of bacteriostatic compounds.

Suaeda is a genus and maritima is species of plants it is commonly known as seepweeds [6] and sea-blites. It has about 110 species and most of the Suaeda species are kept to alkaline soil habitats. Many of them have thick, and juicy leaves, a distinctive seen in numerous genera that flourish in saline habitats. The Arabic and its local name is thermad, and its common name is herbaceous herb and annual seaweed and umiri in India, the endosperm grows annually to reach a length of 0.3 m. The flowers bloom starting from July each year and the seeds ripen starting from August. The endosperm has a hermaphrodite type and from this we conclude that the plant is self-fertile and pollinated by the wind. Endosperm is found in light, sandy, and medium soils, i.e., parasites. The appropriate pH level for endosperm life is the neutral and basic soil (alkaline), and it can also grow and survive in highly alkaline and saline soils. It is a special plant species that cannot propagate in shady places. The plant grows well in moisture soil. It has a pleasant salty flavor, and the leaves of the selected plant are normally mixed with vegetables to decrease salinity. S. maritima grows in agglomerations in the coastal zone. It has an area of ​​about 10 square meters. Contain potent stems, it bears leaves 2–3 cm in length and from 2.5 to 3 cm in width, juicy flowers covered with a waxy layer, and leaves between ovals, rounded to cylindrical, and has a paper like a curved finger that distinguishes it, and the stem is mostly zigzag sticks. Flowers are green, some yellow, and some red purple. It contains strong roots, many branches and starts branching from the base and the branches are non-spiny juicy. The color of its sticks tends to be white, the fruits are yellow-green and you can see a purple color, the leaves are large from the bottom and become small on the top. The young, cooked leaves have a pleasant salty flavor and are normally mixed with other items of vegetables to reduce their saltiness. On the other hand, the young shoots are pickled and eaten on their own or used as a relish. The leaf of S. maritima has been used as a hepatitis medicine [7] and it is reported that the plant has antiviral activity [8,9,10,11]. The paste of leaves of the selected plant species is used to treat liver disorders [12, 13].

Plants are an excellent natural source of biologically active ingredients to treat mankind. The role of secondary metabolites of the plants is also attributed to plant-biological interactions to prevent or minimize their colonization by insects. Until now, more than 80,000 allied phenolic compounds, approximately 25,000 terpenoid derivatives and nearly 12,000 alkaloids are known to be produced by the plant kingdom, thus, represent a large reservoir of biological structures with over 100,000 low molecular mass products [14]. However, such diversity has made it difficult to examine all plant species in the world and only 10% of total plant species have been examined chemically [15]. The selected plant contains a significant number of triterpenoids, and sterols [16, 17]. Nowadays, much research is being done. Researchers are leaning to go towards natural products with less side effects and highly valuable benefits therefore scientists have been studying. From the literature, it showed that the isolated plant constituents gave hepatoprotective activity against CCl4 (carbon tetrachloride) induced liver damage [18, 19]. In this regard, our present study is to prepare the crude extracts from the aerial parts of the selected plant species with different polarities of solvents and to determine their bacteriostatic and antidiabetic activities by using the disc diffusion and enzyme methods.

2 Materials and methods

2.1 Reagents

Varied polarities of solvents e.g., hexane, dichloromethane (DCM), ethyl acetate, butanol, and methanol were used for the extraction as well as fractionation to prepare extracts were purchased from well-known Company (Sigma Aldrich Company), Germany. The plastic petti discs that were used for the assessment for bacteriostatic activity were collected from Rainbow Chemical Supplier, Muscat, Oman. The levofloxacin, dimethyl sulphoxide (DMSO) and all enzymatic reagents were collected from E. Merck, UK.

2.2 Microorganism

The determination of in vitro antibacterial study was carried out against the various bacterial strains including two gram-negative bacteria such as Escherichia coli (E. coli) and Klebsiella pneumonia (K. pneumonia) as well as two gram-positive bacteria such as Streptococcus pneumonia (S. pneumonia), and Staphylococcus aureus (S. aureus), which were obtained from the Microbiology Laboratory in Nizwa Hospital, Al-Dakhelyia, Oman.

2.3 Sample collection and processing

The leaves and stems of S. maritima were harvested from Sur, Sultanate of Oman. After collection of the samples, washed them for the removal of unwanted waste materials. Both the leaves and stems were mixed and dried under a fan at ambient temperature for four days until they were fully dried. After drying, a ball mill was used to grind them into coarse powder form. The collected samples were dried and bought them to the Graduation Project Research Lab, School of Pharmacy, University of Nizwa and stored them at 4°C for further necessary processing. The dried samples were crushed into coarse powder and kept in the plastic bottle until extraction.

2.4 Preparation of crude extracts

The plant powder samples (100 gm) were extracted with direct methanol (2 L) by using cold extraction method for 36 h [12]. For complete extraction, the whole extraction process was repeated twice. The methanol was evaporated from plant extract by using the usual method to obtain the corresponding extract (11.5 gm). The dry prepared extract (10 gm) was defatted with water (250 mL) and shifted the water mixture into separatory funnel. It was re-extracted with various polarities of solvent such as hexane, DCM, ethyl acetate and butanol with increasing polarity pattern [20]. Initially, 30 mL of hexane solvent was used for fractionation for 30 min shaking then it was repeated by adding 20 mL of hexane solvent. Similarly, DCM, ethyl acetate, and butanol solvents were used for fractionation using the same volume and time to get the corresponding extracts. All the fractions such as hexane, DCM, ethyl acetate, butanol and water part were evaporated by using rotary evaporator to give their corresponding extract. The prepared extracts were used for determination of bacteriostatic and antidiabetic potential.

2.5 Bacteriostatic potential

The disc diffusion method was used to assess the crude extracts of the selected plant against Gram (+) such as S. pneumonia, S. aureus and Gram (−) E. coli, K. pneumonia bacterial strains [19]. In this experiment, as a stock concentration 2000, 1000, 500 and 250 μg/mL were used by dissolving dimethyl sulfoxide (DMSO). Discs were prepared from filter paper in 6 mm size. All collected plastic petti dishes were pre-coated with agar gel media and the bacterial strains were applied as layer by cotton buds on the agar media layer. The discs were added to the stock solutions for 30 min. Similarly, the antibiotic levofloxacin (3 mg) was dissolved in 5 mL of DMSO and added discs to the solution. The shocked discs of various concentration and antibiotic were placed on the agar gel. All the applied petti dishes were kept on the working desk for 30 min to dry the DMSO solvent. Finally, all the petti dishes were kept in the incubator for incubation for 24 h at constant temperature 37 °C. After 24 h’ incubation, the growth of inhibition was measured by the scale in millimeters and noted.

2.6 Antidiabetic activity

2.6.1 Urease inhibition assay

In this experiment, a mixture consisting of 20 µL of Jack bean urease (1 unit/well), 100 mM of urea (45 µL) dissolved in phosphate buffer (pH 6.80). Five microliter (5 µL) of each prepared concentration of plant extract was added to 96-well plates and incubated them at 30°C for 15 min. Then mixture of phenol and sodium nitroprusside (40 µL), and the mixture of NaOH and NaOCl (50 µL) were added to each 96-well plates. The final volume was of 200 µL. The urease inhibition was assessed by using the Weather burn indophenols method by the evaluation of ammonia [21]. The absorbance was measured at 630 nm after incubation of 50 min by using a microplate reader (SpectraMax M2, Molecular Devices, CA, USA). In this experiment, thiourea was used as a standard inhibitor of urease [22]. The reactions were performed in triplicate.

2.6.2 α-Glucosidase assay

The sodium phosphate buffer (100 mM, pH 6.8) was made by the addition sodium phosphate dibasic and sodium phosphate monobasic. The enzyme was prepared by the addition of phosphate buffer (50 mL) with a ratio of 0.2U per well. The substrate namely p-nitrophenyl α-d-glucopyranoside was prepared by the addition of same buffer solution (pH 6.8). However, the plant each polarity extract of concentration (0.2 mg/mL) was prepared in dimethyl sulfoxide (DMSO).

2.6.3 Procedure for α-glucosidase

135 µL of prepared phosphate buffer solution was added to the 96 wells plate and then 20 µL of prepared enzyme was added to each plate. Each concentration extract of each polarities extract was added to the 96 wells leaving the last 6 wells. But 20 µL of DMSO as a control were added to leaving 6 wells. All the plates were incubated for 15 min at 37 °C. After incubation, 25 µL of PNGP was added to each 96 wells. The absorbance was measured at 400 nm by the ELISA machine for 30 reads was taken at every 1 min. The inhibition of active compounds was measured (IC50) studies by using serial dilution.

2.7 Statistical analysis

Three replicates of each experiment were conducted. Each experiment was repeated at least two times. The control and treatment groups were compared using the t test. P values ≤ 0.05 were considered significant.

3 Results

A coarse powder sample of S. maritima was used to prepare the methanol extract by maceration method with methanol. The solvent from the extract was evaporated and the dry extract was dissolved in water and fractioned twice with organic solvents with varied polarities e.g., hexane, dichloromethane, ethyl acetate, and butanol in a separatory funnel respectively using solvent–solvent fractionation method. All mother solvents were evaporated from all polarity’s fractions. At the same condition, the most polar water part was also evaporated to prepare water extract. The yield and percentage were calculated, and the data is presented in Table 1.

Table 1 Amount and percentage of each extract of S. maritima
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3.1 Bacteriostatic activity

All the prepared crude extracts of S. maritima at six different concentrations were used to determine their bacteriostatic activity against four different bacterial strains by using disc diffusion method [19, 23]. In this experiment, the growth inhibition results of each extract and each concentration is presented in Table 2. From the results, it showed that the growth of inhibition is not consistent among the applied prepared concentrations. It is also observed that the high concentration extracts gave significant activity against applied Gram (+) and Gram (−) bacteria strains. The highest bacteriostatic activity was obtained from all prepared extracts against the E. coli and S. aurous.

Table 2 The results of bacteriostatic activity of various crude extracts of S. maritima
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3.2 Antidiabetic activity

All the crude extracts from the S. maritima were used to determine their antidiabetic activity using the enzyme inhibitory test method described by several authors [20]. four different concentrations 2000, 1000, 500, 250, and µg per mL of each one fraction that were prepared by methanol solvent. Using DNSA reagent, which gives red color on reaction with reducing sugar. The antidiabetic result is presented in Table 3 and Fig. 1. All the extracts showed the signification inhibition activity against the α-Glucosidase. Figure 1 shows the effect of different compounds on diabetes mellitus these include competitive inhibitor, noncompetitive inhibitor, uncompetitive inhibitor in relation with uninhibited enzyme.

Table 3 The results of antidiabetic activity of various crude extracts of S. Marittima by using α-Glucosidase assay
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Fig. 1
figure 1

The results of antidiabetic activity of various crude extracts of S. Marittima by using α-Glucosidase assay

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4 Discussion

Since the old times, aromatic plants have been used as a medicine to treat diseases. About two hundred and fifty thousand plants and organisms on the globe, many of them have different medicinal properties to cure different diseases. Since the ancient time, more than fifty thousand plants have been investigated by the scientists for their medicinal and therapeutic properties. Some of them showed signification medicinal and therapeutic and are currently used as an herbal medicine in the alternative medicine system to treat diseases [24,25,26,27,28]. In addition, plants and their products have been used to treat diseases in a variety of alternative medical systems, including phytotherapy, complementary and alternative medicine, and phytomedicine. Phytochemicals are divided into two classes: primary and secondary phytochemicals. The primary phytochemicals include carbohydrates, amino acids, chlorophylls, proteins, nucleic acids' purines and pyrimidines, and secondary phytochemicals include alkaloids, saponins, terpenoids, flavonoids, lignans, hormones, and their glucosides. Both phytochemicals are directly responsible for their pharmacology and toxicological activities. More than fifty methods were available for the extraction of phytochemicals from the plant materials. Majority of them are used as a save method for the extraction of phytochemicals. The literature search showed that plant-containing phytochemicals had biological and pharmacological properties, such as antimicrobial, antioxidant, antifungal, anti-helminthic, anticancer, anti-diarrhea, anti-diuretic, or antiviral properties. Researchers have been inquiring about the new drugs derived from plant and marine species during for the last two decades. Nowadays, some phytochemicals are used as a prescription drug for the treatment of diseases.

Huge plants and marine resources are available in the Sultanate. Most of plant resources are available in southern region of Oman. Majority of them are traditionally using by the Omanis to treat diseases. However, most of the plant and marine resources are unknown or undetermined by the ethnic communities. Many medicinal plants have been studied globally for their biological activities [29]. Based on the biological activities such as antimicrobials, antioxidants, and anti-cancers etc. scientists have recently been investigating these traditionally used plants and marine sources to see whether they can develop new naturally occurring drugs to treat diseases and replace synthetic drugs. Many antioxidant-based drug formulations are currently being used to prevent and treat incurable diseases like asthma, multiple strokes, diabetes mellitus, cancer, and Alzheimer's disease [21]. Because of the toxicity of synthetic antidiabetics, study focusing on discovering natural antidiabetics from natural resources has increased significantly recently [29].

4.1 Bacteriostatic activity

The bacteriostatic activity of the plant crude extracts was determined by using agar disc diffusion method described by Musaab and Hossain [20]. All the extracts at all concentrations from the mixture of leaves and stems of the selected plant species gave promising bacteriostatic activity against bacterial strains within the range of 0–11. Among the six plant extracts, the ethyl acetate and DCM extracts showed the highest activity against E. coli and Portus. S with the range of 0-11 mm. The lowest bacteriostatic activity was obtained in water extract against all bacterial strains. The order of bacteriostatic activity against the applied Gram (+) and Gram (−) bacterial strains was ethyl acetate > DCM > hexane > methanol > butanol > water extract. Most of the bioactive compounds are present in the selected that reported earlier played an important role for the bacteriostatic activity. Due to the maximum number and concentration of bioactive compounds are present ethyl acetate extracts therefore the ethyl acetate extract showed the highest activity compared to other extracts. On the other hand, the water extract contains less number bioactive compounds as well as concentration are present in water extract. That’s why, water extract showed less activity compared to other extracts from the selected plant. Our previous study on the leaves extract of the same plant gave the highest activity in ethyl acetate [20]. Similar activity was obtained from the leaves extract of Iranian S. maritima [22].

4.2 Antidiabetic activity

The prepared crude extracts of the selected plant species were determined their antidiabetic activity by enzymatic method with modification [23]. α-Glucosidase was used as an enzyme in the present method that is the directly responsible of the degradation of glucose molecules. Acarbose was used as a positive control that is used in the treatment of diabetes mellitus. Due to the glucosidase inhibitors, digestion and carbohydrate absorption were slowed down. Nowadays, plant natural sources have gained more interest for the discovery of non-sugar dependent alpha-glucosidase inhibitors from the natural resources [24]. The results showed that all the extracts at the concentration 0.2 and 0.5 mg/mL showed promising activity against the control postprandial hyperglycemic compound (Table 3). All the six extracts from the selected plant of S. maritima contain chemical compounds that can inhibit hyperglycemia. The highest IC50 activity among the prepared extracts from the mixture leave and stem parts of S. maritima was in methanol and the lowest was in hexane and the IC50 data is presented in Table 3 and Fig. 1. Based on the data it is clearly shown that all the extracts from the plant give activity means all the extracts contain diabetic responsible compounds.

5 Conclusion

The bacteriostatic and antidiabetic activity of crude extracts of the leaves and stems of S. maritima were determined using diffusion and α-Glucosidase methods, respectively. Among the six plant extracts, the ethyl acetate and DCM extracts showed the highest activity against E. coli and Portus. S and the lowest bacteriostatic activity were obtained in water extract against all bacterial strains. The order of bacteriostatic activity against the applied Gram (+) and Gram (−) bacterial strains was ethyl acetate > DCM > hexane > methanol > butanol > water extract. Similarly, the highest IC50 was obtained in methanol extract and the lowest was in hexane extract from this bioassay. The other plant extracts also showed good activity against the α-glucosidase bioassay. DCM and ethyl acetate extracts of the selected plant may be used as a medication to prevent diabetes, and ethyl acetate may be used to stop bacterial infections, based on their antidiabetic activity. This promising result would require advanced, extensive phytochemical and pharmacological research before the plant can be considered a medicinal plant. The toxic ingredients that have antitumor pharmacological and toxicological potential. Further in vivo and in vitro tests for the chosen plant are needed to confirm the mechanism of action.