Chemical composition and pharmacological significance of Anethum Sowa L. Root
The data on the proximate composition of Anethum sowa L. root has been reported for the first time. The ash content is found very high in the current study, indicating the high quality of essential minerals which is comparable with an acceptable ash range of legumes (2.4–5.0%) [25]. Acid insoluble ash is an indicator of silicate impurity and water soluble ash is indicated the highly soluble mineral contents in the root sample.
The oil from a single source has not been found to be suitable for consumption and medicinal preparation because of their different chemical compositions. So, the necessity for searching of new oil source is a major research interest in the present day. Our previously published data on the fatty acid composition of Anethum sowa seed and flower part [26, 27] revealed that oleic acid was the highest in seed (87.10%) and flower (51.93%) part than our current study. Moreover, palmitic acid content is almost similar to the flower fatty acid (30.74%) but it is found higher than the seed (4.27%) fatty acid. Linoleic acid is one of the essential polyunsaturated fatty acids which prevents cardiovascular diseases and its derivatives serve as structural components of the plasma membrane [28]. It also has a beneficial effect on blood lipids, lowering blood pressure and serum cholesterol. The nutritional value of linoleic acid is due to its metabolism at the tissue levels, which produced the hormone-like prostaglandins [29]. It was found the second highest fatty acid in the present study. The saturated fatty acids like lauric, myristic and palmitic acid have been established as the most important of the dietary risk factors and resulted in a high level of total blood cholesterol [30]. Diets with a PUFA:SFA ratio was found the below of 0.45, which considered inadequate because of their potential to increase blood cholesterol levels [31]. On the other hand, higher SFA stimulates the de nova synthesis of cholesterol in the body. Thus, it indicates that these are not a good source of fatty acids for human health. Moreover, TI was found higher than 1 in cold and hot extracted fatty acids while AI was found higher than 1 in cold extracted fatty acid, but the lower value was found in hot extracted fatty acids. The AI and TI indexes have considered as cardiovascular disease risk factors. Thus, these indices must be kept low. It was reported that lower AI leads to a decrease in the total cholesterol and the LDL-cholesterol in human blood plasma [32]. To the best our knowledge, this is the first report regarding the fatty acids of A. sowa root. This investigation has given us valuable information about the structure of the fatty acids and also indicated that these oils cannot be considered as functional ingredients of human diet but it may be a valuable source for the cosmetic or industrial application.
Primarily, the nutritive value of a protein depends on the capacity to satisfy the needs for nitrogen and essential amino acid. It is indicated that the A. sowa L. root protein is probably basic in nature. There is a dearth of information regarding the amino acid profile of the Anethum sowa L. root sample to the best our knowledge. Lisiewska (2004) [33] reported that leaves of Anethum graveolens L. contained rich in essential amino acid than the whole plant where leucine (10.10 for the whole plant and 9.62 for leaves of g/100 g protein) was the highest essential amino acid. Some amino acids like tryptophan, asparagines and glutamine were destroyed by acid hydrolysis method and therefore these acids were not determined. Cystein was not determined because of the rapid oxidation of this compound to form cysteic acid. The total sulphur containing amino acid (5.49 g/100 g protein) was close to having the recommended protein value (5.8 g/100 g) for infants [34]. This value was well above the 39%, considered to be adequate for ideal protein for infant, 26 g/100 g protein for children and 11 g/100 g protein for adult [34]. The storage of protein (i.e. amino acids) in the different parts of the plant is readily used for germination and seedling growth [35]. The proteins are considered for its essential amino acid profile due to the inability of the human body to synthesize them. The amino acid profile of the studied root sample suggests that its protein is beneficial for human health.
The concentration of elements is not uniformly distributed throughout the plant. In general, the roots contain the highest level of elements followed by stems, leaves, flowers, buds and fruits of the different maturity stages. Nevertheless, uptake of elements by a plant is influenced by various factors, including the type of plant, nature of the soil, climate and agricultural practices [36]. In the current study, the different elemental concentrations were varied due to the above factors. A. sowa L. root accumulated a significant amount of minerals in Bangladeshi geo-environmental condition. The results are also compared with the reported [8] data of Anethum graveolens L. root where K (38,500 ppm) had the highest value, Ca (12,200 ppm) and Mg (6700 ppm) had the lowest values than our current study. The elements, especially Ca, Mg, K, Na, Fe and Al play a significant role in human metabolism and the life processes. The rich amount of Ca is important because of its role in bones, teeth, muscle system and heart functions [37]. Mg has been particularly shown to play a significant role as a regulatory cation in direct and indirect traumatic brain injury [38]. Another report on Mg, it also helps in preventing some heart disorders and high blood pressure [39]. Recently, it has been reported that trace amounts of Rb and Cs help in the breakdown of starch to glucose [36]. Cs was present in the trace amount (21.53 ppb) in the present study. Se has anti-oxidising function and it is essential for providing the organism with triiodothyroxine produced from thyroxine [40]. It contributes to the maintenance of cellular antioxidative balance when taken up at the recommended dietary allowance of 50–100 ?g/day and tolerable upper intake limit is 400 ?g/day [41]. The high dosage of selenate has been shown to normalize hyperglycemia [36]. Li is another element with beneficial pharmacological properties which effectively used in the treatment of manic depressive disorders [42]. The result also showed that many of these elements have vital importance in human metabolism for growth, developments and also prevention and healing of diseases. The non-essential or toxic elemental contents in spice and medicinal plants are attracting attention to the scientist and also the food chemist due to its adverse effect on the human body in respect of medicinal and food preparation. The permissible limits of Hg and As are 1 and 10 mg/kg in foodstuff respectively [43]. The maximum prescribed limit of Cd is 0.3 mg/kg for herbal medicines and its product while the dietary intake limit is 10.3 mg/kg as per who recommendation [44]. Moreover, the toxic elements were found below the prescribed limits in the present experiment. Nonetheless, excessive intake can cause poisoning in the human body. Hg poisoning can result in damage to the brain, kidney, lungs including acrodynia (pink disease), Hunter-Russell syndrome and Minamata disease [45]. The acute sign of As poisoning includes fever, anorexia, hepatomegaly, cardiac arrhythmia, transient encephalopathy and irritation of the gastrointestinal tract [46]. Cd intoxication can lead to kidney, bone and pulmonary damages [47]. Pb and Cd cause both acute and chronic poisoning, adverse effects on the kidney, liver, heart, vascular and immune system [48]. Furthermore, root parts of Anethum sowa L. herb is not usually consumed, it is wasted mostly. The present investigation will be helpful for Ayurvedic and pharmaceutical industries to assess the essential and toxic elemental level for medicinal preparation.
Thermo-gravimetry is a technique in which change in the weight of a substance is recorded as a function of temperature or time. This technique is useful for the pre-formulation study of herbal preparation through physical and chemical changes. It detects the impurity, identified the complex mixture and thermal stability of the plant samples [49]. In the first stage, broad and shallow endothermic effect on the DTA curve indicated a small loss in mass by a dehydration reaction. This peak is due to desorption of moisture of the root powder material together with the evaporation of volatile components or essential oils. The chemical reaction was occurring in the second stage of decomposition by a strong exothermic effect on the DTA curve. A mass loss of the DTG curve was verified due to the elimination of moisture retained in this material. In the second stage, the highest mass loss was reflected by the TG and DTG curves which are due to the destruction and combustion of compounds contained in the root samples. The behaviour of the pyrolysis curve indicated hemi-cellulose and cellulose decomposition, as well as the loss of remaining adsorbed moisture. Lignin decomposition indicated that this structure presents a higher stability than hemi-cellulose and cellulose. The last stage indicated that the presence of oxides (mainly those of aluminium and silicon), which were stable at higher temperatures. The last stage was also associated with a large exothermic effect.
The essential oils and extracts of the medicinal plants have been used for food preservation, scenting agent and as a traditional healthcare since thousands of years [50]. In the GC-MS analyses, apiol and m-diaminobenzene were found the major constituents of A. sowa root essential oil. It was reported that apiol (20%) was found as the main compound in the root essential oil of Anethum graveolens L. [7]. In the earlier studies, phenylpropanoid compounds were the rich level in leaf and stem part of A. sowa L. [51, 52]. On the other hand, apiol was also found in some umbelliferae plants like parsley (Petroselinum sativum and Petroselinum crispum) which have accounted for 18.23 and 17.54% respectively [53, 54]. Moreover, m-diaminobenzene (68.2%) was also found as the highest amount in other Apiaceae plant (Ligusticum jeholense) essential oil [55]. On the other hand, carvone (27.8%) was found the main predominant compound in Anethum graveolens L. followed by limonene (15.5%), ?-phellandrene (14.7%) and apiol (3.1%) [9] while carvon, limonene and ?-phellandrene were totally absent in the present study. The variations of oil composition with Anethum graveolens species may be due to plant genetic base, development and mostly different environmental conditions.
The oil exhibited marked DPPH free radical scavenging activity in a concentration-dependent manner. The antioxidant activity of the oil was evaluated by the decolorisation of stable DPPH radical due to its hydrogen donating ability. The absorption is stoichiometric with respect to the number of electrons taken up [56].
Apiol is the major component of the essential oil and it has contained two methoxy groups in the symmetrical position of the benzene ring. This methoxy (?OCH3) group is a well-known strong electron donating group, which can increase the stability of the benzene ring and enhance the radical scavenging activity as a result [54]. Zhang [54] and Elisia [57] indicated that the antioxidant activity of apiol is much stronger than the myristicin. It was also reported that substitution on the indole benzene ring with a methoxy group had greatly enhanced the radical scavenging activity of the un-substituted compounds [58]. The addition of a methoxy group also confers antioxidant activity to the chalcones [59]. Therefore, the essential oil and its king compound apiol have contributed significantly the antioxidant property being reported for the first time. On the basis of present findings, the essential oil of Anethum sowa L. root may be the potent alternative as natural antioxidants.
The brine shrimp cytotoxicity of the plant extract represents a rapid, inexpensive and simple bioassay technique for cytotoxic and anti-tumor activity. This test is also considered to be phototoxic, pesticidal, trypanocidal, antitumor, anticancer, enzyme inhibition and ion regulation activities. The assay indicated that essential oil is half of the vincristine sulphate toxicity. The apiol was reported to decrease the proliferation of human colorectal carcinoma cells (COLO 205) [60]. Moreover, the acaricidal constituent of apiol was isolated by various chromatographic techniques from Petroselinum sativum seeds and showed very strong acaricidal activity. This activity could be related to allyl (?C3H5) and methoxy (?OCH3) functional groups [61]. The antiproliferative activity of apiol and myristicin of Athamanta sicula L. also reported on human chronic myelogenous leukemia, lung tumor and breast adenocarcinoma cell line activities [62]. Nonetheless, apiol is known to have powerful insecticidal and synergist effect [6]. Therefore, the cytotoxic activity of the essential oil is due to the apiol compound of the A. sowa root. Furthermore, this essential oil may be helpful for treatment of premature ageing and cancer therapy by preventing oxidative damage through lipid peroxidation. Though it is the first report of cytotoxic activity on the brine shrimp, extensive studies are to be needed to assess the anticancer activity on the cell line of the essential oil and its isolated compound apiol.
The antimicrobial activities are responsible for oxygenated monoterpenes [63]. The appreciable antimicrobial activity of the essential oil of Anethum sowa L. may be attributed to the presence of monoterpenes compounds in the oil. On the other hand, the activity of the essential oil can be explained by the chemical structure of the major constituents of the oil. Apiol has a nucleus containing a polar functional group that is known to form hydrogen bonds with the active sites of the target enzyme [64]. It is assumed that the antimicrobial activity may be responsible for its apiol constituents, on the basis of that mechanism. The Gram-positive bacteria are generally more sensitive to the spice and herb essential oil than Gram-negative bacteria due to an outer membrane and a unique periplasmic space in the Gram-positive bacteria [65]. The essential oil degrades the cell wall of the organism by interacting with the essential oil component which causes disrupt cytoplasmic membrane and damage membrane protein [66]. However, it did not completely follow the trend described above and showed the potent activity against Gram-negative bacteria. Nonetheless, the antimicrobial activity of essential oils may be due to the synergistic effect of the major compounds of the oil and also combined with another minor constituent. The results of the standard antibiotic showed the stronger activity against most of the bacterial species than the essential oil.
In the present study, the essential oils inhibited the fungal growth but their effectiveness varied. On the other hand, the essential oil was found to be more effective against fungi of the MIC and MBC assays. This activity may be responsible for the high content of apiol along with other minor constituents in the oil. Further investigations are needed to be carried out for the better understanding of the present issue.