PHYTOCHEMICAL AND BIOLOGICAL STUDY ON CERTAIN PLANTS BELONGING TO FAMILY IRIDACEAE
Iriny Mohsen Mansour Ayoub;
Abstract
Biological Study of Various Extracts of Dietes bicolor (Steud.) Sweet ex Klatt. (Iridaceae)
D. bicolor leaf extract (and its fractions) as well as the flowers and rhizomes extracts were investigated for the following activities:
1. Antimicrobial activity
The crude extractsof D. bicolor leaves, flowers and rhizomes were subjected to comparative antimicrobial screening against two Gram-positive, two Gram-negative bacteria and four fungal strains using the agar well diffusion method. The minimum inhibitory concentrations (MIC) of the tested extracts were also determined.
D. bicolor extracts generally demonstrated notable broad spectrum antimicrobial activities (MIC values ≤ 500 µg/ml) against all tested pathogens. D. bicolor leaf extract showed potent broad spectrum antimicrobial activity with MIC values ranging between 0.24 and 31.25 µg/ml against all tested pathogens. Whilst, the flowers extract exhibited promising antimicrobial activities, displaying MIC values ranging between 1.95 and 125µg/ml against the tested bacteria and fungi. However,the rhizomes extract showed moderate antimicrobial activity with MIC values ranging between 31.25 and 500 µg/ml.
2. Cytotoxicity
The cytotoxic activity of D. bicolor leaf aqueous methanolic extract (DBL) and its fractions, hexane (DBL-Hex), dichloromethane (DBL-DCM) and n-butanol fractions (DBL-But); as well as the crude extracts of D. bicolor flowers (DBF) and rhizomes (DBR) was carried out on a diverse set of cancer cell lines, includingHeLa, DLD-1, HCT 116, T47D, MCF-7, MDA-231, K562, Molt4 and RBL-2H3. IC50 above 100 µg/ml was considered inactive.
DBL-Hex and DBL-DCM exhibitedgood cytotoxicity against Molt4 cell line only after 72 h incubation with IC50 values of 46.23 and 33.71μg/ml, respectively. However, no activity was observed against the other cancer cell lines where IC50 values recorded were found to be above100 μg/ml. Furthermore, the initial cytotoxicity screening ofthe crude extracts of D.bicolor leaves, flowers and rhizomes as well as DBL-But revealed that these extracts exhibited no cytotoxicity against all the tested cancer cell lines recording IC50 values above 100 μg/ml.
3. Antiallergic activity
The effects of D.bicolor extracts and fractions on the activation and degranulation of rat basophilic leukemia RBL-2H3 mast cells were investigated.Pretreatments with n-hexane or DCM fractions of D.bicolorleaf extractsignificantly reduced A23187-induced degranulation in sensitized RBL-2H3 cells as evidenced by a high percentageinhibition of β-hexosaminidase release in stimulated cells, where the calculated IC50 for the n-hexane fraction was found to be 42.4 μg/ml while that for the DCM fraction was found to be 35.4 μg/ml. Resultsshowed that the DCM fraction exhibited the most potent anti-allergic activity followed by the n-hexane fraction. Interestingly, D.bicolor rhizome extract showed pro-allergic effect exhibiting 213.0 ± 26.9% release of β-hexosaminidase compared to 100% release of the control. This phenomenon was previously reported among other members of Iridaceae.
To confirm the anti-allergic potency of the active DCM and n-hexane fractions of D. bicolor leaf extract, we further investigated their effect on antigen-induced degranulation in IgE-sensitized RBL-2H3 cells. Boththe DCM and n-hexane fractions of D. bicolor leaf extractshowed potent inhibitory activity in antigen-mediated β-hexosaminidase releasedegranulation assay, exhibiting IC50values of 65.6 and of 71.6 μg/ml, respectively.
4. Anti-inflammatory activity
The total leaf extract and its fractions were examined for possible anti-inflammatory activity in carrageenan-induced paw edema rat model. D. bicolorextract and its fractions demonstrated a significant reduction in carrageenan-induced rat paw edema where the n-butanol fraction exhibited the most potent anti-inflammatory activity comparable to indomethacin, the standard anti-inflammatory drug. Furthermore, tissues isolated from D. bicolortreated animals exhibited a significant increase in the total antioxidant capacity compared to the control group.
5. Antioxidant activity
The antioxidant activity was determined in vitro using DPPH radical scavenging capacity assay. Both the DCM and n-butanol fractions exerted a moderate antioxidant activity as indicated by the reduction of DPPH• radicals attaining the 50% scavenging activity of DPPH• (the concentration that causes a decrease in the initial DPPH concentration by 50%) at 0.33 and 0.52 mg/ml, respectively.
6. Hepatoprotectiveactivity
In the current study, the protective effects of D. bicolorleaf aqueous methanolic extract and its fractions including theDCM and n-butanol fractions as well as the methanolic extract of D. bicolor rhizomes against Tamoxifen (TAM)-induced hepatotoxicity infemale rats were evaluated. TAM (45 mg/kg/day,i.p., for7 consecutive days) resulted in an elevation in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Also, TAM treatment resulted in the elevation of thiobarbituric acid reactive substances (TBARS), a byproduct of lipid peroxidation. Further, it raised the liver tumor necrosis factor-alpha (TNF-α) level.
Treatment with D. bicolor extracts and fractions (20 mg/kg/day; i.p., for 7 consecutive days) significantly prevented the elevation in serum activity of the assessed enzymes. The DCM and n-butanol fractions of the leaf extract were found to be the most active significantly inhibiting the elevationin ALT levels by 36 and 32%, respectively, and AST levels by 42% as compared to the corresponding TAM group values. Treatment with D. bicolor extracts and fractions significantly improved the antioxidant status considerably as reflected by low TBARS levels (64.29 % for DBL, DBL-But and DBR and 78.57% for DBL-DCM) as compared to TAM-treated group. Moreover, treatment with D. bicolor extracts and fractions significantly decreased TAM-induced elevation in TNF-α level (P < 0.05) where the dichloromethane fraction (DBL-DCM) was the most active reducing TNF- α level by 41.4% compared to TAM-treated rats.
7. Antidiabetic activity
In this study, we examined the antidiabeticactivity of D. bicolorleaf aqueous methanolic extract (DBL) and its fractions,the DCM and n-butanol fractions; as well as the methanolic extract of D. bicolor rhizomes (DBR) in streptozotocin (STZ)-diabetic rats. Injection of STZ into rats exhibited significant elevations in fasting blood glucose (FBG) level by 278% as compared to the normal control rats. These changes were concomitant with a significant decline in serum insulin level by 52.63%, as compared to normal rats. Administration of glibenclamide (GLB), the standard antidiabetic drug, to STZ-diabetic rats eliciteda significant reduction in FBG level by 28.57% associated with a marked increase in serum insulin level by 22.22%, as compared to STZ-diabetic rats.
Administration of the DCMfraction to STZ-diabetic rats elicited a significant increase in serum insulin by 77.78% accompanied by a significant reduction in FBG level by 65.60%, as comparedtoSTZ-diabeticrats, displaying a potent antidiabetic activity. Furthermore, administration of the n-butanol fraction of D. bicolor leaf extract as well as the methanolic extract of D. bicolor rhizomes elicited a significant reduction in FBG level by 55.03 and 47.62%, respectively, as compared to STZ-diabetic rats.
Chapter II
Chemical Composition of the Leaf Extracts of Dietes bicolor(Steud.) Sweet ex Klatt.and Chasmanthe aethiopica(L.) N.E. Br.(Iridaceae)
1. Preliminary phytochemical screening of D. bicolor and C. aethiopicaleaves.
Preliminary phytochemical screening ofD. bicolor leaves allowed the identification of the following secondary metabolites: flavonoids, condensed tannins, sterols and /or triterpenoids, carbohydrates and /or glycosides. However,saponins,cardiac glycosides, alkaloids and anthraquinones were absent.
Qualitative chemical tests performed on the leaves of C. aethiopicarevealed the presence of several classes of compounds including flavonoids, condensed tannins, sterols and /or triterpenoids, carbohydrates and /or glycosides.Meanwhile, saponins, cardiac glycosides, alkaloids and anthraquinones were absent.
2. Phytochemical study of D. bicolor leaves
The objectives of this study aimed at the exploration of the chemical composition of the biologically active fractions including the DCM and n-butanol fractions of D. bicolor leaf aqueous methanolic extract in an effort to isolate the main active secondary metabolites responsible for the observed biological activities.
These fractions were subjected to column chromatography and preparative thin layer chromatography (TLC) leading to the isolation and purification of the individual chemical constituents.
Phytochemical study of D. bicolor leaf extract resulted in the isolation and structural elucidation of nine compounds including three dihydroflavonols, three biflavones, an isoflavone, a flavone-C glycoside and a sterol. Their structures were identified by various spectroscopic techniques including 1H NMR, 13C NMR, DEPT, 2D-NMR (1H-1H COSY, NOESY, HSQC and HMBC), ESI-MS as well as comparison to previously reported data.
The compounds isolated from D. bicolor leaf extract include:
1. Orobol-7,3'-dimethyl ether
2. 3-Hydroxy-5-methoxy-6,7-methylenedioxy flavanone
3. 3,5,7-Trihydroxy-8-methoxyflavanone
4. 3-Hydroxy-5,7-dimethoxy flavanone
5. Lanaroflavone
6. Robustaflavone
7. Amentoflavone
8. β-Sitosterol
9. Vitexin
Among the isolated compounds, a novel compound namely, 3,5,7-trihydroxy-8-methoxyflavanone was reported. In addition, two rare dihydroflavonols: 3-hydroxy-5,7-dimethoxyflavanone (second report in nature) and 3-hydroxy-5-methoxy-6,7-methylenedioxyflavanone (fourth report in nature) were isolated and identified. Whereas, the biflavones: robustaflavone and lanaroflavone were reported for the first time in family Iridaceae.Moreover, orobol 7,3'-dimethyl ether, amentoflavone, vitexin and β-sitosterolwere first reported in the genus.
A chromatographic method was optimized for the identification and quantification of vitexin in the dried leaf extract. The amount of vitexin in the dried total extract was found to be 67.4 mg/g dried leaf extract.
Chapter III
Chemical composition and biological activity of the essential oils of Dietes bicolor (Iridaceae)
In this chapter, a comparative analysis of the volatile oil compositions of D. bicolorleaves, flowers and rhizomes was carried out. Moreover, the antimicrobial activity of the leafand flower essential oils was assessed against various Gram-positive and Gram-negative bacterial strains in addition to four fungi aiming to explore their antibacterial and antifungal activities.
1. GC/FID and GC/MS analyses of the oil
GC analyses of the essential oils ofD. bicolor flowers, leaves and rhizomes were performed aiming to assign the variations in their chemical composition. Examining the physical characters of the oils revealed that all the oils were yellow in color displaying a characteristic odor. However, their yields were variable to some extent being 0.005 and 0.003% (w/w) in the leaves and flowers, respectively.However, only traces of volatile oil were detected in the rhizomes. Through GC/MS analysis, a total of 84 components were determined, accounting for 94.65, 95.63 and 87.09% of flowers, leaves, and rhizomes total oils, respectively.
Analysis of the flower essential oil resulted in the identification of 47 components, in which fatty acids and their esters predominated with dodecanoic acid (22.84%) and capric acid (21.12%) representing the most abundant components. Moreover, myristic acid (14.32%) and methyl caprate (7.90%) were also predominant.
Investigation of the leaf volatiles led to the identification of 42 compounds, where spathulenol (48.44%) represented the major component in the leaf oil, followed by dihydro-edulan I (6.25%), cubenol (6.00%), τ-cadinol (5.90%) and β-bourbonene (4.06%). Regarding the rhizomes oil, only three fatty acids namely capric acid (46.14%), n-hexadecanoic acid (23.84%) and n-caprylic acid (17.11%) were identified representing 87.09% of the total oil content.
The oxygenated sesquiterpene fraction of the leaf oil accounted for 70.07% and was mainly attributed to its high content of spathulenol. Furthermore, sesquiterpenehydrocarbons represented 16.53% of the total leaf oil with β-bourbonene being the most predominant compound. However, only traces of oxygenated monoterpenes were detected in the leaf oil, whereas, monoterpene hydrocarbons were completely absent. Regarding the flower and rhizome oils, fatty acids and their esters together with other aliphatic hydrocarbon compounds showed high prevalence representing nearly the total oil composition. Moreover, the overall contents of monoterpenes, oxygenated monoterpenes, sesquiterpenes as well as oxygenated sesquiterpenes in these oils were very low or even absent.
2. Antimicrobial activity
The antimicrobial activity of both the leaf and flower oils was investigated against four bacterial strains in addition to four fungi using the micro-broth dilution method. The essential oils of the leaves and flowers exhibited notable antimicrobial activity against nearly all the tested organisms showing minimum inhibitory concentrations (MICs) ranging from 0.12 to 31.25 μg/ml. However, the leaf oil showed higher efficacy against the tested Gram-positive bacteria exceeding that of the flowers oil with MICs of 0.12 and 0.49 μg/ml for B. subtilis and S. pneumonia, respectively. Gram-negative bacteria were generally less susceptible, where both oils produced similar effects on E. coli (MIC, 15.63μg/ml) and being completely ineffective against Pseudomonas aeruginosa.
Concerning their antifungal activity, the leaf oil exerted a more pronounced effect than the flower oil on the tested fungi namely G. candidum, S. racemosum and A. fumigatus showing MICs of 0.12, 0.98 and 1.95 μg/ml, respectively except for C.albicans being definitely unsusceptible to the effect of both oils. Noteworthy to mention, the leaf oil exerted a potent antifungal activity against S. racemosum showing MIC value of 0.98 μg/ml being superior to amphotericin B, the standard antifungal drug, which showed an MIC value of 1.95 μg/ml.
D. bicolor leaf extract (and its fractions) as well as the flowers and rhizomes extracts were investigated for the following activities:
1. Antimicrobial activity
The crude extractsof D. bicolor leaves, flowers and rhizomes were subjected to comparative antimicrobial screening against two Gram-positive, two Gram-negative bacteria and four fungal strains using the agar well diffusion method. The minimum inhibitory concentrations (MIC) of the tested extracts were also determined.
D. bicolor extracts generally demonstrated notable broad spectrum antimicrobial activities (MIC values ≤ 500 µg/ml) against all tested pathogens. D. bicolor leaf extract showed potent broad spectrum antimicrobial activity with MIC values ranging between 0.24 and 31.25 µg/ml against all tested pathogens. Whilst, the flowers extract exhibited promising antimicrobial activities, displaying MIC values ranging between 1.95 and 125µg/ml against the tested bacteria and fungi. However,the rhizomes extract showed moderate antimicrobial activity with MIC values ranging between 31.25 and 500 µg/ml.
2. Cytotoxicity
The cytotoxic activity of D. bicolor leaf aqueous methanolic extract (DBL) and its fractions, hexane (DBL-Hex), dichloromethane (DBL-DCM) and n-butanol fractions (DBL-But); as well as the crude extracts of D. bicolor flowers (DBF) and rhizomes (DBR) was carried out on a diverse set of cancer cell lines, includingHeLa, DLD-1, HCT 116, T47D, MCF-7, MDA-231, K562, Molt4 and RBL-2H3. IC50 above 100 µg/ml was considered inactive.
DBL-Hex and DBL-DCM exhibitedgood cytotoxicity against Molt4 cell line only after 72 h incubation with IC50 values of 46.23 and 33.71μg/ml, respectively. However, no activity was observed against the other cancer cell lines where IC50 values recorded were found to be above100 μg/ml. Furthermore, the initial cytotoxicity screening ofthe crude extracts of D.bicolor leaves, flowers and rhizomes as well as DBL-But revealed that these extracts exhibited no cytotoxicity against all the tested cancer cell lines recording IC50 values above 100 μg/ml.
3. Antiallergic activity
The effects of D.bicolor extracts and fractions on the activation and degranulation of rat basophilic leukemia RBL-2H3 mast cells were investigated.Pretreatments with n-hexane or DCM fractions of D.bicolorleaf extractsignificantly reduced A23187-induced degranulation in sensitized RBL-2H3 cells as evidenced by a high percentageinhibition of β-hexosaminidase release in stimulated cells, where the calculated IC50 for the n-hexane fraction was found to be 42.4 μg/ml while that for the DCM fraction was found to be 35.4 μg/ml. Resultsshowed that the DCM fraction exhibited the most potent anti-allergic activity followed by the n-hexane fraction. Interestingly, D.bicolor rhizome extract showed pro-allergic effect exhibiting 213.0 ± 26.9% release of β-hexosaminidase compared to 100% release of the control. This phenomenon was previously reported among other members of Iridaceae.
To confirm the anti-allergic potency of the active DCM and n-hexane fractions of D. bicolor leaf extract, we further investigated their effect on antigen-induced degranulation in IgE-sensitized RBL-2H3 cells. Boththe DCM and n-hexane fractions of D. bicolor leaf extractshowed potent inhibitory activity in antigen-mediated β-hexosaminidase releasedegranulation assay, exhibiting IC50values of 65.6 and of 71.6 μg/ml, respectively.
4. Anti-inflammatory activity
The total leaf extract and its fractions were examined for possible anti-inflammatory activity in carrageenan-induced paw edema rat model. D. bicolorextract and its fractions demonstrated a significant reduction in carrageenan-induced rat paw edema where the n-butanol fraction exhibited the most potent anti-inflammatory activity comparable to indomethacin, the standard anti-inflammatory drug. Furthermore, tissues isolated from D. bicolortreated animals exhibited a significant increase in the total antioxidant capacity compared to the control group.
5. Antioxidant activity
The antioxidant activity was determined in vitro using DPPH radical scavenging capacity assay. Both the DCM and n-butanol fractions exerted a moderate antioxidant activity as indicated by the reduction of DPPH• radicals attaining the 50% scavenging activity of DPPH• (the concentration that causes a decrease in the initial DPPH concentration by 50%) at 0.33 and 0.52 mg/ml, respectively.
6. Hepatoprotectiveactivity
In the current study, the protective effects of D. bicolorleaf aqueous methanolic extract and its fractions including theDCM and n-butanol fractions as well as the methanolic extract of D. bicolor rhizomes against Tamoxifen (TAM)-induced hepatotoxicity infemale rats were evaluated. TAM (45 mg/kg/day,i.p., for7 consecutive days) resulted in an elevation in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Also, TAM treatment resulted in the elevation of thiobarbituric acid reactive substances (TBARS), a byproduct of lipid peroxidation. Further, it raised the liver tumor necrosis factor-alpha (TNF-α) level.
Treatment with D. bicolor extracts and fractions (20 mg/kg/day; i.p., for 7 consecutive days) significantly prevented the elevation in serum activity of the assessed enzymes. The DCM and n-butanol fractions of the leaf extract were found to be the most active significantly inhibiting the elevationin ALT levels by 36 and 32%, respectively, and AST levels by 42% as compared to the corresponding TAM group values. Treatment with D. bicolor extracts and fractions significantly improved the antioxidant status considerably as reflected by low TBARS levels (64.29 % for DBL, DBL-But and DBR and 78.57% for DBL-DCM) as compared to TAM-treated group. Moreover, treatment with D. bicolor extracts and fractions significantly decreased TAM-induced elevation in TNF-α level (P < 0.05) where the dichloromethane fraction (DBL-DCM) was the most active reducing TNF- α level by 41.4% compared to TAM-treated rats.
7. Antidiabetic activity
In this study, we examined the antidiabeticactivity of D. bicolorleaf aqueous methanolic extract (DBL) and its fractions,the DCM and n-butanol fractions; as well as the methanolic extract of D. bicolor rhizomes (DBR) in streptozotocin (STZ)-diabetic rats. Injection of STZ into rats exhibited significant elevations in fasting blood glucose (FBG) level by 278% as compared to the normal control rats. These changes were concomitant with a significant decline in serum insulin level by 52.63%, as compared to normal rats. Administration of glibenclamide (GLB), the standard antidiabetic drug, to STZ-diabetic rats eliciteda significant reduction in FBG level by 28.57% associated with a marked increase in serum insulin level by 22.22%, as compared to STZ-diabetic rats.
Administration of the DCMfraction to STZ-diabetic rats elicited a significant increase in serum insulin by 77.78% accompanied by a significant reduction in FBG level by 65.60%, as comparedtoSTZ-diabeticrats, displaying a potent antidiabetic activity. Furthermore, administration of the n-butanol fraction of D. bicolor leaf extract as well as the methanolic extract of D. bicolor rhizomes elicited a significant reduction in FBG level by 55.03 and 47.62%, respectively, as compared to STZ-diabetic rats.
Chapter II
Chemical Composition of the Leaf Extracts of Dietes bicolor(Steud.) Sweet ex Klatt.and Chasmanthe aethiopica(L.) N.E. Br.(Iridaceae)
1. Preliminary phytochemical screening of D. bicolor and C. aethiopicaleaves.
Preliminary phytochemical screening ofD. bicolor leaves allowed the identification of the following secondary metabolites: flavonoids, condensed tannins, sterols and /or triterpenoids, carbohydrates and /or glycosides. However,saponins,cardiac glycosides, alkaloids and anthraquinones were absent.
Qualitative chemical tests performed on the leaves of C. aethiopicarevealed the presence of several classes of compounds including flavonoids, condensed tannins, sterols and /or triterpenoids, carbohydrates and /or glycosides.Meanwhile, saponins, cardiac glycosides, alkaloids and anthraquinones were absent.
2. Phytochemical study of D. bicolor leaves
The objectives of this study aimed at the exploration of the chemical composition of the biologically active fractions including the DCM and n-butanol fractions of D. bicolor leaf aqueous methanolic extract in an effort to isolate the main active secondary metabolites responsible for the observed biological activities.
These fractions were subjected to column chromatography and preparative thin layer chromatography (TLC) leading to the isolation and purification of the individual chemical constituents.
Phytochemical study of D. bicolor leaf extract resulted in the isolation and structural elucidation of nine compounds including three dihydroflavonols, three biflavones, an isoflavone, a flavone-C glycoside and a sterol. Their structures were identified by various spectroscopic techniques including 1H NMR, 13C NMR, DEPT, 2D-NMR (1H-1H COSY, NOESY, HSQC and HMBC), ESI-MS as well as comparison to previously reported data.
The compounds isolated from D. bicolor leaf extract include:
1. Orobol-7,3'-dimethyl ether
2. 3-Hydroxy-5-methoxy-6,7-methylenedioxy flavanone
3. 3,5,7-Trihydroxy-8-methoxyflavanone
4. 3-Hydroxy-5,7-dimethoxy flavanone
5. Lanaroflavone
6. Robustaflavone
7. Amentoflavone
8. β-Sitosterol
9. Vitexin
Among the isolated compounds, a novel compound namely, 3,5,7-trihydroxy-8-methoxyflavanone was reported. In addition, two rare dihydroflavonols: 3-hydroxy-5,7-dimethoxyflavanone (second report in nature) and 3-hydroxy-5-methoxy-6,7-methylenedioxyflavanone (fourth report in nature) were isolated and identified. Whereas, the biflavones: robustaflavone and lanaroflavone were reported for the first time in family Iridaceae.Moreover, orobol 7,3'-dimethyl ether, amentoflavone, vitexin and β-sitosterolwere first reported in the genus.
A chromatographic method was optimized for the identification and quantification of vitexin in the dried leaf extract. The amount of vitexin in the dried total extract was found to be 67.4 mg/g dried leaf extract.
Chapter III
Chemical composition and biological activity of the essential oils of Dietes bicolor (Iridaceae)
In this chapter, a comparative analysis of the volatile oil compositions of D. bicolorleaves, flowers and rhizomes was carried out. Moreover, the antimicrobial activity of the leafand flower essential oils was assessed against various Gram-positive and Gram-negative bacterial strains in addition to four fungi aiming to explore their antibacterial and antifungal activities.
1. GC/FID and GC/MS analyses of the oil
GC analyses of the essential oils ofD. bicolor flowers, leaves and rhizomes were performed aiming to assign the variations in their chemical composition. Examining the physical characters of the oils revealed that all the oils were yellow in color displaying a characteristic odor. However, their yields were variable to some extent being 0.005 and 0.003% (w/w) in the leaves and flowers, respectively.However, only traces of volatile oil were detected in the rhizomes. Through GC/MS analysis, a total of 84 components were determined, accounting for 94.65, 95.63 and 87.09% of flowers, leaves, and rhizomes total oils, respectively.
Analysis of the flower essential oil resulted in the identification of 47 components, in which fatty acids and their esters predominated with dodecanoic acid (22.84%) and capric acid (21.12%) representing the most abundant components. Moreover, myristic acid (14.32%) and methyl caprate (7.90%) were also predominant.
Investigation of the leaf volatiles led to the identification of 42 compounds, where spathulenol (48.44%) represented the major component in the leaf oil, followed by dihydro-edulan I (6.25%), cubenol (6.00%), τ-cadinol (5.90%) and β-bourbonene (4.06%). Regarding the rhizomes oil, only three fatty acids namely capric acid (46.14%), n-hexadecanoic acid (23.84%) and n-caprylic acid (17.11%) were identified representing 87.09% of the total oil content.
The oxygenated sesquiterpene fraction of the leaf oil accounted for 70.07% and was mainly attributed to its high content of spathulenol. Furthermore, sesquiterpenehydrocarbons represented 16.53% of the total leaf oil with β-bourbonene being the most predominant compound. However, only traces of oxygenated monoterpenes were detected in the leaf oil, whereas, monoterpene hydrocarbons were completely absent. Regarding the flower and rhizome oils, fatty acids and their esters together with other aliphatic hydrocarbon compounds showed high prevalence representing nearly the total oil composition. Moreover, the overall contents of monoterpenes, oxygenated monoterpenes, sesquiterpenes as well as oxygenated sesquiterpenes in these oils were very low or even absent.
2. Antimicrobial activity
The antimicrobial activity of both the leaf and flower oils was investigated against four bacterial strains in addition to four fungi using the micro-broth dilution method. The essential oils of the leaves and flowers exhibited notable antimicrobial activity against nearly all the tested organisms showing minimum inhibitory concentrations (MICs) ranging from 0.12 to 31.25 μg/ml. However, the leaf oil showed higher efficacy against the tested Gram-positive bacteria exceeding that of the flowers oil with MICs of 0.12 and 0.49 μg/ml for B. subtilis and S. pneumonia, respectively. Gram-negative bacteria were generally less susceptible, where both oils produced similar effects on E. coli (MIC, 15.63μg/ml) and being completely ineffective against Pseudomonas aeruginosa.
Concerning their antifungal activity, the leaf oil exerted a more pronounced effect than the flower oil on the tested fungi namely G. candidum, S. racemosum and A. fumigatus showing MICs of 0.12, 0.98 and 1.95 μg/ml, respectively except for C.albicans being definitely unsusceptible to the effect of both oils. Noteworthy to mention, the leaf oil exerted a potent antifungal activity against S. racemosum showing MIC value of 0.98 μg/ml being superior to amphotericin B, the standard antifungal drug, which showed an MIC value of 1.95 μg/ml.
Other data
| Title | PHYTOCHEMICAL AND BIOLOGICAL STUDY ON CERTAIN PLANTS BELONGING TO FAMILY IRIDACEAE | Other Titles | دراسة فيتوكيميائية وبيولوجية لبعض النباتات التي تنتمي للعائلة السوسنية | Authors | Iriny Mohsen Mansour Ayoub | Issue Date | 2015 |
Recommend this item
Similar Items from Core Recommender Database
Items in Ain Shams Scholar are protected by copyright, with all rights reserved, unless otherwise indicated.