ANTIOXIDANT ACTIVITY OF A NEW FLAVONE GLYCOSIDE FROM THE STEMS OF GMELINA ARBOREA ROXB.HTML Full Text
ANTIOXIDANT ACTIVITY OF A NEW FLAVONE GLYCOSIDE FROM THE STEMS OF GMELINA ARBOREA ROXB.
R. N. Yadava and Jyotsna Raghuvansi *
Department of Chemistry, Dr. H. S. Gour Vishwavidyalaya (A Central University), Sagar - 470003, Madhya Pradesh, India.
ABSTRACT: Gmelina arborea Roxb. belongs to the Verbenaceae family, commonly known as Gambhar. It is distributed throughout India, Ceylon, Malayan and Philippine Islands. Its roots have anthelmintic properties. Its flowers are useful in the treatment of leprosy and blood diseases. Its fruit has diuretic properties and aphrodisiac. It is also used in anemia leprosy and vaginal discharges. Leaves have shown analgesic, antimicrobial, and anti-diabetic activities. A new flavone glycosides 5, 7.4ʹ-trihydroxy-8, 3ʹ-dimethoxyflavone- 4ʹ-O-β-D-glucopyranosyl- 7-O-β-D-xylopyranosyl (1→2)-α-L-rhamnopyranoside(A) along with two known compounds Luteolin (B) and Apigenin (C) were isolated from ethanolic extract of the stem parts of the plant. The characterization and structural elucidation of these compounds were carried out by various color reactions, chemical degradation, and spectral analysis. Antioxidant activity of compound A was evaluated by 1, 1-diphenyl-2-pycrylhydrazyl (DPPH) assay system which has shown a significant radical scavenging activity.
Gmelina arborea Roxb., Verbenaceae, Flavone glycoside, Luteolin, Apigenin, DPPH assay
INTRODUCTION: Gmelina arborea Roxb. (Hort. Beng. 1814) belongs to Verbenaceae family and commonly known as Gambhar 1, 2. It is a moderate size unarmed deciduous tree, reaching 18m high, bark greyish-yellow, leaves 10-20 by 7.5-15 cm broadly ovate and petioles 5-7.5 cm long, cylindric and glandular at the top. It is distributed throughout India, Ceylon, Malayan, and Philippine Islands. Its roots have anthelmintic properties. Its flowers are useful in the treatment of leprosy and blood diseases. Its fruit has diuretic properties and aphrodisiac. It is also used in anemia leprosy and vaginal discharges.
Leaves have shown analgesic, antimicrobial and anti-diabetic activities 1. Various bioactive constituents have been reported from this plant by earlier workers 3, 4, 5, 6. In this paper we deal with the isolation and antioxidant activity of a new flavone glycoside (A) 5, 7.4ʹ-trihydroxy-8, 3ʹ-dimethoxyflavone- 4ʹ-O-β-D-glucopyranosyl-7-O-β-D-xylopyranosyl (1→2)-α-L-rhamnopyranoside from ethanolic extract of stem parts of the plant along with two known compound B and C.
MATERIALS AND METHODS:
General Experimental Procedure: All the melting points were determined on a thermo-electrically melting point apparatus and are uncorrected. The IR spectra were recorded at Shimadzu FT-IR 8400S in KBr disc. UV spectra were determined on Shimadzu-120 double beam spectrometer in MeOH. 1H-NMR spectra were recorded on Bruker DRX 300 MHz spectrometer in CDCl3 using TMS as an internal standard. 13C-NMR spectra were recorded on Bruker DRX 75 MHz spectrometer using CDCl3. The chemical shift values are reported in ppm (δ) units and coupling constants (J) in Hz. The FAB mass spectra were recorded on Jeol-SX (102) Mass spectrometer.
Plant Material: The stems of the plant were collected locally around Sagar region and identified by a taxonomist, Department of Botany, Dr. H. S. Gour Vishwavidyalaya, Sagar, Madhya Pradesh, India. A voucher specimen (Bot/H/05/12/05) has been deposited in Natural Products Laboratory, Department of Chemistry of this university.
Extraction and Isolation: Air-dried powdered stem parts of the plant (5 kg) were extracted with ethanol in Soxhlet apparatus for 5-7 days. The ethanolic extract obtained was concentrated under reduced pressure to give brown viscous mass, which was further partitioned with solvents of increasing polarity, pet. ether, CHCl3, EtOAc, Me2CO, and MeOH. The methanol soluble fraction was concentrated under reduced pressure by a rotatory evaporator to obtain the brown viscous mass of 3.95 gm. On TLC examination over silica Gel-G using nBAW (4:1:5) as solvent and I2 vapors as visualizing agent showed three spots indicating it to be a mixture of three compounds A, B and C which were further purified by column chromatography over a SiO2-gel column using CHCl3: MeOH in various proportions (8:2, 7:3, 9:1). The solvents of the eluents obtained were removed and crystallized from the ether, which yielded compound A (1.78 gm), compound B (0.52 gm) and compound C (0.71 gm) respectively.
RESULTS AND DISCUSSION: Compound A has m.p. 272-273°C, m.f. C34H42O20, [M+] 770 (FABMS). It gave Molisch and Shinoda 7, 8 tests confirming its flavonoids glycosidic nature. IR (KBr) νmax cm-1 3450 (-OH), 2988, 2917 (-CH stretching), 2872 (-OMe), 1649 (-C=O), 1623 (aromatic ring system) and 1525, 1478, 1132, 1015 and 830 cm-1. In 1HNMR spectrum of compound A a singlet at δ 6.58 (1H, s) was assigned for H-6 in ring A, and a singlet at δ 6.71 (1H, s) for H-3 in ring C. Two doublets at δ 7.78 (1H, J 2 Hz) and δ 6.61 (1H, J 8.6 Hz) were assigned for H-2ʹ and H-5ʹ in ring B. A double doublet at δ 7.64 (1H, dd, J 8.8, 2.2 Hz) was assigned for H-6ʹ in ring B. A singlet was assigned for –OH group at C-5 position at δ 12.24. Two singlets at δ 3.78 and 3.73 show the presence of –OCH3 group at C-8 and C-3ʹ. The anomeric proton signals at δ 6.02 (1H, s, J 1.6Hz), δ 5.03 (1H, d, J 7.4 Hz) and δ 5.88 (1H, d, J 7.2 Hz) were assigned for H-1ʹʹ of L-rhamnose, H-1ʹʹʹ of D-xylose and H-1ʹʹʹʹ of D-glucose respectively.
A coupling constant at J 1.6 Hz of H-1ʹʹ confirmed the α-configuration for L-rhamnose and coupling constant at 7.4 Hz and 7.2 Hz confirmed the β-configuration for D-xylose and D-glucose respectively 9, 10. The characteristic ion peaks in the mass spectrum of compound A observed at m/z 770 [M+], 608 [M+-D-Glucose], 476 [M+-D-Xylose] and 330 [M+-L-rhamnose and aglycone] were obtained by subsequent losses from the molecular ion of each molecule of D-glucose, D-xylose and L-rhamnose indicating D-glucose at C-4ʹ position, D-xylose and L-rhamnose were linked to aglycone at C-7 position. Acid hydrolysis of compound A with 10% ethanolic H2SO4 gave aglycone A-1, m.p. 229-230 °C, m.f. C17H14O7 [M+] 330 (FABMS) which was identified as 5,7, 4ʹ-trihydroxy-8,3ʹ-dimethoxy flavone.
The aqueous hydrolysate obtained on acid hydrolysis of compound A was neutralized with BaCO3 and BaSO4 was filtered off. The filtrate obtained was concentrated and subjected to paper chromatography, examination showed the presence of L-rhamnose (Rf 0.37), D-xylose (Rf 0.28) and D-glucose (Rf 0.16). Periodate oxidation 11, 12 of compound A confirmed that all sugars were present in pyranose form. Permethylation 13, 14 followed by acid hydrolysis, yielded methylated aglycone and methylated sugars confirmed the presence of methoxy group in compound A. The methylated aglycone was identified as 7, 4ʹ-dihydroxy-5, 8, 3ʹ-trimethoxy flavone which confirmed that glycosidation was involved at C-7-OH and C-3ʹ-OH positions of aglycone. The methylated sugars were identified as 2,3,4,6-tetramethoxy glucose (RG 1.0), 3,4-dimethoxy rhamnose (RG 0.84) and 2,3,4-trimethoxy xylose (RG 0.94).
Therefore it was concluded that C-1ʹʹʹʹ-OH of D-glucose was attached with OH group at C-4ʹ position of aglycone, C-1ʹʹ-OH of L-rhamnose was attached with –OH group at C-7 of aglycone, C-2ʹʹ-OH of L-rhamnose was linked with C-1ʹʹʹ-OH of D-xylose. Thus interglycosidic linkage (1→2) was found between L-rhamnose and D-xylose. Enzymatic hydrolysis15 of compound A by almond emulsion shows β-linkage of D-xylose with L-rhamnose and that of D-glucose with aglycone and further hydrolysis of proaglycone by Takadiastase enzyme liberated L-rhamnose showing α-linkage with aglycone. On the basis of above evidence compound A was identified as 5, 7.4ʹ-trihydroxy-8, 3ʹ-dimethoxyflavone- 4ʹ-O-β-D-glucopyranosyl-7-O-β-D-xylopyranosyl (1→2)-α-L-rhamnopyranoside. Compound B and C have been reported as Luteolin and Apigenin and compound A has been evaluated for its antioxidant activity (See in the experimental section).
Study of Compound A: It was analyzed for m.f. C34H42O20, m.p. 272-273 °C, [M+] 770 found (%) C 53.12, H 5.69, O 41.61 and calcd. form.f. C34H42O20 found (%) C 53.17, H 5.71, O 41.66. UV (MeOH) λmax nm 242, 276 and 350. IR (KBr) νmax (cm-1)- 3450, 2988, 2917, 2872, 1649, 1623, 1525, 1478, 1132, 1015 and 830. 1HNMR (300 MHz, CDCl3); 12.24 (1H, s, 5-OH), 6.58 (1H, s, H-6), 6.71 (1H, s, H-3), 7.78 (1H, d, J 2 Hz, H-2ʹ), 6.61 (1H , d, J 8.6 Hz , H-5ʹ), 7.64 (1H, dd, J 8.8, 2.2 Hz, H-6ʹ), 3.78 (OMe-C-8), 3.73 (OMe-C-3ʹ), 6.02 (1H, br, s, H-1ʹʹ), 4.12 (1H, d, J 3.6 Hz, H-2ʹʹ), 3.68 (1H, dd, H-3ʹʹ), 3.40 (1H, dd, H-4ʹʹ), 3.85 (1H, m, H-5ʹʹ), 1.12 (3H, d, J 6.2 Hz, CH3), 5.03 (1H, d, J 7.4 Hz, H-1ʹʹʹ), 3.75 (1H, dd, H-2ʹʹʹ), 3.49 (1H, dd, H-3ʹʹʹ), 3.41(1H, m, H-4ʹʹʹ), 3.21 (1H, dd, J 12.2, 9.9 Hz, H-5aʹʹʹ), 3.63 (1H, m, H-5bʹʹʹ), 5.88 (1H, d, J 7.2 Hz, H-1ʹʹʹʹ), 3.65 (1H, dd, H-2ʹʹʹʹ), 3.48 (1H, dd,H-3ʹʹʹʹ), 3.43 (1H, dd, H-4ʹʹʹʹ), 3.26 (1H, m, H-5ʹʹʹʹ), 3.46 (1H, dd, J 12.0 5.2 Hz, H-6aʹʹʹʹ), 3.60 (1H, dd, J 12.0, 2.2 Hz, H-6bʹʹʹʹ). 13C-NMR (75 MHz, CDCl3) 168.8 (C-2), 104.9 (C-3), 187.0 (C-4) 152.1 (C-5), 102.3 (C-6), 152.3 (C-7) 129.3 (C-8), 145.5 (C-9), 105.0 (C-10), 127.5 (C-1ʹ), 112.4 (C-2ʹ), 147.6 (C-3ʹ), 143.6 (C-4ʹ), 115.1 (C-5ʹ), 119.1 (C-6ʹ), 56.6 (OMe-8), 56.3 (OMe-3ʹ), 100.3 (C-1ʹʹ), 87.3 (C-2ʹʹ), 70.8 (C-3ʹʹ), 74.6 (C-4ʹʹ), 72.1 (C-5ʹʹ), 18.5 (C-6ʹʹ), 107.3 (C-1ʹʹʹ) 73.2 (C-2ʹʹʹ), 76.4 (C-3ʹʹʹ), 71.2 (C-4ʹʹʹ), 67.7 (C-5ʹʹʹ), 101.5 (C-1ʹʹʹʹ), 74.1 (C-2ʹʹʹʹ), 70.2 (C-3ʹʹʹʹ), 69.1 (C-4ʹʹʹʹ), 73.4 (C-5ʹʹʹʹ), 60.5(C-6ʹʹʹʹ).
Acid Hydrolysis of Compound A: 80 mg of compound A was dissolved in ethanol (15 ml) and refluxed with 10% H2SO4 for 7 h. The contents were concentrated, cooled and the residue was further extracted with diethyl ether. After washing the ether layer with water, the residue was chromatographed over silica gel using CHCl3: MeOH as a solvent to give aglycone. This was identified as 5, 7, 4’-trihydroxy-8, 3’-dimethoxy flavone.
Permethylation of Compound A: Compound A (40 mg) was dissolved in DMF (20 ml) and refluxed for 48 hr with MeI (5 ml) and Ag2O (40 mg), then filtered and washed with DMF. The filtrate was dried and hydrolyzed with 10% H2SO4 to obtain methylated aglycone, 7, 4’-dihydroxy-5, 8,3’-trimethoxy flavone. The aqueous hydrolysate so obtained after removal of aglycone was neutralized with BaCO3 and BaSO4 was filtered off. The filtrate was dried in vacuum and subjected to paper chromatography using nBAW (4:1:5) as a solvent and aniline hydrogen phthalate was used for detection. The methylated sugars were identified as 2,3,4,6-tetramethoxy glucose (RG 1.0), 3, 4-dimethoxy rhamnose (RG 0.84) and 2,3,4-trimethoxy xylose (RG 0.94).
Enzymatic Hydrolysis of Compound A: Compound A (40 mg) was dissolved in MeOH (20 ml) and hydrolyzed with an equal volume of Takadiastase enzyme, which liberated L-rhamnose (Rf 0.37), showing α-linkage with aglycone. Further hydrolysis of glycoside by almond emulsion, shows β-linkage of D-glucose (Rf 0.18) with aglycone and that of xylose (Rf 0.28) with L-rhamnose.
Study of Compound A-1: It was analysed for m.f. C17H14O7, m.p. 229-230 °C, [M+] 330 found (%) C 62.02, H 4.28, O 34.01, Calcd. form.f. C17H14O7 found (%) C 62.06, H 4.33, O 34.04 . UV (MeOH) λmax (nm) 250, 287, 375. IR (KBr) νmax (cm-1)- 3450, 2988, 2917, 2872, 1649, 1623, 1525, 1478. 1HNMR (300 MHz, CDCl3); 12.24 (1H, s, 5-OH), 6.58 (1H, s, H-6), 6.71 (1H, s, H-3), 7.78 (1H, d, J 2Hz, H-2ʹ), 6.61 (1H, d, J 8.6 Hz, H-5ʹ), 7.64 (1H, dd, J 8.8, 2.2 Hz, H-6ʹ), 3.78 (OMe-C-8), 3.73 (OMe-C-3ʹ). 13C-NMR (75 MHz, CDCl3) 168.8 (C-2), 104.9 (C-3), 187.0 (C-4) 152.1 (C-5), 102.3 (C-6), 152.3 (C-7) 129.3 (C-8), 145.5 (C-9), 105.0 (C-10), 127.5 (C-1ʹ) 112.4 (C-2ʹ), 147.6 (C-3ʹ), 143.6 (C-4ʹ), 115.1 (C-5ʹ), 119.1 (C-6ʹ), 56.6 (OMe-8), 56.3 (OMe-3ʹ).
FIG. 1: COMPOUND A
FIG. 2: COMPOUND A-1
Study of Compound B: It was analysed for m.f. C15H10O6 , m.p.-329-330 °C, found (%) C 62.78, H 3.84, O 33.40, Calcd. form.f. C15H10O6 found (%) C 62.74, H 3.82, O 33.43. UV (MeOH) λmax (nm) 253, 265, 348. IR ( KBr ) νmax ( cm-1)- 3394, 1638, 1600, 1560, 1517. 1HNMR (300 MHz, CDCl3); δ 12.94 (1H, s, 5-OH ), 6.72 (1H, s, H-3), 6.48 (1H, d, J 2 Hz, H-6), 7.08 (1H, d, J 2 Hz, H-8), 7.76 (1H, br, s, H-2ʹ), 6.87 (1H, d, J 8.3 Hz, H-5ʹ), 7.42 (1H, dd, J 8.3, 2.2 Hz, H-6ʹ). 13C-NMR (75 MHz, CDCl3); 163.40 (C-2), 102.90 (C-3), 181.81 (C-4), 161.80 (C-5), 101.09 (C-6), 162.48 (C-7), 95.50 (C-8), 158.32(C-9), 105.47 (C-10), 121.11 (C-1ʹ), 114.12 (C-2ʹ), 143.78 (C-3ʹ),149.72 ( C-4ʹ), 116.70 (C-5ʹ), 118.42 (C-6ʹ). It was identified as Luteolin Fig. 3 on comparison with reported literature values 16.
Study of Compound C: It was analysed for m.f. C15H10O5, m.p.-346-347 °C, found (%) C 66.42, H 4.02, O 29.48, Calcd. form.f C15H10O5 found (%) C 66.44, H 4.0, O 29.50. UV (MeOH) λmax (nm) 266, 336. IR (KBr) νmax (cm-1)- 3332, 1644, 1577, 1497, 1464. 1HNMR (300 MHz, CDCl3); δ 12.93 (1H, s, 5-OH), 7.94 (2H, d, J 8.6 Hz, H-2ʹ, H-6ʹ), 6.92 (2H, d, J 8.6 Hz, H-3ʹ, H-5ʹ), 6.82 (1H, s, H-3), 6.86 (1H, d, J 2 Hz, H-8), 6.44 (1H, d, J 2 Hz, H-6). 13C-NMR (75 MHz, CDCl3) ; 163.70 (C-2) , 101.82 (C-3), 182.75 (C-4), 162.42 (C-5), 100.12 (C-6), 164.32 (C-7), 94.88 (C-8), 157.34 (C-9), 102.68 (C-10), 122.15(C-1ʹ), 130.42 (C-2ʹ,C-6ʹ), 115.9 (C-3ʹ,C-5ʹ) , 162.20 (C-4ʹ). It was identified Apigenin Fig. 4 on comparison with reported literature values 16.
FIG. 3: COMPOUND B
FIG. 4: COMPOUND C
Antioxidant Activity of Compound A: Free radical scavenging activity of compound A was evaluated by DPPH assay method 17. 3 ml of DPPH solution (0.1 mM) was mixed with 2 ml of each solution (5-100 µg/ml) of the compound and allowed to incubate for 30 min in the darkroom. After the incubation of 30 min, the decrease in absorbance of DPPH solution was measured at 517 nm against the blank. 99% methanol served as blank. Control solution contains the DPPH solution and methanol. Ascorbic acid was taken as the standard. % inhibition of the DPPH free radical was calculated by the following equation:-
% Inhibition = (Ao-As/ Ao) × 100
Where Ao is the absorbance of the control and As is the absorbance of the sample.
Absorbance of control = 0.915.
TABLE 1: ANTIOXIDANT ACTIVITY OF COMPOUND A
|Concentration μg/ml||Absorbance||% Inhibition|
TABLE 2: ANTIOXIDANT ACTIVITY OF ASCORBIC ACID
|Concentration μg/ml||Absorbance||% Inhibition|
FIG. 5: ANTIOXIDANT ACTIVITY OF COMPOUND A IC50 value of compound A is 47.24
FIG. 6: ANTIOXIDANT ACTIVITY OF ASCORBIC ACID IC50 value of ascorbic acid is 54.40
CONCLUSION: On the basis of above evidence the structure of compound (A) was established as 5,7.4’-trihydroxy-8, 3’-dimethoxyflavone-4’-O-β-D-glucopyranosyl- 7-O-β-D-xylopyranosyl(1→2)-α-L-rhamnopyranosidefrom the ethanolic extract of stems part of the plant. Compound (A) showed significant antioxidant activity and thus it may be used as a potent antioxidative agent.
ACKNOWLEDGEMENT: Authors are thankful to Department of Chemistry, Dr. H. S. Gour Vishwavidyalaya Sagar (Madhya Pradesh) for providing necessary laboratory facilities, Department of Botany, Dr. H. S. Gour Vishwavidyalaya Sagar (Madhya Pradesh) for plant identification. One of the authors is also grateful to UGC for financial assistance.
CONFLICTS OF STATEMENT: The authors hereby declare no conflict of interest in the publication of this paper.
- Kritikar KR and Basu BD: Indian Medicinal Plants. Lalit Mohan Basu Publishers, Allahabad, Edition 3rd, Vol. III, 2012: 1931-35.
- Khare CP: Encyclopedia of Indian Medicinal Plants. Springer-Verlag Berlin Heidelberg, New York, 2004: 236-237.
- Florence AR and Jeeva S: Chemical composition of essential oil from the leaves of Gmelina asiatica Journal of Medicinal Plants Studies 2016; 4(1): 8-10.
- Chigozie UF and Okechukwu OD: Extraction, analysis and desaturation of Gmelina seed oil using different soft computing approaches. South African Journal of Chemical Engineering 2016; 22: 6-16.
- Florence AR and Jeeva S: FTIR and GC-MS spectral analysis of Gmelina asiatica Leaves. Science Research Reporter 2015; 5(2): 125-136.
- Wei G, Xiao-Jiang H, Hong-Xin L, Yue-Hu W and Chun-Lin L: Acylated iridoid glycosides and acylated rhamnopyranoses from Gmelina arborea Phytochemistry Letters 2013; 6: 681-685.
- Leena NP and Aleykutty NA: Isolation and spectral identification of quercetin from the alcoholic root extract of Clerodendrum paniculatum International Journal of Pharma Sciences and Research 2016; 7(1): 47-50.
- Venugopal G, Reddy CS, Rao BN, Rao VB, Rao TV and Rao AP: Pharmacognostic and preliminary phytochemical evaluation of Ocimum basilicum var. pilosum (Willd.) Benth. and O. tenuiflorum var. CIM-AYU. International Journal of Pharmacognosy and Phytochemical Research 2015; 7(3): 519-526.
- Chakravarty A and Yadava RN: Antioxidant activity of new potential allelochemical from stems of Cassia siamea International Journal of Pharmaceutical Sciences and Research 2015; 6(10): 4230-4235.
- Yadava RN and Yadav P: Isolation and characterization of two new compounds from Phaseolus trilobus American Journal of Phytomedicine and Clinical Therapeutics 2013; 1(9): 672-680.
- Kristiansen KA, Potthast A and Christensen BE: Periodate Oxidation of polysaccharides for modification of chemical and physical properties. Carbohydrate Research 2010; 345: 1264-1271.
- Chemin M, Rakotovelo A, Pichavant FH, Chollet G, Perez Silva DD, Conil MP, Cramail H and Grelier S: Periodate Oxidation of 4-O-Methylglucuronoxylans influence of the reaction conditions. Carbohydrate Polymers 2016; 141: 45-50.
- Patil G, Khare AB, Huang FK and Lin FM: Bioactive chemical constituents from the leaves of Lantana camara Indian Journal of Chemistry 2015; 54B: 691-697.
- Khan S, Duby K, Jain R and Vishwakarma UK: Phytochemical constituents from stem of Taraxacum officinale International Journal of Pharmaceutical Sciences and Research 2016; 7(4): 1761-1764.
- Asati N and Yadava RN: Antibacterial activity of triterpenoid saponin from the stems of pulcherrima Linn. Natural Product Research 2017; 32: 499-07.
- Surywanshi V and Yadava RN: Isolation and characterization of new potential allelochemical from Bidens biternata (Lour.) Merrill & Sherff. Journal of Chemical and Pharmaceutical Research 2015; 7(4): 175-79.
- Asati N and Yadava RN: Antioxidant activity of extracts of Lathyrus aphaca Linn. World Journal of Pharmaceutical Research 2018; 7(9): 995-00.
How to cite this article:
Yadava RN and Raghuvansi J: Antioxidant activity of a new flavone glycoside from the stems of Gmelina arborea Roxb. Int J Pharm Sci & Res 2020; 11(1): 198-03. doi: 10.13040/IJPSR.0975-8232.11(1).198-03.
All © 2013 are reserved by International Journal of Pharmaceutical Sciences and Research. This Journal licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
R. N. Yadava and J. Raghuvansi *
Department of Chemistry, Dr. H. S. Gour Vishwavidyalaya (A Central University), Sagar, Madhya Pradesh, India.
31 March 2019
11 July 2019
12 August 2019
01 January 2020