A. Nirmala Menon

Turmeric (Curcuma longa L.) volatile oil inhibits key enzymes linked to type 2 diabetes

Anti-diabetic capacity of Curcuma longa volatile oil in terms of its ability to inhibit glucosidase activities was evaluated. Turmeric volatile oils inhibited glucosidase enzymes more effectively than the reference standard drug acarbose. Drying of rhizomes was found to enhance α-glucosidase (IC50 = 1.32–0.38 μg/ml) and α-amylase (IC50 = 64.7–34.3 μg/ml) inhibitory capacities of volatile oils. Ar-Turmerone, the major volatile component in the rhizome also showed potent α-glucosidase (IC50 = 0.28 μg) and α-amylase (IC50 = 24.5 μg) inhibition.

Essential oil composition of two unique ginger (Zingiber officinale Roscoe) cultivars from Sikkim

Volatile oils from two most popular cultivars from Sikkim namely, Bhaisa and Majulay, were isolated, characterised by analytical GC and GC–MS. Sixty constituents accounting for 94.9% and 92.6% of the Bhaisa and Majulay oils were identified. The major compounds of Bhaisa oil were geranyl acetate (18.8%), zingiberene (16.3%) and geranial (8.2%) and those of Majulay oil were zingiberene (19.8%) and geranial (16.5%). Compared to other ginger cultivar oils, the Bhaisa oil had higher content of oxygenated compounds (43.1%). This is the first report on the essential oils from Sikkim ginger cultivars.

Turmerin, the antioxidant protein from turmeric (Curcuma longa) exhibits antihyperglycaemic effects

A wide range of proteinaceous inhibitors are present in plants to protect themselves from hydrolytic enzymes. In this study, turmerin, a water-soluble peptide in turmeric rhizomes, was evaluated for its inhibitory potential against glucosidase and its antioxidant (AO) capacity. Turmerin inhibited α-amylase and α-glucosidase activities with IC50 values 31 and 192 µg mL−1, respectively. Under the experimental conditions, those values for a standard glucosidase inhibitor, acarbose, were 81 and 296 µg mL−1, respectively. The AO capacity of turmerin was evaluated using in vitro assay systems. Turmerin showed good DPPH (IC50 = 29 µg mL−1) and superoxide (IC50 = 48 µg mL−1) and moderate ABTS (IC50 = 83 µg mL−1) radical scavenging and Fe(II) chelation (IC50 = 101 µg mL−1) capacities. The inhibitory potential showed by turmerin against enzymes linked to type 2 diabetes, as well as its moderate AO capacity, could rationalise the traditional usage of turmeric rhizome preparations against diabetes.

Comparison of Essential oil Composition of Three Ginger Cultivars from Sub Himalayan Region

Abstract Objective To investigate and compare the essential oil constituents of three most popular cultivars from sub Himalayan region namely, gorubathane, shingboi and thingria. Methods Volatile oils were isolated using Clevenger trap and characterized by analytical gas chromatography and gas chromatography-mass spectroscopy. Results Eighty one constituents accounting for 95.24%, 97.1% and 97.03% of the gorubathane, shingboi and thingria oils respectively, were identified. Conclusions The major compounds of gorubathane oil were zingiberene (32.2%) and β-sequiphellandrene (10.9%). The main constituents in thingria oil were zingiberene (12.58%) and ar-curcumene (9.89%) and of shingboi oil were geranial (20.07%) and neral (9.44%). This is the first report on the essential oils composition of three Sub Himalayan ginger cultivars.

Chemical composition and in vitro antioxidative potential of essential oil isolated from Curcuma longa L. leaves

Abstract Objective To determine the chemical composition and antioxidant potential of essential oil isolated from the leaves of Curcuma longa (turmeric). Methods Chemical composition of the oil was analyzed using GC-MS. Antiperoxidative potential was evaluated using linoliec acid emulsion system. Free radical scavenging activity was evaluated using stable DPPH and ABTS free radicals. Results GC-MS analyses showed that major compound present in the turmeric leaf oil is b-sesquiphellandrene (22.8%) followed by terpinolene (9.5%). Essential oil also exhibited reductive potential and antioxidant potential in linoleic acid emulsion system along with DPPH and ABTS free radical scavenging potential. Conclusions The overall result suggests that turmeric leaf oil is capable of retarding oxidation reaction and free radical mediated damage and can be developed as a potent natural antioxidant.

Essential oil composition of fresh ginger cultivars from North-East India

Essential oils of seventeen cultivars of fresh ginger from North-East India were isolated by hydrodistillation and chemoprofiled by gas chromatograph (GC) and GC–mass spectrometry (GC–MS) analysis. Among all the constituents of essential oil, seventeen major constituents of all cultivars were emphasized. Major volatile constituents including camphene (8.49±0.41%), neral (4.95±0.34%), geranial (12.36±0.46%), zingiberene (20.98±2.34%) and β-sesquiphellandrene (7.96±0.66%) were observed. Assam Fibreless cultivar showed highest yield of essential oil (4.17±0.05%) and higher monoterpene hydrocarbon content (38.65±0.11%) than sesquiterpene hydrocarbon (25.38±2.3%), which is unique among all cultivars. Among all these cultivars, Assam Tinsukia had the highest citral content (23.66±1.60%) and Meghalaya mahima had the highest zingiberene content (29.89±0.42%). These results can serve as a valuable database for ascertaining the quality of fresh ginger for trading and manufacturing sectors engaged in ginger processing. This study is the first of its kind where the essential oil compositions of seventeen major ginger cultivars from North-East India are identified and compared.

Influence of Cultivar and Maturity at Harvest on the Essential Oil Composition, Oleoresin and [6]-Gingerol Contents in Fresh Ginger from Northeast India

Severe flooding of the Brahmaputra River during the monsoon season and continuous rainfall in the northeast region (NER) of India cause an enormous loss of ginger crop every year. In this context, the present study investigates the variation in the essential oil composition and oleoresin and [6]-gingerol contents in 10 different fresh ginger cultivars harvested at 6- and 9-month maturity from five different states of NER. Monoterpenes, sesquiterpenes, and citral composition in the essential oil were evaluated to ascertain their dependence upon the maturity of ginger. Except Mizoram Thinglaidum, Mizoram Thingria, Nagaland Nadia, and Tripura I ginger cultivars, all other cultivars showed an increase in the citral content during the maturity that was observed for the first time. At 6-month maturity, a higher undecanone level was found in Nagaland Nadia (7.36 ± 0.61%), Tripura I (6.23 ± 0.61%), and Tripura III (9.17 ± 0.76%) cultivars, and these data can be used as a benchmark to identify those immature varieties. Interestingly, the Nagaland Nadia cultivar showed higher ar-curcumene (9.57 ± 0.58%) content than zingiberene (5.84 ± 0.24%), which was unique among all cultivars. Ginger harvested at 9-month maturity from the Tripura II cultivar had the highest citral content (22.03 ± 0.49%), and the Meghalaya Mahima cultivar had the highest zingiberene content (29.89 ± 2.92%). The oleoresin content was found to decrease with maturity in all cultivars, except Assam Fibreless and Manipur I. Moreover, the highest oleoresin (11.43 ± 0.58 and 9.42 ± 0.63%) and [6]-gingerol (1.67 ± 0.03 and 1.67 ± 0.05 g) contents were observed for Tripura II and Nagaland Nadia, respectively. This study suggests that Tripura and Nagaland are the most ideal locations in NER for ginger cultivation to obtain high yields of oleoresin and [6]-gingerol contents and harvesting at the 6-month maturation will compensate for the loss of ginger crop caused by the Brahmaputra River flooding in NER every year.

Antidiabetic and antioxidant potentials of spent turmeric oleoresin, a by-product from curcumin production industry

Abstract Objective To investigate the antidiabetic and antioxidant activity of spent turmeric oleoresin (STO). Methods Antidiabetic activity of STO evaluated by α-amylase and α-glucosidase enzyme inhibition assays. The antioxidant capacity studied by DPPH., ABTS., superoxide radical scavenging and metal chelating activity methods. Results The STO showed good antidiabetic activity by inhibiting key enzymes linked to type 2 diabetes, viz α-glucosidase and α-amylase with an IC50values of 0.71 and 0.16μg/mL respectively. The IC50values for DPPH. and ABTS. assay were 58.1 and 33 μg/mL respectively. STO effectively scavenged the superoxide free radical with an IC50 value of 61.5μg/mL and showed a moderate iron chelation property. Conclusions The above study reveals that the spent turmeric oleoresin being wasted at present can be used as antioxidant and antidiabetic agent in food and neutraceutical products.

Essential Oil Composition, α-Amylase Inhibition and Antiglycation Potential of Curcuma aromatica Salisb

Abstract Curcuma aromatica Salisb. is an aromatic medicinal plant belongs to the family Zingiberaceae. In the present study essential oil from the rhizome of C. aromatica analyzed by GC-MS. The major constituents in the oil were xanthorrhizol (26.3 %) followed by ar-curcumene (19.5 %) and di-epi-alpha-cedrene (16.5 %). The rhizome extracted sequentially with different solvents (hexane, dichloromethane and methanol) and evaluated its antioxidant activity. The dichloromethane extract showed maximum antioxidant potential and remarkable free radical quenching property. The solvent extracts were also screened for their antidiabetic activity via inhibition of α-amylase, and antiglycation assays. In α-amylase inhibition and antiglycation studies, dichloromethane extract got maximum activity with an IC50 value of 8.97±0.3 µg/ml and (561.37±2 µg/ml) respectively compared to other extracts. These significant activities of DCM were relevant parameters in the management of type 2 diabetes. The better activity of dichloromethane extract might be due to the high amount of phenolic compounds (10.9 %) and flavonoids (6.7 %) present in it.

Modulation of adipogenesis and glucose uptake by Curcuma longa extract in 3T3L1 and L6 cell lines – An in vitro study

Abstract Objective To evaluate the effects of ethyl acetate extract of Curcuma longa against modulation of glucose uptake and adipogenesis in cell line models. Methods We used 3T3L1 and L6 cells to investigate cytotoxicity, glucose uptake with 2-NBDG as probe and adipogenesis. All the analysis was done with flowcytometry. Results The results showed that the extract did not possess any significant glucose uptake activity but it exhibited significant adipocyte differentiation potential. Conclusions Ethyl acetate extract of Curcuma longa exhibits significant antiadipogenesis and can be used as an effective drug for the treatment of obesity and other associated complications.