P. Srinivas

Enzyme-assisted extraction of bioactive compounds from ginger(Zingiber officinale Roscoe)

Ginger (Zingiber officinale R.) is a popular spice used in various foods and beverages. 6-Gingerol is the major bioactive constituent responsible for the antiinflammatory, antitumour and antioxidant activities of ginger. The effect of application of α-amylase, viscozyme, cellulase, protease and pectinase enzymes to ginger on the oleoresin yield and 6-gingerol content has been investigated. Pre-treatment of ginger with α-amylase or viscozyme followed by extraction with acetone afforded higher yield of oleoresin (20%±0.5) and gingerol (12.2%±0.4) compared to control (15%±0.6 oleoresin, 6.4%±0.4 gingerol). Extraction of ginger pre-treated with enzymes followed by extraction with ethanol provided higher yield of gingerol (6.2-6.3%) than the control (5.5%) with comparable yields of the oleoresin (31-32%). Also, ethanol extract of cellulase pre-treated ginger had the maximum polyphenol content (37.5 mg/g). Apart from 6-gingerol, 6-paradol along with 6- and 8-methyl shogaols were the other important bio-active constituents in the oleoresin from cellulase-treated ginger.

Antibacterial and antimutagenic activities of novel zerumbone analogues.

Zerumbone, the key constituent of Zingiber zerumbet Smith, is a very important bioactive phytochemical. Two new compounds viz. azazerumbone 1 and azazerumbone 2 were synthesised by ZnCl2-catalysed Beckmann rearrangement of the zerumbone oxime. The structure elucidation of these analogues of zerumbone was carried out by 1D ((1)H NMR and (13)C NMR) and 2D-NMR (COSY, HSQC and NOESY) spectral analysis. Studies on the antibacterial activity established that azazerumbone 2 had better activity than zerumbone. Among the tested bacteria, Bacillus cereus was the most sensitive and Yersinia enterocolitica was found to be the most resistant. These compounds exhibited strong protection against sodium azide induced mutagenicity of Salmonella typhimurium strains TA 98 and TA 1531. Azazerumbone 2 showed better antibacterial and antimutagenic activity than azazerumbone 1. The antibacterial and antimutagenic activities exhibited by zerumbone and its analogues demonstrate their potential for use as nutraceuticals and in food preservation.

Simple HPLC Method for Resolution of Curcuminoids with Antioxidant Potential

Development of methodology for qualitative analysis and quantitative separation of individual curcuminoids in curcumin removed turmeric oleoresin (CRTO) and study of antioxidant activity of individual curcuminoids have been achieved in the present study. A simple HPLC protocol was outlined for optimal resolution of curcuminoids (I), (II), and (III) on an Exil-NH(2) column using isocratic elution with a mixture of isopropanol and water. CRTO is shown to be good source for the compounds II and III, as they are in an enriched form. The optimum resolution of the curcumin and its analogs in the present method developed, affords a facile method for estimation of individual curcuminoids in turmeric samples, which is an improvement over the standard AOAC method which estimates only total curcuminoids. The free radical scavenging capacity of pure curcuminoids I, II, and III, as determined by DPPH method at 100 ppm concentration was 88%, 80%, and 68% with IC(50) values being 56, 62, and 73 ppm, respectively. Their antioxidant potential could render them useful as important nutraceuticals or functional food ingredients.

Synthesis of amino acid conjugates of tetrahydrocurcumin and evaluation of their antibacterial and anti-mutagenic properties

Tetrahydrocurcumin (THC), the hydrogenated and stable form of curcumin, exhibits physiological and pharmacological activities similar to curcumin. A protocol has been developed for the synthesis of novel conjugates of THC with alanine (2a), isoleucine (2b), proline (2c), valine (2d), phenylalanine (2e), glycine (2f) and leucine (2g) in high yields (43-82%). All the derivatives of THC exhibited more potent anti-microbial activity than THC against Bacillus cereus, Staphylococcus aureus, Escherichia coli and Yersinia enterocolitica. The MIC values of the derivatives were 24-37% of those for THC in case of both gram-positive and gram-negative bacteria. Derivatives 2g and 2d exhibited maximum anti-mutagenicity against Salmonella typhimurium TA 98 and TA 1538, respectively at a low concentration of 313 μg/plate, with comparable activity for THC evident only at 3750 μg/plate. These results clearly demonstrated that the conjugation of THC at the phenolic position with amino acids led to significant improvement of its in vitro biological attributes.

Synthesis and antibacterial properties of 2,3-dideoxyglucosides of terpene alcohols and phenols.

Essential oils and their oxygenated terpene constituents possess potent antimicrobial properties. In the present study, a facile synthetic route to the 2,3-dideoxy 1-O-glucosides of important phenols and terpene alcohols in excellent yields (85-96%) has been delineated. Studies on their antimicrobial action against four food-borne pathogens--Bacillus cereus, Staphylococcus aureus, Escherichia coli and Yersinia enterocolitica--demonstrated that the zone of inhibition, in general, was higher for the 2,3-unsaturated 1-O-glucoside derivatives (1b-6b) and the corresponding saturated glucosides (1c-5c) when compared to the parent alcohols/phenols (1-6). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for these derivatives too were generally lower than those of the parent compounds. Furthermore, the time-kill and bacteriolysis assays too demonstrated the greater antimicrobial potential of the derivatives. The 2,3-dideoxy 1-O-glucosides of phenols and terpene alcohols were more effective in their antimicrobial action than the corresponding parent compounds. The study indicated that these novel derivatives can find useful application in control of food-related pathogenic microbes in foods.

2,3-Dideoxyglucosides of selected terpene phenols and alcohols as potent antifungal compounds.

The antifungal activities of novel 2,3-unsaturated and 2,3-dideoxy 1-O-glucosides of carvacrol, thymol, and perillyl alcohol were tested against Aspergillus flavus, Aspergillus ochraceus, Fusarium oxysporum, Saccharomyces cerevisiae and Candida albicans. In the agar well diffusion tests, zones of inhibition for the derivatives of carvacrol, thymol and perillyl alcohol were higher (15-30mm) in the case of filamentous fungi than those for the parent compounds. Their MIC and MFC values indicated that the 2,3-unsaturated and 2,3-dideoxy 1-O-glucosides of carvacrol and thymol exhibited more fungicidal activity than the other compounds. Further, the 2,3-dideoxyglucosides of carvacrol and thymol, exhibited antitoxigenic effects against A. ochraceus and A. flavus and inhibited the production of ochratoxin and aflatoxin-B2. Propidium iodide influx assay demonstrated the lysis of C. albicans cells by carvacrol and its 2,3-unsaturated 1-O-glucoside and the loss of the membrane integrity. These new 2,3-dideoxyglucosides can be useful as antifungal agents and condiments in foods.

Anti‐hypercholesterolemic influence of the spice cardamom (Elettaria cardamomum) in experimental rats

BACKGROUND Cardamom (Elettaria cardamomum) is an aromatic seed spice grown extensively in India and used as a flavoring in sweets. In this study, the anti-hypercholesterolemic effect of cardamom was evaluated in Wistar rats by inducing hypercholesterolemia with a high-cholesterol diet for 8 weeks. Dietary interventions were made with (a) cardamom powder (50 g kg-1 ), (b) cardamom oil (3 g kg-1 , equivalent to 50 g kg-1 cardamom) and (c) de-oiled cardamom powder (50 g kg-1 ). RESULTS A significant reduction in blood total cholesterol (31%) and low-density lipoprotein cholesterol (44%) was observed by oral administration of cardamom oil in hypercholesterolemic rats, accompanied by a marked decrease in serum triglycerides by 42%. The cholesterol content of cardiac muscle was beneficially lowered by 39% with administration of cardamom oil in hypercholesterolemic rats. Liver triglycerides were reduced by 33%. Incorporation of cardamom oil/powder in the diet did not alter feed consumption by rats. Compromised activities of hepatic antioxidant enzymes in the hypercholesterolemic situation were generally countered by dietary cardamom. Treatment with de-oiled cardamom as well as cardamom oil countered the diminished activity of catalase in hypercholesterolemic animals. Cardamom also enhanced the activity of heart superoxide dismutase in the hypercholesterolemic situation. The concentration of ascorbic acid in serum was significantly increased by dietary cardamom or its fractions in the hypercholesterolemic situation. CONCLUSION This animal study has established the potential of cardamom oil in restoring the alteration in lipid homeostasis in conditions of hypercholesterolemia. The significant reduction in atherogenicity index by dietary intervention with cardamom powder and cardamom oil indicates the potential cardioprotective effect of cardamom.

Eco-friendly kinetic separation of trans-limonene and carvomenthene oxides

AbstractKinetic separation of trans-limonene oxide and trans-carvomenthene oxide was achieved in high yield by selective ring opening of their cis-epoxides in the presence of InCl3 catalyst in water. Catalytic activity of InCl3 was conserved up to 10 cycles. Nucleophilic addition of methanol in presence of InCl3 was also selective as cis-epoxides preferentially reacted leaving behind trans-epoxides, which were separated by fractional distillation. Graphical AbstractThe kinetic separation of trans-limonene oxide and trans-carvomenthene oxide was achieved in high yield (97%) by selective ring opening of the corresponding cis-oxides in a reaction of 1:1 mixture of these epoxides with water or methanol in the presence of InCl3 catalyst.

An Improved Route to the Preparation of 6-, 8-, 10-Gingerols

Ginger (Zingiber officinale) is one of the important spices known since ancient times and has numerous health promoting properties. It is used in the treatment of various ailments such as catarrh, rheumatism, gingivitis, toothache, asthma, stroke, constipation, gastric ailments and diabetes and as a spice especially in Indian cuisine. It has found applications in Ayurvedic, Tibb-Unani and Chinese herbal formulations. The major constituents of the ginger rhizome are volatile and non-volatile pungent compounds. While the volatile components are mainly terpenoids which contribute to the aroma of ginger, the non-volatile phenolic compounds such as gingerols, shogaols, paradols (Figure 1) and zingerone contribute to its pungency. Fresh ginger is rich in 6-, 8-, 10-gingerols with the S-(C)-stereochemical configuration, whereas dry ginger contains mainly 6-, 8-, 10-shogaols. Both gingerols and shogaols are key pungent compounds and very important phenolic nutraceuticals possessing various biologically useful properties. 1–15 The isolation of the individual gingerols (where n D 6, 8 and 10) from ginger extracts is tedious as they contain homologous compounds that are difficult to separate by normal chromatography; in addition the spice also contains other phenolic compounds viz., shogaols and paradols (Figure 1). Among these compounds, [6]-gingerol is the most useful and important because to its biological activity. Some of its derivatives such as azagingerol, a compound that has the ability to reduce the accumulation of body fat and