Seasonal Variation in Essential Oil Compositions and Antioxidant Properties of Acorus calamus L. Accessions.

Background:Acorus calamus (Sweet flag) is a known herbal drug commonly used in traditional medicine. Our aim was to perform seasonal and altitudinal phytochemical screening to assess the antioxidant activity of the essential oils in the rhizome and leaves of A. calamus from three different altitudes. Methods: Phytochemical screening was performed using GC/MS analysis and in vitro antioxidant assay was done by different methods. Results: The essential oils mainly contained α-asarone, ß-asarone (35.3-90.6%), and Z-isoelemicin (1.7-7.3%) as the major constituents, besides linalool, Z-methyl isoeugenol, shyobunone, kessane, etc. All the oils exhibited vast molecular diversity in terms of quantitative ingredients. All essential oils were studied for their antioxidant activity by different methods, including their effect on the DPPH radical-scavenging activity, reducing power, and chelating properties of Fe2+. The oils isolated in all the different seasons exhibited antioxidant activity as a function of concentration, with IC50 values ranging from 475.48 ± 0.08 to 11.72 ± 0.03 compared to standards. Conclusion : From the results obtained it can be inferred that the herb may be a good source of bioactive compounds and can work as an antioxidant to prevent oxidative deterioration in food. The data provide a basis for its in-situ investigation for judicious exploitation.

neo-Clerodane Diterpenoids from Ajuga macrosperma var. breviflora.

Six new naturally occurring ajugarin-like neo-clerodane diterpenoids, ajugaflorins A-F, along with six known compounds [the parent ajugarin I, ajugalides B and C, ajugamarin F4, ajugamacrin E, and ajugatakasin B] were isolated from A. macrosperma var. breviflora. The structures were elucidated by extensive NMR spectroscopic and MS analyses and comparison with data previously reported.

Chemical diversity in Mentha spicata: antioxidant and potato sprout inhibition activity of its essential oils.

The essential oils from fresh aerial parts of Mentha spicata L. collected from ten different natural habitats of Uttarakhand, India were analyzed by a combination of GC, GC/MS and NMR spectroscopy. The analysis revealed that monoterpenoids (46.1%-91.6%), mainly carvone (15.3%-68.5%), piperetenone oxide (24.0%-79.2%) and alpha-humulene (0.1%-29.9%), were the major constituents of the essential oils, but with significant qualitative and quantitative differences among the other constituents. Cluster analysis of the oil composition was carried out in order to discern the differences and similarities within different accessions collected from different natural habitats. The essential oils were also screened for their antioxidant activities by chelating properties of Fe2+, DPPH radical-scavenging activity, and their reducing power. The essential oils of two chemo variants (viz. carvone and piperetenone oxide types) were also tested for potato (Solanum tuberosum L.) sprout suppressant activity. The results showed that these oils exhibit good sprout inhibition activity in comparison to CIPC and iodine, the standard sprout suppressant.

Chemical diversity in Himalayan Elsholtzia species.

The terpenoid composition of essential oils from the leaves of five Elsholtzia species, viz., E. eriostachya Benth., E. cristata Willd., E. polystachya Benth., E. flava Benth., and E. pilosa Benth., collected from the Himalayan region (India), was examined by GC, GC/MS, and NMR analyses. Comparison of the results with previous reports revealed new chemotypes. Cluster analysis was carried out in order to discern the similarities and differences within the essential-oil compositions at their subspecies/chemotype level. Based on the major constituents of the essential oils, six chemical groups were obtained.

Phytoecdysteroids from Ajuga macrosperma var. breviflora roots.

Three new phytoecdysteroids, ajugacetalsterones C (1) and D (3) and breviflorasterone (2), were isolated from the roots of Ajuga macrosperma var. breviflora along with five known compounds, namely, 20-hydroxyecdysone, cyasterone, makisterone A, 20-hydroxyecdysone 3-acetate, and 20-hydroxyecdysone 2-acetate. The structures of 1-3 were elucidated on the basis of extensive 1D and 2D NMR spectroscopic studies. The new compounds possess acetal oxygen bridges between C-26 and C-20/C-22, or C-26/C-23, or a lactone bridge between C-26 and C-23.

Terpenoid compositions, and antioxidant and antimicrobial properties of the rhizome essential oils of different Hedychium species.

A phytochemical study of the rhizome essential oils of four different Hedychium species was performed by means of GC and GC/MS analyses. H. ellipticum mainly contained 1,8-cineole, sabinene, and terpin-4-ol, while H. aurantiacum possessed terpin-4-ol, para-cymene, and bornyl acetate as the major entities. Similarly, trans-meta-mentha-2,8-diene and linalool were noticed in H. coronarium. Three different collections (I-III) of H. spicatum showed amazing differences in the relative contents of their essential oils, 1,8-cineole and 10-epi-gamma-eudesmol being identified as markers for samples I and II, terpin-4-ol and sabinene being the major compounds in sample III. The rhizome essential oils of the above species were studied for their antioxidant activities by different methods, including their effect on the chelating properties of Fe(2+), DPPH radical-scavenging activity, and reducing power. Antimicrobial screenings of the oils by the paper-disc method were performed against Staphylococcus aureus, Shigella flexneri, Pasteurella multocida, Escherichia coli, and Salmonella enterica enterica, and the respective minimum-inhibitory-concentration (MIC) values were determined. The rhizome essential oils from all Hedychium species exhibited moderate-to-good Fe(2+) chelating activity. H. spicatum from collection site III showed a completely different DPPH radical-scavenging profile than the samples from the other collection sites.

Compositional diversity of terpenoids in the Himalayan Valeriana genera.

In an effort to determine the chemical diversity of the Valeriana genera of the Northwestern Himalaya (Uttaranchal), V. wallichii, V. himalayana (syn. V. dioica), V. pyrolaefolia, and V. hardwickii var. arnottiana were investigated for their terpenoid compositions by means of GC and GC/MS analyses of their essential oils, as well as by one- and two-dimensional NMR studies of the isolates. Our results establish that V. wallichii DC. includes two stable chemotypes, with no mixed population, chemotype I being characterized by the presence of maaliol (1), and chemotype II having patchouli alcohol (2) and 8-acetoxypatchouli alcohol (3) as major compounds. V. hardwickii var. arnottiana was also found to exist as two independent chemotypes. Here, chemotype I is characterized by alpha-kessyl acetate (4), valeracetate (5), and 8-epikessyl glycol diacetate (6), whereas the chemotype-II species contain maaliol (1) and kessanyl acetate (7). V. himalayana Grub. had maaliol (1), valeranone (8), kessane (9), and alpha-kessyl acetate (4) as major compounds, and V. pyrolaefolia Decne. contained patchouli alcohol (2) and valeranone (8) as markers.