Black pepper associated bacterium BP25 was isolated from root endosphere of apparently healthy cultivar Panniyur-5 that protected black pepper against Phytophthora capsici and Radopholus similis - the major production constraints. The bacterium was characterized and mechanisms of its antagonistic action against major pathogens are elucidated. The polyphasic phenotypic analysis revealed its identity as Pseudomonas putida. Multi locus sequence typing revealed that the bacterium shared gene sequences with several other isolates representing diverse habitats. Tissue localization assays exploiting green fluorescence protein expression clearly indicated that PpBP25 endophytically colonized not only its host plant - black pepper, but also other distantly related plants such as ginger and arabidopsis. PpBP25 colonies could be enumerated from internal tissues of plants four weeks post inoculation indicated its stable establishment and persistence in the plant system. The bacterium inhibited broad range of pathogens such as Phytophthora capsici, Pythium myriotylum, Giberella moniliformis, Rhizoctonia solani, Athelia rolfsii, Colletotrichum gloeosporioides and plant parasitic nematode, Radopholus similis by its volatile substances. GC/MS based chemical profiling revealed presence of Heneicosane; Tetratetracontane; Pyrrolo [1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl); Tetracosyl heptafluorobutyrate; 1-3-Eicosene, (E)-; 1-Heneicosanol; Octadecyl trifluoroacetate and 1-Pentadecene in PpBP25 metabolite. Dynamic head space GC/MS analysis of airborne volatiles indicated the presence of aromatic compounds such as 1-Undecene;Disulfide dimethyl; Pyrazine, methyl-Pyrazine, 2,5-dimethyl-; Isoamyl alcohol; Pyrazine, methyl-; Dimethyl trisulfide, etc. The work paved way for profiling of broad spectrum antimicrobial VOCs in endophytic PpBP25 for crop protection.

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Bioactive constituents of Eupatorium adenophorum were investigated for antifungal activity. A structure-antifungal activity relationship of cadinene sesquiterpenes was predicted by evaluating individual derivatives. Cadinene derivatives were extracted from leaves of Eupatorium adenophorum using ethyl acetate. Five cadinene sesquiterpenes were isolated by column chromatography and Preparative Thin Layer Chromatography. Bioactivity of these cadinene sesquiterpenes were evaluated in vitro against four phytopathogenic fungi using poison food technique. Purified sesquiterpenes were spectroscopically elucidated as cadinan-3-ene-2,7-dione (1), 7-hydroxycadinan-3-ene-2-one (2), 5,6-dihydroxycadinan-3-ene-2,7-dione (3), cadinan-3,6-diene-2,7-dione (4) and 2-acetyl-cadinan-3,6-diene-7-one (5). Antifungal evaluation of these compounds against pathogenic fungi was found to be selective. Compound 1 was highly inhibitory towards S. rolfsii (ED50 181.60 ± 0.58 μgmL(-1)) and R. solani (ED50 189.74 ± 1.03 μgmL(-1)). Availability of plant material and significant antifungal activity makes the plant a potential source of antifungal agent and that can be exploited for the development of a natural fungicide.

A gas chromatography-mass spectrometry method was developed for the quantitative determination of capsaicinoids, vitamin E, and phytosterols in chili peppers using a simple extraction technique for rapid screening. These components were extracted with acetonitrile and were injected into gas chromatography attached with mass spectrometry. The mean recovery values for triplicate analysis were between 90.6-99.7%. Besides major capsaicinoids (capsaicin, dihydrocapsaicin, nordihydrocapsaicin), four more minor capsaicinoids (nonivamide, nornordihydrocapsaicin, homodihydrocapsaicin I and II) were detected in chili samples. α-Tocopherol was also detected in the same run along with three phytosterols (campesterol, γ -sitosterol, and stigmasterol). Variations were observed across the chili sample in all of the constituents except a few minor capsaicinoids. The method was suitable for simultaneous estimation of capsaicinoids, vitamin E, and phytosterols in a single run from any types of pepper. Thus, the method is effective for rapid screening of peppers for its nutraceutical composition using single solvent extraction.