Seasonal influence on bioactivity of seaweeds against plant pathogenic bacteria Xanthomonas axonopodis pv. citri (Hasse) Vauterin et al.

Abstract

In the present study, thin-layer chromatography (TLC) method was adopted for the fractionation of antibacterial substances from the crude extracts obtained in 1:1(v/v) chloroform : methanol of red seaweeds comprising Portieria hornemannii (Lyngbye) P. Silva, Gracilaria crassa (Harvey) J. Ag., brown Dictyota bartyrensiana Lamouroux, Hydroclathrus clathratus (C.Agardh) M.A.Howe, Sargassum wightii Greville, green Ulva (Enteromorpha) compressa (Linnaeus) Nees, and Halimeda macroloba Decaisne collected along the Coast of Pamban (Rameswaram, Gulf of Mannar, India) at four different seasons namely post-monsoon (February), summer (May), pre-monsoon (August) and monsoon (November) seasons for the year 2009. Fractionated substances detected under UV (Mechanical + disinfection) and iodine were tested for antibacterial activity against the plant pathogenic bacterium Xanthomonas axonopodis pv. citri (Hasse) Vauterin et al. which cause canker in citrus. Number of active fractions with high antibacterial activity was recorded from the crude extracts obtained in seaweeds collected during monsoon and post-monsoon whereas seaweeds collected during summer and pre-monsoon showed low antibacterial activity. UV active substances fractionated at R f 0.23 from red seaweed Porteiria hornemannii showed maximum antibacterial activity among the fractionated substances obtained on TLC from the crude extracts of all the seaweeds investigated.

Phaeophyta Extracts Exhibit Antiviral Activity against Feline Calicivirus

“…pinnatifida extracts were slightly lower than those reported previously (Kim et al, 2010). This difference may be due to harvesting during a different season or the different origin of the raw materials (Arunkmar and Sivakumar, 2012). Interestingly, the cytotoxicity of Phaeophyta extracts against CRFK cells was higher than that of territorial plant extracts, including those of Allium scorodorpasum, Capsicum annuum, Hovenia dulcis, and Citrus aurantium (Kim et al, 2009;Oh et al, 2013), suggesting that the Phaeophyta extracts exert a more negative effect on cell adherence and growth compared with extracts of medicinal herbs and spices.…”

The potential of seaweeds as a rich natural source for novel bioherbicide formulation/development

“…Seaweeds are morphologically complex organisms with diverse chemical compositions that vary greatly depending on factors such as seaweed species, location of habitat, and environmental conditions. These factors could influence variable extraction yields, which might indicate an alteration in the availability or concentrations of the desired bioactive compound(s), and could in turn lead to reduction or loss of efficacy (Afonso et al 2021; Aroyehun et al 2019; Arunkumar and Sivakumar 2012; Marinho-Soriano et al 2006; Sanz et al 2023; Tan et al 2012). Thus, it is challenging to standardize the extraction process and ensure consistent bioherbicide formulations with predictable concentrations of the desired bioactive compounds.…”