64 Khaled A. Selim, Mohamed M. S. Nagia and Dina E. El. Ghwas
10.3. Glycosides
Since decades the search for potentially antioxidant compounds from
natural sources has drawn the attention of scientists as they may contribute in
the treatment of diseases attributed to oxidative stress (Rice-Evans and
Diplock, 1993). The culture broth of the endophytic fungi Eurotium rubrum
which was derived from the stems of marine mangrove plant Hibiscus
tiliaceus and from which a novel anthraquinone glycoside designated 3-O-(α-
Dribofuranosyl)-questin (31) together with three known related glycosides
were tested for DPPH radical scavenging activity (Li et al., 2009). Another
Eurotium sp. identified as Eurotium cristatum isolated from the marine algae
Sargassum thunbergii produce a new anthraquinone glycoside, 3-O-(α-D-
ribofuranosyl) questinol (32) (Du et al., 2014). In 2015 the antioxidant activity
of a steroidal saponin isolated from an endophyte Lasiodiplodia theobromae
identified from Saraca asoca was investigated (Jinu et al., 2015).
Marine derived endophytic fungi provide us with an everlasting resource
for chemically and structurally different and varying novel natural products
(Bugni and Ireland, 2004). From a marine mangrove Scyphiphora
hydrophyllacea derived fungi a novel fatty acid glycoside was isolated whose
structure was identified by combining spectroscopic and chemical methods as
R- 3 - hydroxyundecanoic acid methylester- 3 - O-α-L-rhamnopyranoside (33)
(Zeng et al., 2012). As an emphasis on the importance of marine mangrove
plants one Penicillium sp. was derived from the plant Avicennia marina that
produced a novel aurone glycoside. Its structure identified as (Z)-7, 4'-
dimethoxy- 6 - hydroxyaurone- 4 - O-β-glucopyranoside (Song et al., 2015). The
endophytic fungus Phomopsis sp. (ZH76) isolated from the stem of the
mangrove tree Excoecaria agallocha found in Sea cost at south chine
produced a xanthone O-glycoside for the first time namely 3-O-(6-O-α-L-
arabinopyranosyl)-β-D-glucopyranosyl-1,4-dimethoxyxanthone (34) (Huang
et al., 2013).
Various types of glycosides have been identified from different genera of
endophytic fungi. A macrolacton glycoside was identified from the endophytic
Lecythophora sp. derived from the Indonesian plant Alyxia reinwardtii. It was
designated 23-methyl- 3 - (1-O-mannosyl)-oxacyclotetracosan- 1 – one and it
exhibited antifungal activities against Aspergillus and Candida (Sugijanto
et al., 2011). Figure (5) summarize the diversity of glycosides compounds
isolated from endophytic fungi (structures from 31-34).