Triterpenoid saponins from the aerial parts of Trifolium argutum Sol. and their phytotoxic evaluation

Abstract

A B S T R A C TFour triterpenoid saponins (1-4) were isolated from the aerial parts of Trifolium argutum Sol. (sharptooth clover) and their structures were elucidated by comprehensive spectroscopic analysis, including 1D and 2D NMR techniques, mass spectrometry and chemical methods. Two of them are new compounds,,24-dihydroxyolean-12-ene-22-oxo-29-oic acid (2). The occurrence of 3b,24-dihydroxyolean-12-ene-22-oxo-29-oic acid (melilotigenin) in its natural form is reported for the first time as a triterpenoid aglycone within Trifolium species. The phytotoxicity of compounds was evaluated on four STS at concentration 1 mM to 333 mM. Compound 1 was the most active, showing more than 60% inhibition on the root growth of L. sativa at the higher dose, with IC 50 (254.1 mM) lower than that of Logran 1 (492.6 mM), a commercial herbicide used as positive control. The structure-activity relationships indicated that both aglycones and glycosidic parts may influence the phytotoxicity of saponins.

Recent advances in allelopathy for weed control: from knowledge to applications

“…Similarly, friedelin, isolated for the first time from Banisteriopsis anisandra , reduced germination of Lactuca sativa and growth of Allium cepa . Two new triterpenoid saponin analogs of caraganin B and soyasaponin‐I, and four new steroidal saponins, isolated from Trifolium argutum and Furcraea hexapetala , respectively, were phytotoxic on STS – particularly against L. sativa …”

“…140 Two new triterpenoid saponin analogs of caraganin B and soyasaponin-I, and four new steroidal saponins, isolated from Trifolium argutum and Furcraea hexapetala, respectively, were phytotoxic on STS -particularly against L. sativa. 32,141 Among the triterpenoids, numerous authors have focused on acid derivatives. These compounds are mainly active against monocotyledon species, and tend to have higher activity than other triterpenes.…”

“…Among the most relevant SAR studies, some authors have identified the glycosidic chain linked at C‐3 of the aglycone moiety as being a key factor in phytotoxicity (Fig. b).…”

Flavonoid Derivatives from the Aerial Parts of Trifolium trichocephalum M. Bieb. and Their Antioxidant and Cytotoxic Activity

“…Trifolium species are also forage crops that have economic value; especially Trifolium pratense L. is largely cultivated [6]. Up to date, many phytochemical investigations were performed on Trifolium species from which mainly isoflavonoids, saponins, flavonoids, and megastigmane glycosides have been isolated [4,[7][8][9][10][11]. Trifolium species, known as clover, have been patented as commercially available extracts on the market all over the world [4].…”

Phytotoxicity of Quillaja lancifolia Leaf Saponins and Their Bioherbicide Potential

“…These molecules are widely distributed among plants and have several significant industrial and pharmacological applications [ 19 ]. Some studies have reported phytotoxic or allelopathic properties for saponins [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ], which suggests that untested saponins could be evaluated as potential bioherbicides [ 14 ].…”