Control of root‐knot nematodes using Waltheria indica producing 4‐quinolone alkaloids

Abstract

BACKGROUND: Waltheria indica exhibited strong nematocidal activity against Meloidogyne incognita, a causal agent of root-knot nematode disease. This study aimed to characterize the nematocidal metabolites and to evaluate the efficacy of the formulated extract of W. indica in the biological control of M. incognita under both pot and field conditions. W. indica (W. indica WP20) at 26.7, 53.4 and 106.8 mg a.i. kg −1 soil significantly reduced the formation of galls and egg masses on the roots of tomato plants in a dose-dependent manner. In addition, application of 20 mg a.i. per plant W. indica WP20 effectively reduced gall formation on the roots of melon plants and population density of nematode in soil compared with untreated control under field conditions. CONCLUSION: W. indica can be used as an effective botanical nematicide in the eco-friendly control of root-knot nematode disease. RESULTS: Three 4-quinolone alkaloids, 5 ′ -methoxywaltherione A, waltherione A and waltherione C, were isolated and characterized as nematocidal metabolites. 5 ′ -Methoxywaltherione A and waltherione A caused high mortality in juveniles of Meloidogyne arenaria, Meloidogyne hapla, M. incognita and Bursaphelenchus xylophilus, whereas waltherione C exhibited significant nematocidal activity against only root-knot nematodes. In pot experiments, application of a wettable powder-type formulation of the ethyl acetate extract of

Paliasanines A–E, 3,4-Methylenedioxyquinoline Alkaloids Fused with a Phenyl-14-oxabicyclo[3.2.1]octane Unit from Melochia umbellata var. deglabrata

“…Compound 1 is the first characterized natural product with a phenyl oxabicyclo-octane unit fused at C-5 and C-6 of a 3,4-methylene­dioxyquinoline. Only six related 3-alkoxy-4-quinolones have been found as secondary metabolites, waltheriones A–E and helicterone A, in three Waltheria species, ,,− three Melochia species, ,, Triumfetta grandidens , and Helicteres angustifolia . The absolute configurations of these six compounds have not been established.…”

A review on Borreria verticillata: A potential bionematicide, channeling its significant antimicrobial activity against root-knot nematodes

“…The isolated compound called drupacine and the crude alkaloid extract suppress the plant-parasitic nematode hatch, activity of mixed life stages, and population numbers on plant roots. The roots of Waltheria indica exhibited strong nematocidal activity against Meloidogyne incognita hence study was carried out to characterized the constituents responsible for this significant activity ( Jang et al., 2019 ). Three alkaloid compounds, they are 4-quinolone alkaloids i.e.…”

Synthesis, Fungicidal Activity, and Mechanism of Action of Pyrazole Amide and Ester Derivatives Based on Natural Products l-Serine and Waltherione Alkaloids

“…The development of new green fungicides based on the structural optimization of natural products can effectively solve the problems of low safety and high pathogen resistance of traditional fungicides, which is a hot research field of green agrochemicals. − Waltherione alkaloids are 4-quinolone compounds isolated from traditional Chinese herbal medicine Waltheria indica L. of the Sterculiaceae family. To date, 20 waltherione alkaloids have been successfully isolated, including waltherione A-Q, antidesmone, 8-deoxoantidesmone, and vanessine (Figure ), − and were found successively to have antiviral, antitumor, antitrypanosomal, bactericidal, fungicidal, nematicidal, and other biological activities. − …”