Streptomycesalbus strain CAI-21 has been previously reported to have plant growth-promotion abilities in chickpea, pigeonpea, rice, and sorghum. The strain CAI-21 and its secondary metabolite were evaluated for their biocontrol potential against charcoal rot disease in sorghum caused by Macrophomina phaseolina. Results exhibited that CAI-21 significantly inhibited the growth of the pathogen, M. phaseolina, in dual-culture (15 mm; zone of inhibition), metabolite production (74% inhibition), and blotter paper (90% inhibition) assays. When CAI-21 was tested for its biocontrol potential under greenhouse and field conditions following inoculation of M. phaseolina by toothpick method, it significantly reduced the number of internodes infected (75% and 45% less, respectively) and length of infection (75% and 51% less, respectively) over the positive control (only M. phaseolina inoculated) plants. Under greenhouse conditions, scanning electron microscopic analysis showed that the phloem and xylem tissues of the CAI-21-treated shoot samples were intact compared to those of the diseased stem samples. The culture filtrate of the CAI-21 was purified by various chromatographic techniques, and the active compound was identified as “organophosphate” by NMR and MS. The efficacy of organophosphate was found to inhibit the growth of M. phaseolina in the poisoned food technique. This study indicates that S.albus CAI-21 and its active metabolite organophosphate have the potential to control charcoal rot in sorghum.

The present study was designed to evaluate the effects of eighteen different extracts derived from basil (Ocimum basilicum L.) leaves on spontaneous contractions, as well as contractions induced by potassium chloride (KCl) and acetylcholine in the ileum of rats, under in vitro conditions. The extracts were prepared with 96% v/v, 80% v/v, and 60% v/v ethanol, and absolute (100%) v/v, 80% v/v, and 60% v/v methanol, employing extraction techniques that included maceration, digestion, and sonication-assisted methods. Chemical characterization of the extracts revealed the presence of various phenolic acids, including rosmarinic, chlorogenic, caftaric, salvianolic acid B, cinnamic, caffeic, and chicoric acid, as well as flavonoids such as rutin and salvigenin. The evaluated extracts produced significant, concentration-dependent inhibitory effects on rat ileal contractions. Notably, the extract obtained via maceration with 80% methanol exhibited the most pronounced relaxant effects on spontaneous muscle contractions, achieving a maximum reduction of 46.16 ± 2.11%. Furthermore, the extract prepared with the same solvent using sonication-assisted extraction demonstrated superior efficacy in diminishing both the frequency and amplitude of KCl-induced ileal contractions, reducing contraction intensity caused by elevated potassium ion levels to 59.48 ± 3.34% at a maximum concentration of 1.5 mg/mL, thereby indicating its potential as a potent calcium channel blocker. Additionally, the extract prepared with 60% methanol through sonication-assisted extraction resulted in the most substantial reduction of acetylcholine-induced ileal contractions, decreasing contraction intensity to 35.74 ± 1.54% at the maximum concentration of 1.5 mg/mL, which suggests a high level of neurophysiological activity. By comparing extracts with different phytochemical profiles, this study provides additional insight into how variations in phenolic composition may influence different mechanisms of smooth muscle relaxation. This study affirms the significant spasmolytic properties of basil leaf extracts, thereby supporting their potential application in the management of gastrointestinal motility disorders.