Accumulation of the antioxidant alkaloid brachycerine from Psychotria brachyceras Müll. Arg. is increased by heat and contributes to oxidative stress mitigation

•Brachycerine accumulation was induced by different types of heat stress.•Brachycerine induction had a threshold temperature trigger of 40°C.•Oxidative parameters indicated P. brachyceras is heat tolerant.•Brachycerine application protected sensitive species against heat stress.•TDC activity and tryptamine concentration increased under heat.